When/why do I need a fuel pressure regulator?

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Dec 23, 2008 | 02:15 PM

#61

joseph k

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From: Meesuhsipeee

Quote:

Originally Posted by Mellon Tuning

I don't get too hung up on IDC's until I see that I'm adding fuel and the AFR aren't improving. I've never had an high IDC injector failure anyway and I've been at it since the late 80's

i have been at it since the early 80's

jfwy sir

Dec 23, 2008 | 02:23 PM

#62

Mellon Racing

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From: Virginia Beach, Virginia

Quote:

Originally Posted by joseph k

i have been at it since the early 80's

jfwy sir

remind me to slap you around every chance I get

Dec 23, 2008 | 02:44 PM

#63

theshadow

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Okay - so while you guys are at it - can someone explain how to choose injecotr sizes? I got 680s because I was told they would be plenty for my turbo - so why are some people all hopped up on 1000ccs?

I heard that smaller injectors are easier to tune but who knows - someome - why is bigger better or, more accurately, when is it good to go small? Are 1000ccs really necessary for a stock frame turbo?

E85 OK but SRSLY - 1000cc injectors are becoming like high top shoes in the early 90s.

Also, it seems that an AFPR is actually a useful thing to have - to a point - but if I'm seriously runnign out of fuel then I'd need to change up. Correct?

Dec 23, 2008 | 07:42 PM

#64

Slo_crx1

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From: Simpson, PA

Quote:

Originally Posted by theshadow

Also, it seems that an AFPR is actually a useful thing to have - to a point - but if I'm seriously runnign out of fuel then I'd need to change up. Correct?

You've pretty much got it! Smaller injectors are easier to tune for idle, usually for part throttle and full throttle it's pretty much normal as long as the latency voltage is good. That's why when you input the injector size into EcuFlash you should take the actual size of the injector, multiply the size by around 85% and use that number as the injector size. It makes tuning idle a bit easier and leaves some overhead on the injector. Most injector companies say not to run IDC's past 85% though. The last time I talked to Chad he suggested 780cc for the BBK turbo you have, and I agree with him. 1000cc injectors and larger are great for E85 setups and if you ever want to go with a larger frame turbo down the road, so I think that's why some suggest them.

Dec 23, 2008 | 09:23 PM

#65

Slo_crx1

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From: Simpson, PA

Quote:

Originally Posted by KevinD

yeah, the IDCs in evoscan are simply the injector pulse width and the period for two revolutions. the period is calcuated from the RPM. your not "logging" idc, your calculating it from the IPW and RPM. so i don't know what "Descaling" is either, but thats not the reason

the scale of the injectors is not in that equation.

latency control for idle is done with the battery voltage latencys, and all that is taken into consideration when you log IPW, as the IPW is the PW from the table and the correction factors, then the latencys added to it.

*edit: it appears as if the newer evoscan might have some funny calculations for IDC which are obviously wrong

but for anyone who wants to know their IDC, all you need is RPM and pulse width.

edit #2: no need to sift through math. take your rpm/60. then take the inverse. them multiply by 2 and that will give us the period (in seconds). then take the IPW and divide by the period, making sure your units are the same. that will give you your IDC. your a electromechanical engineer

you should have this stuff down by memory

I must of missed your post before. I've been looking over the evoscan calculation, it does look pretty weird. The calculation you have is what I do by hand (more like calculator lol) using the logged pulsewidth. I'm still trying to play with how the voltage latencies and injector scalings affect the STFT and LTFT, never had to deal with that too much on Honda obd1 lol (heck, they're only 32kb file sizes).

Jun 25, 2009 | 12:28 PM

#66

Mellon Racing

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From: Virginia Beach, Virginia

old thread but I ran out of fuel at 37-40psi on Q16 where DLL showed 700awhp and the AFR shot from 12.5 to 13.5 for a second with the twin walbro + 1000cc PTE. Got a Buschur fuel rail ready to go in soon.

Jun 25, 2009 | 01:48 PM

#67

joseph k

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From: Meesuhsipeee

sounds kinda weak dood

Jun 26, 2009 | 03:36 AM

#68

MR. EVO MR

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From: :noitacoL

[quote=davidbuschur;6406666]The answer is...............

So, if you are running the stock regulator and you have a set of injectors maxed out (no matter what size injector you are running) if you add an adjustable regulator to the equation you will end up no longer needing to upgrade your injectors.[/quote]

so you can run stock injectors with an adjustible regulator on example e85, it wont max them out?

Feb 2, 2011 | 03:12 PM

#69

motocooney

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From: Grand Rapids, MI

Back to the original question and also the title of this thread "When/why do I need a fuel pressure regulator"...

If you upgrade the fuel rail and are running lareger injectors (850cc in my case) , do you need to also upgrade the FPR? Even if the IDCs are nowhere close to 100%?