3 bar fuel pressure regulator

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Nov 10, 2008 | 09:35 PM

#21

phasemaster1

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From: florida

Quote:

Originally Posted by thunder550

Dropped the fuel pressure to somewhere around 43-44 psi. The pitch of the pump increased quite a bit. My 96# injectors were rated 96 lb/hr at 3 bar, so I had them in the tune as about 110 lb/hr to match the 4 bar fuel pressure. I just turned the pressure down, changed the IFR table back to 96 lb/hr, and everything worked fine without having to tweak any of the airflow tables at all. Very simple

At 5600 RPM and 10psi I'm still only seeing 51% IDC max, lol.

What was your IDC before?

Nov 10, 2008 | 09:40 PM

#22

thunder550

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At the identical boost level, RPM, and AFR my max before was 41%. Looks like it added about 10% to the duty cycle.

Question for those who have studied this....if I drop my fuel pressure by 25% but it only raises my IDC by 10%, does that mean I gained a significant amount of efficiency?

Nov 10, 2008 | 09:46 PM

#23

Stoichiometric

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I think that would depend on how much fuel the injector can deliver at each pressure. The fuel delivery curve of the injector might not be linear.

Nov 10, 2008 | 09:52 PM

#24

thunder550

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Then I'm likely in a more efficient part of the curve right? Or something like that?

If the curve is not linear, but my calculated IFR at 4 bar was linear, then this should also remove a lot of "noise" from my tuning. Sounds like it's a good deal all around.

Nov 10, 2008 | 09:56 PM

#25

Stoichiometric

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I guess I would say yes. I don't really know what's happening but I'll give you an answer anyway

Nov 10, 2008 | 09:58 PM

#26

thunder550

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Thanks, that makes me feel better

Nov 11, 2008 | 11:46 AM

#27

budhayes3

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What is the reasoning behind the factory running such high fuel pressure? Is it for better fuel atomization?

Nov 11, 2008 | 11:55 AM

#28

PSM

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I would assume so. Look at what the direct injection gas a nd diesel trucks run for pressure

Nov 11, 2008 | 12:26 PM

#29

dewmanshu

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Quote:

Originally Posted by budhayes3

What is the reasoning behind the factory running such high fuel pressure? Is it for better fuel atomization?

That plus I'd imagine they have some guidelines ro goals to meet for injector costs. Just running a higher pressure rate keeps them within their guidelines without having to increase the injector size. I just made that up on the spot but sounds good to me.

I am quiet surprised thunder you hadn't locked onto this much earlier. I have always contemplated doing it just see if the moto 60's were any easier to idle tune.