1989 406

I only have experience with the L98 supercharged.

First why am I reading that if you want to modify, you can do more with the L98 then the LT1?

Second if the LT1 and LT4 have the same torque, is there a big difference in the power. I know the difference in horsepower, but torque is usually the real factor. Is the performance that much more noticeable in the LT4?

Thanks.

Pete K

Both respond similarly to mods. There is a much larger factory and aftermarket parts selection for a Gen 1 (L-98) small block than there is for an LT1 or LT4, but ample support for both. L-98 stuff is often a few bucks cheaper.

Every LT4 I have ever been in ran signifcantly faster than the 30 extra HP it claimed to have. It has always been my thought that GM underrated the LT4 to make the brand new (1997) LS1 engines look like a step up.

rocco16

No, not really. The extra horsepower comes from the torque being sustained at higher rpm (remember; horsepower is torque X rpm). In my experience the difference between the LT1 and LT4 is that the 4 simply pulls just as hard, only longer.

As far as the power of the LT4 being underrated, I put my stock LT4 on a chassis dyno the same morning a friend put his stock LS1 (rated at 345hp) on the same dyno. His LS1 charted 4 horses more than my 330hp-rated LT4.
One possiblity is that the LT4 actually IS underated.....by 10hp. Another possibility is that the 3% extra horsepower is well within the range of normal deviation. I don't believe the stories of stock LT4's putting out 370-380hp, at all. There just isn't that much deviation in engine specs allowed by manufacturing....if there were, then there would be just as many 270hp LT4's as there are 370hp LT4's....???

Larry
____________
not easily impressed....

tombrammer

I have an old CHP mag. March 99 it has an article where Mike Osucha of MORE performance put an out of the box stock set of LT4 heads on a stock LT1 motor out of a camaro. It made 360hp @ 5600 rpm and 378 tq @ 4600 rpm w/o a tune. So the LT4 must of produced more than the factory rated 330hp. The motor in that article was running the water pump, headers but otherwise stock exhaust, but not the alt. so that would still be close to true net hp.
Also the LT4 came with only the 6 spd tranny and 3.45 rear gears. Once you get out of 1st you are only dropping about 1000 rpm at each gear shift, so tq doesn't really enter the picture, you are constantly in the peak hp range for the motor, that equals quicker acceleration than a stock LT1, especially the auto.