I am not fan of of the stock LT1 intake with its short runners and uneven air distributiion.

I was thinking of using an Edelbrock or Professional Products carb single plane for EFI with a the long low profile Edebrock elbow(for the increased plenum volume) and a 90mm LSx type TB. But I have been reading on the web that guys have been getting 50+ RWHP gains by switching their OEM style TB's w/elbows for 4 barrel TB on their single plane intake. Besides the RWHP gains they say that they have been getting more HP and torque under the curve and also a much smoother running engine. Granted these are on built big cube motors but the principle still applies across the board.

So is this true??

If I am going to go the single plane intake route should I save up my pennies also for a 4 barrel TB with progressive linkage instead of the OEM type LTx or LSx TB with an (90 +degree) elbow.

I really came to appreciate the elegance of the carb style single plane intake manifold with its ability to keep ramming air into the engine and not have the different cylinders to rob air from one another and also have all cylinders feed off of the plenum from a common point. I know this set up has been applied to an all out race application but I think that there is a high performance street application can immensely benefit as well with the longer intake runners helping in low to midrange torque production.

How much more plenum volume you think I would gain over a stock LT1/LT4 intake?

I want to put this on a quaility budget rebuild of my '96 LT1 longblock. My goal is to make 420 RWHP and 400 RWTQ but with better low to mid torque than what the LTx intake can provide. My 9C1 has 3.73 gears, a cold air intake and I plan to put 4 into1 long tube headers on a 3" dia exhaust (with 2.5" tailpipes) and an "x" pipe. I am also thinking of going to EFI Connection's LS1 PCM and coil-on-plug conversion.

B'klyn9C1
Brooklyn, NY

 

That 50+ rwhp is usually on LSX engines with heafty cams. The reason they gain so much is the issue with cowl clearance leaves them with rather sharp curves in the elbow for the air to follow. The answer is yes, the 4 hole with have the air coming straight down so it feeds the cylinders better. Now if your rinnung maf still, it may be in your best interest to run a 102mm LSX TB with a elbow from Aaron @ intakeelbows.com. He will make it to however you want it as far as size and shape, so if you make the curve more of a gradual one then a quick 90 the uneven distribution will be much less of a problem.