PM reply sent!

 

Its going to be a tough thing to calculate rather than just trying it out.

I think the walbro 400 and 485 are too large for the stock assembly. But that doesnt mean I dont think they will work, and they might work better than I am predicting. But for the cost and simplicity versus going with multiple pumps, I think that its something that needs to be explored.

My concerns:

A: fuel pickup. At lower tank levels, its possible that the canister itself will restrict the pump from being able to pull fuel to its capacity. this can be remedied with holes in the canister, but that has side effects of increased fuel slosh starvation. as far as higher tank levels, should be no problem, fuel can easily fill over the side of the canister.

B: internal fuel filter. depending on how clean your gas tank is when you switch to e85, it can end up cleaning it for you and moving all the built up crud into the non-replaceable fuel filter. This will reduce output capacity.

C: fuel pressure control. Non-RFS out of the question. no way. with RFS, I worry about keeping a reliable balance in the transfer venturis. If they are too small, pressure will be out of control at idle and low load situations, if you have to open them up too far in order to get fuel pressure in check, than they may not pull adequate vacuum while the engine is under load and return volume is lower. This can promote starvation if the transfer venturi is not adequately recovering fuel from the drivers side of the tank.

D: current draw... I would upgrade all the pump wiring every where i could. I havent even looked at what the 485 pulls, but i am just going to assume its a ton more than a 255.


If there are no problems getting the full capacity of the 485 through the stock assembly, than this would be a perfect application for some type of fuel pump controller or voltage reduction system like a lot of cars in the 90s had, where they would lower pump voltage with a resister pack under low load.

 

Greatly appreciate the detailed reply. The Haltech can PWM a fuel pump, not sure this is possible with this Walbro or not - will have to check with Hal. Using voltage reduction at idle is something I had not considered, but a great thought for curbing the ridiculous flow capacity at low load. Maybe for your point "B", I need to run E85 before switching fuel pumps - not sure on that.

 

I am not a very knowledgeable electronics guy, but I dont think a PWM will work out with a Walbro pump. You could probably use the Haltech to control a relay set for a resister pack though. It would be ideal if you could operate it at the voltage that makes it perform like a 255, and have the swirl jet drilled for a 255, and then have it switch over to full voltage around 500rwhp... that should make the venturis and everything operate perfectly.

 

Thank you Charles for your input. Using a single relay, Hal has managed to get this pump operating seamlessly at around 10 volts below 4 psi, and around 17 volts above 4 psi. He is a wizard with wiring. We are using your CJM stage 2 set up with 1000cc HKS injectors and your new fuel rails with dampeners. Will let you know how it all turns out.

EDIT: Of course, not just a relay - the relay integrates an Acura fuel pump resistor and a Kenne Bell Boost a Pump.

 

Sounds like a good clean setup. Let me know how it all performs

 

thats how the stock supra's fuel system is setup Raj.

 

im pretty sure most of the cars in the 90s were like that... i know supras and mr2s, honda/acura, rx7s. i dunno, at least everything i worked on from back then.

 

sounds more complex than the twin pump setup. I don't like playing with wiring and relying on electronics to keep things working properly. I've had too many electrical things fail on me in my lifetime with cars and bikes.

 

^^^ aside from electronic configuration preference... I am still confident that the 485 will be somewhat held back by the fuel pump housing and it's restrictions. Time will tell how close it will keep up to the twin 255 setup.

 

I'm very interested in the 255 + 485 dual pump setup you mentioned Charles. I would love to upgrade my CJM twin 255 to that. I think it would be ideal to max out my setup on E85 and still have some headroom to go with a larger turbo down the road.

 

I'll be sure and post up when I hear back some results on the one being tested

 

Resurrecting this thread from the dead...I'm thinking about upgrading my setup to E85, and upping my fuel setup...

Does anyone think the 485 pump by itself can handle 2000cc? Or will the 2000cc outflow it and I have to get the twin pump?

 

6X 2000cc Injectors will Flow 720 LPH @ 43.5 PSI, that should be enough for at least 1400+ HP on E85

Those are some MF Big Injectors

 

Yeah I agree, I would think that would be overkill for a measley +650 whp Vortech...but I'm currently already using ID 1000cc for my 91 octane setup and I found a good deal on some 2000cc injectors that I can't refuse...

Hoping to avoid having to upgrade to twin pumps if possible

 

if you have 1000cc now, why change? They should be big enough.

What are you trying to do?

 

i would not go to 2000cc for your power level. your will be making alot of compromises for not even coming close to needing them.

a single 485 is going to support about 650ish whp on E85. a twin pump (like I have) will only support about 750ishwhp. Injector size doesnt matter, and you most certainly will not be avoiding going to a twin pump by adding bigger injectors.

the 2000cc injectors need almost 4 485 pumps to max them out. and at least 2 485 to max out 1000cc's injectors on E85

 

I'm trying switch to E85...my current setup uses 1000cc/Walbro 400 for 91 Octane w/ meth...I will also be running with an ATI crank instead of my fludampr, so my boost will probably increase as well...

So just to make sure I have some margin, how big should I go with the injectors to run E85? Or shoudl I just focus on upgrading my fuel pump to the 485 or a twin pump?

 

opps

 

Finally getting to this point of my install. I'm assuming this pump is the way to go for E85 with my small 800's.