calib17a

Is it normal to set fuel pressure to 65 psi on fi with Hondata? Bubba at Trackmaster's did the tune. I've read, I believe on Hondata's web site, you set it at 45 psi and ajust the fuel map accordingly so you don't have to overwork the injectors. Check out sig for my setup specs.

Kwuaymaikrup

When I went for initial tuning my fuel pressure was at 55psi. They tuned it down immediatally. It is now at 38psi but I am running 1000cc's. I am not finished tuning so who knows what it will end up at. What fuel pump are you running? I think Cort ran 65psi with his 255 intank though.

-Ryan

calib17a

Holly 255 lph in tank.

lazerus

i would say if on race gas or high boost etc. if you are nearing your max INJ duty cycle, its not uncommon to up the base fuel pressure to eek out a little more flow to ensure you have a "safety barrier"

but unless you're using it, there is no reason to run higher fuel pressures, it will probably just make the car have worse idle quality.

Kwuaymaikrup

That might be why they bumped pressure up so high. I am no tuner but that is my guess.

-Ryan

wHOAlly

its said to have better atomization with higher psi

pissedoffsol

but only to a certain extent. i see NO need to go over 50 psi with properly sized injectors

calib17a

What's up Mase just want to hear a tuner's input on this.

Mase

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by calib17a &raquo;</TD></TR><TR><TD CLASS="quote">What's up Mase just want to hear a tuner's input on this.</TD></TR></TABLE>

sorry i missed this post.


OK, well here's what i normally do:

If the car has a strong fuel pump and they are looking to flirt w/ the max of the injectors, then ill suggest a higher fuel pressure.

When raising the fuel pressure, you are raising the ceiling limit (as long as the fuel pump can handle it of course)

typically I like staying 45 psi or so.

most people dont realize, you can seriously get away safely with the stock components w/ just some 550 cc injectors up to 350 whp or so.

calib17a

Thanks Mase!

danl

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pissedoffsol &raquo;</TD></TR><TR><TD CLASS="quote">but only to a certain extent. i see NO need to go over 50 psi with properly sized injectors</TD></TR></TABLE>

Exactly.

I don't like going below 36 psi for the low point, and even then some injectors don't work good at that low psid (yeah, i ment psid).

pornstarSR

wasnt there a problem with bigger injectors not opening because they didnt have enough fuel pressure behind them....i thought i read that somewhere...could be wrong

pissedoffsol

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pornstarSR &raquo;</TD></TR><TR><TD CLASS="quote">wasnt there a problem with bigger injectors not opening because they didnt have enough fuel pressure behind them....i thought i read that somewhere...could be wrong</TD></TR></TABLE>

injectors are controlled by your ecu/electronics... not fuel pressure.

ek9turbo

so if u have 550's that r running at 100% duty cycle at 45psi fuel pressure, what would happen if u raise the fp to 50psi???
r they gonna run at a lower duty cycle??

DIRep972

iTrader: (1)

You also gotta keep in mind that you have a 1:1 regulator so when you boost 20psi your fuel pressure goes up 20psi as well. Setting the Base fuel pressure higher will raise the ceiling on the injectors like Mase said, but you will also get dimenishing returns on the fuel pump w/ more and more fuel pressure.

pornstarSR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pissedoffsol &raquo;</TD></TR><TR><TD CLASS="quote">

injectors are controlled by your ecu/electronics... not fuel pressure.</TD></TR></TABLE>

thanks for the answer captain obvious....

i could have sworn i read on here someone was having issues with big injectors not opening(or closing) because they didnt have enough seat pressure for the pintle

but i guess im mistaken

danl

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pornstarSR &raquo;</TD></TR><TR><TD CLASS="quote">

thanks for the answer captain obvious....

i could have sworn i read on here someone was having issues with big injectors not opening(or closing) because they didnt have enough seat pressure for the pintle

but i guess im mistaken</TD></TR></TABLE>

Big injectors typically don't atomize as well as smaller ones. Lower fuel pressure compounds this problem. The added mass of the pintle also affects the dead time which compounds things to a large degree at idle.

Raising base fuel pressure helps a lot with idle. Allthough their are other alternatives when choosing larger injectors (such as the 650's on my car that idle better than stock).

1SlowSi

newb question. When tuning, i know that you can get more power wtih lower fuel pressure 35-45psi. What controls how low the fuel pressure stays? Is that done through Hondata? I know that with a bigger fuel pump, high volume and big injectors that the pressure stays low. Just wanna know how you can control it. thanks.

Suprdave

The reason your regulator goes up 1:1 is because you have boost thats pushing against the injectors opening...

kpt4321

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ek9turbo &raquo;</TD></TR><TR><TD CLASS="quote">so if u have 550's that r running at 100% duty cycle at 45psi fuel pressure, what would happen if u raise the fp to 50psi???
r they gonna run at a lower duty cycle??</TD></TR></TABLE>

If all you do is raise the fuel pressure, you will run richer and the duty cycle will not change.

The difference comes because the higher pressure makes the injectors have more effective flow. Therefore, you can retune and turn the duty cycles down, and still have the same amount of fuel be delivered.