Date: Tue, 15 May 2012 23:36:28 -0700
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: Adjustable rate fuel pressure regulator? anybody try one?
In-Reply-To: <CAHTkEuKkVsapey8kTXULrvNjPue+Rn1mUCbPt68SPyPggNJN6g@mail.gmail.com>
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if it's Motronic EFI ..
that is a version of ordinary pulsed injectors I believe.
How long, in milliseconds, the injectors are held open, determines how
much fuel is going in.
'normally' ..on our engines , fuel pressure is held within a fairly
narrow range..
roughly 32 to 38 psi ..something like that..
the Fuel Pressure regulator is affected by engine vacuum..
more open throttle ..lower vacuum ..equals higher fuel pressure.
it's even a test for an FP regulator ..compare FP with vac line
disconnect and connected.
I have an adjustable fuel pressure regulator I am fairly sure..
looks just like the ones we use (on waterboxers ) ..Came off a Saab I thik.
it's adjustable ........if anyone wants to play with it I'll give ya a
fair deal on it.
on your 'one piece' fuel rail, on the inline fours ...with the FP
regulator on the end of the fuel rail.. ..someone may sell an adjustable
FP regulator ..
but without also increasing air ..such as with turbocharging ...
just increasing fuel pressure to get more fuel to spray in would not
keep the air-fuel ration in the right range I wouldn't think..
the oxygen sensor would tell the ecu to compensate a little though.
sure ..go for it. Then it'l be ..what happened to my good fuel milage
? lol.
On 5/15/2012 9:54 PM, Don Hanson wrote:
> Curious. My other German vehicle in the past, it was fine-tuned by the
> engine builder on a Mustang chassis dyno...every modification we added
> entailed another trip to the dyno and repeated runs..This was (I think) a
> Motronic EFI at that time...One of the tricks this engineer used was the
> adjustable rate fuel pressure regulator...he would vary the fuel pressure
> by "so many flats" on the adjustment control bolt and gain up to 20hp with
> that alone....on a 415hp motor, but still...worth doing...
>
> I surmise it has to do with the injector spray pattern, but there could
> have been something else happening too. We had no way to control the
> pulse length...I don't think.....I was more concerned with the whole
> package of racing the car and left the motor pretty much up to him while I
> worked mosty on the suspension and my racing skills.
>
> It might be worth trying one of those if anyone has access to a dyno to
> mess with it.... Just recalling from the past...
>
> Don Hanson
>
