What would you do?

[Forzfed]

So I'm rebuilding my 4.1 and thinking of dropping a smaller cam in it so I don't have to rev it that high.  Buzzing the motor past 6300rpm I can rip off mid 11's on pump gas.  I use to have 9:1 compression but the last guy that machined the motor got me diamond pistons that took me down to 8:1.  I would like to get the compression up but not looking forward to buying new pistons.  That is why I thought I might drop a smaller cam in.  Anyone know if I can get a thinner head gasket?  Should I shave some off the heads?  What would you guys do?

[Steve Wood]

I would buy the thinnest shims shims that Jason sells if they fit 4.1's, and take some off the heads, myself.

if Flat tappet, I would just as soon have a cam with a duration around 208 but a 212 is okay with a few extra inches.  I see no point in revving over 5800...I will take boost over rpm any day.

If it hooks, high tens should not be a problem with the right turbo

[williambavila]

I would turn up the boost and call it good. 

[Forzfed]

I currently have a 224/224 roller in it.  I was thinking of going with Full Throttle's 215/220 roller.  I was thinking a little bigger than 212/212 because it of the extra cubes of the 4.1.

[Scoobum]

That's a 9/11 in that car. What stall? What turbo and exhaust housing size? What heads are on it?

[Forzfed]

It has a 9/11 3200 with champion ported steel heads.  The turbo is a CPT-66 S trim with .63 exhaust housing.

[Scoobum]

It has a 9/11 3200 with champion ported steel heads.  The turbo is a CPT-66 S trim with .63 exhaust housing.

With the cubes you've got I assume it spools well. How much boost have you put to it so far?

[Forzfed]

Most it has seen was 22psi and you could tell it launched a lot harder!  It spools pretty good.  I can still break the drag radials loose.

[Scoobum]

Most it has seen was 22psi and you could tell it launched a lot harder!  It spools pretty good.  I can still break the drag radials loose.

You've got more turbo...more cubes...and a convertor when locked that will have a lower slip percentage than mine. Bump the boost up to 26 psi and dial in your low gear fueling and timing. Use race gas. You can run silly amounts of low gear timing...and to date I haven't seen a hint of KR with it. As far as compression ratio listen to Steve or others who have messed with it. Contact Bison for cam selection. He can custom grind one for you.

[TexasT]

With that low Cr more boost would be in my future and 26psi would be a stepping stone. I'd keep turning it up probably past 30 if you can keep it from retarding the timing or seeing any knock.

[Scoobum]

With that low Cr more boost would be in my future and 26psi would be a stepping stone. I'd keep turning it up probably past 30 if you can keep it from retarding the timing or seeing any knock.

Jack Cotton sold/sells 66's. He'd be able to tell ya' where they run out of steam. My guess would be 28 with his heads/cam.

[Steve Wood]

I bought that turbo from Jeremy several years ago.  28 is no problem