[tjZ28]

I'm under the impression you can legally swap a LS1 and the accompanying T56 into an older ('93-'97) 4th Gen Fbody for ESP. So, assuming that is correct what do you think would be the better combo?

* LT4 built to the limits of ESP rules + the '93 Trans gearing

or

* LS1 built to the limits of ESP rules + '98+ Trans gearing?

Let's assume this is in a '97 Hardtop Z28 built to the full limit of ESP rules also. The car generally would run on a large, fast, smooth, ultra-grippy concrete lot. BUT it would hopefully see Nationals in the next 2-3 years so it'd need to work on smaller, slippery surfaces too.

Running the numbers on 2nd gear only (since that’s where the car will spend at least 90% of it’s AutoX time) the ’93 Trans gearing would give about a 14% increase in RPM vs. the ‘94+. For example, if the ‘94+ gearing would have you at 3,000 RPM the ’93 would have you at 3,420 RPM.

I think it’s safe to say that the LT4 can match the LS1 on torque/hp until maybe 4500 or 5000 RPM. Only losing out a bit right up to ~6200-6300. But can a LS1 make as much torque/hp at 3,000 RPM as a LT4 could at 3,420 RPM?

Thoughts?

-TJ

PS- Yes, my head hurts too.

This post has been edited by tjZ28: Jul 11 2007, 12:53 AM

[tjZ28]

I would go with the LS1 combo personally. With the allowed computer programing, the low end torque can be obtained from the LS1. Plus they seem to be more reliable. A late '00 LS1 will have the same heads as a 2001. I have one of each and they have the same heads (at least if you go by the casting numbers). The '00 with and LS6 intake makes more power than a stock '01 which already has the LS6 intake.

Hmm, if late '00s had the '01+ heads but the early cam that should mean you could put an early can in any '01-02 since that combo was originally available from the factory. The catch of course would be documenting it.

I know I can make as much low end torque with a LS1 build as a LT1 build, probably more in fact. I'm a huge fan of the Gen III/IV motor and like them a lot better than the LT-funs for many reason. They seem to be much more reliable. Hell, just the OptiSpark is enough of a reason to stay away from LTs. But LT's are also known for oil leaks, are weak 2 bolt mains in the LT1s, don't like to rev as high etc. The LS1 really is an amazing motor, and I'd much rather build one. However, it's still hard to argue the 14% gearing advantage you can gain w/ a '93 Trans behind a LT motor.

I'd go LT4 combo only based upon my experiences with the LS1s and my LT1 with 93 trans. Great throttle response out of the slow stuff and gearing to help you a little, plus all of the breathing and HP you need up top. It's the best of both worlds.

Thanks for the input... so you're still with an LT1 not a LT4. Do you have it modded to the full extent of the ESP rules? What are you dynoing?

-TJ