DR

Hi Tony,

>Have these changed since then?

YES, since about 3 years ago they are no longer modifed stock regulators but are fully billet aluminum regulators and are boost sensitive.

Thanks for reminding me that the pic on our website is way out of date!

They look more like this ,.. but with proper 928 ports



Merry Christmas!

hacker-pschorr

When you say "boost sensitive" do these act like a rising rate regular as boost increases?

Nice looking piece - is the price on the site accurate for the new unit?

DR

>When you say "boost sensitive" do these act like a rising rate regular as boost increases?

Yes, in simple terms they increase fuel pressure as the boost increases

>Nice looking piece - is the price on the site accurate for the new unit?

Yes the price is accurate, sorry again for the old pics, not sure how that happened.

Here is a quick crappy quality pic of an actual 928 version (late style)...

DR

Hacker,

Here is a very early test run (August/September?) using only our Adjustable Regulator on our early Twin Screw Prototype system with no tuning (or newer enhancements) at approx 6psi and stock cats.

Also keep in mind that the A/F readings are from a tailpipe sniffer, my wideband showed 1 full point different (11s). I was purposely running in the the low 11s for safety as I was still very overly cautious with my engine back then :-)

Even with those conservative settings back then, 320-325 ft/lbs of Rear Wheel torque at 2000rpm (with no "tip in" issues :-) was pretty darn fun!!

Also of note, the "dip" in the mid RPMs A/F is where the LH computer still thinks it had a flappy valve. Just after that fuel "dip" you can see that a dip also shows up in the HP and torque when you magnifiy it ( you can see it a little on this chart). This can now be easily smoothed out with the SharkTuner!

hacker-pschorr

My two cars are L-jet and CIS, does shartk tuner work with either one?

Daryl

Dave,
Can you quickly tell us how you adjust the regulator to meet idle/full power requirements?
I think I need one of those!

DR

>My two cars are L-jet and CIS, does shartk tuner work with either one?

No, BUT they don't have Flappy Valves either so that dip shouldn't be there :-)

DR

Hi Daryl,

>Can you quickly tell us how you adjust the regulator to meet idle/full power requirements?

OK, in "quick terms" On a dyno (or street test) you adjust the regulator "screw" to get the fuel pressure that will give you the WOT A/F mixture you desire at approx. 5000 and up rpms.

>I think I need one of those!

We have always recommended and used them even for non-boosted 928s for 8+ years. It is a fine tuning device for adjusting fuel pressure to get optimum A/F at WOT and will help get the most out of any mods you make (exhaust, Crossover, etc. etc,) to your 928.

Daryl

Tony, I don't know what the pressure is under full throttle. I can tell you my A/F gauge reads 12s at upper RPM levels. It drops as the RPMs rise. The fuel pressure is 30lbs at idle.

BrianG

Dave: What is your initial presssure set at, at idle?
(with/without vacuum?)

DR

>Dave: What is your initial presssure set at, at idle?

If you are talking about a stock 928 I always recommend to start with stock pressures and then adjusting the pressure for best WOT A/F mixture. The Computers will then adjust for the idle and "cruise" settings.

If you are talking about the TwinScrew system if I recall on that dyno run it was around 30-32psi ? I have the GT disassembled at the moment as it is getting its first (the first) production version intake installed for testing so I can't confirm what I had it at recently. I also concentrated on the WOT pressure settings and it was always still in the correct range for the stock computers to get the proper mixture at idle.


>(with/without vacuum?)

Opps, I missed that part. Those settings I described were with vacuum.

Daryl

Mike,
Ok, lets just say that I might consider a little more boost. Theres my smokin happy face. More smoke please!
How would the pulley setup work? My SC pulley is looking small to me at 8lbs.

BrianG

Oh......... here comes trouble!!

Daryl

Hey Brian,
We're just talking and much more smoke please!

FlyingDog

I haven't used DR's unit (yet), but I do not believe it is rising rate. It should increase pressure with boost, but not as a rising rate. It should be linear like a stock regulator. If you add 6lbs of boost to a stock fpr or an adjustable fpr, you should see close to a 6psi increase in fuel pressure. To use the question that Tony asked, a stock 80-86 fpr (2.5bar/36psi) with 8lbs of boost should yield close to 44psi. A 2:1 rising rate fpr would yield 52psi, 10:1 would yield 116psi.