Oops............edited, woke up at 1:38 am, information incorrect.

 

For information on the double pumper thoughts please see one of the last posts I made in the other thread on this pump.

 

Scheides - quite a few DW301 installs now i have seen fuel pressures go up quite a lot. and had a lot of trouble tuning them as (i assume) pressure seems to fluctuate a fair bit. This is on 93, i guess using less fuel the problem is worse than on E85.
But repeated runs on the dyno with the same tune, AFRs through the midrange would be in the 10s one run and in the high 12s another run, then spot on for the third run.
Drilling out the return/siphon a little settled the issues in my experience. but this also affect the fuel pickup when tank levels get below 1/3 tank or so which lots of people have encountered.

I'm no pro tuner, but that's just what I've noticed
I'm also guessing that maybe the point the fuel pump relay cranks up the voltage messes with this aswell. maybe a constant voltage to the pump would increase pressure at idle/cruise more, but at least base fuel pressure would be more constant?

I can only guess things would be "worse" with this pump.
If Buschur or anyone else comes out with a good solution for this i, and many others i'm sure, will be stoked.

Drilling out the return with the effects we have seen on low fuel pickup , compounded with the whole "lean out after turning left" thing that us road course guys have to deal with, makes the fuel setup on the X a real handful if you want to keep it all in-tank.

 

Then maybe the best solution for the X is our double pumper too...

 

^ i think in terms of ease of tuning you are absolutely right David.
Even with a surge tank, twin pumps with the second switched on a Hobbs sounds very sensible to me.

But even with a surge tank, the darn thing still pressurizes unless you drill out the return/siphon.
The only intank solution i can see, for the cornering fuel pickup issue, is a small intank "lift pump" on the other side of the OEM tank and feeding into the swirl pot from the top, so the siphon effect isn't needed. Then it can be drilled out to a large bore, and viola no return pressure issues.
No one has tried this yet AFAIK.
But then you may as well just get a fuel cell and be done with it

So maybe the lift pump to negate "road race lean out" , coupled with a BR double pumper = win??

 

I'll be installing one of these in my 2010 RA Sportback from hell (tm) here pretty soon.

It's currently maxing out the fuel system with ID1000's and single Walbro on E85. You can see the details of that here.

I'm not sure if I will keep it in the car but I will for sure get data for people. Should be interesting.

 

Here is just an idea.

Why not split the return fuel supply. One end goes to the stock siphon location to retain the venturi effect. The other end goes to fill just the bucket. Meaning drill a hole ontop of the housing install 90 degree 1/4 NPT fitting. That will just fill ontop of the bucket. You can also add a adjustable valve to control that secondary return split. So you can modulate it so the siphon gets enough fuel to build pressure and retain the venturi effect.

In either case a FULL size FPR will be needed. The MINI fprs are harder to fine tune the flow vs. the large sized counter parts.

 

Bryan, your pump has been shipped.

 

FWIW, my car: I took a DW300 and MAP's kit w/ the stock hose and put it in my car, did not touch the return/siphon at all. Stock FPR and all lines stock as well. On pump gas w/ DW800cc injectors, the car idled and ran perfectly. Swapped in FIC1680's and got the car to run good on pump gas using ecu tuning, no problems. Converted to E85, maxed out the fuel pump. Boo. MAP Proving Grounds was only a few days away so I got my hands on a BAP and this solved all fueling but my system is nearly maxed out at 34psi, so I run 31psi to keep it safe.

At the drag track, at 1/3 tank, I had the same issues you are describing. At the top of fourth on the drag strip the car bucked like crazy. Added fuel, next run it was fine. So I don't think it really has a ton to do with the siphon, but who knows. The car is a street car so I just usually fill it at 1/3 tank and don't worry about it, E85 is everywhere around me and I only drive 10 miles per day so it's not a huge issue (for me).

What size do you generally bore them out to? Maybe if we all get our heads together we can figure out what the magic bullet is for a few different levels of setups, specifically with this pump.

Is it easy to install a fuel pressure gauge on a stock-ish car? Or should I just do a full FPR setup? I want to know what the car is doing now so I can know what is happening whenever I put this new pump in.

Dave, you mentioned the stock return line being the next issue, think that will be a problem with a single one of these pumps on an e85 X?



LOL @ 'Sportback from hell' !!! You crack me up, love it. Please let me know how this works out for you, all info above considered

 

We don't typically drill the siphon. I believe TedB has had to mess with that quite a bit with his fullblown set up and if my memory serves me correctly he came up with 9/32nds as the size to drill it to, do some searching in his threads on his fuel problems, it's in there I think. My RS I was seeing a spike in the fuel pressure when the second pump would kick in, idle was fine etc., but had a spike in pressure. I drilled the siphon on mine and it had minimal, if any effect, on that spike in pressure. The spike caused no problems, I was just experimenting with what was causing it.

The stock fuel lines are "small" granted you can push enough fuel through them to supply 800+ whp, so for most never will be a problem. It is the one area that can be improved when the time comes without changing your tank/pump.

 

My siphon is drilled per TedB's specs on my Evo 8 with a big rewire on my primary pump using a Buschur double pumper with AEM triggering the secondary pump @ 10psi also on a big rewire. My Fuel pressure was around 58~62psi at idle. Drilling mine out resolved my fuel pressure, brought it down to I think 45~48 (on my stock regulator), and dead lock lean issues I got off and on from extreme pressures. Not that it matters in the range that this issue happens but both my Walbro's are modded also.

I have also confirmed on many occasions and even posted pictures for proof that I had complete usability of my entire fuel tank. I'd think if the setup is the same on the Evo X, this will be money like on the 8's.

 

sub'd.. good stuff in here.

 

We've got kits ready for anyone looking to try one out. They claim this pump flows ~80lph more than the DW301 at base fuel pressure so proceed with caution until we get some data on these things with and without siphon modifications. Monitoring fuel pressure in some way is a must at this point!

Walbro 400lph Fuel Pump with MAP Install Kit (Mitsubishi Evo X)

 

On a somewhat unrelated note we drilled out my siphon to 1/8" and although I never tested with pump gas fuel pressure on E85 was in check and there were no issues with fuel level or ability to siphon.

 

Having a lower fueling requirement for the engine I'd think if it worked well on e85 it would work better on the suction portion of the siphon. The big question is if the pressure is low enough not to cause issues.

Any chance you can run some 93 octane for us inquiring minds?