How far did your stock 4.6 3v fuel pump take you? Warning, mild benchracing thread.

[BruceH]

So I'm wondering how far people have gone on the stock fuel pump. I've maxed it out at 409rwhp with a whipple and 32lb injectors a few years ago.

I'm asking because it's close to maxing out on pump gas right now. I had an opportunity to do some logging this weekend. A wot pull resulted in a 95% duty cycle with stock 5.0 (32lb) injectors pushing 50psi of delta pressure. This is with the stock power wire.

FWIW I'm na with a 322 cubic inch Big Bore Boss based motor. This was the first time I've been able to do a log since changing from GT500 pumps to the stock unit. As a result of the log I went ahead and added an inertia switch controlled relay with an 8 gauge power wire from the ebc to the fpdm. This should give me some headroom for 92 octane pump gas but I'm not sure if it's going to be enough for E85 when and if I go back to it.

The bench racing portion is now coming up. I will be hitting a dyno in the near future to finalize the tune. I'm wondering where others have maxed the stock fuel pump with stock wiring in relation to rwhp?

Please post up what you made when the stock fuel pump wouldn't supply enough fuel. There is only one other person I'm aware of who has maxed the stock pump on pump gas while n/a. He is also running a Big Bore but his is 304 cubic inches. I'll follow up with a dyno sheet once I get it. Probably going to shoot for Friday or Saturday. I'm thinking that the 8 gauge power wire will cut the duty cycle by about 10%.

Thanks,
Bruce

 

[skwerl]

The wire upgrade is a huge difference. With the wire upgrade I was about 86% at 435hp (I think).

 

[Pentalab]

With 10 ga wire, from battery POS terminal to FPDM, you will see at least 10% drop in FPDC. With 8 ga wire, quite a bit more. For real hardcore folks, you could also install bigger ga wire from FPDM to fuel pump itself. Every time you reduce the wire gauge by 3 increments, the dc resistance of the wire drops exactly in half. You could also achieve the same results by paralleling 2 x identical gauge wires. IE: 2 parallel 10 ga wires = same as a single 7 ga wire etc. You can see both effects in any wire table.

If you plan on adding a bap at a later point, you would want the bigger wire gauge installed...1st.

 

[jodadejss06gt]

KB 20a BAP I made 460/490 on 39lbrs on stock pump.
It was close to maxed out.

 

[Pentalab]

KB 20a BAP I made 460/490 on 39lbrs on stock pump.
It was close to maxed out.

I would have thought that a BAP would have taken a FI 3v, close to 500 rwhp at least..and probably more.

 

[eighty6gt]

Some people don't have the luck. I apparently have a 600 rwhp capable fuel system that's at 88% DC with 430 rwhp.

 

[BruceH]

With 10 ga wire, from battery POS terminal to FPDM, you will see at least 10% drop in FPDC. With 8 ga wire, quite a bit more. For real hardcore folks, you could also install bigger ga wire from FPDM to fuel pump itself. Every time you reduce the wire gauge by 3 increments, the dc resistance of the wire drops exactly in half. You could also achieve the same results by paralleling 2 x identical gauge wires. IE: 2 parallel 10 ga wires = same as a single 7 ga wire etc. You can see both effects in any wire table.

If you plan on adding a bap at a later point, you would want the bigger wire gauge installed...1st.

So where were you at when your stock fuel pump was maxed?

 

[BruceH]

Let me rephrase. With the stock fuel pump and 92 octane gas the duty cycle was 95%. The motor is naturally aspirated. What's that going to equate to in horsepower/torque when I finalize the tune on Friday?

It's just for fun. Bench racing the dyno sheet.

 

[skwerl]

Before I did the wire upgrade I was at 435 on the stock pump and almost 90% duty cycle. So my best guess is going to be between 440-450.

Let me bold that so it doesn't get overlooked. I'm going to guess between 440-450hp.

 

[Pentalab]

So where were you at when your stock fuel pump was maxed?

FPDC was sitting at 96%...with 390 rwhp on an automatic. ( that equates to aprx 425 rwhp on a manual). Then the 10 ga wire mod was installed. Zero difference on duty cycle. Then the duty cycle got worse..and was 98%. Then the real problem was sorted out....after it gagged. The fuel sock was clogged really bad. Once that was cleaned out, FPDC dropped to 78-80%. It now sits at 36% at idle...and 80% at 6250 rpm, with gas mashed and blower on in 2nd or 3rd gear.

That's with 6.0 psi boost, twin 62mm tb, 94 tune, LT's, and mating catted H, DSS-DS and 3.31 rear gear + eaton tru-trac and 27" tall rear tires.

I'll go out on a limb and say aprx 450 rwhp with fpdc sitting at 90-95%....and that's b4 adding any BAP. (assuming the wire mod installed).

Install the bap on top of the wiring mod..and I will guess close to 500 rwhp..and that's assuming LT's used.

 

[bcb06gt]

Before I did the wire upgrade I was at 435 on the stock pump and almost 90% duty cycle.

+1. I was at 430rwhp on stock pump at 95%. Reduced after wire upgrade.

 

[retfr8flyr]

Bruce, I never had the stock pump maxed out so I don't know what Hp level it will reach. I do know that for E85 you are going to need a different fuel system, including injectors, even though you're NA. Do you still have the GT500 setup? I would get with Jeremy and see what he would recommend as the best bang for the buck on E85.

 

[s8v4o]

My pump is maxed out. My example isn't the data you're looking for though. I have very few boltons but my duty cycle hits 99-100% The reason for this is I'm running E85 with the stock injectors so my pressure drop across the injectors hits 60 psi. At this high of fuel pressure the total flow of the pumps drops quite a bit.

 

[eighty6gt]

This might be my issue, the 52 lb roush injectors demand a higher pressure and even the 405 pump has a drop off in flow.

 

[BruceH]

Went on the dyno today. The wire upgrade knocked the fuel pump duty cycle down by about 9% which is on par with what most report.

The numbers are lower than expected. 385/387 uncorrected. This compares with 437/387 for the same motor with e85.

It's hitting a hard airflow limit at 6k. I've changed the intake manifold and cai along with shorty headers vs long tubes before. Everything else is the same including having cats.

I was able to command 28 degrees of spark and actually get 28.75 because I have an adder/subtracter that hasn't been accounted for and it decided to add a little spark.

Previous testing with the same fuel has shown that the stock intake tanks at around 40-41lbs of airflow as measured by the maf. This figure is dependent upon having accurate inputs for other tune parameters so it's not a hard figure but it is a good ball park number imo.

Max airflow was right at 40 lbs today. Once the limit was hit the exhaust heated up enough to trigger cat protection at about 6500 rpm. It's noticeable by the fuel source going to 2 and by the a/f dipping quickly into the 10's.

I'm pretty sure that adding long tubes and the frpp intake would help. I'm also thinking that just going with e85 might mitigate most of what I saw today.

What e85 would do is lessen the requirement for airflow because it's oxygenated. That means that the 40 lbs of airflow would support a higher rpm due to some oxygen being in the fuel already. It would also negate cat protection because it burns cooler. It would also allow for as much spark as I wanted to throw at it. IIRC the e85 tune for this motor was at 34 or 35 degrees of spark advance. That allows for a more complete combustion and should add at least 30rwhp on it's own without the added power that comes from e85.

So the synopsis is that it's down 50rwhp from the last time it was dynoed on the same dyno in similar weather conditions. Weather corrected with e85 was 422/377 and today sae corrected is 374/376 so the differences are just about the same no matter what correction factor is applied. Changes are fuel, intake, air intake, and headers.

I can see it coming already. I have some time off coming during the holidays. I might as well switch over to e85 and keep everything the same to see what the difference is.

 

[BruceH]

Here's an overlay of both setups. They are pretty close up to 5k but then the e85 setup really took off. Keep in mind that this is gasoline and e85. E85 produces more torque so the fact that they are almost the same shows how much more torque and power is produced by the stock intake manifold in the lower rpms vs the FRPP intake.

I don't think a stock displacement motor would flow enough to see the airflow limit of the stock intake. My past na logs with an 11:1 285 inch motor that had the same ported heads maxed out at 37 lbs of airflow with a stock or frpp intake. This is in comparison to 40-41 lbs with the Big Bore and stock intake. The BB and FRPP intake maxed at around 43 lbs iirc.