selecting an intake for a 383 lt4

[grumpyvette]

Hey Grumpy, I've got a set of AFR 195 cc competition ported heads being delivered next week. They told me that they work best with a LT1 intake and not a LT4. I'm wanting to go with a Holley Stealth Ram or a converted Single Plane like the Victor E. Do you know of anyone that does this conversion or is it something that I can do myself? What would be your recommendation on an intake.

I will mainly be street driving this thing and want good street manners but I also want the ability to raise a little Hell if I'd like.

The cam that I already had ground is a solid roller and it will be used with Jesel shaft mount rockers. The cam is a fairly mild street grind (for a solid roller) and the specs are 236/242 112 LSA and lift is .603/.609. As you can see the cam will not be too crazy for a 383 and I'm wanting your opinion and sources for the best intake for this set-up.

I sold my LT4 heads and intake to a forum member so I don't have any intake now although I do have the 58mm TPIS throttle body. Compression is 11.2 and I have headers and a good exhaust. What say ye'? Thanks for the help.

next youve got several options and the route you select obviously depends both on your wallet balance and what your trying to accomplish plus under hood clearance issues, the cam you selected is likely to be a good choice IF you have the correct rear gear ratio and transmission because the stock rear gears won,t allow the engine to operate in that cams "sweet spot" or power range which will be near the 3500rpm-6500rpm band in a 383, that will require a 3.73 rear gear and a manual transmission or about a 3300rpm stall converter on any auto trans, to allow the engine to spend most of its operational time in the power band the cams designed for, that would produce an exceptionally responsive engine for what your stated needs are.
I'm forced to point out that an LT1 engine has reverse flow cooling so I'm assuming your referring to these LT1 heads

http://www.airflowresearch.com/index.php?cPath=27_28

there are darn few intakes that are designed for the LT1/LT4 cylinder heads with reverse coolant flow COMPARED to the GEN 1 design, as the earlier gen 1 heads have coolant return and radiator hose connections that the LT series of intakes doesn,t use!
yes its easily possible to make the LT1/4 run decent but since your limited to either a custom or fabricated intake or one of the

EDELBROCK LT4 CLONE INTAKES
http://www.summitracing.com/parts/EDL-7107/

HERES DD2000 SOFTWARES WILD GUESS AT THE RESULTS OF SUCH A COMBO, with THAT FIRST TPI assuming MINOR PORT & RUNNER CLEAN_UP

HERES A FEW OPTIONS and related info

http://www.firstfuelinjection.com/products.htm

"The FIRST® manifold is now available for the LT1 motor for all of you LT1 guys that want to bring back some of that lost torque!"

IF I was building that engine and my goal was having the best combo for 90% plus street use ID be very prone to buying a FIRST TPI LT4 intake designed for those LT1 heads as it has significantly larger TPI style runners that would allow the engine to spin 6000rpm with that cam you listed and ID get the DYNAMIC compression down to 8:1, theres little doubt that that FIRST intake may cost you a few peak horsepower but its also likely to produce a far higher and more street friendly increase in mid rpm range torque

http://www.tpis.com/parts/view/36

viewtopic.php?f=55&t=823

http://www.edelbrock.com/automotive_new ... -lt4.shtml

http://www.gmhightechperformance.com/te ... to_03.html

http://www.gmhightechperformance.com/te ... to_22.html

http://www.carcraft.com/techarticles/cc ... ewall.html

viewtopic.php?f=32&t=6224&p=19467&hilit=rear+seal#p19467

READ THIS LINK
http://www.eecis.udel.edu/~davis/z28/bu ... ttle-body/

the FIRST INTAKE COMES WITH A SINGLE THROTTLE BORE THROTTLE BODY, ITS NOT A DIRECT REPLACEMENT OR EASILY CONVERTED TO FROM THE STOCK TPI DUAL THROTTLE BODY BUT AN ADAPTER CAN BE MADE AND INSTALLED

IF you already spent the cash to buy a twin 58 mm throttle body it only makes sense to make up an adapter to use on the FIRST INTAKE as a throttle body, as it flows enough air and makes installing the stock TPI throttle linkage far easier

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

IF you do install one of these air foils 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

 

[1963SS]

I was really after something like the HSR. I read some of your earlier posts on here and it seems like a real good HP/dollar intake. I'm not overly concerned with the hood clearance. :mrgreen: I've got a few extra inches to play with.

I like the idea of the torque that manifold will make but I have the solid roller setup because I also like to rev it once in a while. DO you still like the Holley Stealth Ram? You had mentioned gears. I have 3.45 D-44 in the car and I have a 3600 (give or take) Edge Racing stall. I've had real good luck with Andre at Edge. I have seen.....somewhere......that people will convert a Vortec type manifold over to the LT1 bolt pattern. I just can't find that info to save my life. I found it when I didn't need it but now.....????? Someone even took a Performer Air Gap Dual Plane manifold and it did great up to 6500 RPM. They compared it to a single plane and the dual plane won hands down. I can't find that now either. Maybe old age or lack of patience or something!

The engine's built except for the LT4 stuff that I sold to a forum member. He got the Lloyd Elliot stage 3 ported LT4 castings and matching intake. I measured the intake runners and they came out to be 227 cc. That was fine for my first goal but my plans changed. Here is the stuff on my almost ready to drop in engine.

Now I just have 8 holes in there and no heads on yet. :cry: Here's a view of the bulletproof valve train. I don't like to worry about valve float.

I like that dyno program that you have. How did you figure the intake flow. Was it just an edjumacated guess? I've been told that the heads after Tony massaged them flowed 304/235 @ .600 and that is right where my cam is. I'm hoping to get about 500 torque and horsepower.....well, at least that's a goal. It may not happen but we should be close. The FIRST intake, while very pretty is also very expensive. If we can find someone that converts Vortec style manifolds what would be your first choice for a great driver and occasional stop light Grand Prix racer? I could have sworn that you like the HSR awfully well.

 

[grumpyvette]

the engine mods youve done so far look rather impressive, congrats!
the Holley stealth ram is what I have on my 383 (BUT MINES EXTENSIVELY PORTED AND MODIFIED) it makes really impressive power above about 4500rpm in a 383 compared to what you would expect from a FIRST/TPI but it certainly has noticeably less low and mid rpm torque that the other design and you stated youll rarely be racing, and its a 90% street used car?
IM unaware of it if HOLLEY makes a STEALTH RAM intake to fit the later LT1 heads , but obviously the first gen intakes can be modified if you have the time and cash to do so
If you decide on the Holley stealth ran youll need to do extensive porting as the runners need to be significantly ported(near the heads welded and enlarged and the runner entrances extensively opened up, as they are rather small and restrictive as they come out of the box for a serious engine) and LT1 ports are higher so your almost sure to need the welding and porting to get them to fit and function
you can certainly make a killer combo either route, and the ported stealth ram will make more peak power but its also going to be a bit less responsive just driving on the street.
try not to fall into the trap most guys do that is thinking only about the impressive peak hp numbers most guys get fixated on that and ignore the fact that they spend 90% of the time or more on the street where the engine seldom sees rpm levels exceeding 5500rpm
BTW I have 36 lb injectors in my 383, they are too small, marginal in the upper rpm range ID swap them for 40lb-42 lb if I was not saving to do a big block engine swap


If your thinking about installing a first gen intake on your engine or something like a TPI intake designed to fit first generation heads on the newer vortec head design, youll need to do a careful test fit because there might be sealing issues, both VORTEC and LT1/LT4 heads have slightly higher port locations than the standard first gen intakes , the vortec heads are a closer match to the LT1 than the first gen heads, youll need to measure carefully, I needed to weld my intake runners to add aluminum before I could port them to match my heads ports

standard intakes don,t fit some vortec heads because the vortec head ports extend higher, so a VORTEC STEALTH RAM should be a closer match than a first gen stealth ram intake
you might want to read these links and the sub links

viewtopic.php?f=32&t=430

viewtopic.php?f=55&t=431&p=756&hilit=holley+stealth+mods#p756

viewtopic.php?f=52&t=5078

viewtopic.php?f=55&t=583

viewtopic.php?f=52&t=462&hilit=runner+porting

viewtopic.php?f=55&t=5378&p=16106&hilit=port+match#p16106

viewtopic.php?f=52&t=4664&p=12600&hilit=port+match#p12600

viewtopic.php?f=52&t=5537&p=16750#p16750

 

[Indycars]

Damn that engine is pretty....oh and the car is not too bad either!!!

 

[grumpyvette]

these threads might be of interest to you, now I did rather extensive testing, between the Holley single plane EFI and a Holley stealth ram, in out of the box form them mildly ported on both also and with both the 90 degree elbow and a BBK 1000cfm 58mm dual throttle body and later with the standard 1000 cfm throttle body.
the reason was that the single plane intake option appeared to make it far easier to work on the engine and allowed use of the original hei distributor while the stealth ram required the use of the smaller base remote coil distributor and made access and installation noticeably more difficult, yet testing relieved that a properly ported stealth-ram
(basically a tunnel ram intake converted to EFI) the stealth-ram once correctly modified, consistently produced better mid and upper rpm power , I also tested more than a dozen cams while screwing around with various EFI intakes, and while I did not try every potential combination I did get a really good idea of how various duration in cams effected results in three similar 383 sbc engines and how a serious roller cam and better flowing cylinder heads consistently made it obvious that changes to the drive line gearing and converter stall speed were required to maximize the better flow rates of the components being tested.
I consistently see guys posting about this or that cam or heads but if you dig a bit and ask questions far to many guys are sticking a larger cam or better heads on what is basically a stock short block then they act amazed when the parts that were installed can,t produce nearly the expected results.
you need to keep in mind that even the best heads or cam can,t produce good results unless the engine operates in the intended rpm range and all the components like the headers and exhaust are designed to operate in that same rpm range and at the same flow rates.
it does little good t port a stealth ram to flow 280 cfm and use 280 cfm aftermarket heads if the stock exhaust system is hooked to good headers and you still have a 3.07 rear gear or a 2200 stall converter. or the cams lift and duration won,t allow the valves off the seats high enough or long enough to reach that rpm and flow band where that 280cfm is potentially useful.
read the links
http://garage.grumpysperformance.co...at-manifold-air-temp-sensor.10349/#post-42530

http://garage.grumpysperformance.co...elay-switch-locations-and-info.728/#post-9217

http://garage.grumpysperformance.com/index.php?threads/cooler-denser-air.8961/#post-54496


viewtopic.php?f=55&t=2377&p=7091&hilit=stealth+ram+holley+single#p7091

viewtopic.php?f=55&t=4275&p=11245&hilit=throttle+body+adapter#p11245

http://www.eecis.udel.edu/~davis/z28/wi ... 31229.html

viewtopic.php?f=55&t=1200

viewtopic.php?f=70&t=855&p=8931&hilit=holley+distributor+890%2F160#p8931

viewtopic.php?f=55&t=1509&p=3459&hilit=1205+1206#p3459

viewtopic.php?f=32&t=601&p=1228&hilit=1205+1206#p1228

using these components ON my 383

THEN THESE
http://www.holley.com/9901-101-1.asp

http://www.summitracing.com/parts/BBK-1544/?rtype=7

with the hard to locate discontinued
Accel 74882 90 Degree Plenum Adapter

this is what the stock as cast holley single plane intake manifold ports, look like matched to a 1206 gasket,the stealth ram ports are a bit closer to the 1206 gasket but still require porting obviously the runners need porting to flow to the full potential

this holley intake and 36 lb injectors, with everything else the same as the Holley stealth ram intake I tested, at the time BOTH intakes were as they came ,out of the box theres ZERO question that even in that condition the Holley single plane intake was more restrictive and once the stealth ram was ported it became a laughable comparison
http://www.holley.com/9901-101-1.asp

 

[grumpyvette]

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