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what kind of numbers are you guys seeing before having to change the stock pump ?
Dustin,

The numbers I posted was on the stock pump, but I was pushing the 440 injectors to running 100% DC at WOT, which is obviously not good. I wouldn't run it at the track that way, but it got me through a dyno session and around town...

I'll do some testing and data logging of the FP with the stock pump just to get a real numbers look at what is happening to FP with the 440s and then with the 550s just so that we have some recorded data, as there doesn't seem to be a ton of it out there...

At the end of the day, the hard parts are done on this setup. The bits to iron out are what sort of infrastructure changes need to be made to the fuel and intake system to really utilize the potential of it...

Best,

Phil
 

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I'm not seeing any numbers? Graph of fuel pressure during a dyno run would be nice -- is this all just speculation? What charts?

46.7 lbs for a fuel pump -- uuuuuh, that can't be right??

It tells me Lotus are stupid $60K+ S car and Lotus want to save $5 on a less capable fuel pump??? A pint of beer right?

So you're saying the 2.5" on a stock fuel pump with 550's is guaranteed to run out of fuel? The very same Kit FF sell ;) I might just agree with you there.

So if I get this right, I can just drop in a Walbro 255 and good to go? No adapters?

Thanks phil, I'm not see any hard data on FP, would also be interested in the HOT wire Fuel pump FP numbers too (see if there is any difference). BTW, I did go back to running the stock battery and put my Braile aside for now.

What can I say, I'm a data guy, like to see real charts and numbers :)
 

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My tuning software data logs the runs, but i don't always save them since they're not that useful if it doesn't work, but this is what i recall it being.

440's hit 80% at about 6000 RPM, 100% by just over 7, not enough fuel was being delivered at this point and the afr's headed directly into the 13's so the run was aborted.

stock fuel pressure is 46.7

The S's pump is perfectly fine for the S, stock is 160, cup is 190, we typically switch to the higher volume 255, not higher pressure.

No speculation, and you can calculate it all for yourself with some basic math.
 

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Installing a new fuel pump is relatively easy - I did mine in around two hours and don't consider myself a master mech. I didn't drop the tank, replaced the unit via the access port behind the drivers seat. It did involve dremeling the access port slightly larger. But I wanted easy access without dropping the tank. Before/After pics -
Did you create a bigger lid to cover the larger hole you made? Might be dangerous to leave a gap open if you get into an accident.
 

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We ran the stock fuel pump on the XP car with 750CC injectors running about 370HP with the turbo setup. This ran for about 1 year until the pump gave out. We decided to replace it with a Bosch -030 motorsports pump with swirl tank etc to stop the fuel starvation issue. The stock pump with 550s should be good all day long.
 

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That just can't be, 550cc's on a 160lph pump just doesn't make sense, you can certainly be running at 100% DC and maybe getting enough fuel, but thats stretching the definition of 'works'.

say its 370 HP at the flywheel. 4 injectors, 80% duty cycle, turbo so .55 BSFC, fuel pressure 46.7 lbs = 650cc's, 61.84lbs/h

you'd have to be running 90% DC minimum to get 550cc's to work at that BSFC and HP, and thats if its flywheel.

( 370 * 0.55 ) / ( 4 * 0.80 ) / sqrt( 46.7 / 43.7)


The thing i don't get about all this, is that Phil has already shown that his data backs up the math and my data, and the dyno, he's running out of fuel on the 440cc's, the 550cc's buy you some headroom but you'll still run out, its just not as quickly.

if that still isn't enough information, here is a dyno sheet from a car that i added fuel to i ran out of scaler and map, no matter how much i added ( and you can see how rich it got) it would not add any more fuel, and thats simply because the pump wasn't keeping up., look at the power drop off, the lower rev etc, at heavy load its in the 13's. each run had increased fuel, and the DC was way over 80% you can see just how linear the drop off is as the pump struggles to keep up.

i can probably go and find a boxful of sheets that look just like this.
 

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For a supercharged or turbo engine that makes 300 HP, 114 liters per hour is usually considered the safe area for a pump.

In one of my cars I've run a Bosch external pump for several years; got rid of the intank pump. It can be changed in about 10-15 minutes as it's mounted to the frame. If you need a pump there seems to be plently of room to mount an external below the fuel line in the Elise/Exige.

I'm not saying it's optimal, but with volume that keeps the pressure up I've seen injectors run past thier way past their DC for short bursts without lunching the engine. But the fuel supply never dropped off.
 

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Ok, I'm not actually seeing any charts showing fuel pressure readings? Am I missing something? I understand the calculations, but I like to see real world. I'm not a strong believer of using AFR alone as indicator of fuel delivery issues.

But I agree on the surge tank -- does anyone make a viable solution for the slosh problems with these cars? It's really annoying (and slower) to have to run these cars with a full tank every session -- especially at 6lbs per gallon.
 

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rob, the injectors are running at 100% DC and the AFR's are going above 13, what does that tell you ? 440s and 550s, with only a minor change in the RPM they max out.

i think vf are planning something.
 

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Charlie,

We were running at 325RWHP and targeting 12.5-13:1 with the VP C12 race fuel which can run leaner on the 750ccs. We topped out at 282RWHP on the 550s. That was turbo limited rather than injector.
 

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Still wanna see the FP values, sorry I'm anal that way. Of course I'm currently no where near those wHP values, on 2.5" 550 I was at 255 wHP (91 oct), so I would imagine 3.0" (8.9 psi peaked on a cold night) + 550 + RLS I'm around 230 wHP on 91 oct.
 

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rob, the injectors are running at 100% DC and the AFR's are going above 13, what does that tell you ? 440s and 550s, with only a minor change in the RPM they max out.

i think vf are planning something.

Charlie,

I could be mistaken, but I am pretty sure all the ForcedFed cars including the 340 and 380 used the stock pump. Maybe Casey will chime in. I wonder if the car you took the data on had a fuel pump on its way out. That's what happened to my car while on the dyno with Kris after a year or so on the 750ccs. when we pulled that pump out of the tank after, it would make stock pressure but deliver zero volume. Yanked it for another new stocker and it was fine. While we had the tank out we made the swirl tank etc etc.
 

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Charlie's math is valid overall (but only if the values are static). I think the values are not 100% applicable (in all cases) b/c BSFC is a dynamic variable. I've monitored BSFC on SuperFlow engine dyno's with a plentiful of analysis tools and it is not a fixed value throughout the power band. Regardless, the BSFC of a turbo engine is not going to be the same as a SC engine, and/or NA engine.

As Rob stated...we need to see fuel pressure data (at the minimum)

I'd be curious to see an overlay of fuel pressure, Lambda ratio and the actual injector ms over RPM.

Kris
 

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Next time i'm at the dyno i'll be sure to save the data logs from my tuning software, it logs ms/DC etc, but i maxed out the injector scalers and the maps, 100% DC and no fuel.

we had all the tools on the car at the time though, turboxs make and sell all sorts of monitoring equipment, kid in candy store for me.

i keep trying to locate that snap in fitting that SST have for the toyota fuel line, supposedly snap on sell it, i did get to use a neat fuel line to can bus adapter once, but that wasn't mine, and we did log fuel with that.

jermaine and i sat on the dyno, changed the injectors from 440s to 550s ( well he did ;) ) hit 100% DC at over 7000% , and no more fuel.

did the same thing with matts car at the weekend in texas, same exact problem, went through the same thing on franks car as well.

Kris is of course right about BSFC not being constant, SC cars are typically .50 to .60, turbo cars are .55 etc, but i did the math for a few different values, it really doesn't change it that much, it'd have to be super efficient to make it, just take the above calculation and change the .55 around.

How much HP and boost its making is obviously going to change the fuel consumption.

I should be back at the dyno shortly, i may have the traces saved somewhere, so i'll dig them out, but the dyno sheets show the AFR's going over 13 on 550s for a car making 280RWHP and 100% DC.

we've also go the rising rate regulators with a gauge on them on a couple of cars too, so able to watch the fuel with that.
 

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Seems logical to replace the pump and be done with it. Why cheap out on a $150 part? There's good evidence that it's not even marginal. People here are considering a $3,000+ upgrade from BOE and they're debating a $150 part? rotfl

Only the know-it-alls are debating it. It's not even a question for me...
 
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