I believe you are right about S2000Junky running an FPR with a VAFC, but it is different with FI, since the FPR will increase fuel pressure as boost increases. In an NA application, you'll get full fuel pressure any time intake vacuum drops. It might be much more difficult to tune.

 

It's hard to say how much you would gain, since that depends on how rich your AFR is before the VAFC. Do you have access to a wideband O2 sensor / datalogger?

 

Well before i would throw this sucker on King Motorsports dyno, i was thinking bout getting an AEM UEGO wideband to help with the tuning process..

 

[QUOTE=gernby,Nov 2 2010, 07:31 AM] I believe you are right about S2000Junky running an FPR with a VAFC, but it is different with FI, since the FPR will increase fuel pressure as boost increases.

 

The '00-'05 S2000 does have variable fuel pressure based on manifold vacuum. Acording to the Helm's manual, the fuel pressure should be 38-46 PSI, and at WOT it should go up to 47-54 PSI. There are different types of adjustable FPR's. The one that I had in my '90 Integra was variable rate with no boost.

That said, tuning would be more difficult, especially with a VAFC. To really get the tune right, you would need to take advantage of the part throttle features, and spend a lot of time on the dyno getting the part throttle tune right. Otherwise, it would run pig rich at higher load levels with large NEGATIVE short term fuel trims.

 

[QUOTE=gernby,Nov 2 2010, 10:49 AM] The '00-'05 S2000 does have variable fuel pressure based on manifold vacuum.

 

Would it be smart to get a adjustable FPR to tune with my UEGO and VAFC?

 

If you are a do-it-yourself type and you don't mind having to do a lot of experimentation and learning, I'd say go for it.

You won't want to do this if you have to take it to a tuner every time you have a hiccup.

 

After extensive tuning experience with VAFC type devices on my '02, and even building my own self-tuning device, then spending many hundreds (if not thousands) of hours geeking out on my FlashPro tune for my '08 for full and part throttle ... I think it would be a signficant challenge for anyone to get an FPR / VAFC tune "right". Full throttle tuning is simple, but part throttle tuning is a bitch.

 

I managed to add a maximum of +2 with my VAFC2 n/a after that it bogged down - however it didn't richen up the mixture that much but my car mainly needed leaned out throughout the rev range so i was lucky.

The AFR with my VAFC2 and CT RRFPR on my SC in WOT was pretty good TBH but part throttle as Gernby said resulted in high'ish - STFT and -LTFT.

Brad, i put a gauge on my RRFPR SC setup and at idle is just less than 60psi and at max revs just less than 89 psi - watched on a dyno.

My fuel trims are now much better with the greddy EMU since tuning and generally the LTFT and STFT values follow each other.

I think there is a change in the fuel pressure system with DBW models, however exactly what has escaped me and IIRC there is a subtle difference with UK cars - however dont quote me on this, I'll check my notes.