I'm looking for some information on the stock aluminum heads that was supposed to be an option for the 96' LT1 engine, head casting number that should be for this motor is:# 12551561. Is this really a 350 HP engine, as it's claimed? If it is, what would the code # for these heads be, that is part of the code options listed with each vehicle? As I'm a novice, any help here would be highly appreciated.

 

Where did you get this information?
There are no magic stock casting heads that came out in '96 which made a stock LT1 engine produce 350hp.

 

Just total
No such thing.

 

Didn't the lt4 come out in 96 in the vette. I think it was rated at 330 hp, which is close. just thinking out loud

tia

andy schuck

 

in 97 you could get the lt4 in a limited number of ss cars that was rated at 330 hp, but i have never heard of any option for a 350 hp lt1 and yes in 96 the lt4 was an option for the vettes.

 

No such thing, carry on.

 

That casting # is the standard LT1 head for 96-97 f-bodies, and 96 LT1 vettes. They flow slightly better in stock form than the 92-95 "643" castings, but certainly not 75hp better.

The other guys are right, there's no such thing as a factory built 350 hp LT1. The 96-97 f-bodies with these heads were rated at 285hp, and the 96 vette LT1s were rated at 300hp.

With that being said, there was an LT-1 installed in camaros rated at 360 gross horse power...but that was back in 1970 and those motors are nothing like the modern LT1s

 

The LT1 in my 95 was factory installed and it made about 350hp at the flywheel.. put down 314rwhp through a 9" so i'd say it's pretty close w/ the supporting mod's I.e headers, etc.. i've seen a few others on here as well. a stock LT1 will easily do 350hp..

 

I agree....however I think he is meaning "showroom stock" or no mods at all. Just not gonna make those numbers in 100% stock form. And what we are all trying to explain is that there was no "special" LT1 with "special" heads. There is nothing special about a 561 casting head.

 

i think you are talking about the lt4 heads.. and the ;t4's were underrated at 330hp.. mine 96 c4 lt4 dynoed 298/303 stock...

 

I thought the 561 casting were specific to a 97 LT1 ? Mine put down 323 rwhp & 343 rwtq with all the bolt-ons, its a 96 LT1.

 

Mine's a 96 as well, and it had 561s on it

 

What rear? 10 bolt? they're all gonna dyno about the same if the mod's are compareable.. at least they're consistant..

 

It is my impression the original post has nothing to do with heads supporting 350hp with all the bolt-on bells and whistles. Reads more like if there was a LT1 engine in '96 that made a factory produced 350hp. Clarification?

 

Well from what i gather yea, i think it was meant as a advertised factory 350hp LTx but i kinda took it as he's looking for a crate motor type setup using these heads therefore exhaust sys. is up in the air.. either way.. 350hp is a realistic number for a stock head/cam LT1 if that is what he's asking..