quick walbro 255 question

[sleepyvr4]

at 14v what does a 255 take the base fuel pressure to on stock fpr?? waiting on my adolescant ecu to get finished so I can slap in kadaver chip which has 45psi bfp setting. I kinda remember reading somewhere 8 years ago it took it up to 50 something...

I've searched a few forums including rre and vfaq - no definitive answer on 255 bfp though.
thanks

Colin

 

[gvr4ever]

Why would you want to know this? The problem with the 255 and the stock FPR is that the fuel might not be correct will you are well in boost. Also, I don't know how much boost the stock FPR can keep raising fuel 1:1. If its limited as to how much fuel it can control, it's probably limited on how much it can allow to flow too. I just remember it having rather small ports and pretty basic and small over all.

Just get an adjustable fuel pressure regulator.

 

[sleepyvr4]

I am aware of the "flaws" - however I am more aware of quite a few people that have made well over 400whp with stock fpr, lines, fuel rail etc.

anyone else want to tell me what to buy lol - because if it were up to me I'd never bought another car in the first place - I would have purchased a f*ckin liveaboard.

but here we are...

 

[Barnes]

Did you want the base fuel pressure in the Keydiver chip to match what you are going to see with the stock FPR?

 

[sleepyvr4]

that would be nice - but I'm not holding my breathe. Keydiver chip was free. I sent my non eprom ecu to ECM for socket conversion to accommodate...

 

[atc250r]

The root of the problem isn't the extra pressure, its more that you will no longer have a proper fuel pressure curve. Lets say it over runs the FPR to 50psi, you're fuel pressure from full vacuum until about 12psi of boost will be the same, at that point it will begin to go up. That makes it pretty much impossible to tune around.

John

 

Every car and installation is different, you can't predict it. Too many variables: 255HP or regular 255? Rewired or not? The lower the pressure you are trying to set the base for, the more it will overrun.
What injectors are you running? If you are really set against buying an AFPR your best bet is to use the regular 255 pump and DON'T rewire it.

 

[belize1334]

Quote:

I am aware of the "flaws" - however I am more aware of quite a few people that have made well over 400whp with stock fpr, lines, fuel rail etc.



I think that your understanding of FPR overrun is flawed. It's true that you can make lots of power on the stock fpr, but that's only because when you're making big power you're using alot of fuel, at which point the over-run issue goes away.

At idle the pressure will spike because you're overrunning the fpr. Once you get into boost that is no longer the case and the pressure behaves like normal. So, you either get to assume stock fuel pressure and run rich at idle but good in boost, or you compensate for the increased fuel pressure at idle and then you run WAY lean under boost (when the over-run issue goes away). A rich idle is stinky but it won't blow up your motor...lean under boost will.

If you're dead set on running a stock fpr then get a chip set for stock fuel pressure and get used to having a rich idle. That's how your anecdotal 400whp on stock fpr was made. Otherwise, set up a variable voltage to the pump so that it isn't pushing so much fuel at idle. Either way, getting a chip burned to compensate for the increased idle fuel pressure is gonna cause you to run way lean once the over-run issue goes away under boost. I recommend against this unless you REALLY like rebuilding motors.

 

[gvr4ever]

Will a 2G FPR bolt on? I seem to remember those being able to control a walbro 190 without problems. Not sure about a 255.

 

[turbowop]

I think our stock FPR's can handle a 190 without issue. I never had problems with overrun with mine back in the day.

 

[donniekak]

From my own recent experience. A non hotwired walbro 190 over ran my stock 1g turbo (37 psi) regulator way more than a hotwired 255hp does on a non turbo(47 psi) regulator. It isn't real hard to tune around if you have some time to play with the dead time settings in the ecu. The fact that i run e-85 also makes my over run not as bad, as i am using a lot more of the fuel in the rail. But, every car and setup is different.

 

I also have a 43psi EVO X FPR that you can try. It shouldn't overrun near as much, if at all, because their stock pump is about the same as a 255 pump.

 

[belize1334]

^^ Are those compatible w/ the stock rail?

 

[4thStroke]

English Racing has used an OEM FPR up to 600+ AWHP.

Just throwin that out there.

 

[Lonewolf64]

No one is saying you can't make power on the stock FPR, but I'm willing to bet that car was stinky rich at idle.

 

[turbowop]

Werd. Overall WHP and driveability are two different things. The stock FPR doesn't limit horsepower, it limits tuning at lower fuel pressures.

 

[prove_it]

What about the 2nd gen regulator, does it have the same issues as a 1g or not?

 

I'm pretty sure it does, but I've never cut one apart to measure the return orifice. The only factory FPR I hold out any hope for is the EVO X, since the factory put such a huge fuelpump in them. They must have upgradeed the FPR to accomodate it, because its a completely different unit.

 

[sleepyvr4]

Well - not sure about what 255 model I have (it was free). Pump is rewired - that's why I asked about bfp at 14v. I'll find out more today - and the car will be running. Tuning with safc+wideband after everything said and done. 780cc precision injectors - chip set to 750cc.

 

PTE lies about their injector sizes. They are the same Delphi injectors everyone else is selling, and they typically flow