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Author Topic: 8v fuel pressure.  (Read 6329 times)

Offline gazareth

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8v fuel pressure.
« on: 03 August 2013, 14:13 »
hey guys. has anyone increased the fuel pressure on their digifant? from 3bar to 3.5bar. if so. does it make much difference to top end pull? heard talk off digis running lean at top end. and also when the pressure is increased is it possible to turn the mixture down enough at idle to keep emissions within spec?
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Offline gazareth

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Re: 8v fuel pressure.
« Reply #1 on: 03 August 2013, 21:08 »
nudge nudge :angry:
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Offline Sgt_Lemon

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Re: 8v fuel pressure.
« Reply #2 on: 04 August 2013, 01:45 »
Nudge, prod. Would also like to know
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Offline gazareth

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Re: 8v fuel pressure.
« Reply #3 on: 04 August 2013, 18:08 »
think im going to try it anyway at some point when I get a chance. theres always something else that needs doing though lol.
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Offline gazareth

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Re: 8v fuel pressure.
« Reply #4 on: 10 August 2013, 15:28 »
still no takers? :rolleyes:
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Offline gazareth

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Re: 8v fuel pressure.
« Reply #5 on: 21 September 2013, 14:10 »
so finally got round to trying the 3.5 bar fuel pressure regulator on my digi 8v. doesn't seem to feel much different at lower rpm but quite noticeable extra pull between about 4k and 6k. so should work well on a modded engine. probably need slight mixture adjustment after.
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Offline Sgt_Lemon

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Re: 8v fuel pressure.
« Reply #6 on: 21 September 2013, 18:16 »
Where did you get the fuel pressure regulator, this mod sounds interesting.
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Offline danny_p

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Re: 8v fuel pressure.
« Reply #7 on: 21 September 2013, 21:30 »
you can squeeze them.

riseing rate fuel pressure regs are a hidious bodge in so meany ways but they work quite well on a 8v digi. mines got a 4 bar FPR in it atm goes better when it revving but i have stuffed a ca in it,  stall it when cold and on the cold start enrichment it takes quite a lot of starting tho
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Offline gazareth

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Re: 8v fuel pressure.
« Reply #8 on: 21 September 2013, 22:46 »
Quote from: Sgt_Lemon on 21 September 2013, 18:16
Where did you get the fuel pressure regulator, this mod sounds interesting.
its actually a regulator I ripped out of an old bmw fuel filter at work. cant remember the exact model. I only have it bodged on to the engine at the moment with a mk3 gti 8v agg fuel rail just to try it out. as danny says you can crush them slightly to up the pressure but you really need to gauge it as your crushing so you don't go to far as you cant uncrush it. I think there is a Porsche 3.5 bar that bolts straight on. 944 maybe.
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Offline gazareth

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Re: 8v fuel pressure.
« Reply #9 on: 21 September 2013, 22:51 »
Quote from: danny_p on 21 September 2013, 21:30
you can squeeze them.

riseing rate fuel pressure regs are a hidious bodge in so meany ways but they work quite well on a 8v digi. mines got a 4 bar FPR in it atm goes better when it revving but i have stuffed a ca in it,  stall it when cold and on the cold start enrichment it takes quite a lot of starting tho
I think rising rate regulators are a farce because any increase in pressure is going to be rising rate. as pressure and injector duration has to be taken in to account. basically as the pressure increases the fuel slope gets steeper.
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