Ill be doing a surge tank and possibly a fuel cooler. Well see this winter goes.....

 

Yes, if you are going to have a surge tank, you would size it according to your expected use. Texas mile, Bonneville salt flats, make it big!

I think for my use I don't want to mess with a surge tank and won't need it. When I looked up those numbers from the 255 and 044 charts, I really was thinking of a simple 2-pumps in series without a surge tank. 255 intank to 044 external. My idea was to figure out if there would ever be a negative pressure condition in the line connecting the 255 to the 044. The idea being that if the pressure in that line is never negative, then there should never be any chance of cavitation at the external pump. The Walbro 255 and Bosch 044 look like a perfect pair in that respect.

So I think that should be a good way to go if it is enough for a person's needs. If you needed bigger, keeping with the same idea-2 pumps in series with no surge tank, I think you would want to make both pumps bigger, not just the external. Maybe Geoff's idea of a 416lph followed by a Kenne Bell boost-a-pump would be good for this. At some point with going bigger I think speed control of the pumps would be a huge plus.

Oh heck the Kenne Bell boost-a-pump isn't even a pump is it? It's a speed controller/voltage booster, sorry about that.

The positive and negative pressure I'm talking about is of course gage pressure, where atmospheric pressure is 0. Positive would be greater than 0, negative less than 0.

Yeah I wanted to get all the high current wiring out of my gas tank, but maybe it just isn't meant to be.

 

A short clip taken from Carl Ruiterman's V11 Subaru WRX STI.
Turbo - BW EFR 7670, T4 TS external wastegate. Running approx 22-24psi for the day.
Great turbo sounds on this clip

http://www.facebook.com/carlruitermandrifting

 

can someone please measure how thick the T4 turbine housing is at the mounting points of the bolts betwen the housing and manifold?

Thanks

 

between .400 and .600" just from memory.

 

flange thickness @ the machined flats is 0.475"

T3 EFR 7064 and T3 EFR 8374 in stock now. T2 6258 and 6758 also in stock. Next week is SEMA and we're expecting some good news in the way of tracking #s... fingers crossed

 

^ very cool!

 

Thanks for the info

What about T4 ........What about T4.........???

 

This may be an odd/silly questions but...

Why not use an oil accumulator-like setup for the fuel delivery. You size the pump in the fuel tank for above the average fuel consumption at the pressure you require and then size an accumulator for peak fuel consumption (WOT) for the longest time period you would expect to be at.

IE: for 2150cc injectors at 100% IDC for 10sec of WOT you would consume 1.6qts of fuel. Why couldn't you just use an accumulator that will maintain 70-80psi (or whatever you need) for 1.6qts over 10sec with a fuel pump still contributing to the flow? This would be entirely dependent on the track.

This way, you would not need to size fuel pumps for peak demand but around average demand allowing for a smaller fuel pump, less heat, less wiring, etc.

 

the pump(s) need to maintain the flow and pressure, an accumulator wouldnt work because it would drop pressure when the pump maxed out.

 

You know what - that might work.
It might just be too complicated and expensive, and kind of big.
You would need a constant pressure accumulator (one that doesn't drop pressure as it pushes out). You would need a relief valve between the pump and accumulator to bleed off excess flow back to the tank when the acc is full and demand is low (that would be easy). The pump would always be running at full pressure, unless you have extra control valving to let it relax a little when demand is low.

So what would a constant pressure accumulator be? Hmm. Well I found some patents for them. And I found a NASA tech brief that proposes one. And that's about all I found. Ok forget that idea.

If you used a normal accumulator (non-constant pressure) the residual pressure (when empty) would have to be high ~ 80 psi or so, and the pressure would go higher as it fills up with fuel. So the pump would be working against a pretty high pressure. Or the accumulator would be large and heavy to have a large compressed gas volume. Or some such complication that would make it impractical I think.

 

Man do I really want to upsize my 8374 to a 9180. Geoff any help?

 

My idea is to use the accumulator pre-FPR and not be connected straight to the fuel rail line.

You wouldn't need constant pressure as long as the fuel line pressure before the FPR is above your tuned injector psi + boost psi. For me at 27psi peak, I would only need to maintain above 69psi in the system pre-FPR (stock FPR puts the rail at 42psi I believe). You would just need to keep the fuel pressure on the system and accumulator as high as possible when not at WOT for higher overhead. You could also run bigger injectors and an aftermarket FPR to run the injectors a few psi down to get a bigger overhead. The idea would be that the accumulator is capable of providing a specified quantity of fuel above your required psi at whatever fuel flow your injectors demand.

As for a relief valve, there is already the fuel return system to the tank and I was considering the possibility of a throttling valve that would be actuated by a differential pressure across an orifice plate for the accumulator. If there is high enough flow into/out of the accumulator, throttle the fuel return line. I am just worried how that would fluctuate the fuel pressure at the fuel rail if FPRs do not respond to transients well.

If I had a better understanding of accumulators and how they worked, I can't see how this would be outside the realm of possibility.

But, this is a bit off topic from the thread so I should probably let my silly idea just die here.

edit: Just talked to another Engineer at work and he said my system would work just fine and I shouldn't worry about throttling the return line as the return line valve should be controlled by pressure anyway. The only thing that would need changing would be the seals on a typical oil accumulator. He also said a bladder accumulator would be prefereable to a piston accumulator. Any reason why no one has done this yet?

 

Yes, it would be a "T" off of the line to the fuel rail.

To keep accumulator size and weight "reasonable" you would probably have a factor of 2 difference in pressure between empty and full. That gets the "full" pressure way up there. Probably could combat this with 2 small pumps in series (1 intank plus 1 external) which would do it for the pressure I think.


I think the FPR won't work right if its outlet (the return line) is throttled, as I think your other person at work is saying.
As for transient response of an FPR, I could post a pic below that shows a test I did using my Fuelab regulator, and a Honeywell transducer part #
MLH100PGB06A. The fuel pressure is in the window labeled "boost" and you have to multiply it by 2 to get the actual number in psi. This was a throttle blip as quick as I could make it, car in neutral, from idle, so not exactly the ultimate torture test. The other window is throttle position.

I had in mind that the relief valve would be set to bleed off excess flow from the pumps starting at a set pressure = to the pressure of the full accumulator.


I don't think it's silly. As for topic - epic thread! As is the thread it came from.

 

Here's the pic. Logger sampling is .04 sec per sample.

[IMG][IMG][/IMG][/IMG]