Skimming head

[maupineda]

What would be the value to skimm the head to still be able to get a few bhp more by remapping the car to suit? What would be the new CR with that value?

My car is a phase 2 172, which is its CR, 11.2:1 or just 11:1?

Thanks

 

[sammyhale22]

i think the F4R is 11.5:1

 

[maupineda]

That what I thought!

Making the question more interesting. How much can it be skimmed and still fit CAT 428's!

 

[sideways danny]

i think the F4R is 11.5:1

10.5:1 IIRC (might be 10.9:1, I can't find the CD, so that's from memory) definitely not as high as 11.5

 

[Fred@BTM]

11.2 IIRC the 197 is now 11.5

 

[sideways danny]

Found it. F4R 730 is 11:1

 

[maupineda]

Ok, and what about skimming it and fitting 428's?

 

[partyboy23]

id assume you would have to open up the valve seats as in make them deeper on the piston head if you want to run 428s with a skimmed head,guess it all depends on how much you skim it tho,i may be wrong tho

 

[maupineda]

Thanks partyboy, I am hoping someone has done this in the past to leverage in that experience.

Anyone?!?!?!? bump

 

[maupineda]

No one else?

 

[stan*]

I woulsnt be cutting seats back to increase piston:valve clearance---counter productive really.

I would either: not bother skimming it by such an ammount as the gains are going to be negligable anyway; back the lift at tdc off; or relieve pockets on piston crowns to give the desired clearance if you have clearance issues.