Fuel Pump Flow Rate / BSFC = HP Supported

[Sinister Fiero]

This topic came up over on Old Europe and I felt it was worth noting here.

I have a formula that shows how to calculate the amount of HP a given amount of fuel flow will support based on BSFC. (flow in lb.hr / BSFC = HP supported). The Brake Specific Fuel Consumption (BSFC) of the typical N/A gasoline engine is about 0.5 and for super/turbocharged engines it's about 0.65.

The weight of a gallon of gasoline at room temperature is about 6 pounds.

The only OE-replacement fuel pump I recommend for a 3800 Series 2 SC (stock or lightly modded) into a Fiero is the Delco EP381. NAPA sells a Delphi pump # FE0114 which is for the same application as the EP381. NAPA says the FE0114 flows 32.4 gal/hr @ 61 psi.

3800 Series 2 N/A and SC engines both have fuel pressure regulators that are set to 3.5 bar which equals about 50psi. That's the pressure you should see at the fuel rail with 0 boost and 0 vacuum. On super/turbocharged engines, as boost acts on the FPR, it should cause fuel pressure to rise about 1 psi per pound of boost it sees. So if you're getting 10 pounds of boost, you should have about 60psi of fuel pressure.

Using the formula and FE0114 pump, we get this: 32.4 gal/hr x 6 = 194.4 lb.hr. 194.4 / 0.65 = 299 hp it will support which is fine for a stock or lightly modded 3800 Series 2 SC swap in a Fiero.

Now as some of you may know, for a long time the EP376 pump was pushed by certain people as a suitable pump you could use in a L67 Fiero swap. I looked up the Delphi equivalent for the EP376 pump over at NAPA is the FE0111 which they rated at 27.6 gal/hr @ 50.8 psi. 27.6 gal/hr x 6 = 165.6 lb.hr. 165.6 / 0.65 = 255 hp it would support on a SC or turbo engine IF you were only running about 51 psi of fuel pressure.

Electric fuel pumps put out less volume of fuel flow the higher the pressure goes. So even at 51psi, the EP376 barely supports the stock 240hp the L67 makes out of the box; but there's a problem because the stock L67 is going to be wanting more fuel pressure than 51psi when boost comes up. Bottom line: If you're doing an L67 swap into a Fiero and want an OE-replacement fuel pump, you had better at least get the Delco EP381 equivalent and not the EP376.

For the record, the EP376 is the stock replacement pump used in the 94 Corvette LT1 and other similar applications.

The EP381 is the stock replacement pump first used in the 91-93 Syclone/Typhoon 4.3 Turbo applications.

-ryan

[Jinxmutt]

Good point to bring up. I mentioned the EP381 over there in a few threads, and even still, people will post "Oh, I'll just get the EP376"

Do you know the ratings on the stock 2.8 pump?

[Sinister Fiero]

NAPA Online lists a Delphi FE0113 as being used in the 1988 Fiero 2.8 application. They say it flows 14.4 gal/hr @ 50.8 psi.

Looked up one for a 1987 Fiero 2.8 and they give Delphi p/n: FE0039 which specs 18.4 gal/hr @ 50.8 psi.

www.napaonline.com

[The Dark Side of Will]

All of this is assuming that the specs are right. NAPA doesn't build or test. They just reprint and resell. I trust NAPA, CarQuest, FIsher, etc. a hell of a lot more than I trust Advance or AutoZone, though.

I *frequently* see obviously wrong specs in catalogs. That's why "catalog engineering" frequently fails.

I think I have the EP376 Corvette pump in my Northstar car. It does fine at that power level and is very quiet. Of course I'm not boosting that engine, so pressure requirements are limited.

I have a Walbro in my Formula. At 135 HP, it's obviously not taxed at all, but it's significantly louder than the pump in The Mule.

[Sinister Fiero]

All of this is assuming that the specs are right. NAPA doesn't build or test.

I agree 100%. And we've been over this before about different brands of fuel pump and those of the same brand and part number not being made in the same place (USA, Mexico, China, etc) and of course - all will probably have different flow specs if you actually tested each of them.

I think I have the EP376 Corvette pump in my Northstar car. It does fine at that power level and is very quiet. Of course I'm not boosting that engine, so pressure requirements are limited.

The EP376 would support up to 331hp on a N/A gas engine that has a BSFC of 0.5, using NAPA's published numbers.

I have a Walbro in my Formula. At 135 HP, it's obviously not taxed at all, but it's significantly louder than the pump in The Mule.

Walbro's typically have metal gears compared to factory style pumps that have plastic vanes. That's why the walbro's are loud, and that's also why they can be damaged if you run the tank low on fuel (and starve the fuel pump of fuel which it needs to keep those metal gears in the pump lubricated).

[The Dark Side of Will]

The EP376 would support up to 331hp on a N/A gas engine that has a BSFC of 0.5, using NAPA's published numbers.

From published numbers... I believe that pump is also used with LT4 Corvettes with a factory rating of 330 HP, probably closer to 350 IRL. I haven't heard much about Corvette guys needing fuel pump upgrades... haven't looked too hard, though.

[Sinister Fiero]

The EP376 would support up to 331hp on a N/A gas engine that has a BSFC of 0.5, using NAPA's published numbers.

From published numbers... I believe that pump is also used with LT4 Corvettes with a factory rating of 330 HP, probably closer to 350 IRL. I haven't heard much about Corvette guys needing fuel pump upgrades... haven't looked too hard, though.

True, but that's at 50.8 psi. The LT1 and LT4 only ran a max fuel pressure of about 45-47 psi, IIRC. And at pressures lower than 50.8 psi, this pump will flow more fuel than what it is rated to flow at 50.8 psi (so it'll support more power at lower pressures).

The LT1 and LT4 engines could be more efficient than 0.5 BSFC too, which would mean they would require less volume of fuel to make each HP.

[The Dark Side of Will]

Yes, lower pressure fuel systems contribute, etc.
Yes, BSFC is a critical parameter that's difficult to know. The TPI 305 develops 220 HP on the ragged edge with 19 PPH injectors. The Northstar develops 300 HP, also on the ragged edge, also using 19 PPH injectors.