Aeromotive or stock FPR

[Hiitman]

they guys up at rre said that with my setup i can still run a stock fpr. they said what mainly restricts the fuel is the lines, not the regulator. any suggestions?

2.4L. wiseco pistons and eagle rods. hks 272s. aem tru time cam gears. arp head studs. fluidyne radiator and 1360 cfms push/pull slimline fans.

3" dejon intake, NGK plugs and wires, greddy turbo timer, 3" Thermal downpipe, high-flow cat and catback. AEM wideband UEGO, 255 lph, 850s, dmbc, 1g BOV, sbr exhaust manifold w/ turbosmarts 38mm wastegate, sbr-G50. godspeed fmic.

 

[kahl23]

Well they're sort of right. Once you go up to the 255 you need to run something like the Aeromotive AFPR. That said, it doesn't do anything without upgrading the lines. This is especially true of the return line, which is the biggest restriction. Some people will tell you that it doesn't do anything because there is a siphon in the stock fuel pump setup which is the biggest restriction in the system. They are correct, but the name of the game is minimizing restrictions. Anyone who has taken a fluid dynamics or electrical circuits course (the principals of resistance in this case apply to both circuits and fluids) can tell you that even if a long line (or wire) isn't the narrowest part of a system, the length of the line or wire results in a total resistance equal to a much narrower orifice that is only a cm long. Enjoy!

 

[romeen]

I am running the 255 FP with an Aeromotive FPR and all STOCK lines and was able to dial in my base fuel pressure to a rock steady 43 psi. Before adding the AFPR my BFP was 50 psi.

From everything I have read as well as my own personal experience I would recommend getting the AFPR. I believe the stock lines should be fine. I am surprised that RRE told you what they did. But then again they do know alot more about these cars than I do.

 

[DSMunknown]

This is especially true of the return line, which is the biggest restriction.

Many others would argue that the fuel feed line is the most noteworthy restriction, not the fuel return line. You can purchase and see one installed here.

Without considering any of the OP's modifications, the 255 fuel pump and 850cc injectors are enough together (even with DSM Link, I would argue) that an AFPR is a must. No question about it. Now add in all your other modifications and this question really starts to become ridiculous IMHO. Stop dicking around and get an AFPR!!

 

[oldman]

From everything I have read as well as my own personal experience I would recommend getting the AFPR. I believe the stock lines should be fine. I am surprised that RRE told you what they did. But then again they do know alot more about these cars than I do.

RRE has been telling people that for years (myself included), I suspect when they say "the restriction is in the line" they are refering to feed line/performance, not return line/overrun, reason why they're the only DSM vendor I know that still pushes the B&M stock FPR modifier, for some reason they think the purpose of an AFPR is only for raising the BFP to get more out of the injectors, not for dialing down BFP and ensure 1:1 intake to fuel pressure ratio.

 

[dsm-onster]

Just to add. . . the stock lines fuel rail, fittings, and filter are all plenty fine for that 50-trim and the fuel supply for it you have now. Get that AFPR and you'll be fine.

 

[oldman]

Get that AFPR and you'll be fine.

Just make sure it isn't the B&M Command Flo units.

 

[dsm-onster]

Oh sorry, that's what I meant. Figured that point was nailed earlier. You definately don't want a fpr that can't lower flow to maintain a 1:1 ratio better than a stock unit when you have a very high flowing pump

Uncle Bruce always knows best .

 

[oldman]

Oh sorry, that's what I meant. Figured that point was nailed earlier. You definately don't want a fpr that can't lower flow to maintain a 1:1 ratio better than a stock unit when you have a very high flowing pump

I know you know, I'm just making sure OP gets it, RRE will try to sell him the B&M (like they did me) since that is the only one they carry.

 

[DSMunknown]

They are correct, but the name of the game is minimizing restrictions. Anyone who has taken a fluid dynamics or electrical circuits course (the principals of resistance in this case apply to both circuits and fluids) can tell you that even if a long line (or wire) isn't the narrowest part of a system, the length of the line or wire results in a total resistance equal to a much narrower orifice that is only a cm long. Enjoy!

And I bet there's a median with this rule, huh?

 

[Hiitman]

is 43psi a good fuel pressure for my setup or do you recommend something else?

 

[UMR98GSX]

With those injectors and a 255 there is no reason you should run out of fuel at stock pressure for that 50 trim

 

[Hiitman]

awesome thanks

 

[kahl23]

And I bet there's a median with this rule, huh?

There always is

 

[DSMunknown]

There always is

Go on...

 

[kahl23]

Sorry Anthony, I thought you were being sarcastic. In actuality, there is a type of average in the equation, that being the resistivity of the material in use. Obviously, I don't know this property for 3/8 inch i.d. tubing with 93 octane running through it, but if we were to switch over to electrical resistance for a second so I can provide a real example, it would be something like the resistance of copper is 1.7E^8 ohm-meters (at room temperature). As for the rest of the equation, it is total resistance (R) equals the resistivity of the material in question (p) times the length of the material (L) all divided by the cross sectional area (A). In other words: R = (p*L)/A. Hope that helps.

 

[snowborder714]

is 43psi a good fuel pressure for my setup or do you recommend something else?

43.5psi for a 2G.

 

[DSMunknown]

43.5psi for a 2G.

^ With the vacuum line off.