LT4?

[TheBandit]

How can i check to make sure that the engine in my car is definitely an LT4? just bought the car and want to make sure of it and everything.. casting numbers im guessing? if so what should i look for? i beleive its an engine from gm performance

[Batman]

If it's a factory LT4 the bright red plenum should be a giveaway, what year car? The 8th digit of the VIN will tell you, but I don't know what the LT4 was

[Pampered-Z]

I don't know of any different casting numbers on the block, it's a standard corvette 4 blot main LT1 block with upgraded internals. The LT4 engine used in the Grandsports corvette used a different tensioner, but other then the red intake and valve covers nothing else external is different. The LT4 heads are part # 12555332.

[TheBandit]

hmm alright... no red plenum, i dont think this is from the factory.. its a 94 formula but he pulled the lt1 that was in it for an lt4.. was just trying to verify that it was an lt4

[Bandit]

RPO on the door should also list LT4..

LT4 came in the following

96 Corvettes (silver body color)
94 or 95 Corvette GS
97 Camaro SS 100 made
97 Firehawk 29 made

I am sure there are a few more models that may of had the LT4. Odds are if its not one of the above mentioned its an aftermarket kit.

[Pampered-Z]

The reference material I have list the LT4 as a one year offering in 1996 in the corvette from the factory as a 330HP option, in either the base model or the SE Grand Sport package. I've seen a 96 black vette with the optional LT4. It was part of GM's showroom stock racing package and had the Getrag M6 trans in them, not the T56.

The LT4s that SLP used were actually hand assembled and blue printed and rated at 345HP.

I think the only way to verify your engine is a true LT4 would be to pull it apart and verify the part numbers, main caps, rods, pistons, crank and all special part # in an LT4.

[BonzoHansen]

GS was 96 only as well, correct?

[Batman]

It may be an LT1 with LT4 heads and cam, but all the LT4's had the red intake and it wasn't available in an F-body in 94

[Bandit]

GS was 96 only as well, correct?


Yes, I was not sure of the year. It was only 96. The RPO on the vettes should list LT4. On the Fbodies they were LT1, but it was an 18K option in 97 installed by SLP.

[Pampered-Z]

GS was 96 only as well, correct?

Thats right Zippy!

[TheBandit]

it was definitly not stock.. the motor was pulled, he claimed he put in a gm crate motor lt4.. i just wanted to verify if that was true or not, i know it didnt originally come with it

P.S. - Stock 94 firebird formula rearend.. posi i assume but whats the gear ratio?

[Batman]

Gear ratio is probably either 2.73 or 3.23, so he is saying it is an LT4 engine with an LT1 intake setup? If memory serves there was more differences in the intake then just the color, I think it at least had bigger throttle bores and the runners may have been different too. so he may have an LT4 longblock, but it still isn't an LT4 crate engine

[97ws6]

Pull the valve cover and see if you can find casting number 12363287. That is the casting number of an LT4 head, if it has that head, it has to have the LT4 intake, an LT1 intake wont fit. At least then you know you have the intake and heads, they are the most important thing.