Better Combo in a '97: LT4 & '93 Trans vs. LS1 & ' - F-Body Road Racing and Autocross Forums

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 View Member Profile	Jul 10 2007, 10:29 PM Post #1
Member Group: Advanced Members Posts: 91 Joined: 27-January 05 Member No.: 626	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

sgarnett View Member Profile	Jul 15 2007, 01:03 PM Post #2
Seeking round tuits Group: Advanced Members Posts: 5,522 Joined: 24-December 03 From: Kentucky Member No.: 33	Gearing is always going to work both ways, depending on the course. In general, I think the 2.97 is ALWAYS better for launching, even in slick conditions. I've always preferred controlling wheelspin with my foot instead of by bogging the engine. With 2.97, I can launch with however much wheelspin I choose (down to none) and still drive out of it without bogging. After the launch, it all depends on the course layout. Sometimes 2.97 is better and sometimes 2.66 is better. Besides the top speed, it also depends on where the good shifting points are. If the course starts getting busy right off the launch, there's sometimes no good place to shift without upsetting the tail. If there's no place to short-shift and not enough headroom to make it to a short straight, then shifting in the middle of a slalom or whatever is going to hurt your time. The 2.97 trans is certainly more fun coming out of a turn, though (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif)