LT4 "real" HP
I know that we all believe that the LT4 motor was underrated at 330 hp. I would like to hear from any of you who have had a dyno test done on a stock LT4. I read of one a couple of days ago that tested at 365hp at the crank and this was claimed to be pretty typical.
LT4 Vert, blk/blk
From my research, it looks like 360hp or so is the most typical. It is claimed that there was wide variation in stock horse power on the LT4. Ranging from 330hp to nearly 400hp. But the extreme ends of that range were rare.
As a relatively new owner of an LT4, I'm pretty surprised that there should be this wide variation in stock HP. I don't doubt that its true, but doesn't it kindof imply a lack of manufacturing quality control? Either that or there is a really wide range of state of tune out there. Any body got a good explanation why this variation exists?
LT4 HP - This 1's had a few lengthy discussions . . .
Here's the link . . .
Originally Posted by StanA
Later . . . . . .
Mine dyno'ed with 298rwhp a few months ago. Only mods were, K&N filter, muffler elims, and hypertech programmer (turn fans on earlier) 160deg t-stat.
2004 Z06 mod red interior.
1996 LT4 (sold)
I saw a stock one dyno at 301 rwhp about a year ago. That comes out to about 354 hp.
GM has a 5% quality control standard on engine power (so figure +2.5% and -2.5%).... They purposely under-rated the LT4 (to protect the ZR1 owners, and to make sure they didn't look stupid spending millions on the LS1 platform). so figure it should have been rated at 345-350 HP... with this in mind, The normal high end would be in the 360 range, the normal low end would be 340 range.... GM also has a good track record when it comes to giving you the HP that they advertise... meaning, if GM says you are getting 350 HP, you usually get 350+ HP, not 'close to' 350 HP (this is how ford does business... their track record is to advertise a power output, then get within the range plus or minus)
Originally Posted by nearmiss
I have yet to see any significant variation in HP with stock LT4. I have compared 4 with dyno pulls and there is no more than 2 or 3 HP difference. For me to believe the stories of wide variation, I would have to see it for myself. Stock will yield right at 300 RWHP (SAE corrected on a dynojet chassis dyno). If one opens up the intake, installs HOT cam, headers, and hi flow cats w/ good aftermarket exhaust, you can expect 340 RWHP with stock programming. Throw a little LT1 editing in there and one can get another 15 to 20 HP. If anyone has a difference of opinion, please back it up with a dyno pull sheet.
red lt4 w/corsas, hot cam, headers, hi flow cats, 52mm TB 343 HP/334.5 torque. '03 Z06 - Honker intake, 359 HP/ 347 torque
Thanks. This would appear to track with what several others have stated as well. 300RWHP equates to about 353 HP at the crank, right? And, +/- 2% would make the probable range in the neighborhood of 345-360.
Originally Posted by wx briefer
I have a 96 LT4 with almost 25K miles. It has a K&N air filter, other than that...bone stock.
I just took it down to the dyno to get some baseline numbers, as I am about to do some work on it.
It ran 294.6rwhp (@ 5750 rpm), with 315rwt. Top run was 307.2 rwhp, with 327 rwt.
Explains why I haven't lost to a LS1 yet!!!
What kind of work are you about to do to your LT4? I am a fairly new owner of an LT4 myself, and would like to do some work on mine as well. Not being an expert, I'm not sure what to do to increase performance.
My Dyno results
I'm looking at my dyno sheets right now done at LD Motorsports May 22, 2004. It has an x-pipe, K&N open filter, and corsa mufflers. The three dyno pulls were:
I agree, these are in the normal range. I wish I had some of the higher torque ratings some had. I am planning on a few mods but I want to get some baseline times in first. Maybe its because of some past cars I've had, but this car doesn't pull as hard as them, or feel as strong (and it isn't). I am hoping that with the mods it will have that Z06 type pull I'm looking for.
Hey Ken, were did u get your x-pipe??
Originally Posted by kblack_LT4
Dave at R-D racing has one he was going to use on his race car for sale.
Originally Posted by stgry1
It's a Dr. Gas 2.5" x-pipe for $100, if anyone is interested.
Call him at: Dave Cooper
R-D Racing Enterprises, Inc
573-756-6372 Fab Shop
Tell him Gary says hi........
The x-pipe purchase
Originally Posted by stgry1
Sorry to be so late but I've been out of town. I got it off ebay, they are on there a lot. Do a search for x-pipe, there are magno flows in different diameters for about what I paid for mine ($57), lots cheaper than retail! Best of luck.
My home email is firstname.lastname@example.org
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