car will have le2 heads, le3 cam. stock bore size with forged rods and pistons.
the car is a weekend driver on pump gas ( 93 )

the guy at the machine shop said if i go with a 11:1 compression ratio, my car will need a mixture of pump/race gas. but i searched here on cz28 and saw that people are more around 11.3:1 or 11.5:1 on pump gas ??
the guys said i should shoot for 10.3:1 compression. i don't want to get this engine together and figure out i have a ****ty compression ratio
what would be the best compression ratio to go for? the highest compression i can run on pump gas will yield the most hp correct?

reason i'm concerned. my buddy JUST got his forged head/cammed LS1 with a very low compression, and dynod 357 rwhp. should be over 400rwhp for sure.
thanks guys a bunch
-Jason

 

high 10's should be fine, I wouldn't aim for higher than 11:1 for a DD

stock is 10.5:1

 

Jason,

It's best to ask the guys who worked up that package..... ;-)

The best thing to do on that setup is run a flat top piston. Run the heads as is with a 55-56cc chamber and zero deck the block with a fel pro gasket.... Your shooting for about .040" quench height. That will give you the right compression and burn characteristics for that setup.

If you need any help with parts shoot me a e-mail.

You might want to look into WHY your buddy did so bad on his motor. It could be because it's from a shop that didn't get the machine work right.

Bret

EDIT: stil wondering what the stroke of this puppy is.....

 

well i guess i'll go with the guy's word and try to get around a 10.3:1 cr.

as far as my buddies car, i think he just saw pistons and bought them. but ya kinda sucks, he's really disapointed with his #'s

 

Jason,

The LE 3 HC package was meant to work with a certain CR range. If you are familiar with Dynamic Compression Ratio, you know that cam timing effects that and the engine's need for octane. Your post indicates that perhaps your "guy at the machine shop" doesn't understand that.

FWIW, if you don't know, SStrokerAce (Bret) is doing Lloyd's cams. Email him as he suggested. He'll help you out. Both he and Lloyd have a very real ($) interest in having you as a satisfied customer. Unless things like static CR and machine work are correct, you are setting yourself up for a disappointment.

When in doubt, go to the horse's mouth (LLoyd and Bret in this case), not the other end of the horse.

Good luck.

 

Hey Old SStroker, Thanks!

I could do that thanks in person but I figured I would give you one for Lloyd too.

Mystic97Z,

We are not talking about a little difference in performance here, this is EASILY 20hp down, plus your average power is going to be off 3.5% (which is no easy feat to get back, this is 25 points on the Engine Masters rating scale), drivability will be worse, all just because you are off on the compression ratio. I'm a engine builder and this setup will work to a tee. I'm doubting that your engine guy has stock bottom end LT1's making 400+rwhp on head/cam packages under $1500, THAT'S WHY YOU WENT TO LLOYD IN THE FIRST PLACE! Look at the quote/link in my sig, there is a reason it's there. Changing a engine combo will kill the power.

BTW this will work on 91-93 octane without issue.

Bret

 

Talked to Jason some more on this...

Ends up that his heads are 52.5cc, and there is a Ross -9cc Revearse Dome piston that's perfect for his 355. Should get him 11.5:1 which is perfect for the LE3 cam.

Bret