I need opinions please. I have searched but want views on my setup.
I am going to get the LE2 done from Lloyd. He has said for NA, my chambers will be 55cc and I should look for 4-6cc piston. I will also be going .030 over on the bore. Using .026 head gaskets with a stock deck height of .025 and 5cc piston, I get a CR of 12.0:1. If I ZERO the deck, it's 12.9:1.

How much is too much for 93 octane and would I get a noticable increase by zeroing the deck? I am not going to the track, merely a fan of power/speed. I am also not planning on spraying or using SC. I know I would need to lower the CR to do that.

If all else fails, I can return my .026 head gaskets and get .039 which would give me 11.7:1 stock deck height or 12.5:1 zero deck height.

Also, if I go this high on CR, is there extra consideration on forged vs hyper pistons?

I beleive I saw a post that had somebody doing 13:1 on pump gas.

Which would you do?
11.7:1?.....12:1?.....12.5:1?.....or 12.9:1?

 

I wouldn't use a 0.026" gasket with a zero decked block, that't too tight of a quench. Look for something around 0.04" quench distance, a zero decked block with 0.039" gasket will be good, or 0.015" deck height with 0.026". And don't assume ya have 0.025" deck height, you must measure.

 

I think the dynamic compression ratio will be of more use to you when figuring your compression out. The dynamic compression ratio takes into account cam overlap to give you a sort of "working" compression ratio if that makes any sense.

As was said, I would not do the .029 headgasket with a zero deck. If you're going to zero deck it use the Fel-Pro 1074 headgasket which is .039 if I remember correctly.

 

I agree with the above. You can have 12:1 static comp pression but have 9: dynamic which is pump gas friendly. You can also run a big cam with lots of overlap to bleed some of that cylinder pressure out as well. And you dont have to lower you compression for the bottle.

 

Chuck...

you got something screwed up there pal...

A -5cc flat top, 55cc chamber, .040" x 4.125" gasket ZERO DECKED on a 355 is 11.58:1

I think you gotta either take the - out of your piston volume or throw it in there.

What I listed for the combination is EXACTLY what I would run for the LE2 setup... a 355 can setup up to a LE3 cam, but thats more of a race cam than a street cam.

Bret

 

If I'm looking for -5cc, how come on the calculator from this site I get a totally dif outcome then if I leave the " - " outa there? I do get 11.5 on it when I say 5cc.

 

Certain calculators do it differently, perhaps the one you are using says "piston dish volume", that would automatically mean that whatever number you have in there is a dish and not a dome. With this situation you would put the "-" to show that is the opposite of a dish, because 2 negatives makes a "+".

 

No, no it doesn't

Rich

 

LOL!!

 

Rich is right!!!!
A minus number means to take away from the chamber volume=more compression.That is a dome,no valve reliefs,shortening the deck height,leaving the piston out of the hole or thinner gasket all of which take away from the chamber volume.


Never seen a calculator that did the opposite.

 

The one on this site does LR.... it makes no sense whatsoever either. Only dam comp calc I have ever seen that doesn't go by the standard.

Bret

 

You did it the right way then Chuck!

 

Sounds like they need to fix that problem.. Never used it but that's screwy--sure could mess up somebody's figgurin.

 

Tell me about it.... now if they convince them not to use .050 IVC to figure DCR we wouldn't have to post so dam much.