Ish_944

Hahaha, just to be clear: the 174 rwhp 924S was _not_ mine!
Nevertheless, must be a terrific motor!

Noah: Sorry about your "new" head. Some people really do not deserve to come close to these cars...

Arominus

Damn, thats brutal in the cam journal.... Yeah you can't do anything there. WTF.

Noahs944

Thank you guys for all your inspiration, offers & support.

I am disappointed & relieved with the news of the 16v head. I knew going in that head damage was on the menu, and my bar was a good block. Which it has!

I really have always been gearing up for 8 valve heaven with the understanding I can adapt most my junk over to Turbo if ever that was in the cards for Wilson.

I just don't like all that Turbo stuff under the hood. Wilson is a free spirit!

Anyway, thanks again.

V2Rocket

Noah...
If you take a peek over on the turbo side of the forum, there is a guy experimenting with a 928 4-valve head on his 944T.

The head is almost identical to the 944S head but has a larger-cc combustion chamber, about the same CC as the standard 944-2valve head...which means you get more airflow without needing spicier gas.

I've got access to 2 such heads if you're interested...

SloMo228

Interesting... Any idea what this would lower the CR to on an S motor? I have had a supercharger build in the back of my mind for a while but the high CR of the S was always a concern.

V2Rocket

the guy said the 928 head was 56cc chamber. 944S is 42.
rough estimate, it'd drop you into the low 9's.

SloMo228

Thanks. Gives me something to think about for my future engine build.

V2Rocket

summit racing's compression calculator...not 100% accurate but should be in the ballpark.

Ish_944

I'd like to see somebody doing this conversion!

What sort of an intake manifold could be used with the 928 head?
The 56 cc head is close to the 8v, mine measured 59 cc. That would give a ~0.4 boost in cr.

V2Rocket

the "S" manifold might work, but the port shapes are different - might be a custom job.

Noahs944

V2, now that is interesting...

Decided the next engine mod will probably MegaSquirt with the guidance of Michael. Using Map instead of MAF probably.

This won't happen immediately.

Got a question about intake manifolds, Where can I purchase components to build a similar intake design, things like flanged tube ends & such. I can weld aluminum (sort of).

V2Rocket

yeeeesssssss

Noahs944

Can a person use MAP on a n/a with a external draw of crankcase gases (such as a pump or one way exhaust siphoning valve)?

V2Rocket

recirculating the PCV into the intake actually works better than exhaust/draft tubes, for power.

odonnell

What would you be running that needs a pressure signal from your crankcase pressure?

MAP (manifold absolute pressure) looks at the vacuum that is created within your manifold, so you'll want to tee in a MAP sensor off of the intake tract downstream of the throttle blade. Mine tees into the thin vacuum line that goes to the FPR and damper and is physically mounted on the throttle body, no issues with signals.

For a speed density tuned setup, that signal tells the ECU what load the engine is under. An NA car will be under full load when the MAP = atmospheric. For reference, my car idles and cruises around 38 kPa, engine braking = 0 kPA, WOT = 102 kPa, and general driving is between 40-90 kPa throughout the rev range. Once the ECU sees the MAP reading, it combines that with the measured RPM to look up a value in a table known as a VE (volumetric efficiency). A VE is simply a ratio, it represents the amount of air used in a complete engine cycle relative to theoretical amount that it could be using given displacement, # cyls, etc. The VE table is what you actually tune... it's something you find experimentally. Or hope someone else shared their VE table