Allright, basically what I want to do is run dual fuel systems.

Normal driving, 93 octane pump would be activated.

At a preset boost level Hobbs switch turns on relay which activates race fuel pumps, and simultaneously activates relay which inturrupts power to 93 octane pump. An off-delay relay could also be used on the race pumps so there was no switching between systems during shifts.

There is a 3 way diverter valve only on the return line, normally open to return 93 to proper tank. When the race pumps are activated, a time delay relay is activated for the 3 way diverter valve. A 1 second delay would flush all the 93 out of the lines before switching return to the race fuel tank. Possible slight loss of race fuel to the 93 tank, but no contamination of race fuel with 93.

The race fuel and 93 octane fuel lines would "Y" just before the fuel rail, and have 1 way check valves right before the "Y", so 93 could not contaminate the race fuel line all the way back to the pump.

My fuel rails and crossover holds .04 gal of fuel. Two Walbro 340's at 15 volts will move about .044 gallons per second (I think). So, if this was setup to switch over automatically, you would have appox 1 second delay from where the hobbs switch was set to activate, and the last injector being fed race fuel?

I'm just wondering if I figured that out right. When it switches from 93 to the race fuel pumps, obviously the engine will still be consuming fuel, but will the 93 and race fuel stay separated until the 93 is flushed out (as in the column of 93 will be ahead of the race fuel), or will it be at least partially mixed as soon as it switches?

I would like to run this setup as load-dependent, but if I figured right, and it is truly a 1sec delay, the systems will need to be run off a toggle switch for low/high octane and low/high boost.

 

you definitely want race fuel to be there when you hit high boost...but im sure you know that already!

sounds like a pretty sweet setup if you get it working right!

 

You will want to put the Y up by the fuel rail and use check valves so the switch can happen fast and not be mixed very much.

 

Hence- "The race fuel and 93 octane fuel lines would "Y" just before the fuel rail, and have 1 way check valves right before the "Y", so 93 could not contaminate the race fuel line all the way back to the pump. "



I think I may just try and do a bench test of this setup. Probably the easiest way.

 

My fuel rails and crossover holds .04 gal of fuel.
Two Walbro 340's = 680 liters/hr at 15 volts

680 liters = 179.64 gallons/hr
179.64 g/hr is 2.993g/min
2.993g/min = .0498 g/sec

Looks ok to me.

 

Well, I did this on the bench today.

Wired up 2 walbros, all the injectors together, off of a momentary contact switch. Ran acetone through the system and it held pressure. Switched pump inlets to race fuel. Took -3- seconds to flush out acetone and have race fuel spraying out of the last injector.

Needless to say, that is too long. I would either have to have the systems on a toggle switch, and run low/high boost and 93/race fuel. (which would suck)

Or, run 2 sets of injectors and staged injection. Which FAST no longer has as an option.

I may switch over to BS3, as staged injection is supposed to be available with them.

 

Did you have a regulator on it? What is the internal relief pressure check valve on the walbros and could that have influenced your results?

I dont have the answers, but sometimes im good at asking the right questions...

 

Yeah, I had a regulator on it, and it was making about 40psi fuel pressure and held it while I switched from the acetone to the fuel.

Pumps had a steady 14 volts.

I'm suprised it took as long as it did. It was entertaining to watch, but made alot of fumes

 

Why wouldn't you want to just run a standard alcohol injection system?

Or, you could run a Bully Dog propane injection system for diesel trucks - CNG is about 130 octane, and the state change from liquid to gas would really cool the intake charge; plus, you wouldn't have any issues with fuel distribution since it would go into the engine as a gas...

 

I don't really have much faith in alky injection.

I know others use it with success, but it will never be on my car.

Even if the propane injection could supply the 400+hp worth of fuel I would need to run on top of 93 octane, I would not do it unless it could be tuned manifold pressure vs rpm.

 

So you are saying you would consider running two sets of injectors with separate fuel sources but Y'ing into one tank?

Sleeper (Jake) and his buddy both have run 2 fuel tanks with manual switches.

 

Well, I could use the system I described in the first post, if I switched over from 93 and race fuel for low and high boost. (But there would be a 3 sec delay between switchover).

I've decided to run a BS3 with staged injection, which will have two separate fuel systems (tanks, lines, rails, injectors, regulators). It will cruise around on the 93 octane fuel system and injectors, and at a specified duty cycle, the race fuel system/injectors will begin operating on top of the 93 octane system (staged injection).

That way, I can always have the boost controller set for high boost, it will only use 93 for regular driving, and the addition of race fuel will be instantaneous.

 

Sounds expensive

 

James... James Bond.

It would be cool to have the race gas go thru the same lines and just switch over but it would always have be to cycling.

 

lmmfao!!! how fast does the car need to be on the street! lmao!!!! like you couldn't walk away from pretty much anything sorry i couldn't resist!

that would be like me runnign around with a full bottle armed and ready! totally useless even with nittos! ha ha!!!