I may be running this setup soon and need opinions. I am already leaning to using dual pumps. I have 2 Walbro 255's but would rather not run dual pumps unless I have to, for obvious reasons. Is this doable? What are your opinions?

Setup will be a Gt35/74 @ 20-22PSI 850cc/1680cc with 11.5 A/Fs on pump with 550cc water injection.

Any input is appreciated. Thanks.

 

I run 20lbs and run two 255's no problems in three years its not worth the risk to find out its not enough!

 

J-rat has a dyno sheet of him doing around 550 and 25psi on a single walbro, T04R turbo.

I have personally done 21psi on a T04S with a single Supra pump. I think the key is to rewire it with good relay and high quality wire around 10 gauge in size, and set base fuel pressure to at least 40psi.

 

Mine is rewired running at 14 volts.

 

On stock fuel lines?

 

J-rat has done 550 to the wheels on stock FC3S fuel lines. They are 5/16" lines. He uses the stock top feed FC3S rails. I am running 6AN lines but if I could go back and do it again, I'd use stock ones and get an FPR that had NPT inlets like the Aeromotive universal carb/EFI regulator: http://www.aeromotiveinc.com/products.php?prod=157 . PM J-rat yourself if you want more info on his setup.

Most AN hose setups (the 6AN ones) just clamp to the hard line on the fire wall (mine included)... which is exactly what the stock hoses do. I don't see how they really help in terms of fuel delivery. I mean if you like the look (and many do, and they are willing to pay for the look) or it gives you the warm and fuzzies somehow, get them. And I don't think running in parallel matters until you start making huge power. I run in series with no problem, first 21psi on a T04S and now almost 16psi on a larger T04R.

I have a friend who used to run in the 600awhp range on his Vr-4, running 25psi on his Evo III 16G turbos. The stock rails (one for each cylinder bank) are in series, connected by a factory hardpipe. He never had any problem with that.

 

I agree with arghx, except there are differences in sequential injectors on a VR4 and massive Batch injectors on a 7. This is a long going debate that I won't touch, but just keep in mind it's not apples for apples.

But, braided hose really is pretty...

 

You could always go re-wired single walbro with a B-A-P. That's what I'm running, I'll be testing it up to 20-24 psi

 

My only options are run 1 or run 2. I can't afford to be buying more stuff right now.

 

well, if you can't afford to set yourself up right, then you can't afford to run 20 psi, simple as that. Running out of fuel under boost is gonna be a lot more expensive then doing the right thing now.

 

what makes you think that Rx-7's are batch fired?

 

I am running 15 pounds, same secondaries, t70 1.10 A/R, Stock FPR, Walbro 255, and stock fuel lines without any issues. No 20psi, but you get the idea. I think the stock fuel lines, FPR, and 255 pump are plenty for a road car.

 

^ so you have an aftermarket fuel rail and you just installed NPT --> barb fittings to hook up regular fuel line?

 

Doesn't your article say that all except Australia have the front and rear injectors fire at the same time on the FC? That would be batch injection. Same with the FB. I didn't realize the 3rd Gen was Sequential, but anyways.

Back on topic, J-Rat has run 554 RWHP @ 26 psi on a single walbro, so give 'er.
https://www.rx7club.com/time-slips-dyno-128/new-dyno-pull-just-joined-500-club-789374/

 

What I mean when I say I cant afford it is that I am not going to go buy a boost a pump when I have 2 fuel pumps laying around. I dont see how running dual pumps is not being set up right. I just do not want to run them if I don't have to, but from what I've been reading, I will be on the edge of my single pump, so, it looks like that is what I am going to have to do.

 

on 720 pri/1860 sec @ 20psi a single 255 was enough for me. I didn't have meth/water injection either. 255's flow a **** ton of fuel.

 

sorry, I thought for some reason you weren't wanting to do dual. Dual pumps will work fine for you. Another option (maybe cheaper?) would be to ditch both 255's for a single Bosch044 (good for 300lph) which should be more than enough on pump. Plus no need to build a dual pump holder.

 

If your FC has a distributor [sic] then you are "except Australia." So basically every FC you and I have ever seen has sequential fuel injection. See the 86 training manual, Fuel and Emissions control section.

 

Stock lines? What are your a/fs at 20psi?

Also, for people who used jrat as a comparison, you can't because he was running meth which requires less pump fuel and thus a weaker fuel pump.

 

yeah stock lines. I ran a Y to the fuel rail and then into an A1000.

I don't recall the afr's but they were right where I wanted them to be.

 

I wouldn't recommend it. I don't trust walbros for anything more than 350 rwhp. I have seen several fail. You will need 2 Walbros at minimum, but I would do it right and get twin supra pumps or bosch 44s