Le Lt4 intake flow

[meen95z]

I have a 385, le3 lt4 heads, le solid roller cam and a max ported le oem lt4 intake. Thinking on going with torq head so I can rev it alittle higher. Anyone know how good a ported and welded lt4 intake actually flows? Good enough for what I have or do I need to convert to single plane. Intake has a money maker kit also, so a chunk of change invested in it. 58mm tb and monoblade opening on intake.

[Camaro96]

When I was doing research it was difficult to find reliable numbers. Hers an article that may help you.

Hear is an article that might help you.
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Intake Systems , fuel systems and related
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selecting an intake for a 383 lt4
grumpyvette
grumpyvette
Administrator
Staff Member
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/
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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!"
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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/

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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
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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
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this type of air foil thats retained by the plastic air tube



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[Camaro96]

@NightTrain66

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[NightTrain66]

A ported LT1 intake is the best choice for most set ups. 90% of the people reading this will be better off with the ported LT1 intake.

I have seen people spend A LOT of $$$ gettinga s ingle plane intake on their car and see very little gain (or NO gain).

If The intake already has the bolts converetd for LT1 intake bolt pattern (or heeads are converterd to SB bolt pattern), already has the fuel inj bungs in place, already ported and you already have the fuel rails and linkage worked out, elbow, etc, slap it on and try it.

If all (or most of this) still needs to be done it just depends on what your budget is and how important it is to sget that intake on there.

If you are inot in the most common 90% mentioned above but in the "other 10%", get a single plane converted, ported, etc.

Lloyd,

[DMBlack]

I have been pondering the same question as to where the "limit" is on the LT1/4 intake when ran on a 383/396 in N/A form? I know the intake flows well for most applications and I am sure it is all that I need but, what would be the max HP or RPM restriction one normally will see with a ported factory intake a 396 with say a set of Competition ported 227 (or similar) heads?

[Camaro96]

Thanks Lloyd

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[NightTrain66]

The LT1 intake isn't bad at all but once you start making 600+ HP N/A and using heads with offset intake rockers, there will be some gain by going with a fully ported single plane instead.

NOT a lightly modified/lightly ported single plane but a FULLY ported single plane.

The average person reading this on this forum that has some ported GM LT1 heads, mid 230 duration hyd roller, spinning 6500 RPM or so and wants to put a single plane on their engine is about to spend alot of $$$ for very little gain and not be happy about the gains.

Just getting the LT1 intake FULLY ported is all most will need based on the "HP gain to $$$ spent" ratio. When I say FULLY ported I do not mean a gasket match and polishing the runners a lil but actually FULLY PORTING the intake and opening up the runners A LOT., makeing then taller, wider all the way thru, removing as much as you dare at the inj ski slope and making the port steadily taper larger as it goes back to the plenum, opening up the front for a 58 MM TB, removing TONS of material behind the TB and in the plenum.

Most of the intakes that people claim taht are 'ported" have very little done in the important areas and alot of times you can still see the casting lines in the side walls of the runners.

People send me a lot of pics and links of heads and intakes for sale. Most of the intakes that people claim that are 'ported" have very little done in the important areas and a lot of times you can still see the casting lines in the side walls of the runners. You also see a lot of haeds that people claim are FULLY PORTED and they still have casting lines in the side walls, have a thick valve guide with very little removed, etc, and anyone that has done much portwork will know right away that they "CFM #'s" that they are claiming are NOT gonna happen on that head.

I guess to recap, most do not need a single plane but if you are class racing (where EVERY little bit matters) or run mid 10's N/A (or faster) and it's in the budget . . . .go ahead and swap over to a single plane. Just make sure that the suingle plane has quite a bit of work done to it also.

Lloyd