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AFPR...nessecary??

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mustg5

15+ Year Contributor
278
0
Nov 3, 2003
Pushing over 400whp, with a walbro 255 and 600cc injectors, is it necessary to run a FPR, becuause i have heard, it is hard to tune with a bigger pump and injectors unless you do get a FRP, and the stock FPR will be over run.....but ive also heard that the stock FPR is good for over 500whp.........Now if im going to be pushing 28psi of boost on my 50trim, do you think a AFPR is necessary??
 
"To tune the car correctly, you do not need a good fuel pressure regulator. It helps, but is not required. To get the car to idle correctly, you DO need a good fuel pressure regulator. The thing is that the 255lph pump flows a great deal of gas, more than the stock FPR can handle, therefore backing the fuel up into the fuel rail, causing the injectors to dump too much fuel. Unless you are going to make over 400WHP, go with a lower flowing pump, such as the 190lph."

RRE
 
^^^beat me to it

Yes most people find that the stock fpr is overrun by the walbro 255. The stock fpr cannot return enough of the unused fuel in the lines so pressure starts to build. So your injectors will be flowing more than what you would think. Now if you have a safc or some tuning device you can correct for this problem but it is more of a bandaide and not a solution. just my .02

Chris
 
thanks guys, so what your saying is at idle the car will run rich, but other than idle the car will run fine?
 
At WOT you can tune the car but idle and low throttle situations will be affected. I run 550cc RC injectors with a 255 fuel pump and I don't have any noticable problems but I can smell gas every once and awhile. OMG
 
i absolutly needed one for my car to idle at all with my 255.

the base idle with stock fpr was 63psi OMG
 
I'd get one anyway. They'll help with tuning in the long run. Just my .02 psi:thumb:
 
Aeromotive, BR/SX, and SX are probably your best bets. The BR/SX is a direct bolt on to your fuel rail, but the other two there are numerous write-ups on how to install them. Just don't get a afpr without a 1:1 ratio.
~Mark
 
Are you running one of these AFPR's? I'm just wondering if you are able to set you stock fuel pressure to approximatly 43 psi and for every boost pressure it raised the fuel pressure raises 1psi as well...
 
On the 1G the fuel pressure is lower than the 2G is it recommended to bump it up to 48 or so if planning on making more than 400 whp? Thanks in advance.
 
I believe that is one of the advantages of having a good AFPR. You can keep your stock fuel pressure at idle and when not boosting, but as soon as you start boosting, it adds fuel, which gives you a nice, smooth fuel curve.
 
Originally posted by markgholland
Are you running one of these AFPR's? I'm just wondering if you are able to set you stock fuel pressure to approximatly 43 psi and for every boost pressure it raised the fuel pressure raises 1psi as well...
Click to expand...

I don't but several others are and yes it was designed for dsm to w/ a base at 43 and a 1:1 rise in pressure. If you want to know more about it, feel free to ask at www.fullthrottletech.com
 
Originally posted by whitegst97
On the 1G the fuel pressure is lower than the 2G is it recommended to bump it up to 48 or so if planning on making more than 400 whp? Thanks in advance.
Click to expand...

Bumping your base pressure up to 43 psi will make your injectors the size you think they are. Most injectors are rated at 43 psi, not 38 like a 1g runs.
 
I contacted Cosmo about that FPR and asked if had the 1:1 rise in pressure like the aeromotive or the SX. They told me that it did not, so I don't know how good of a buy it would be.
~Mark
 
yea thx for the info yea and incase you didnt read this it was at the bottom

"Only fits on late 95' up DSM 4G63 Turbo engine! Can not fit on N/Turbo 2.0L DOHC A588 engine. .**non 1:1 rising ratio regulator; you might need to upgrade the fuel management to reach the best air/fuel mixture for your own setting. "

so this means...
 
fook that i just order the one from fullthrottlespeed.com
i mean i have read many post regarding their FPR and i have only read good things about it so hey im going with what everyone else is getting
it may take a while for me to get it cause on their forums they said they had some back orders. Im sure the wait will be worth it
 
Originally posted by madracer247@aol
yea thx for the info yea and incase you didnt read this it was at the bottom

"Only fits on late 95' up DSM 4G63 Turbo engine! Can not fit on N/Turbo 2.0L DOHC A588 engine. .**non 1:1 rising ratio regulator; you might need to upgrade the fuel management to reach the best air/fuel mixture for your own setting. "

so this means...
Click to expand...

HA, that blurb wasn't there when I visited the page.... Must have been getting a lot of questions regarding the rise in pressure.
 
I have the Fullthrottlespeed AFPR, and it works great. It was installed at the same time as a Walbro 255, so I don't know if my stock FPR would've been overridden, but I have no idle or other problems with it installed. On any FPR, at WOT, you will be fine, but the idle is what will suffer if your stock FPR is being overrun. It _can_ be corrected out in other ways, but you should do it the right way honestly.

It's a very high-quality piece, and installation was fairly painless (though getting at the small bolts was a little bit annoying, had to turn them like 1/4 turns at a time) It works great, is 1:1 rising rate, and the pressure was spot on at 43 pounds.

I highly recommend it.

-Jesse
 
Originally posted by Enigma_Man
I have the Fullthrottlespeed AFPR, and it works great. It was installed at the same time as a Walbro 255, so I don't know if my stock FPR would've been overridden, but I have no idle or other problems with it installed. On any FPR, at WOT, you will be fine, but the idle is what will suffer if your stock FPR is being overrun. It _can_ be corrected out in other ways, but you should do it the right way honestly.

It's a very high-quality piece, and installation was fairly painless (though getting at the small bolts was a little bit annoying, had to turn them like 1/4 turns at a time) It works great, is 1:1 rising rate, and the pressure was spot on at 43 pounds.

I highly recommend it.

-Jesse
Click to expand...

My comment was directed at the link to the cosmo FPR, but that's good to know about the full throttle FPR.
~Mark
 
You think the Full Throttle one is pricey??? You should check out the bolt on AFPR from Buschur or an Aeromotive with the install kit. It's $144 vs. $250-275.
~Mark
 
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