I was doing theoretical calculations on fuel needs at different boost and I found that the ideal fuel curve while using 440's and running 17 psi boost is not linear, it is a parabola. The slope progressively gets steeper as you reach 17 psi boost. I was thinking of hooking up the bleed valve, but i think this will dampen the fuel curve instead of make it progressive. anyone spent any time messing with the sfmu to see if there is a way to do this?

Thanks
James

maybe playing with springs could do the trick
there are springs with variable density the spacings between turns are not equals
they could take less pressure to compress a little than a regular spring but much more pressure to compress deeper than a regular one

Alain

I think the bleed valve will make the fuel curve non-linear. But, I think it will be opposite of what you want. I think it will probably leak more air as boost increases (2nd curve).

Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire

yup that's exactly what I thought regarding the bleed valve it seems like the only way to have a progressively increasing slope is to vary the internal spring but it would have to be a reverse progressive wound spring like it would need to get softer as it is compressed. Or you could progressively alter the pressure input from the mani, but I dunno how you would go abot doing that.

lates
james

increase the voltage to the pump with this:

MSD fuel pump booster

Fuel Pump Booster
PN 2350



**either that or find some way to mess around with injector pulse duration**
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96 talon esi-t
san clemente, ca

Uberingram> I bow down to the Geo

Well, what if you make the bleed valve a boost valve? I don't really know if it would work - but if bleed gives the wrong curve maybee boost'll give the right one.

EDIT: I'm not really sure if this'll work. Thinking about it a bit more - maybe you'd have to bleed some from the regular boost input as well as introduce boost to the bleed valve to make something like that work....Maybe.
:shrug


95 Eclipse RS : 5 speed
15.901 @ 88.34mph
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

Just an idea, you could try to hook up a manual boost controller to the output of the bleed valve. From 0 to a set amount of boost, you would have a linear rise rate, then, once the boost reaches so much, the MBC will start to shut off more airflow out from the bleed valve..an intersting theroy :) Would take some playing around with though...

Originally posted by XtremeRS
Just an idea, you could try to hook up a manual boost controller to the output of the bleed valve. From 0 to a set amount of boost, you would have a linear rise rate, then, once the boost reaches so much, the MBC will start to shut off more airflow out from the bleed valve..an intersting theroy :) Would take some playing around with though...

yea i didnt think of that eithwer, you could get a boost controller and let it hold the wastegate till full boost was met. that way your fuel would just skyrocket when you hit full boost instead of gradually go up with vac lines



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96 talon esi-t
san clemente, ca

Originally posted by XtremeRS
Just an idea, you could try to hook up a manual boost controller to the output of the bleed valve. From 0 to a set amount of boost, you would have a linear rise rate, then, once the boost reaches so much, the MBC will start to shut off more airflow out from the bleed valve..an intersting theroy :) Would take some playing around with though...

Thats similar to what I've been running now for about 3 months...

I have my cartech fpr seup to have the base fuel pressure real low... because of my 450CC injectors.... and hten I have a manual boost controller hooked up to the air bleed on the cartech.... so then the boost controller bleeds off the correct amount of air so that I get the rate rise that I need...

Lee.

anyone else doing this, because it sounds interesting enough to do.