Dual Fuel System

[Turbo1dr]

In case anyone hasn't been on my web site and following what I've been doing here's the goods!

Years ago I've often pondered the thought of having two separate fuel systems...one for just 93 octane and the other for pure race. Well, I've finally took this challenge. In theory, the 93 octane (pump gas) injectors operate normal under cruising conditions. When boost is applied, a pressure switch wired into a relay takes the 12v power supply away from the 93 injectors and applies it to the 116 (race gas) injectors. While all this is happening, the ECM continues to pulse the injectors normally. Since only one set of injectors will have 12v power the ECM never pulses 2 injectors at one time. It conserves race fuel & helps eliminate contamination to the 02 sensor by not being burned all the time while driving. This system also eliminates the mixing of the fuels that was always apparent with mechanical switching valves on the fuel lines and it also provides INSTANT switching so there's no delay in getting race fuel into the engine if you suddenly encounter a street race.

Beginning stages below with diagram of how it "should" operate.




Dual fuel rails with regulators are completed! Below are pictures of both fuel rails installed on the intake.






I shot a couple of video's so you can see the system in action while bench testing.

Bench test 1: Dual Fuel Demo 1.WMV 17MB

Bench test 2: Dual Fuel Demo 2.WMV 11MB



Although I haven't got the second 116 octane fuel tank plumbed in just yet I did hook up the "116 octane" fuel rail to an injector cleaning machine, it's called a MotorVac. I had the engine running at idle while on the cars "93 octane" fuel rail. I touched the relays ground wire to a good ground and the engine stumbled but it picked back up without a problem. Mind you, that this was the first time these injectors seen any fuel in about a year so I believe they needed to be initially "primed" to get all the air out of each injector. After that first time I couldn't tell when I was switching them while listening to the engine! Just so I didn't think I was crazy I had the engine running on the 116 fuel rail and then I turned off the MotorVac machine. When I did the engine died just like it was suppose to do when you take the fuel pressure off it. After that I tried switching them at a higher RPM and still the engine didn't miss a bit. It's as if it never switches. I also tried brake boosting the car up to 4 to 6 psi and switched the injectors! Again, it also worked just fine!! AMAZING...I believe it's going to work just like I wanted it to. There was a couple of times I could hear the engine change it's exhaust tone at high rpm but I believe that is due to the bad gas that was in the MotorVac machine or it's because I have 60lb injectors in the 93 rail and 55lb injectors in the 116 rail...most likely that's probably the problem. This system has passed the inital testing under light to low boost settings while in the shop. I have to test it under normal street duty to comfirm if it's 100% perfect!

Anyway, I just thought I'd share what I've been tinkering with. I know it's a more complicated set-up than alcohol but I didn't want alcohol. Now you guys think I'm crazy huh?

[Doc1of7]

Originally Posted by Turbo1dr

AMAZING...I believe it's going to work just like I wanted it to.

There's no satisfaction as good as that....
Congrats.........

[WIKEDV6]

Awesome work Vern, I always wondered about how and when someone would come up with something. This is great info, Keep us posted.

Prasad

[turbo dave]

great idea, it looks like it should work pretty well. I am very interested to hear how well it works for you in street driving, and how cost effective it is compared to using alky. how are you going to kick in the fuel pump for the race gas fuel system? you could likely use the same relay as your using to switch rails, but your fuel system will need to pressured up and ready at all times- you may need a primer switch or something to make sure its always pressured up. i know the system is supposed to hold pressure but it will likely bleed off some pressure if not used often. i'm sure you figured that out already though. I wonder if you can get a turbo-tweak chip burned for this set up that may help give you a nice tune on both fuels and help the transition- this could be a pretty nice setup. good luck, you got me thinking about that setup for my rx7 hybrid now. please keep us updated on your progress.

[Turbo1dr]

Originally Posted by turbo dave

how are you going to kick in the fuel pump for the race gas fuel system?

Each fuel system will have their pump running all the time so there will no delay when the system switches and it will never have to be primed since pressure will always be available. The injectors themselves will be acting like "check valves" to keep the fuel from leaking into the intake when they are not firing (unless you have a leaky injector). Also the fuel pressure regulator on each fuel rail will bypass the fuel just fine when the injectors are not firing.

My plans are to take the double pumper out of my existing 93 tank and use it in the 116 tank. They will still be staged just like they are now. I'll be replacing the 93 pump with a single pump since that system won't require the fuel demands as the 116. I'm making this set-up totally automatic so there isn't anything that the driver has to do except mash the gas and go. It would also be VERY easy to have the system manually switched using a switch in the console to trigger the switching relay. That way it will stay running on which ever fuel octane they wish....just don't forget to switch it to race gas when you hit the gas....OUCH!

Originally Posted by turbo dave

I wonder if you can get a turbo-tweak chip burned for this set up that may help give you a nice tune on both fuels and help the transition- this could be a pretty nice setup. good luck, you got me thinking about that setup for my rx7 hybrid now. please keep us updated on your progress.

A good chip designer could make a chip where its tables are tuned for 93 octane (low load) and under high boost tune those tables within the chip for race gas (high load).

[Nashty]

Nice work Vern.

[Speeder]

This is a cool idea, and has given me some ideas about doing my Stage's fuel system.

I will be running two sets of injectors, controlled by an Electromotive TEC3r in a staged fashion - the second set coming into operation at a set boost+rpm point.

What if I had two fuel cells (one with race gas) and two fuel pumps? hmmmm.

My only concern with this setup would be for the "high boost " fuel pump (and fuel) overheating maintaining pressure in the race gas fuel rail against closed injectors. Probably would need some sort of controller, activated by the boost switching system, to let the pump run on reduced voltage until the injectors operate, then full voltage. What got me thinking on this track is the fact that almost all the high flow EFI pump OEMs (Aeromotive, Weldon, etc.) recommend pump controllers to do just this for extended low-flow situations such as street use.

[Turbo1dr]

VIDEO of it running and switching under light load

Here's a full unedited (as taken from my video camera) 5.1 surround DVD quality video of this system in action while under load. You can see that I have noid lights on both #3 injector harnesses. The upper light is for the 93 inj and the lower light is for the 116 injectors. The engine is missing on # 3 cylinder and is only running on 5 cylinders so I could show how the systems switches.

Just a reminder that I have mismatched injectors (55's and 60's) so there will be some change in exhaust tone when it switches. Once I get 12 injectors of the same size it'll probably be almost unnoticable.

Sorry about the file size. I wanted it to be full quality with the best sound as possible so you can actually hear what's happening.
http://www.turbomalibu.com/videos/dualdemorunning.mpg 44MB

Here's the same video for the 56k guys. BUT in this compressed video you can hear what sounds like an engine miss just before it switches. You can't hear this in the 44MB video above. Dunno why... Maybe it's the compression I used. Download both and you can see.
http://www.turbomalibu.com/videos/dualdemorunning1.WMV 5.1MB

[Turbo1dr]

UPDATE:

I figured I'd update this old post of mine so here goes.

I've been running this system since October 2006 and it works perfect. I can't ask for it to do any better. No skips, misses or studders while it switches from 87 octane to 116 octane. It switches totally automatic and all I have to do is keep gas in the tanks.

I've not run into any fuel pumps over heating by letting the pumps run all the time. I figured the fuel that's circulating is getting cooled by the fuel lines running up and down the chassis. I doesn't get any hotter than the factory tank under the car that's close to the mufflers and tailpipes.

I now have video's of the car on the dragstrip and the dyno with this system working. So far I've only used about 3 and a half gallons of 116 race fuel since it's been working. That included running a few times at the dragstrip and running it on the highway testing and tuning. I'm really surprised that's its lasted so long. I think the gas is stale now it's been so long...lol. When it sprays in the engine only when needed 5 gallons of C16 goes a long way!

I've updated some of the photo's in my first post and the one below. Here is a very detailed page on my website about how this works including pictures and video's.

[87bigcut]

Really neat idea, how much does a gallon of c16 compare to a gallon of meth? Running 87 is really nice too, much cheaper and less timing at cruise etc. I'm a big fan.

Joe

[VxTurboxV]

Hats off to you that is awesome!

[PRSRIZD_V6]

Originally Posted by Speeder

What if I had two fuel cells (one with race gas) and two fuel pumps? hmmmm.

I did that for a while. My was on a switch, kicked on one pump instead of another, then had a delay and it would switch over the return line. Then there was just a check valve in front of each pump so you couldnt backwash the pressure line. Worked good, flick the switch, thumb through a few positions on the thumbwheel, and away you go.

The cheapo tank switch valve from the ford truck kept puking out on me... so ditched the whole setup and bought and alkycontrol.

This idea is really cool though, good job dude.

[Speeder]

In case you didn't catch it:

S2 4 bbl intake EFI conversions

Scroll down to my input to that thread.

The motor is still in the machine shop - 1year and counting.

-Rick

[Turbo1dr]

Originally Posted by Speeder

In case you didn't catch it:

S2 4 bbl intake EFI conversions

Scroll down to my input to that thread.

The motor is still in the machine shop - 1year and counting.

-Rick

I seen that! Look nice.

Are you still going to try a staged injector control using the Electromotive TEC3r? I'm thinking its going to operate just like my set-up except you're going to use the TEC3r to do the injector switching instead of a boost pressure switch and a relay like I have.

Another question, when it does the actual injector switching will it be an "instant on/instant off" or a gradual decrease/increase to the other set of injectors?

[Speeder]

The TEC3r allows you to specify what rpm/manifold pressure to start the secondary injectors operating. At that point, the primaries' injector pulsewidth is reduced so that the transition is smooth. My two sets of 85s will act like 85s until the switch point, then 170s on up, with no step in fuel delivery at the transition point.

I have done one other staged injector setup (using a Megasquirt on a 350hp turbo Toyota 4cylinder) and it worked really well.

Actually, Turbo1dlr, it was your early posts that got me thinking about the dual tank/pump setup for my staged system.

I tolerate gross mechanical work on engines just so I can play with electronics/computers - and have all the cool fueling stuff ready to bolt on to my engine. This waiting for machine work to be done is pure torture.