a mild high torque TPI combo

grumpyvette

Administrator
Staff member
OK your stock 350 TPI engines got a ton of miles on it and needs replacing but you still want a dependable daily driver with zero head aches...but still a bunch more hp would be nice!!
if your not changing the cam or heads the rear gear swap to a (3.73:1 ideally) will be far more beneficial than the higher stall converter alone but both a 2700 stall and the rear gear will do amazing things with good slicks,on a stock engine,and adding a low restriction exhaust on decent headers, sure helps especially if you upgrade the cam and heads later.but think it thru carefully, if you intend on using better heads and a larger cam in the future, your effectively raising the power band the engines intended to operate in,and in most cases a larger cam requires increased compression to provide its full potential power,if your going to increase the compression the best way is thru a stroker kit so you also gain displacement, select the cam and converter to match and the heads to match the displacement and intended rpm /power band,
yes its a bottomless money pit if you just keep wanting more and more!
Think it thru carefully ,set a goal, and buy/install what you need to slightly exceed that goal. but don,t compromise the cars drive ability or durability if its used as transportation,
, (383 0r maybe a 406?) remember to select the cam and converter stall to match and the heads to match the displacement and intended rpm /power band

OK to keep things simple you'll want an engine as close to the basic stock physical type as the original engine, now that rules out the lt1-lt4
but you can have huge increases in hp/tq with the basic sbc l98 design parameters
If you do build a second performance engine rather than modify your single existing original cars engine,theres some advantages, that us older geezers have come to appreciate at times.
as a general rule, its best to take your time and build a separate performance engine that you can swap into the car over a weekend, this has several advantages
(1) you will not be tying up the car, in an un-driveable condition waiting for weeks on parts to arrive or waiting on machine work to be done,
and you can always swap the original engine back into the car,
to have the car as dependable transportation while the performance engines being built or worked on.
(2) you can sell either engine separately from the car itself and still have a drive-able car.
(3)having your performance engine out on an engine stand certainly makes it far easier to work on.
(4) having a second engine available allows you to drive the car while you make repairs on the original engine
(5) if you screw something up, your not effectively stuck with a non-driveable car for long.
(6) with some experience you,ll find an engine swap between two similar engines can be done in a day , or at most a weekend by yourself, with a skilled and experienced local buddy, a long afternoon!
lets keep things simple

this short block

http://www.ohiocrank.com/chev_sb_shortb.html

406 SBC Shortblock with new Dart SHP block
Price
5140 steel crankshaft
6" Steel Rods w/ ARP bolts
SRP forged pistons
Race rings and bearings
Internally balanced
Dart SHP block
$3095
assembled


these heads
http://www.jegs.com/i/Brodix/158/1021004/10002/-1#

$1,025.99

http://www.jegs.com/i/Comp+Cams/249/1302-16/10002/-1

$285.99 these roller rockers


this semi-mild cam (FLAT TAPPET HYDRAULIC)if you want it to run as a basically stock engine

http://www.crower.com/misc/cam_spec/cam ... &x=26&y=10

obviously if you up the converter stall speed, rear gear ratio, displacement and compression ratio a larger cam can also be used to gain a good deal more hp, so talk with both the engine builder and several cam company's about your options


oil pan
$290

http://www.cantonracingproducts.com/cgi ... key=15-240

http://store.summitracing.com/partdetai ... toview=sku


the rest is reused stock components, and new gaskets

you can very easily assemble and install that combo yourself and easily exceed an extra 100 more hp plus over the stock engine with noticeably more tq and no bad traffic manors, the idea is no bad manors no problems and a noticeable improvement without needing computer changes or new injectors etc.
 
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GRUMPY??
Let me get this right you are saying that stock fuel injectors will support 340 horse power.

if youve got the engine tunned correctly its doable , yes the injectors will be totally maxed out at high rpms but you can get there,
now IM not suggesting a 24 lb-30 lb injector would not be a big plus here but a stock 22 lb injector will function well over most of the rpm range and only get really lean over about 5000-5500-rpm, well past the point where the stock TPI intake on a 406 displacements still getting a decent air flow.

http://www.rceng.com/technical.aspx

http://www.fiveomotorsport.com/Injector_SetsTPI.asp

http://www.carcraft.com/techfaq/116_070 ... index.html

http://www.rceng.com/technical.aspx

http://www.superchevy.com/technical/eng ... to_17.html


remember the idea here is to use most of the stock components and build a torque monster for the street not a race car.

BTW its NOT THEORY, IVE built similar combos for guys and they used the stock injectors untill they could afford to upgrade the injectors, and they got by quite well for weeks-months (again not ideal but doable)
keep in mind guys run stock 350s up to 5800rpm all the time,(well past where the TPI breaths effectively) a 406 spinning 5000rpm will use the same fuel air ratio, and air volume

keep in mind pulling 450-470ft lbs at about 4400rpm with that combo should be easy and 4400rpm x 450ft lbs=376hp

http://www.superchevy.com/technical/eng ... sults.html


http://www.mre-books.com/chevy/engines/tpi.html
 
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if your confused here after reading other combos with larger injectors,

its fairly simple
stock 22lb injectors will allow the car to run and function and make about 100 extra hp(compared to the stock 230hp) in a mild combo designed for cruiseing (your looking at making only about 340-350hp) and youll rarely exceed 5000rpm in that performance arena, buy running the injectors up to about 90%-95% pulse duration(well past thier intended pulse durration)

36-40 lb injectors should probably be used for racing,or hot street combos with a larger cam, more agressive gearing, higher compression, bigger heads and a much higher average operation rpm band that would easily result in not the 340-350hp of the mild build but the 450-500hp of the more agressive combo and its far higher air flow and hp rates, running the engine up to 6300rpm or so would be comon place,the object of the mild build was MINIMAL changes and a streetable low cost combo, not max hp.

read this

http://www.superchevy.com/technical..._stealth_tpi_induction/dyno_test_results.html

or put another way, the choice of a mild cam and small stock injectors are limiting your hp above 5000rpm , and holding you back to the tune of an additional extra 100 plus hp.
 
I think many of these posts overlook the fact that its BOTH high compression, and efficient cylinder burns with good volumetric efficiency at low engine rpms AND efficient over drive transmissions in reasonably light cars that get the best fuel efficiency. power great but if your looking for good mileage think thru your combo, it will require a compromise in parts selected.
example
a 10:1-10.5:1 cpr 400 chevy with a set of vortec heads, a decent roller cam designed to maximize the power in the 1500rpm-3500rpm band and a tpi intake , matched to a 700r4 trans in a car that weights under 3100lbs can easily get 25 mpg plus with a good driver.
its the effective use of the torque produced, and keeping the total air flow and fuel rates reasonably low thru high volumetric efficiency that helps the fuel efficiency.
yes high volumetric efficiency REQUIRES a low restriction tuned intake and exhaust and a cam MAXIMIZING that cylinder fill, burn, and scavenging and decent fuel octane that allows the high compression to gain the best thermal and mechanical gains
 
read these threads

viewtopic.php?f=52&t=5078

viewtopic.php?f=55&t=2773&p=7200&hilit=+port+match#p7200

viewtopic.php?f=52&t=462&p=2833&hilit=+port+match#p2833

viewtopic.php?f=69&t=1060&p=2031&hilit=plenum+runners+porting#p2031

http://www.cis.udel.edu/~davis/z28/buildup/plenum/

http://www.chevyhiperformance.com/techa ... index.html

viewtopic.php?f=53&t=726&p=8809&hilit=quench+squish#p8809

viewtopic.php?f=52&t=181

viewtopic.php?f=52&t=90

http://www.superchevy.com/technical/eng ... sults.html

heres a different route to follow thats popular

http://www.airflowresearch.com/index.php?cPath=24_25

heads


http://www.summitracing.com/parts/CRN-114132/
cam

btw
802-16 rockers won,t hurt
http://www.pbmperformance.com/store.php ... dparent=24

these components make a real nice combo but Ill point out that swapping to a 3.73:1 rear gear ratio makes it even more effective

the slight loss in compression, swapping from stock L98 heads with a 58cc combustion chamber to the larger 65cc combustion chamber on the AFR heads is more than off set by much increased air flow rates, with the new heads and as a bonus the slight reduction in compression reduces detonation OR if used with a 383 stroker keeps the cpr nearer the original levels
with flat top pistons, but naturally you need to calculate the true cpr with and rotating assembly ,or head gasket or block deck height changes
l98 heads flow about 199/164cfm at .400 lift
AFR heads flow about 240/178 cfm at .400 lift
thats potentially easily 70 hp or more gained when combined with the new cam, and ported plenum and runners.
remember to order the L98 plug angle heads
"SBC 180cc Street Heads, L98 angle plug w/heat riser, 65cc chambers, complete w/parts
[0918*]"

I don,t know if the rockers clear a stock corvette valve cover off your year engine,as Ive always strongly preferred tall valve covers,and/or never gave removing drip tabs a second thought,when using those erson rockers and yes IM well aware the darn windshield washer motor is in the way preventing use of tall valve covers until its modified or replaced on many c4 corvettes, or the valve covers are modified to clear
 
HEY GRUMPYVETTE?
Lope Separation
I know I should be looking for a lobe separation of 112 to 114.

But can I get a 110 Separation to work with a good tune. (Lunati 60122)

SLP runners and Eldenbrok Hi flow base.

It will also be in a 383.

The RPM range is 2400 to 6200 What I was told the 383 will put the RPM range down lower so this might just miter work out for the 383 DD street motor.
Do you think this is a good cam choice for a 383 with 10.5 to 1 195 heads though full lenghts headers and TPI intake for a DD.

What your 2 cents on this.


LSA (LOBE SEPERATION ANGLE) alone is NOT the main factor that causes problems its the combination of duration,lift,LSA and valve train acceleration
a good tuner can compensate for a great deal, and yes if your willing to make compensating changes in the sensors or the programing you can run the tighter LSA, but it WILL REQUIRE changes to run a tighter 110 LSA once the duration has increased to the point that it effects the sensor data feeding to the CPU, tighter LSA tends to increase OVERLAP and increase intake runner reversion pulse strength, but your compression ratio, displacement and exhaust scavenging efficiency also effect the sensor data

READ THESE

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=480

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=4065

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=1070

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=1477

http://www.summitracing.com/parts/LUN-60122/


IT WILL REQUIRE a 3.54:1-3.73:1 rear gear and a 3000rpm stall converter or a manual transmission to function, and 30-36 LB injectors and a better than stock ignition and low restriction exhaust to perform to its full potential, yes if you carefully match all the requirement it should produce a very nice combo, but if you try to get by with a few components that require changing in stock form it will be just as big of a dog

READ THIS

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=430

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=82

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=399

http://forum.grumpysperformance.com/viewtopic.php?f=71&t=1715

http://forum.grumpysperformance.com/viewtopic.php?f=71&t=741




GRUMPYVETTE??
What cam would you go with the new block I getting I found out is a roller block so might as well take advantage of it.

I was planning to use a Lunita 60101 cam if it was a flat tappet or should I just use the flat tappet anyways.

I have everything for it already.

Lunati 60101 cam 256/263 484/498 lift 213/219@ .050 112 C/L at 4 dregee retard cam timming it where I like the Op range where it will be a DD.

I am running a 2500 stall converter the 307 rear end.

I was also thinking having the same grind made into a roller cam with a steeper ramp angles.

Will it be worth the extra $500.00 for the swap over.


you can run a roller cam and see gains over a similar flat tappet design, if your not willing to change the converter or rear gear ID go with something like this, as it will work and give a nice boost over most of the TPI cams WITHOUT MAJOR PROBLEMS

http://www.crower.com/products/cams...roller-cam-for-efi-smallbase-circle-4139.html


IF you want to push, and potentially gain a few more hp
As always ID check with several cam manufacturers like CRANE,CROWER,ERSON, and LUNATI and get their input, keep in mind youll obviously need to verify your clearance limitations and valve spring load rates before selecting a cam or you'll have clearance issues, but a 383 with that intake will produce very impressive mid rpm torque and be impressive to drive
http://www.crower.com/products/camshafts/chevy/chevy-262-400-hydraulic-roller-cam-for-efi-4140.html


but be aware thats about the, limit the stock rear gear and stall can BARELY FUNCTION WITH and ONLY AFTER A GOOD TUNE, with a stock drive train and even thats pretty radical if its a daily driver, with a stock CPU and 24 lb injectors

READ THESE LINKS< AND SUB LINKS

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=3802

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=181

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=399
 

"HEY GRUMPYVETTE?
I have a friend of mine with a 90 C4 that is in the process of an engine rebuild. I have been having trouble finding info for aftermarket parts for these engines. I am looking to see what y'all suggest to get close to 400hp.
It is an automatic transmission car and it has the TPIS upper and lower plenums.
What options does he have for heads while keeping the center bolt valve covers?
Can he make good power without doing a stroker kit?

Would also like to have everything as close bolt on as possible, since this is his daily driver.

Mainly looking for a good combo for a street-able 400hp. Let me know if any of you have a combo like this that works well..




400 flywheel hp is going to be far easier than 400 rear wheel hp, which are your trying to get and whats your budget and skill level?
with the emphasis on "street-able" Id be really looking at a supercharger and decent aftermarket heads and a cam upgrade,

http://www.shopsupercharger.com/p-117-c ... ystem.aspx

http://www.tobefast.com/procharger-chev ... 01407.html


http://www.hotrod.com/how-to/engine/ccrp-1209-eight-budget-sbc-head-shootout/

http://www.airflowresearch.com/index.php?cPath=24_29

http://airflowresearch.com/articles/art ... /A8-P1.htm

http://airflowresearch.com/articles/article122/A-P1.htm

the main power restriction is the stock heads and cam , and restrictive exhaust on that car,if the goals 400 hp , the cam and heads require serious upgrades and youll need to swap to a 3000 rpm stall converter and a 3.73:1 rear gear to match a cam that will move the intended power range high enough to make that intended power range
it would also be far easier with a centrifuge supercharger , because your trying to boost the engine from a stock,
Horsepower @ rpm 250 @ 4,400
Torque @ rpm, ft lbs 350 @ 3,200

a typical sbc makes about 1.1 ft lb of torque per cubic inch of displacement

your torque curve depends mostly on your engines displacement,compression,head, & intake flow and cam timing

the formula for hp is torque times rpm divided by 5252=hp
a higher torque peak generally increases power


example
400 ft lbs at 3500rpm=267hp
400 ft lbs at 5500rpm=419hp



you'll want to run about 10:1 cpr on the street to maximize performance


heads that flow about 250cfm or more at .500 lift are going to be a huge asset

you'll usually need a 3.54:1-3.73:1 rear gear and a manual transmission or a 2700rpm-3000rpm stall converter to maximize acceleration, with a cam that's designed to maximize power in the 3000rpm-6300rpm band

you'll need a low restriction exhaust and headers
 
My '89 Formula 350 stock with 3.23 gears got 22 mpg on the highway and ran 14.20's, actually one of the quicker ones I'd seen stock. We pulled the intake and heads, ported the base, and basically left the runners alone because the good aftermarket units were big money then. Milled .010 from aluminum L98 heads, ported, polished and did a performance valve job, port matched everything as well as we could, and used a set of Comp valve springs that matched the stock cam as well as aluminum keepers and retainers. I got Jim Parks of Inject USA to do a set of injectors and an ecm chip for it and advanced the cam 4 degrees. Replaced all the fire related parts in the ignition with a high output single fire system that was popular at the time and I can't remember the name.
On no traction Gatorbacks it ran 13.30's and got a legitimate 29 mpg on the road. :cool:
 
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