CAMDUP

i think your gonna find MMR to be right.....9.1-9.3 is prob where you'll end up..i didnt know earlier that you had 23cc dishes......and "i think" DSS may be wrong about 44cc bein OEM

Fobra

if your not against race gas 9+ is better in many circles. Personally I think the 8.5.1 is ideal, but on the 4.6 the latter might be better.

Tim99GT

Well i talked to TF today after talking t you guys and he said that my CR with his 38cc heads and my MMR 900 will be 9.12:1



Thats the thing... I was always told that 8.5:1 CR is the best CR for boosted apps, but after talking to these guys, its not.
I'll elaborate..

street driven boosted car is (according to them)is best to be in the say 9.0:1 - 9.3:1 CR

track cars that are going to be running high boost all the time(lets say 20+ PSI) need to be in the 8.3:1-8.5:1 CR range. This allows them to run higher boost levels and be somewhat safe from detonation.

Basically,from what i was told, a 8.5:1 CR street driven car will be extremely weak on the hp/tq side under normal driving conditions.Jim Cushman said that you lose something like 3% of you hp/tq per point in comp lost. This is the reason of running a 9:1-9.3:1 cr.
With this CR, your car isnt such a slug without boost. Granted you cant run as much boost as you would be able to with a 8.5:1 CR, but it will be a better driving vehicle.
Tim @ MPH said that he can make more power at say 17 PSI with a 9.2:1 CR than he can a 8.5:1 CR.
So all in all, i kind of see there point now. You would have to run more boost with a 8.5:1 CR to equal the same hp/tq that you would get with 9.2:1 or so.
IDK if this is all comming out right and you all are able to understand it...

amoosenamedhank

That makes sense.... with the high CR and lower boost I would assume that to be less stress on the short block because of the lower combustion chamber pressure.

Fobra

Well I was trying to avoid typing stuff that wasn't pertinent. I agree that keeping a little higher on the 4.6 is better, both for power and powerband/drivability. But I am not going with 4.6 so my opinion is little biased, when running a larger displacement the effect of running that lower cr is mitigated to larger extent... but to make crazy power... in either setup you should run a lower CR. But for mid level power and drivability I completely agree with the way your going

Fobra

My thing is that I dont want to run race gas... so that to me is #1

Tim99GT

I wont be either. Nor will the car really ever see it.
I will be running 93 oct for this setup. Tim said that with 93 oct., 17-18 PSI, and the ~9.2:1 CR, i will be making aroung 620-660RW hp and like 580-600RW tq with a safe tune. He told me i could make more, but the likely hood of you ever needing 700rw on the street is slim to none. I think i will be happy with 600RW+ for now
I asked him if everything would be nice and streetable and he said, " to an extent.... I'm mean, its not going to be a honda or anything. we are talking about you running 600+rwhp on the road here..(he laughs) ". IDK, i have faith in Tim though. He has tuned quite a few of these motors with this blower and all have come out good.
I think i am going to go ahead and order the heads today so i can start to get this thing together.

Tim99GT

Just bought my heads!!!!!!

Ordered:

38cc TF twisted wedge heads
ARP head stud kit
Complete plug and dowel kit for the motor

The really good news is they are going to ship today!!! should have them by next week!

steve0914

thats awesome!!!

10inch Terror

Those should work great! Congrats!