I already searched and can't find much. Is it correct that really the only thing causing a significant difference in power between the engines are the heads and intake? I looked earlier at the dynograph at the STS site for their turbo setup on an LT1 and on an LS1. The LS1 with 8 psi makes about 100 more hp and tq from 3 to 6k than the LT1 with 7 psi. ! That was with both engines stock except for the turbo and maybe alcohol injection. And of course there's a lot of articles out there with 480 fwhp LS1's with just basic heads/cam/intake setups. But the STS dynograph really makes me want to sell mine and get an LS1.

I wonder though why, if the heads and intake are making the real difference, an LT1 can't be made pretty much the same. I know there are no aftermarket intake manifolds for the LT1 because they just don't help. But I assume the ones that were tried were desined to fit the stock-type heads right? And I assume again that all the aftermarket heads are designed to fit the stock intake manifold. So why doesn't someone design a new heads/intake for the LT1 and get LS1 performance?

 

Good question! I want to know too! The LS1 heads flow around 280 or something from the factory. LT1's are 220 or something. Someone should make an LS1 "perform-a-like" top end for the LT1.

 

Because of money. If GM made a second generation of the LT1/LT4 motor like they did with the LS1/LS6 LS2/LS4/LS7, there would be a market for new intakes. But even the LS1 crowd only has the F.A.S.T. intake.

 

The LS1 heads have "cathedral" intake ports ... they're not the traditional rectangular port that most/all SBC's had. I think they just really did their homework when these heads were designed? Also, the valve arrangement of LSx engines is the same as BBC's, and different from older SBC's. Instead of E-I-I-E-E-I-I-E they're E-I-E-I-E-I-E-I ..... I don't know if that makes any difference, but I think I maybe balances the heat throughout the heads? Instead of having that high concentration of heat between cylinders 3 & 5 and 4 & 6.

But yeah, in the big picture of things, the heads are the main difference, but then you've got other things to consider like the coil-on-plug ignition system. It doesn't require any mods to it until you start getting into real high HP applications. On the other hand, how capable (or reliable) is the opti-spark?

 

The big difference in the heads is the valve angles.... 23deg for the LT1, 15deg for the LS1. Put a set of 18deg or 15deg heads on an LT1, and see how well they flow.

http://www.idavette.net/hib/ls1c.html

 

"From a performance standpoint, cylinder heads are the most significant feature of LS1"
-from the suggested site, http://www.idavette.net/hib/ls1c.html

That clears that up. But then I don't see why we have guys with LT1's straining, going to solid roller cams, getting 12 mpg, and poor driveability, to make 460 rwhp NA if LS1's can make this relatively easily and the only major difference between the engines is heads and intake. It just seems like AFR or someone could design a heads/intake package copying the LS1 design for about $3500 that would make 460 rwhp with a reasonable sized hydraulic roller. Not enough demand like Camarocracy suggested?

 

What sort of MPG are the LS1 guys with massive HP getting? Such as 400, 500, 600 RWHP? (with or without FI)

 

headers is a good point why no one has done a conversion. If they switched the heads to a different style, they would need to make new style headers for all the cars that the LT1/LT4 came in to fit the new heads.

 

I've heard that it's fairly hard to get 500 rwhp with a NA LS1 but they probably get about 20 mpg at 450 rwhp. About the same I would guess as a NA LT1 with 430 rwhp.

I see what you mean; you would need a new fuel rail setup and longer pushrods, but I don't see why the lifters or rockers would need changing if you had LS1-like heads and intake.

The headers for Camaros and Vettes are all the same as far as I know, so there would only have to be one new header design.
I suppose AFR and other companies that make aftermarket heads for the LT1 know what they're doing and if they could have gone to a design with less valve angle like the LS1 heads they would have. Or maybe they have, I don't know.
I'm tempted to really look into this.

 

N20Dave seems to have solved the LT1's head needs.... 705 flywheelHP on a pair of SB2.2 heads. And that was just an early dyno pull.

http://64.65.63.61/forums/showthread.php?t=375560

 

That is impressive.
I'm being lazy by not looking myself, but is it true that all aftermarket heads for LT1's must, and do have the same valve angle as the stock heads?
It looks like the best AFR's are ~$2500. I don't know how similar their design is to LS1 heads. Maybe not very similar. http://www.airflowresearch.com/Airflow_Racer.pdf
But again, they're probably designed to fit the stock intake manifold and headers. I wonder what kind of head AFR would design for the LT1 if they could match it with a newly designed intake and matching headers?