just got a call from G-force and come to find out my car has an iron block in it. This could be good or REALLY bad! Had th car for 2 years, never checked the block.....

 

That's a good call! Bore and stroke it to a 408!

 

well all this time I thought it was a stock LS1, but they are saying if its a 5.3 block then definately got fucked.....bought it from a dealership, they would have never known and it was never in an accident. I am hoping its an LS1 iron block with forged internals

 

the tuner said if its a 5.3 it will show on the dyno, I dont think it can be because I have LS1 numbers at the track. I am hoping it is a 6.0 iron block

 

Unless it's the 4.8/5.3L block

I had the same thing happen to me. I bought a car from out of state, and it was down a dirt road so very dirty under the hood when I bought it and checked it out. I couldn't see anything iron vs aluminum. I will take a magnet with me next time. I got back here and put it on the dyno to baseline before heads/cam, and it was terribly low on power (5.3L)

 

Forgot what side it's on, but there's a marking on the block itself as to what it is. Also, isn't iron a darker shade of grey as apposed to the much lighter looking aluminum?

 

yes you are right about the color, but on a dirty block its hard to tell untill you tear into it.

 

Nah all you have to do is stick a magnet to it, no need to tear it down unless you're curious as to the internals.

 

G-force just called, and they said its definately a 5.3or 4.8 block. I dont get how theyd know without tearing into it but thats just me. I PM'd matt, my car puts down low to mid 13/s on street tires in 90 degree heat with just headers and exhaust. seems all this talk about a 5.3 would put me at much higher et's

 

a LS1 with headers/exhaust should run low 13's to high 12's so the numbers agree with it being a 5.3 & the block should also be stamped with what liter it is as well. I believe its on the rear passenger side so they could have check with it on a lift.

 

Like we said, there's an external stamp on the block that denotes what type it is. There's no need to tear it down simply because you can bore a 5.3 block to ls1 specifications, so if it was indeed bored to that you wouldn't even be able to tell from taking it apart. You would know simply by the casting mark on the block itself.

For all you know, it could be the same displacement as an ls1.