Dave, did you have chance to review the flow bench charts that were posted? In your opinion, how do they look? Obviously, flow bench numbers only tell part of the story, but just in terms of shear airflow volume, what is your opinion on them?

 

Mine are coming.... can't wait !!!

 

Congrats! Do you have cams already? Are you staying with the stock bottom end?

 

Running the JWTs. Getting the Cosworth FI ones, once they are available. Building the engine with forged coated pistons and forged rods. ARP studs. Cosworth 3metal bearings. Anti-headlift mod. 14psi pulley on ATI Procharger but going for a higher redline, so I will get more boost. SnowPerformance Water-methanol injection.

Any more ideas ?

Thanks

Danny

 

Found out these heads are 58 CC's. The stock VQ35 heads are 56 CC's. This will lower CR from 10.3 to approximately 10.

Stock CC's =

Swept: 583.0704
Total Chamber: 62.6957

With Cosworth Heads & stock bottom end.

Swept: 583.0704
Total Chamber: 64.6957

 

if you milled them 14 thousandths you could get back the compression

 

Has Cosworth released specs on their FI cams, and availability dates? Seems like good NA cams won't be good FI cams, but so far everyone is saying theirs are great for both, which I don't believe.

-E

 

The chamber is bigger so you have less compression. How would milling (making the chamber even bigger, right?) get you back the compression ?

Thanks

Danny

 

Just about now those 8.5:1 pistons I bought are starting to seem like a very bad choice and I'm kicking myself in the head for not going for the 9:1 ...

Danny

 

you would be making the chamber smaller by milling it, your removing material not adding it. it's 5-7 for every CC

 

Ok I'm lost. I Thought that if you milled (removed material from the sides of a) hole (chamber) you would make it bigger (able to hold more content)

Help me out here, thanks

Danny

 

He's talking about milling the bottom deck of the heads, not the chamber. This would lower the chambers closer to the pistons, making the entire thing smaller. At least, that's my impression.

This is a bit off topic, but how does boring to 100mm affect the compression ratios, since the chamber size (I'm guessing) doesn't change? I'm assuming this would raise the compression ratio in an otherwise stock engine to something like 11.1 or so...

And in a stock engine, to lower the compression to 9.0, you'd have to add 10.2 CCs or so to the combustion chamber with a dished piston, yea? And finally, 9.0 compression pistons with a Cosworth head on a 100mm block would be (if all my math isn't horribly wrong) 72.9 cc chambers with a 634 cc stroke, for a 9.7 compression ratio overall? Or am I misunderstanding the relationships here? I rounded all my numbers for the sake of simplicity, but you get the idea. Does boring change the chamber size to a significant extent?

Also, does increasing the size of the bore without changing the shape of the combustion chamber increase chances of having hotspots/detonation?

-E

 

Couldn't you run more boost?

 

SC, not turbo...



Danny

 

Could, but it's always a tradeoff... his 8.5 pistons would actually be more like 8.3 with the extra chamber size. Non-boost performance is going to suffer more.

-E

 

you should be kicking yourself in the head for going with the ati instead.

i keed, i keed!

 

No offense taken. (don't you just love this new rule )

Well, I had my reasons (at that time). Temperature is always very high here, the choice of turbo kits was very limited at that time (APS refused to sell me a kit b/c of the lack of load bearing dynos in the country), ease of tuning and install, and at that point I wasn't going to build my engine. I should've know myself better...

Danny

If I had to make the decision over, I'd probably go TN ST

 

We're in the process of doing some Cosworth heads on a Subaru right now. Their work is amazing though.

 

Congrats Joe! You will love those beautiful heads!!! And with a set of 11.1:1 compression pistons and a set of wild cams (Nismo Spec 2 cans suit your needs), you should be at 320rwHP+!

cheers,

richie

 

im just messin with ya man.