do you need a dual 58mm throttle body on your TPI?

[grumpyvette]

I get asked frequently if installing a larger than the stock 48mm TPI throttle body will significantly help on a corvette engine, Ill save you some reading right off if you want, yes a 58mm can potentially increase hp if your engines highly modified and your still useing a stock 48mm throttle body.
but the restriction a stock 48mm throttle body represents is not as significant and the gains to be had are not that large in most cases, your intake manifold and cam selection, plus your stock heads are the major restrictions. the stock 48mm throttle body flows about 650cfm-700cfm and has more than enough flow to support about 475hp-500hp,
(keep in mind as the plenum vacume, increased so does the effective flow)
rated flow is at a lower test vacume, than the engine produces
bored to 52mm it will support about 500hp,-525hp, a 58mm can support about 600hp, but keep in mind theres lots of factors other than just throttle body size that determine potential hp

Keep in mind even the factory 502 cubic inch big block used the stock L98 TPI throttle body size and made 500 horse power

yes a 58mm can potentially increase hp if your engines highly modified and your still using a stock 48mm throttle body, but its hardly a big restriction, and your probably going to gain more with other mods
using or modifying a throttle body to flow more than 1000cfm -1200 cfm like a 58mm twin bore potentially flows is a waste of money, heres why
the largest displacement sbc your likely to build is a 434cid, that requires a 4" stroke crank and youll be limited to about 6500rpm even with top quality parts if you want the engine to last any time at all, now you might not realize it but the time necessary to fill the cylinders gets limited very quickly at higher rpms and the volumetric efficiency falls off quickly after about 5000rpm simply because theres just not enough time to allow the cylinders to fill completely. at 5000 rpm theres 41.6 intake strokes per second, per cylinder, by 6500 rpm its up to 54 intake strokes per second, per cylinder thats only 0.018 seconds for the intake port to flow into the cylinder per intake stroke. but theres yet another factor!!! thats the time for the full intake stroke!!!, while theres 720 degrees in the repetitive cycle and Ive given you a full 360 degrees worth of time, the truth is that your cam/engine combo, seldom allows anywhere near that duration!!!! even a radical race cam seldom exceeds 250 degrees in effective duration for port flow, so youll need to knock about 45% off that time, now your down to only about 0.012 seconds or less of effective flow per intake stroke per cylinder, is it any wonder the cylinder can,t fully fill at high rpms??
now the theoretical 434 were working with here even if it could fill its cylinders 100% at 6500rpm which is totally impossiable at that rpm would require 434 (the displacement) x 3250(the number of intake strokes)=1410500 (the full 100% in cubic inches /1728(to change to cfm) = only 816cfm.... now even if you could ram tune the exhaust and intake pulse perfectly and get the cylinders to pack the cylinders to 120% (a total impossability without a supercharger or turbo) thats till only 979 fcm
but in the real world your volumetric efficincy falls off fast after 5000 rpm with a 4" stroke and youll be exceptionally lucky to pull 80% efficiency at over 5000rpm
drop your displacement to a more comon 383 and your rpm limit to the fairly comon 6500rpm and youll drop even the theoretical air flow requirement to below 875cfm

http://users.erols.com/srweiss/calchpaf.htm

http://users.erols.com/srweiss/calccarb.htm

heres the ramjet ZL1 454
http://www.sallee-chevrolet.com/ChevyBigBlockV8s/ramjetzl1.html

viewtopic.php?f=55&t=1509

http://garage.grumpysperformance.co...rottle-body-size-52mm-vs-58mm.641/#post-26207

http://www.summitracing.com/parts/sum-227702
yeah you might not believe it but it's got a stock 48mm twin bore TPI style chevy throttle body feeding that 454 engine, do you think chevy would do that if it was a significant restriction to hp production??

the restriction is not the throttle body its the port size, valve size and flow the heads have and intake manifold runers restriction,and cam lift and duration... install an intake manifold,cam and heads that can flow 300cfm and the 58mm aftermarket throttle body will still effectively feed the engine, remember that while even 300cfm ports at full flow only pull air about 250 degrees out of 720 degrees in the cycle and are spaced 90 degrees apart, that means that 1000cfm can feed all 8 cylinders a full 833cfm they could in theory flow ,and that 300cfm per port can support roughtly 600hp

 

[grumpyvette]

OK IVE JUST GOT TO ASK?
why would you buy a 52mm vs a 58MM throttle body????
now PLEASE don,t get me wrong,
the 52MM has a nice improvement in air flow over the stock throttle body, but in most cases that extra air flow is not used, especially on a mild engine or one with stock gearing and displacement, and the 58mm won,t in most cases increase the performance, and yes IM well aware from testing that the MAF sensors and the intake manifolds , and heads are the big restrictions, and that with out inproving those areas the stock throttle body works just fine.
BUT NEITHER WILL THE 58MM HURT a damn thing EITHER??
I tried BOTH on my 383 with BOTH the TPI and STEALTH RAM intakes, (I borrowed a friends 52mm to test) and there was no real difference untill I was up in the 6000rpm range, and even then the difference was minor, but again WHY buy the smaller unit, that could potentially be a restriction with future mods done??
its NOT like a carb, you won,t get a big loss of throttle response, in fact I could detect ZERO difference once it was correctly tuned) or for that matter experience any down side to the larger unit provided of course your tuning skills are decent.
and before you guys get crazy, do some research!
I don,t remember ever seeing a dyno on anyone elses engine EITHER that showed a LOSS to the larger unit, just a few that showed no IMPROVEMENT in a particular application, and if your thinking of pointing out a lack of throttle response thats been repeatedly shown to be due to tunning issues like low fuel pressure, too small of injectors,or the TPS voltage was off the mark, the IAC was not set correctly or the ignition timing curve was not ideal, or in a few cases the compression ratio was to low for the cam selected, get the LCA or duration wrong for the application and AIR FLOW REVERSION in the runners CAN cause problems, like a bog when you transition from idle to W.O.T. almost instantly, but in no case IVE seen was the extra potential air flow a problem, especially once you realize that the plenum/ports carry only AIR, and the fuels injected in the last 4 inches of the runners

BTW
http://www.sallee-chevrolet.com/frame.html?/sales.html

RAM JET 502 - FACTORY FUEL-INJECTED BIG-BLOCK POWER
P/N 12499121 [Old P/N 12497323]
The recipe is simple; one part attitude, one part driving perfection, one part leading factory technology, and five hundred and two parts hungry rat motor. Ram Jet 502, you either have one, or you want one! When the idea of an all new big block fuel injection system first came up, we all thought it was a good one. When it was proposed that it be integrated with our 502 crate engine, we thought someone had clearly lost their mind. Who could possibly need the awesome, flat, broad torque curve only available with a long runner dry manifold? And who would want the neck-snapping throttle response of MEFI 4 controlled port fuel injectors? And what would be the need for aggressive tunnel ram styling? But then we remembered we’re not building 100 mile per gallon, 0 to 60 in a week, eco scooters. We’re in the hot rod business! So we called together engine management system experts from GM Powertrain, our own GMPP engineers, and fuel injected race engine builder and GMPP Pro Mod racer Harold Martin. After some great discussions, a little debate, a lot of late nights and 50 gallons of coffee we had an intake manifold design like no other. By leveraging leading fuel management technology, numerous production developed components, the industry standard MEFI 4 controller and the great Ram Jet name from the 50’s, the Ram Jet 502 is reality.
The new undisputed heavy weight champion, the Ram Jet 502, makes 502 horsepower at 5100 rpm and 565 ft.lbs. of torque at 3200 rpm. The instantly throttle responsive Ram Jet 502 drives like no other big block you’ve ever driven. With over 500 ft. lbs. of torque from 2,200 to 5200 rpm, the Ram Jet 502 is a tire shredding monster making more torque throughout its operating range. This is possible because Ram Jet has a larger plenum and runners than would ever be possible in a carburetor application. This means greater intake efficiency and greater torque without sacrificing drive-ability. The Ram Jet manifold is so efficient that we’re able to make all of this horsepower and torque with a production L98 throttle body assembly, you know, the one that Fire bird and Camaro owners always replace when trying to make more power in their 350 engines. It’s all about airflow quality, velocity, and fuel and spark management. You’ll just have to drive one to appreciate it. If the one-second cold starts, no stalling, instant throttle response, and the solid pull from idle to red line don’t convince you that a Ram Jet 502 is for you, then maybe you would be more interested an a competitor’s futuristic dream of a 100 mile per gallon, 0 to 60 in a week, eco scooter or a good old fashion bicycle for those weekend events to impress all your friends at the local hot rod club or for those weekend cruses out on the highway to impress everyone else on the road.
The Ram Jet 502 is designed for ease of installation needing only 12V, ground, fuel feed and fuel return to run. Included are an instruction sheet, service manual and diagnostic tool for ease of installation and service. As with any GM Performance Parts Ram Jet engine, an in tank fuel pump is recommended to avoid possible vapor lock. See instruction sheet for fuel pump recommendations. Also included is complete throttle linkage that accepts your production throttle cable and transmission cable. Includes pre-programmed MEFI 4 ECM and wiring harness. This revised electronic and closed loop system gives a much smoother idle and better performance then the MEFI 3 ECM system it replaced.
The Ram Jet manifold stands eleven inches tall as measured from the front and rear “china wall†on the cylinder block. That’s just half an inch taller than a typical single plane high rise manifold, Holley carb and air cleaner combo.


RAM JET 502 TECHNICAL INFORMATION

 

[grumpyvette]

those TPI throttle body air foils

I frequently get asked if the throttle body air foils are worth the money?
the first thing Id point out its theres several versions and some can be potentially dangerous to use, because theses small components that can come loose under rare conditions but when they occur they can damage the engine. ID suggest you avoid the types that use a bolt that screws in from the front like the black plague

http://www.summitracing.com/parts/sum-227702
summit sells a 58mm throttle body, obviously youll need to verify it fits and works in your application
USE THE CALCULATORS to match port size to intended rpm levels... but keep in mind valve lift and port flow limitations
http://www.wallaceracing.com/runnertorquecalc.php
http://www.wallaceracing.com/ca-calc.php
http://www.wallaceracing.com/area-under-curve.php
http://www.wallaceracing.com/chokepoint.php
http://www.wallaceracing.com/header_length.php
http://www.circletrack.com/enginetech/1 ... ch_engine/

below is a picture I took about 9 years ago, a very early proto type version on my test mule corvette 383 engine where I was testing cams with versions of the custom intake during research.

YOU REALLY NEED TOO
read these RELATED linkS
http://garage.grumpysperformance.com/index.php?threads/tpi-flow-info.10382/#post-42908

http://garage.grumpysperformance.co...otal-panic-over-an-easy-fix.12177/#post-58940

http://garage.grumpysperformance.com/index.php?threads/recipe-for-my-91-vette.14530/


http://garage.grumpysperformance.com/index.php?threads/stealthram-dyno-results-and-other-info.433/

http://www.iroczone.com/2009/10/install ... e-airfoil/

IF you find your throttle body is starting to wear and the throttle blade shaft binds or leaks air or the TPS sensor seems to bind, Ive had new bushings and throttle blade shafts installed in older TPI throttle bodies ,the cost locally was at that time parts& labor near $170 Id never do it again, the BBK 52mm-or 58MM throttle body seems to be at least to me a better deal in every respect.
now I have had my bbk 58mm throttle body on my 383 , used both on an extensively ported TPI and Holley stealth-ram intake, both as delivered and later with several custom plenum designs , and after using it id be hesitant to go back to a factory throttle body , it just seems to operate better and while it may not be a significant increase in power it looks better, it operates smoother and I'm sure it flows more air. keep in mind the throttle body's basically an AIR GATE and while you may not need its full potential, its not in control of your engines fuel/air ratio control, to near the extent a larger carburetor on a stock carb intake would be, simply because the computer controls the injector pulse duration and sensors control the fuel/air ratio, and the TPI plenum and runners are restrictive, so theres just no way adding a larger throttle body hurts mid and upper rpm power, yes it might slow off idle responsiveness very slightly but if your building a kick-butt, performance engine just the upgraded cam duration already does that to a larger extent.also notice the 58mm throttle body has the air foil machined into its design

this type of air foil thats retained by the plastic air tube and worm gear clamp, rather than a bolt in the air foil body is far less likely to cause engine failures
http://www.jegs.com/i/Holley/510/120-140/10002/-1

GOOD DESIGN ABOVE

POTENTIALLY BAD DESIGN ESPECIALLY IF NOT INSTALLED CORRECTLY

IF you do install one of these air foils (LIKE THE PICTURE ABOVE) that are retained to the throttle body with a bolt be DAMN SURE you use GREEN LOCTITE on the BOLT THREADS , Ive seen several of those come apart over time, get sucked into a runner and do really nasty things to the valves and piston of the cylinder it fell into

this extra 2 hp looks like its hardly worth the effort but its basically semi-free upper rpm hp, and rarely causes problems if the air foils properly installed

heres the stock throttle body with no air foil to smooth air flow

the better aftermarket throttle body designs come with a built in throttle body air foil and MUCH BETTER FLOW plus TWIN 58 MM bore size that easily supports 550-600hp PLUS hp

Ive read that a single bore throttle body flow rate
was measured on some smaller engines

49mm TB flows 252cfm
52mm TB flows 283cfm
55mm TB flows 317cfm
60mm TB flows 377cfm

but a dual 58mm can rather easily support 550 hp plus
chevy used to sell a big block with the stock TPI throttle body


lets do some basic math
the area of a circle (throttle body bore) is found by multiplying Radia's squared times 3.147 (PI)
lets look at that 60mm TB posted above,
30 x 30 x 3.147=2832 sq mm of area and when tested it flowed 377 cfm
lets assume you have an aftermarket 90mm throttle body,
45 x 45 x 3.147=63726 sq mm, or 2.25 times larger than the 60mm TB mentioned earlier, while the correlation's not exactly the same you can assume the flow increase , with the larger TB, would easily be close to 2.2 times as high.(thats 830 cfm)
your engine potentially makes about
HP = cfm x .2575 X # of cylinders....horsepower potential.
a DUAL 58 mm throttle body, 29 x 29 x 3.147 x 2=5293 sq mm
or 1.87 times the 377cfm of the single 60mm throttle body, or over 709 cfm
we know that dual 58mm throttle body on a chevy v8 can potentially easily support 550hp and actually flows over 800cfm in tests

http://www.bgsoflex.com/flowcalc1.html

http://garage.grumpysperformance.com/index.php?threads/hp-vs-tq.16482/#post-100318

http://www.wallaceracing.com/Calculators.htm

http://users.erols.com/srweiss/index.html

http://users.erols.com/srweiss/calcafhp.htm

http://users.erols.com/srweiss/calchpaf.htm
keep in mind some of these calculators measure individual air flow per port, vs full engine air flow required

http://www.jegs.com/webapp/wcs/stores/servlet/topcategory_10001_10002_-1

https://www.ebay.com/itm/Weiand-908...For-Use-With-144-174-Blower-Kits/400669303867

https://www.musclecardiy.com/performance/induction-math-high-performance-engines/


https://www.ebay.com/itm/Weiand-622...r-Small-Block-and-Big-Block-Chev/112273744933

Stealth TPI Induction - L98 Stroker Installation - Super Chevy Magazine

This Chevrolet L98 TPI engine has its displacement stroked to 383 cubic inches and has stealth mods installed including a new cam and an extrude honed tuned port injection system to make 458 HP - Super Chevy Magazine

www.motortrend.com

IF YOU HAVE THERMOSTAT TO THROTTLE BODY CLEARANCE ISSUES

Have one to sell? Sell now
Weiand 6221 Offset Thermostat Housing Adapter For Small Block and Big Block Chev
your problem is VERY COMMON, if the throttle body and thermostat housing has a clearance issue on some modified EFI intakes, heres the usual cure
I just spent a couple hours helping one of the guys I know pull the upper engine off on his TPI corvette BECAUSE he FAILED TO USE LOC-TITE ON THE AIR FOIL RETAINER BOLT THREADS, the engine sucked in the air foil retainer bolt that came loose, after several years of use with no problems, , it worked its way thru the plenum and runner and wedged between the valve and piston locking up the engine and damaging the valve, cylinder head, piston etc. the heads, combustion chamber ,the heads valve seat, the valve and the head and intake gaskets will obviously need to be replaced the heads machined, and repaired, all because of the loose bolt being sucked into the engine , and he was darn lucky that the piston and block were only damaged cosmetically and can be polished and re-used, because he shut the engine off the instant he heard something obviously go wrong.
with more air you need larger injectors and a larger fuel pump

http://www.bbkperformance.com/catalog_request.php

http://garage.grumpysperformance.co...ive-are-the-stock-tpi-engine-components.1509/

http://garage.grumpysperformance.com/index.php?threads/how-big-a-fuel-pump-do-you-need.1939/

http://garage.grumpysperformance.com/index.php?threads/setting-up-your-fuel-system.211/

http://garage.grumpysperformance.com/index.php?threads/calculate-fuel-injector-size.1200/

http://garage.grumpysperformance.com/index.php?threads/fuel-pressure-regulators.635/


BETTER THROTTLE BODYS
http://www.summitracing.com/parts/SUM-227707/?rtype=10

http://www.summitracing.com/parts/BBK-1544/

http://www.summitracing.com/parts/EDL-3810/

YES IVE INSTALLED A twin 58MM throttle body like this on MY custom holley stealth ram intake

Ive always been rather amused at the guys who do swap to a 58mm throttle body on a stock or nearly stock tpi intake because the darn things are so restrictive even if ported that they can,t possibly use the increased flow, especially if sucking air thru a MAF sensor that flows about 670cfm
if your engine doesn,t have the necessary components to make at least 450hp, like decent heads cam and low restriction exhaust headers, your wasting your money on a 58mm throttle body on a nearly stock TPI

before you go crazy over worrying about the difference in flow potential between a 52mm and 58mm throttle body, thats mounted on your TPI intake,to increase air flow and potential power, take a deep breath and remember the stock M.A.F. sensor, and both the stock cylinder head ports and stock T.P.I. intake runners and manifold are a larger restriction to air flow and power than the throttle body is more restrictive to air flow
related threads

Came across this info while doing some research and thought I'd share.

http://www.hobracing.com/tech/tpi_flow.asp
TPI Intakes and runners

The following airflow tests were performed on the University of Northwestern Ohio's SuperFlow SF600 Flow Bench. All CFM values are corrected for airflow at 28 inches of water. Injector flow rates are flowed at 43.5 PSI on an injector flow bench using test fluid with same density as gasoline.

AirFlow

Stock TPI/LT1 48mm Throttle Body w/o airfoil -- 783.0 cfm

Stock TPI/LT1 48mm Throttle Body w/ airfoil -- 821.9 cfm

TPI/LT1 52mm Throttle Body w/o airfoil -- 848.9 cfm

TPI/LT1 52mm Throttle Body w/ airfoil -- 898.8 cfm

Stock 98 Camaro 3800 II Throttle Body -- 554.3 cfm

Stock TPI Bosch MAF sensor w/ screens -- 517.8 cfm

Stock TPI Bosch MAF sensor w/o screens -- 658.4 cfm

Stock 87 GN 3.8L Turbo AC MAF sensor w/ screen -- 584.2 cfm

Stock 86 2.8L AC 5-wire MAF sensor w/ screen -- 576.2 cfm

Stock 96-up AC 3100 V6 MAF sensor w/ screen -- 616.4 cfm

Stock 96-up AC 3100 V6 MAF sensor w/o screen -- 670.7 cfm

Stock 94-up LT1 MAF Sensor w/o screen -- 719.0 cfm

Stock 85-87 Firebird TPI airbox mid piece -- 499.3 cfm

Stock 4.3/5.0/5.7 2bbl TBI complete -- 574.1 cfm (dry)

Stock 4.3/5.0/5.7 2bbl TBI w/o injectors -- 584.7 cfm

Stock 3800 vin L throttle body w/ screen -- 419.1 cfm

Stock 3800 vin L throttle body w/o screen -- 444.8 cfm

4bbl MPFI Holley Throttle Body -- 1287.6 cfm

Another source sent in these flow numbers

Flow and HP ratings for Throttle-bodies:

Flow (cfm) Max. NA HP
Stock 668 300
Stock w/airfoil 710 350
52MM w/airfoil 835 400
54MM (AS&M) 900 450
58MM 1050 500


TPI Intakes and runners flow rates

Stock intake manifold with runner
Stock....................198.72 cfm
ACCEL................213.52 cfm
Extrude/ACCEL....217.11 cfm
Super Ram............220.67 cfm

the stock TPI has a hard time flowing 230cfm even with minor port work, look here
most of this info is right off the accel,holley,edelbrock, and TPIS sites, add a little math and the results become much clearer!!!

Intake....... length ....... port in -- out
Stock GM Base--- 6.375"------ 1.47"- 1.96x1.2
TPiS base------ -6.125"------ 1.75"- 2.09x1.28
Accel base----- -6.125"------ 1.75"- 2.09x1.28
Holley base------- 6” runner 2.3”- 1.9”x 1.23 (2.337 sq inches)
Runners
Stock TPI----- -- 7.250"------1.470" round(1.70 sq inchs)
SLP ----------- - 6.625"------1.600" round (2.01 sq inchs)
Accel LTR------- 6.625"------1.615" round (2.05 sq inchs)
TPiS----------- 7.625"------1.660" round (2.168 sq inchs)
Mini ram -----3.5”
LT1 ----------3”

Runners (measured individually)
Stock....................203.17 cfm
ACCEL................242.02 cfm
Extrude/ACCEL...275.83 cfm
Super Ram............289.18 cfm
Intake manifold with 3/8 inch radiused intlet.............................222.45 cfm
Holley stealth ram ………..275cfm

Stock intake manifold with runner
Stock....................198.72 cfm
ACCEL................213.52 cfm
Extrude/ACCEL....217.11 cfm
Super Ram............220.67 cfm
Holley stealth ram …..275cfm

ACCEL Hi-Flow intake manifold with 3/8 inch radiused inlet.........251.51 cfm

ACCEL Hi-Flow intake manifold with runner
Stock....................215.83 cfm
ACCEL................232.53 cfm
Extrude/ACCEL....243.21 cfm
Super Ram............240.24 cfm

Extrude-Honed ACCEL Hi-Flow intake manifold with 3/8 inch radiused inlet ...............275.83 cfm
Extrude-Honed ACCEL Hi-Flow intake manifold with ACCEL runner ..............266.94 cfm
Edelbrock Performer RPM manifold (Stock)..........286.51 cfm
Edelbrock Victor Jr. ............275.24 cfm

HOLLEY STEALTH RAM
the HOLLEY STEALTH RAM FLOWS at 275cfm out of the box, and has the potential when matched to the correct heads and cam to totally out flow most other intakes available,can easily reach 300cfm with minor port work and costs much less
Stock…………………………… 275cfm
Ported…………………………..300cfm

Runner lengths
Stock tpi manifold 8” runners 11.25”, cylinder head 6” total 25.25”
Accel super ram manifold 8” runners 7” cylinder head 6” total 21”
Holley stealth ram manifold 6.26” ” cylinder head 6” total 12.26”
Edelbrock performer RPM runners 6” ” cylinder head 6” total 12”
Edelbrock vic jr , runner length 5.5” ” ” cylinder head 6” total 11.5”



Also interesting TPI mods. Not so sure I agree with the one on bumping up the initial timing.
http://www.hobracing.com/tech/tpi_mods.asp


Basic TPI modifications
Friday, May 23, 2014





Basic TPI Mods: by DEBBIES87

There are a few basic mods that should be done to any TPI car, I call these "entry-level" modifications.

1) Cut the air box open without letting air in the engine without going through the air filter & remove the additional plastic piece below the air box to get more air into the engine.

2) Modify the mass air sensor; remove the screens, & and if your brave cut down the fins.

3) Port the plenum (upper intake). There are two small ridges sticking up in the entry-behind the throttle body, remove these. The throttle body openings are already 52mm, so don't go crazy when porting.

4) While the plenum is off for porting, it is now a good time to get a adjustable fuel pressure regulator & a MAT sensor relocater kit. The Adj. FPR will aid in tuning, and the new MAT sensor will improve throttle response as well. The new LT1 style MAT sensor is placed in the air box instead of the plenum, this allows it to read cooler air and advance the timing accordingly.

5) Advance the base timing to 12-13 degrees. Note: the harmonic balancers on these cars tend to drift with age, adjust timing to where the car still starts good and doesn't detonate.

6) If legal in your area, gut the catalytic converter and remove the smog pump belt (85-87), or run a shorter serpentine belt to bypass the pump (88-92); you will need to remove the smog pump on the 88-92's to reroute the belt properly. Check local smog laws first.

7) On automatic cars, adjust T.V. cable (throttle valve cable), so that the car shifts out between 4200-4500 RPM under wide open throttle. TPI motor power drops off drastically after 4500-4700 RPM, they peak at about 4200-4400 RPM. No need to over-rev these motors.

8) Bypass fan relay to make fans come on manually, or install aftermarket relay to turn on fans sooner.

All together these mods should make the car perform like it should have from the factory, gains should be between .6-.9 tenths of a second from these modifications.




T.V

 

[Big_G]

Re: those TPI throttle body air foils

Many years ago I had a 1992 'Vette, 6 speed. Pure stock. Went to the local 1320. Best it would do was 13.50's. Installed a tb air foil, K&N air filter in a cut-open air box, 1.6 ratio rockers and a Hypertech chip. Even cut out the MAF screens and trimmed the heat sink fins. Maybe mid 13.40's. What a waste of money. Goes to show Chevy did things pretty good from the start.

 

[Grumpy]

COMMON SBC INTAKE PORTS
felpro # 1204=Port Size: 1.23" x 1.99"=2.448 sq inches

felpro # 1205=Port Size: 1.28" x 2.09"=2.67 sq inches

felpro # 1206=Port Size: 1.34" x 2.21"=2.96 sq inches

felpro # 1207=Port Size: 1.38" x 2.28"=3.146 sq inches

felpro # 1209=Port Size: 1.38" x 2.38"=3.28 sq inches

felpro # 1255 VORTEC=Port Size: 1.08" x 2.16"-2.33 sq inches

felpro # 1263=Port Size: 1.31" x 2.02"=2.65 sq inches

felpro # 1266=Port Size: 1.34" x 2.21"=2.96 sq inches

felpro # 1284 LT1=Port Size: 1.25 x 2.04''=2.55 sq inches

felpro # 1289 FASTBURN=Port Size: 1.30" x 2.31" 3.00 sq inches
http://users.erols.com/srweiss/calccsa.htm

stealthram base

you may be amazed to find a great deal of research and testing has been done and theres actually proven facts rather than random guess work to use in planing a well built engine combo
https://www.summitracing.com/parts/anm-cp7838

and rev the engine a few times and watch the fuel pressure it should in theory remain in the 38 psi-42 psi range for most TPI and TUNED PORT efi

http://garage.grumpysperformance.co...h-ram-and-other-efi-intake-manifold-info.431/

http://www.superchevy.com/how-to/vemp-1010-edelbrock-pro-flo-xt-intake/

http://garage.grumpysperformance.co...o-flow-firsts-tpi-intake-etc.1052/#post-37126


http://forum.grumpysperformance.com...=8460&p=32923&hilit=curtain+flow+angle#p32923

http://garage.grumpysperformance.co...rger-intake-runners-l98-tpi.13785/#post-70716

http://www.wallaceracing.com/max-rpm2.php

http://www.force-efi.com/machefi.htm

http://www.rbracing-rsr.com/runnertorquecalc.html
http://www.wallaceracing.com/header_length.php

http://www.bgsoflex.com/bestheader.html

http://garage.grumpysperformance.com/index.php?threads/what-to-look-for-in-a-good-engine-combo.9930/

A VERY USEFUL set of CALCULATORs
http://www.rbracing-rsr.com/runnertorquecalc.html

http://users.erols.com/srweiss/calccsa.htm

http://users.erols.com/srweiss/calcplv.htm

http://users.erols.com/srweiss/calcfps.htm

http://users.erols.com/srweiss/calcacsa.htm
http://www.jegs.com/webapp/wcs/stores/servlet/topcategory_10001_10002_-1

https://www.ebay.com/itm/Weiand-908...For-Use-With-144-174-Blower-Kits/400669303867


https://www.ebay.com/itm/Weiand-622...r-Small-Block-and-Big-Block-Chev/112273744933

Have one to sell? Sell now
Weiand 6221 Offset Thermostat Housing Adapter For Small Block and Big Block Chev
your problem is VERY COMMON, if the throttle body and thermostat housing has a clearance issue on some modified EFI intakes, heres the usual cure

reading a few links and sub links, in this or any other thread,
is well worth the time and effort
ignore the linked info and its very likely to cost you a good deal more cash and time in the long term
http://garage.grumpysperformance.co...-calculators-and-basic-math.10705/#post-46582

http://garage.grumpysperformance.com/index.php?threads/port-speeds-and-area.333/

http://garage.grumpysperformance.com/index.php?threads/using-the-charts-calculators-and-basic-math.10705/#post-50173

http://garage.grumpysperformance.co...ing-parts-and-a-logical-plan.7722/#post-51341

http://garage.grumpysperformance.co...-well-thought-through-1985-vette-combo.14289/

How to Adjust your Early C4 TPS and Idle Speed
By Lars Grimsrud
SVE Automotive Restoration
Musclecar, Collector & Exotic Auto Repair & Restoration
Broomfield, CO

This tech paper will discuss the procedure for correct adjustment of the Minimum Idle Speed and for adjustment of the Throttle Position Switch (TPS) on the early C4 Corvette TPI systems. These steps apply specifically to the 1985 model year, and it general to other years. Later models do not have adjustable TPS's.

General:
Idle speed and off-idle response on the early TPI systems is determined by correct adjustment of the minimum idle speed screw combined with a correct setting of the TPS. I've seen many of these cars that have had their idle speed "corrected" by well-intentioned mechanice and owners by simply screwing the minimum idle speed screw in a few turns. This really messes up the settings, and will not make your car perform properly. Doing a correct setup of the TPS is one of the easiest ways make your car feel and respond better. To maximize the benefit of this procedure, I recommend that you first remove your Throttle Body (TB), disassemble it (it's incredible easy - there are a total of about 5 pieces in it...), clean the TB up really good with some spray carb cleaner, and put it back together. A nice clean TB will really put an edge on the performance improvement you will get by doing this procedure.

The Service Manual has instructions for doing these operations, but the directions are scattered through several sections of the Manual. Here is the complete, step-by-step process for doing this (not including TB rebuild). All specs and steps are taken directly from the Manual (all 3 different sections), and this process is absolutely correct.

Tools and Equipment
You will need the following tools and equipment:
1. A set of Torx wrenches. You can buy a complete set in a nice, genuine plastic pouch at Sears
2. A good digital voltmeter that will read voltages less than 1 volt
3. A paper clip
4. A small screwdriver

Procedure
There are two electrical components on the TB that you will be working with: The TPS and the Idle Air Control Valve (IAC). Make sure that the connectors for these two components are easily accessible and that you can easily disconnect the IAC. You will also be playing with the diagnostic connector under the dash. Remove the cover (if it’s still in place). Bend your paper clip into a “u” shape. You will be playing with the two top right hand terminals (“A” to “B”) in the connector.

1. First step is to set the minimum idle speed. If nobody has messed with this on your car before, the set screw will be covered by a pressed-in plug. It’s located on the driver’s side of the TB. Remove this plug if it’s there.
2. With the IAC connected and the ignition “OFF,” stick the paper clip into the diagnostic connector from “A” to “B.” This grounds the diagnostic lead.
3. Turn the ignition to the “ON” position without starting the engine. Wait 30 seconds.
4. Now, with the ignition still in the “ON” position, disconnect the IAC connector at the IAC.
5. Remove the paper clip from the diagnostic connector.
6. Start the engine and allow it to reach normal operation temperature. The idle speed will probably be really low, and you may have to coax the engine a bit with the gas pedal to keep it running for a while.
7. If your car is an automatic, set the parking brake and put the transmission in “DRIVE.” If your car is a manual, leave it in neutral.
8. Adjust the idle speed screw to obtain 400 rpm in drive or 450 in neutral.
9. Shut off the engine and reconnect the IAC.

That’s it for idle speed. Now on to the TPS.
There are 3 wires stacked vertically on the TPS. You will need to be able to measure the voltage between the two top wires. You can either buy a special harness connector that breaks these wires out (from Min America), or gently pierce the insulation of the wires with the pointy prongs on your volt meter. You can also stick a paper clip into each of the two top locations of the connector and clamp onto the paper clips to measure the voltage. Whatever is easiest for you.

1. Turn the ignition to the “ON” position without starting the engine.
2. Loosen the TPS Torx adjustment screws.
3. Set your volt meter to the low scale DC volt setting that will accurately read less than 1 volt.
4. Measure the voltage between the two top TPS wires.
5. Adjust the TPS by rotating its position until you get a reading of .54 volts.
6. Tighten the Torx screws and recheck the voltage. Readjust if necessary to make sure voltage is right at .54
7. Turn the ignition “OFF.”

Addition by CorvetteForum Member Charles Warner

As an addendum to “How to adjust your early C4 TPS and idle speed,” I would like to add that checking your WOT TPS voltage is also, potentially, a worthwhile endeavor. Frequently the TV cable that controls shifting pressure to the transmission binds the throttle linkage thereby not allowing for WOT. After measuring and, if necessary, adjustiong the idle voltage (nominally .54 volts) check the WOT voltage and ensure that approx. 4.5 volts is realized. A minimum of 4 volts at WOT are required for the ECM to go into fuel enrichment mode (FEM). If you are not seeing over 4 volts at WOT you are probably not opening the throttle to the stops and are not seeing FEM. A significant performanceimprovement is possible with this adjustment.
Charles Warner


OK IVE JUST GOT TO ASK?
why would you buy a 52mm vs a 58MM throttle body????
now PLEASE don,t get me wrong,
the 52MM has a nice improvement in air flow over the stock throttle body, but in most cases that extra air flow is not used, especially on a mild engine or one with stock gearing and displacement, and the 58mm won,t in most cases increase the performance, and yes IM well aware from testing that the MAF sensors and the intake manifolds , and heads are the big restrictions, and that with out inproving those areas the stock throttle body works just fine.
BUT NEITHER WILL THE 58MM HURT a damn thing EITHER??
I tried BOTH on my 383 with BOTH the TPI and STEALTH RAM intakes, (I borrowed a friends 52mm to test) and there was no real differance untill I was up in the 6000rpm range, and even then the differance was minor, but again WHY buy the smaller unit, that could potentially be a restriction with future mods done??
its NOT like a carb, you won,t get a big loss of throttle response, in fact I could detect ZERO difference once it was correctly tuned) or for that matter experience any down side to the larger unit provided of course your tuning skills are decent.
and before you guys get crazy, do some research!
I don,t remember ever seeing a dyno on anyone else s engine EITHER that showed a LOSS to the larger unit, just a few that showed no IMPROVEMENT in a particular application, and if your thinking of pointing out a lack of throttle response thats been repeatedly shown to be due to tuning issues like low fuel pressure, too small of injectors,or the TPS voltage was off the mark, the IAC was not set correctly or the ignition timing curve was not ideal, or in a few cases the compression ratio was to low for the cam selected, get the LCA or duration wrong for the application and AIR FLOW REVERSION in the runners CAN cause problems, like a bog when you transition from idle to W.O.T. almost instantly, but in no case IVE seen was the extra potential air flow a problem, especially once you realize that the plenum/ports carry only AIR, and the fuels injected in the last 4 inches of the runners.

for some reason many guys seem to think the throttle body size is far more restrictive than it is while IGNORING the fact that as your engines horse power expectations increase the need to supply fuel to the engine also will increase and they find the engines tendency to loose power at 4500 rpm-5000 rpm , and blame it on a lack of air flow exclusively, when in fact its generally BOTH a lack of fuel and air flow rates that cause the power curve to nose over as rpms increase.
yes youll need a larger flow rated set of fuel injectors AND A BETTER FUEL PUMP, if you plan to exceed 400 plus hp
Inj Flow Rate (@ 40psid) Naturally Aspirated hp (@ 0.50)
19 lb/hr 258 hp @ 85% Duty Cycle
24 lb/hr 326 hp @ 85% Duty Cycle
30 lb/hr 408 hp @ 85% Duty Cycle
32 lb/hr 435 hp @ 85% Duty Cycle
39 lb/hr 530 hp @ 85% Duty Cycle
42 lb/hr 571 hp @ 85% Duty Cycle
47 lb/hr 639 hp @ 85% Duty Cycle
60 lb/hr 816 hp @ 85% Duty Cycle
BTW To TEST an INJECTOR with a multi meter for OHMS resistance, remove the connector from the injector, push carefully in the middle of the locking clip, with your thumb, This will make the sides, and tips move OUT WARD in their connector slots allowing the tips that hold the injector into the connector to slide out of the way from the injector body, and you can then pull the sides away. WATCH the locking clip - IT can and WILL come off and get lost, if your not careful put your V.O.M. meter on OHMS and put the leads across the two connectors ON THE INJECTOR ,it should read about 11-16 OHMS in most cases, a few are designed to read up to 19 ohms, or as low as 9 ohms , BUT GENERALLY READINGS LOWER THAN 11 OHMS tends to point to a problem with the injector , The Ford motorsport injectors in the 24lb-hr flavor test a little lower (14.1-14.3 ohms) than the bosch's @ 22lbs/hr. (15.9-16.3) BUT ALL INJECTORS IN A SET SHOULD READ WITHIN ONE OHM OF EACH OTHER if its out of that range by a wide margin ITS MORE THAN LIKELY DEFECTIVE, checking the OHMS reading as a first step will frequently detect a defective injector, naturally using your trouble codes , a shop manual and a fuel pressure gauge won,t hurt and a shop scope , or engine analyzing software with a read out to your laptop computer helps and can further isolate the problem, at IDLE speeds placing a finger tip on the side of the injector will usually allow you to feel it (CLICKING) adding a couple cans of injector cleaner and about a pint of MARVEL MYSTERY OIL to a full tank of fuel can sometimes free a sticky injector that partly clogged, but don,t do it frequently as its very hard on the CATS and O2 SENSORS if done constantly

partly clogged injectors tend to reduce power and increase emissions

notice, the injector resistance is usually stated in the description

Brand: ACCEL
Product Line: ACCEL Fuel Injectors
Part Type: Fuel Injectors
Part Number: ACC-150826
Injector Advertised Flow Rate (lbs/hr): 26 lbs./hr.
Injector Advertised Flow Rate (cc/min): 269.0cc/min
Injector Impedance: 14.4 ohms
Driver Type: 12 V saturated circuit
Overall Height (in): 2.880 in.
Seat to Seat Height (in): 2.270 in.
Manifold O-Ring Outside Diameter (in): 0.573 in.
Fuel Rail O-Ring Outside Diameter (in): 0.574 in.
Outside Diameter (in): 0.943 in.
Injector Plug Style: Bosch/Amp-style
Wiring Harness Included: No
O-Rings Included: Yes
Quantity:

http://www.megamanual.com/v22manual/minj.htm

FUEL LINE SIZE Fuel line size is determined by the horsepower of the engine. Up to 350 HP 5/16" or 4AN Up to 500 HP 3/8" or 6AN Up to 700 HP 1/2" or 8AN Up to 1200 HP 5/8" or 10AN RETURN LINE SIZE Return line size is determined by the output of the fuel pump. Up to *29 gal/hr (110 liters/hr) 1/4" or 3AN Up to *45 gal/hr (170 liters/hr) 5/16" or 4AN Up to *90 gal/hr (340 liters/hr) 3/8" or 6AN Up to *180 gal/hr (680 liters/hr) 1/2" or 8AN *Pump output @ 45psi PUMP SIZE Pump size is determined by the horsepower of the engine. Horsepower x .083 = gallons per hour @ 45 psi Example: 500hp x .083 = 42 gal/hr or Horsepower x .314 = liters per hour @ 45 psi Example: 500hp x .314 = 157 liters/hr NOTE: add 25% to pump size for supercharged applications.


TPI Torque Specifications

Below are the torque specifications as designated by GM for Tuned Port Injection intakes. Please note that some specifications are in lb. ft., and some are in lb. in.

Manifold to Runner Bolts 25 lb. ft. Runner to Manifold Bolts 25 lb. ft.
Fuel Rail Attaching Bolts 15 lb. ft.
Throttle Body Attaching Bolts 18 lb. ft.
Throttle Position Sensor 18 lb. in.
Idle Air Control Valve 13 lb. ft.
Throttle Body Coolant Plate 27 lb. in.
Throttle Body Cover Plate 30 lb. in.
Power Brake Vacuum Fitting 108 lb. in.
Fuel Line Nuts 20 lb. ft.
Fuel Tube Bracket Bolt 25 lb. ft.
Fuel Pressure Connection 115 lb. in.
Pressure Regulator Base to Rail 44 lb. in.
Pressure Regulator Bracket 44 lb. in.
Outlet Tube to R/H Rail Retainer 44 lb. in.
Id suggest the 24lb

THESE LOOK STOCK
https://www.ebay.com/i/391440066276?chn=ps&dispItem=1

THESE DON,T
https://fuelinjectorconnection.com/products/24lb-bosch-3-for-tpi
either choice , of these would work
keep in mind the cpu will read the sensor data and modify the injector pulse duration,
to provide the engine with the intended fuel/air ratio, and the difference in the rated size is of zero concern as long as its properly tuned.
the rated size limits the upper flow rate but has almost no effect on mid and lower rpm flow.

https://www.corvetteactioncenter.co...il-removal-fuel-injector-replacement-827.html

http://garage.grumpysperformance.com/index.php?threads/diagnoseing-tpi-lt1-problems.1241/

http://garage.grumpysperformance.co...ive-are-the-stock-tpi-engine-components.1509/

http://garage.grumpysperformance.com/index.php?threads/c4-corvettes-fuel-system-info.67/#post-37351

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=1401&p=8895&hilit=start+sequence#p8895

http://garage.grumpysperformance.co...ey-grumpy-do-i-need-bigger-injectors.5583/#po

http://garage.grumpysperformance.com/index.php?threads/calculate-fuel-injector-size.1200/#post-4041

http://garage.grumpysperformance.co...easonably-effective-tpi-combo.1060/#post-2031

http://garage.grumpysperformance.co...-other-efi-intake-manifold-info.431/#post-530

http://garage.grumpysperformance.com/index.php?threads/ideal-tpi-build.12203/#post-76070

http://garage.grumpysperformance.co...-stock-tpi-engine-components.1509/#post-74581

http://garage.grumpysperformance.co...rger-intake-runners-l98-tpi.13785/#post-72541

http://garage.grumpysperformance.co...lay-switch-locations-and-info.728/#post-66935

http://garage.grumpysperformance.co...intake-for-cross-fires.2796/page-7#post-56659

http://garage.grumpysperformance.co...8mm-throttle-body-on-your-tpi.290/#post-54181

http://garage.grumpysperformance.co...ps-on-building-a-tpi-383-c4.10434/#post-51507

http://garage.grumpysperformance.com/index.php?threads/can-you-get-there-with-tpi.10494/#post-44299

http://garage.grumpysperformance.com/index.php?threads/tpi-flow-info.10382/#post-43474

http://garage.grumpysperformance.co...m-dyno-results-and-other-info.433/#post-37683

http://garage.grumpysperformance.co...y-current-corvettes-383-combo.430/#post-32660

http://garage.grumpysperformance.co...g-tpi-crossfire-or-lt1-vette.1401/#post-39419
I found this info posted on a different web site

The minimal cross-sectional area of the head sets the maximum RPM potential and the head flow determines the maximum HP potential for a given engine. Intake flow equal to or greater than the head flow helps to insure it will not limit the potential HP capability of the head. An intake with a minimal cross-sectional area equal to or greater than the heads MCSA helps to insure it will not limit the RPM potential of the engine. HOWEVER, due to the physics involved, any intake runner length much over 3 on a SBC will start to reduce the RPM potential/capabilities. So, a longer runner will never be able to match the RPM potential of a short runner intake on the same engine.

When building a racing engine, as long as youre not exceeding the parts capabilities, RPM is king its easier to make higher HP numbers at higher RPMs. For racing, big heads, big cam, steep gears, and high stall speeds are part of the equation. However, the power under the curve (a factor of shift point, stall speed, and shift recovery RPM) is a major consideration as well. You see a lot of tunnel rams on racing engines with runner lengths greater than 3, so giving up some RPM potential for the extra power under the curve the longer runner length gives is not a bad thing even for a racing engine.

For a street engine, if youre not concerned about the idle speed and vacuum or the stall speed and gear ratio, you can treat the build similar to that of a racing engine. However, most street engines are a compromise of idle speed, vacuum, stall speed, and gearing the milder or the more compromised the build (smaller cams and lower stall speeds) the more critical that power under the curve becomes. Adding runner length increases midrange power but at some point it will take more power away from the top end than it can make up under the curve. That point will vary depending on different sized engines and with different transmissions.

I agree that the power band and cliff cant change much if using the stock GM type TPI runner systems especially on stock heads and even aftermarket heads and intakes (based on the GM style TPI) wont help much. However, while the runner length is the main contributor to the steep RPM and power drop off point, the diameter of the runner also affects the peak RPM capability for both TQ and HP.

Concerning the FIRST, the inherently bad runner to base and base to runner transition points of the stock type TPI intake systems have been eliminated with the FIRST and an unported base can flow over 300cfm. The amount of flow doesnt really help the limitation of the runner length, but does give the engine the potential to make a lot more power under the limit (more beneficial to larger engines).

The inside diameter (ID) of a stock FIRST runners is 1.75 (area 2.4). This targets peak torque around 4800rpm for a 350 (1200rpm more than a stock TPI), 4400rpm for a 383, and 4200rpm for a 406. The FIRSTs MCSA of the base (1.85 runner opening) is 2.69 and the runners can easily be opened up to that this bumps the peak TQ target RPM to around 4900 for a 383 and 4600 for a 406.

While the FIRSTs runner length (fractionally shorter than a stock TPI) still limits peak HP RPM and determines the tuned RPM band, due to the large ID of the FIRST runners it allows HP to peak at a higher RPM. The larger diameter of the runner also widens the tuned torque curve range. Another benefit of the larger diameter runners is you can select a cam to make peak TQ at the target RPM based on the runners MCSA. For instance, opening up the runners to 1.85 ID will target peak TQ for a 406 at 4600rpm. If you cam for that, its almost like adding an additional TQ peak, giving the sense of extending the tuned TQ curve even more.

For those wanting to crunch numbers, heres a calculator to find the area of a runner:
http://www.wallaceracing.com/chokepoint-rpm.php

Below is a good calculator that shows peak TQ RPM in regards to the area of the runner used:
https://rbracing-rsr.com/runnertorquecalc.html

This one (second input box) shows the relation between optimal runner length AND area (a function of diameter) based on engine size and cam duration.
http://www.wallaceracing.com/runnertorquecalc.php

While the FIRST kinda looks like a stock TPI, thats where the similarities end. The runners are cast with an INSIDE diameter of 1.75 and can be ported out to 1.92 INSIDE diameter. Thats an as cast FIRST runner on the far left, a set of stock TPI runners in the middle, and on the right is the FIRST runner ported to 1.92".

The entrance on the FIRST base is cast with a diameter of 1.847.

The intake flange is cast to a 1204 sized gasket, but inside the intake it curves down to a 1204. About an inch or so in, its comparable to a 1206 gasket and can be taken out to a 1207 sized gasket.

Ive run a fully ported TPI base (not welded) with fully ported and siamesed SLP runners, a box stock FIRST, and a StealthRam on the same engine in the same car only an intake and a little tuning for each were swapped. Same high 80-degee temps. The TPI/SLP shifted at 5500/5300 and ran low 13.0s to high 12.9s; the FIRST (box stock) shifted at 5800/5500 (ran the same times shifting at 6200/6000 though) and ran high 12.5s; the StealthRam shifted at 6400/6200 and ran low 12.6s. On this relatively mild 355 with a TH350, 3,000 stall, and 3.23 gears, I liked the FIRST better. It had a LOT more throttle response and was a lot more fun playing around on the street than the StealthRam. If it had been a 5 speed car with a bigger cam, or I had been running more stall speed and gearing, I probably would have preferred the StealthRam. So, whats best depends.

Here's some numbers from a May 1991 Popular Hot Rodding article.
9:1, 355, AFR 180 heads, mild hydraulic cam

RPM - FIRST - MiniRam - AZ Speed & Marine (Extrude base and Large Tube Runners)
2500 - 175 ---- 175 ----- 180
3000 - 237 ---- 222 ----- 238
3500 - 295 ---- 263 ----- 295
4000 - 350 ---- 300 ----- 325
4500 - 377 ---- 350 ----- 352
5000 - 388 ---- 375 ----- 350
5500 - 366 ---- 398 ----- 330

The FIRST made 443 TQ vs the Miniram's 395 TQ at 3500 rpm thats 48 lb/ft more
The FIRST made 460 TQ vs the Miniram's 394 TQ at 4000 rpm thats 66 lb/ft more

With all that said, there is no question that a short/shorter runner intake will make more peak HP than a long/longer runner intake. If you cam, gear, and stall for the short/shorter runner it will always perform better at the drag strip compared to a long/longer runner intake. Close ratio manual transmissions also favor short/short runner intakes. However, its possible that a long/longer runner intake like the FIRST can deliver similar and sometimes better results at the drag strip when atop a milder combination with a wide ratio automatic transmission, lower than optimal stall speed converter, and lower numerical rear gears especially in heavier vehicles.

 

[Grumpy]

http://noel.prodigitalsoftware.com/NCtpi.html

http://garage.grumpysperformance.com/index.php?threads/ideal-tpi-build.12203/#post-76070

http://garage.grumpysperformance.co...-stock-tpi-engine-components.1509/#post-74581

1986 iron head l98 corvette valve spring question

Picked up A crane 114132 cam for my iron head vette (seen multiple good things with with cam on almost stock engine) and seen a post by grumpy saying works really well with 1.6 rockers so I'm changing out my springs and everything to what crane recommends but going to the 1.6rr with the stock...

garage.grumpysperformance.com

Nos 05151NOS Gm Tuned Port Inj Kit W/10 Lb

Nos 05151NOS Gm Tuned Port Inj Kit W/10 Lb Lethal Performance is proud to offer the entire line of Holley and ALL Subsidiaries products!

www.lethalperformance.com

http://garage.grumpysperformance.co...rger-intake-runners-l98-tpi.13785/#post-72541

Stealth TPI Induction - L98 Stroker Installation - Super Chevy Magazine

This Chevrolet L98 TPI engine has its displacement stroked to 383 cubic inches and has stealth mods installed including a new cam and an extrude honed tuned port injection system to make 458 HP - Super Chevy Magazine

www.motortrend.com

http://garage.grumpysperformance.co...lay-switch-locations-and-info.728/#post-66935

http://garage.grumpysperformance.co...intake-for-cross-fires.2796/page-7#post-56659

http://garage.grumpysperformance.co...8mm-throttle-body-on-your-tpi.290/#post-54181

http://garage.grumpysperformance.co...ps-on-building-a-tpi-383-c4.10434/#post-51507

http://garage.grumpysperformance.com/index.php?threads/matt383-engine-swap.8925/#post-91116

http://garage.grumpysperformance.com/index.php?threads/can-you-get-there-with-tpi.10494/#post-44299

http://garage.grumpysperformance.com/index.php?threads/tpi-flow-info.10382/#post-43474

http://garage.grumpysperformance.co...m-dyno-results-and-other-info.433/#post-37683

http://garage.grumpysperformance.co...y-current-corvettes-383-combo.430/#post-32660

I rather enjoy the , local Saturday night "run what your brought"
racing, yes your limited to about a 13 second car,
but its still fun to watch because its mostly guys in street driven cars
what screws it up is theres always some guy that could run low 10 seconds with $5000 plus in computer controlled equipment,
that basically lets the car run the race, and click off boringly consistent runs
making the guys with basic street driven cars at a huge disadvantage in the long term.
when I first got my 1985 corvette it would consistently run about 14.5 seconds in its O.E.M. condition,
once I tweaked a few things and added a few parts .
consistent 13.3 second runs.
at this point I had a great deal of fun with the corvette.
yeah I decided to tweak the combo a bit, changed cams, several times, ported heads,added a 3200 rpm stall,
swapped to a custom ported and significantly modified stealth ram,much larger injectors, a new ignition,added slicks,
added a better 3" full length and well designed low restriction,exhaust ,
and low 11 second runs, with a 250 hp, wet nitrous kit ,
and getting told I could no longer race the car was a huge P.I.T.A.

related threads,
ignoring reading the links and sub-links is always a mistake

http://garage.grumpysperformance.com/index.php?threads/my-current-corvettes-383-combo.430/

http://garage.grumpysperformance.co...ive-are-the-stock-tpi-engine-components.1509/

http://garage.grumpysperformance.com/index.php?threads/how-big-a-fuel-pump-do-you-need.1939/

http://garage.grumpysperformance.co...n-jumping-in-with-both-feet.14918/#post-84132

http://garage.grumpysperformance.com/index.php?threads/ideal-tpi-build.12203/#post-76070

http://garage.grumpysperformance.co...ht-through-1985-vette-combo.14289/#post-72935

http://garage.grumpysperformance.com/index.php?threads/a-high-torque-406.12184/#post-68419

http://garage.grumpysperformance.com/index.php?threads/calculate-fuel-injector-size.1200/

http://garage.grumpysperformance.co...electing-a-torque-converter-stall-speed.1715/

http://garage.grumpysperformance.co...n-jumping-in-with-both-feet.14918/#post-84073

http://garage.grumpysperformance.com/index.php?threads/installing-a-big-block-chevy-in-a-c4.6/

http://garage.grumpysperformance.co...lap-on-factory-headers.3155/page-2#post-66721

http://garage.grumpysperformance.co...rger-intake-runners-l98-tpi.13785/#post-72541


USE THE CALCULATORS to match port size to intended rpm levels... but keep in mind valve lift and port flow limitations[/color]
http://www.wallaceracing.com/runnertorquecalc.php

http://www.circletrack.com/enginetech/1 ... ch_engine/
calculate horse power from intake port flow rates
http://www.wallaceracing.com/calcafhp.php

http://www.wallaceracing.com/calchpaf.php

http://www.wallaceracing.com/ca-calc.php

http://www.wallaceracing.com/max-rpm.php

http://www.wallaceracing.com/lpv.php

http://www.wallaceracing.com/chokepoint.php

http://www.wallaceracing.com/chokepoint-rpm.php

http://www.wallaceracing.com/area-under-curve.php

http://www.wallaceracing.com/piston-speed-velocity.php

http://www.wallaceracing.com/header_length.php

 

[Grumpy]

AUTOWIZ POSTED THIS INFO

I love building fuel injection systems and tuning them. I have put together a few packages to correct C4 EFI systems and I have another great idea for an aftermarket EFI conversion for the LT1/LT4 motors. To help get away from that optispark. Without tearing down the front of the LT engine.

When LS1 first came out it had a bigger throttle body than LT1 but notably it just had 1 throttle blade instead of the 2 small things inside of the LT TB. This early LS throttle body had a 3-bolt flange. Later on in 2005 when LS2 came out GM moved to a larger 92mm throttle body with a 4-bolt flange. This 92mm throttle body size is the standard of the day and for all the american V8's we love to play with we really don't see sizes smaller than this.

The stated goal of this EFI conversion is higher HP support through greater airflow. That is this would be a good swap if you have also swapped the 5.7 out of your C4 for something with greater than 400ci displacement. Or are running a hot cam with numerically lower LSA. This will let you keep the MAP sensor reading 105kpa at WOT.

The 92mm cable operated throttle body complete with GM IAC and TPS can be had right here: Throttle Body 92mm with TPS IAC Throttle Position Sensor For LSX LS LS1 LS2 LS7 | eBay

That flange is big and square and will not bolt to any LT1/LT4 intake manifold. However, with this elbow that 92mm t.b. will bolt right up to a 4150 carb flange: HOLLEY 4150 FLANGE EFI INTAKE ELBOW - BLACK - 300-240BK

And this intake manifold here will bolt right up to the vortec style heads and provide a distributor hole, a 4150 carb flange, and fuel injector ports, and even comes with little fuel rails: https://www.jegs.com/i/Holley/510/3...Ar9w2JWVoUfvZUqVxl7QHSJMq4YoQQLgaAmRIEALw_wcB

The fuel injectors need to be sized for the engine's output, fuel type, and ultimately demand.

This should be setup for sequential fueling and so a Dual Sync distributor should be used for this setup. Like this: Holley EFI 565-200 Holley EFI Dual Sync SBC/BBC Distributor

And then we can apply this EFI kit from Holley: Holley EFI 550-936 Holley EFI Terminator X Universal MPFI Kit


This kit is for higher engine output at higher RPM and is designed around a single plane intake and large throttle blade. This kit will do best with a manual transmission as it will let you wind out the engine as far as your valvetrain will allow. If we wanted to apply this to an automatic C4 with 4L60E and a loose converter then instead of the above Terminator X kit we would need a Terminator X Max kit like this one here: Holley EFI 550-942 Holley EFI Terminator X Max - Universal MPFI Kit

 

[Grumpy]

https://web.archive.org/web/20230328113407im_/http://www.grumpysperformance.com/portedhsr.jpg

there are noticeable gains if the holley intake is correctly ported and better heads and a hydraulic roller cam are used
especially if a higher stall speed converter larger injectors and better rear gear ratio,is used
yet in my experience even better gains can be had with the FIRST TPI INTAKE WITH SIMILAR MODS

 

[Grumpy]