Well my RS ran 9.97 at 142 mph a few weeks ago and it was being limited by the fact I was out of fuel. I had 1200 cc injectors in it and the duty cycle was maxed out.

I didn't want to change fuel lines or put a fuel cell into the car so the quest began for a solution.

I built a dual intank fuel pump set up for the factory tank. I am using two of our HO Walbro pumps, the modified versions we sell.

Anyway, put the car on the dyno this morning just like I ran it at the track. I made two dyno pulls, one in 3rd gear, one in 4th gear. I did this to verify the injector duty cycle and such. Duty cycle hit 105% at 35 psi boost.

I then turned the switch on to trigger the second pump at 6,000 rpm and 30 psi of boost. Instantly made the car so rich it wouldn't run, pegged the AFR's at 9:1. GREAT SUCCESS!!!

After some tuning and continually pulling fuel out of the car I was back to the same power level I started with BUT the duty cycles were way down, below 65%!

I then turned up the boost to make sure things were going to stay the same, I turned it up to 40 psi and ran the car out to 8500 rpm in 4th gear. BEAUTIFUL, AFR's nice and flat, duty cycles at 65%!

The system needs a little more refinement before we start to sell it but it is very straight forward.

You simply remove the stock fuel pump assembly and then replace it with ours. The factory fuel gauge works, the primary pump works like always and the second pump, if using some type of engine management that can trigger a relay, is turned on by any parameter you choose. If you are not running a system that is configurable like that we will be offering this kit with a simple pressure switch that will turn it on at a pre-set boost level.

The pumps feed into a single external fuel filter that is tucked away next to the gas tank under the car and then from the filter it goes into the stock fuel line.

I do have an aftermarket fuel pressure regulator on my car. I am going to bolt the stock one back on and see if it will work, it should work out great. This will mean the stock lines, feed and return, fuel rail and fuel regulator will work and supply all the fuel any street car is going to need.

I think I should actually be able to drop my injector size back to 880-1000 cc's now if I choose to.

Cost of this kit is $550 complete with a pressure switch, you have to send in your core.

The best thing, in my opinion is the factory fuel lines all stay intact, factory tank, siphon system, main fuel pump wiring and fuel gauge are all completely stock.

Pretty proud of this one. It will require you send us in your fuel pump assembly for a core or if you choose to buy it outright the price will go up around $150.

Thanks,

 

that's awesome. where was this 6 months ago when I bought the AMS race fuel system?

 

Can this system be reliable day in and day out? It seems like turning one pump on and off all the time would eventually take its toll. Is there any reason to not run them both all the time?

 

Great news. Just tested the car with the stock regulator on it. Works perfectly!! So there you have it, stock rail, stock lines, stock sending unit etc. Dual intank pumps. My car made 590 whp this morning like this. 65% duty cycle at 40 psi.

 

Dave,

How can your duty cycle go down if you're using the same injectors, unless your dramatically increasing the fuel pressure via the second pump?

And, if you're increasing the fuel pressure that much, I doubt the stock FPR wouldn't be overrun, yet you say that it works fine. Isn't the stock FPR slightly overrun at idle even with one normal 255?

Am I missing something here?


Eric

 

I'm very interested in this. Please keep us up to date on this as I'll be looking for a fuel system shortly.

 

i am awsome system i have been considering the ams system but its too much $$$$, this sounds like a great deal

 

hey this sounds great but if you are using the stock lines, rail and fpr, Doesn't 750 seem a little high.

 

So you're using two of your higher output Walbros, but they're both pushing into the stock fuel line, to the stock rail, and the stock fuel pressure regulator, at stock pressure? How would that provide so much additional fuel that your injector duty cycle would go from 105 ----> 65 (35% drop). When you trigger the second pump, doesn't the fuel pressure increase substantially? How do you account for that in setting the tune for the car?

 

Wow, unbelievable work dave..I will add this on to my AEM, and engine build list for next summer!

 

105% was at 35psi above base fuel pressure. 43.5+35 is 78.5psi. At that pressure a single Walboro (modded or not) has dropped in flow significantly. Add another pump and you arent increasing pressure per se, just flow.

 

great set up dave! simple but gets the job done.
Just curious was that 595 HP on race gas on a GT35 setup?

 

Nice work Dave as always, I will definetely need this with my next setup that way I can keep my 1000ccs over there

 

Good to hear Dave, can't wait for you to get it on the market, put me down as #1 on the order list.

 

So it's not the pressure sitting at the injector that screws up everything, it's the differential pressure across the injector under higher boost that this system kicks in for, which is required to get more fuel in combustion