Everyone compares LT1's to LS1's, but how bout the LT4's. How do they match up with the LS1's. Just wanted to hear some of your opinions.

 

Theyre fairly even in a race, but i think the LS1 would still pull a tad in the top end...

 

Stock for stock, the LS1 would win if the drivers were equal.

 

Check out the dyno results for various LT4s on http://www.grandsportregistry.com/dyno.htm

Stock they seem to put down about the same 300rwhp as your average LS1. They hould probably pull your average LS1 Fbody due to Vette vs Fbody differences, and run door to door w/ your average C5...

 

The LT4 C4 would walk away from the LS1 C5 initially due to the availability of more torque down low, but where it starts to peter off is where the LS1 car would come running by, probably just past the 1/8th.

 

Vette's seems to dyno just a bit higher numbers than f-bodies with the same motor for some reason, maybe just the slight driveline differences or exhaust.

 

It's not going to run by anything, the power curves between the two are very similar, the LT4 makes it's peak power at nearly the same RPM as the LS1 does, and is within 5-10 rwhp on average. They would be very very closely matched.

 

Thanx for the opinions guys.

 

How bout a LT4 on a F-bod vs and LS1 F-Bod???

 

Actually, Y-bodies with the same engine dyno lower RWHP due to the IRS.

You may be thinking of the factory flywheel ratings, which are higher for the Y-body due to intake and exhaust differences, and perhaps also because of marketing.

 

Just from my observations at my friends dyno shop, seen 3 of the same basic build ups of 383's and 396's dropped in 4th gen Vettes and F-bodys, and the vette always had about 25rwhp over the same build up in the f-bod, both in M6 and A4s.

 

In my LT1_Edit program, I compared the LT1 (stock) program to the LT4 (stock Y-body) program and there are significant differences. It seems from my observation that GM spent more time with the LT4's programming and it shows in a more elaborate fuel mix (WOT), timing and a lot smoother PE tables. The MAF table is also slightly different (not sure about actual part though). Though both engines are 350s the LT4's performance jewels are more in the heads, intake, cam and programming. The heads have bigger valves and porting and requires a different intake. The camshaft for an LT4 is different too (along with 1.6 RRs). The LT4 doesn't use an EGR valve and it has 26# injectors instead of the 24# on the LT1. Also the LT4 has a 4-bolt and different connecting rods, but that should not translate into any more effective power, just more durable. I believe the LT4's redline is 6400, not sure though.

All-in-all, the net result is 330HP vs 310HP for a 1996-1997 LT1 SS with performance exhaust. Back in the old days when my SS was stock, it pulled 262RWHP, about par with most LT1s.

 

Own a LT4 Vette and when purchased new I actually had the chance to buy a LS1 Vette and purposely choose the LT4 mostly because I knew how to hotrod the LTx stuff and the LS1’s at the time were not responding to mods very well. Plus there was a subjective difference in that the LT4 felt faster. Kinda like a rocket bike vs a Harley. The Harley just feel fast.

At the track with a 100% stock engine I was able to run a number of low 12.7’s around 112mph on factory tires and aftermarket exhaust. I only remember being beat by one LS1 at the time and then the car had an exhaust leak.

Obviously now the LSx is the engine of choice but when they were first introduced, the LTx modded cars ran all over then. Things change.

 

I believe the LS1 engine is also about a 100 lbs lighter due to the aluminum block.

 

really all in all, i think if you put money into both engines, they will run close to the same. If you are talking about bolt on situations, I feel the LSx would win.