Hi All --

I'm very intersted in increasing the compression of the F20C from 11.1:1 to something around 12-12.5:1.

I was wondering what would I need in terms of parts to do this and maintain a certain level of reliability in the car?

Thanks in advance!

 

I would suggest that you look into the type of gas required for 12:1 compression and if the pistons and walls can handle that particular racing gas. I'm sure that 93 octane *might* be ok, but probably something a bit higher and more expensive would be required. Also, there might be some issues with the piston - valve clearance.

Play it safe, just get a thinner head gasket (Spoon) which will help out your compression gains.

 

i'm sure ben would love to help you with a set of spoon lightweight pistons and gaskets

 

Hahahaha -- Rich! Forever a diplomat!

We can get 94 pump gas here in Vancouver -- I'm confident we can run at least 12 *safely* with the proper equipment and installer...

 

12.5:1 is no problem with 93 octane... basically all you need to do is get a thinner head gasket and if thats not enough ..you would have to mill the head, to get that kind of compression... another way would be to welding the combustion chambers , that is welding aditional material to the quench zones of the combustion chamber to increase the amount of quench and to increase CR ( compression) ratio. This produces more turbulence in the chamber , thus promotind better mixing of the fuel air mixture as the piston approaches TDC. and ofcourse the other way would be high cr pistons.

 

OK... I give up. What do y'all know that I don't?

1) How can raising the compression to 12:1 or higher work on 94 octane when people complain of detonation, stock, on 92 and 93 octane? From what I've read, a compression bump that drastic would require MUCH higher octane than that.

2) Why are you (Shamu) confident you can run 12.5:1? Or is "proper equipment" a lower temp t-stat, programmable ignition and a/f...

3) Why do you want to bump that much? Just power?

I would suspect that 100 Octane gas would be required, but I don't have a good feel for what static CR = what octane on our motor. I find it hard to believe, though, that a 1-2 octane number drop would cause reduced power but a 1 point-plus bump in static CR wouldn't require more than a 1-2 increase in octane.

I doubt it would damage anything, though- but I would expect a loss in power. I would suspect most of the advance to be dialed out.

Maybe with some cooling mods... then again, I *still* think it would require a higher octane fuel.

 

[QUOTE]Originally posted by Shamu
[B]Hahahaha -- Rich!

 

Spoon has this:



And this:



But you'll pay this:

$$$$$$$

 

very very true Wes -- and for the piston/ring set, you gotta wait a very long time!

I'm strongly considering the head gasket, but I'm wondering if it's worth the install effort....anybody with experience with the Spoon head gasket?