[chucktv]

I've read somewhere around here that you can crush your fuel pressure regulator to increase fuel pressure. It also mentioned that it takes some time for the trionic unit to adjust to the increased pressure and richer fuel mixture. My '87 is jetronic. Will it adjust in the same manor or will other adjustments be required?

 

[steisan]

Why crushing your FPR? you could just pick one from any N/A Saab in a junkyard, they all should be 3.0 bar when yours is 2.5 AFAIK.

Crushing as always a risky operation, and it's not reversible.

Your car isn't Trionic. You need no adaptations nor adjustments

The 3.0 FPR is a good bas to start to raise the boost, tweaking the APC

Be aware that fuel economy wouln not be as before.

But if you're not happy with the new setup, you shouls have the old one to but back in...

 

[chucktv]

So you're saying that I can get one from a later engine and it would be pre-set at the higher 3.0 level? If I'm understanding you correctly (and I may not be) that would be a breeze, not to mention cheap.

Grazie, Stefano

 

[billj]

Wouldn't it run rich, Stefano? Will the '87 LH injection be able to adjust the mixture to cope with the different pressure like Trionic does?

 

[John Vaughan]

There are several companies here in the States that offer an LH fuel injection chip. Couple this with an APC chip and the Normally Aspirated (NA)fuel pressure regulator at 3.0bar and you should have no fuel delivery problems up to about 250hp. If you go above that figure,I believe that a rising rate FPR would be needed along with larger injectors. Just a thought.

 

[steisan]

So you're saying that I can get one from a later engine and it would be pre-set at the higher 3.0 level? If I'm understanding you correctly (and I may not be) that would be a breeze, not to mention cheap.[/b]

Almost there . Any injected non turbo Saab (900 or 9000) should have a 3.0 bar FPR stock. So it's not a matter of vintage, but whether the engine is turbo or not. So you can find one for cheap in any junkyard, if you have saab ones in your zone.
Sorry if I wasn't clear in the first time.

Wouldn't it run rich, Stefano? Will the '87 LH injection be able to adjust the mixture to cope with the different pressure like Trionic does?  [/b]

Yes, it would, but only at full throttle, where before it was a bit lean. O2 sensor would help LH injection to keep things on the right side. If your car wasn't catalyzed, so no O2 sensor like mine, (but I don't believe so because you're in US), yes it would run a bit rich but it just should affect mileage. Stock injections are always a bit on the lean side, and it's always better being rich than lean. In every sense... .

I did not do it in my car because I run on LPG, but I read lot of people on TSN doing it. Anyway, I could be totally wrong, because it's not experience of mine...

What a pleasure being allowed to quote other boards without getting banned is!

 

[chucktv]

Thanks again, Stefani! A partially parted 900 sits at my friends house right now. That's a freebie! I'll let you know what happens. Still fighting my idle problem though but getting closer.

 

[Al]

A similar question - is it a "good thing" to fit a rising rate FPR to a turbo engine?

I seem to remember reading somewhere that it could create problems, but as I had an NA car at that time I didn't take much notice.

Cheers

Alyn

 

[ylee coyote]

a rrfpr seems to be a good mod for the t16 but I have not heard of anyone fitting it to a trionic...
I fitted one to my t16s and it seemed a bit more responsive for the short time before one of the fittings broke

 

[billj]

The main reason for not fitting it to Trionic is that, as far as I know, all Trionic engines have more than adequate fuel pressure for their standard power output and more. The 9000 turbo, at least the 2.3, has a fuel system that can cope with up to almost 300hp. I would also think that a non-linear fuel pressure with increasing pressure might cause Trionic a little confusion.

 

[Al]

BillJ,

If you don't need one....... I'll save my cash

Alyn

 

[mark e]

I had an RRFPR on my Trionic for a while. It seemed to make a difference to response when I first fitted it, but I've since changed back to a stock unit and can't say I noticed a difference going back...

 

[gorper]

Originally posted by Stefano:
[qb]Crushing is always a risky operation...
[/qb][/b]

hi,

what is risky about crushing a bosch fpr? the top portion is simply empty space with a spring in it. also, the metal is pretty malleable, and i'd bet that all of the capsules are physically/dimensionally identical, with only the spring rate differing from 2.5 to 3.0 to 3.5 bar, etc., so extra spring force won't compromise the unit.

as long as you don't clamp the lower half by the sides (and the protruding rim in particular), you shouldn't have any problems.

still, the 3.0 is the way to go.

cheers...

 

[steisan]

Hi Gorper,

welcome to Saabscene

I saied it's a risk because it's not a reversible operation. If you crush too much, you can risk to have a 3.5 or more FPR when all you needed was a 3.0, without possibility to remediate.

Cheers!

 

[chucktv]

Well Stefano, I got the fpr off a n/a 900 but mine fits directly into the fuel rail with just an o-ring and the 900 one screws into a brass fuel line first. I'm contemplating a way to mod it so I'll let you and everyone know how I solve the problem and how it performs.

Cheers all