[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

[BigEnos]

I don't have a dyno graph as the car is now. It is not even nearly modded to ESP ruleset. It's a 145,000 mile unopened '95 LT1 that has had regular maintenance and has an underdrive pulley, CAI, and C.A.M. tuning. I have the cast iron manifolds and a Stainless works y-pipe/cat with fabulous pieced together cat back.

Ask Phil how it compares with his LS1, he drove his and mine this weekend.

[pknowles]

I don't have a dyno graph as the car is now. It is not even nearly modded to ESP ruleset. It's a 145,000 mile unopened '95 LT1 that has had regular maintenance and has an underdrive pulley, CAI, and C.A.M. tuning. I have the cast iron manifolds and a Stainless works y-pipe/cat with fabulous pieced together cat back.

Ask Phil how it compares with his LS1, he drove his and mine this weekend.

Yep Brian was nice enough to let me take a run in his car, since I haven't driven his car with the 93 trans. That trans really woke up his LT1. The course had a few slower pin turns and his car did pull out of the slow stuff better then mine, it's not huge but the LT1/93 trans was a better out of slow corners. The LT1/93 torque was right there when I rolled into the throttle, my LS1 still pulled hard, but needed to pick up a few RPM to pull really hard. I honestly think down low and low to mid range (~3k) the motors make similar torque (or a least similar enough that it's not a big deal), but the gearing advantage really made Brian's LT1 shine. If we had a really tight/slow course it might be different, but the course wasn't that slow. However, my LS1 pulls like a bat out of hell til redline and Brian's LT1 ran out of steam in one section of the course.

Sean is right that the gearing goes both ways. The 93 trans helps you out of corners, but you hit the rev limiter faster. Considering that at the ProFinale last year Brain's LT1/93 trans was edging out Eguina's car (LT4/93 trans) off the line, I'm not so sure an LT4 has the same low end torque as an LT1. But we are all bench racing at this point. (IMG:http://www.frrax.com/rrforum/style_emoticons/default/wink.gif)

I would say build what you want the combo's are really close. There maybe a slight advantage to an LT4/ 93 trans, but it's not that much. Plus documentation for the LT4 is hard to come by unless it comes with the car. If you plan on running any big events you better be sure to have the proper documentation for the LT4.