Duel Fuel Setup For Economy And Power, Anyone Else Thought Of Doing This?

[GTRNUR]

I'm sure many of you know about the Nelson racing engine cars from youtube. These guys setup their insane horsepower cars with a duel fuel system that allows them to cruise on low octane fuel, and then switch to race fuel when the power is needed.

With rising fuel prices in mind, I just had an idea that might be useful for those of us driving thirsty skylines.

You could leave the most of the fuel system standard in the car and just change to a billet twin entry rail and a set of 1000cc ID injectors.

(Have a look at my diagram)

Then install a 20lt fuel cell in the boot with external pumps and an under-car surge tank, with its own larger supply and return lines.

The plumbing at the rail would use seperate fuel delivery from two regulators.

Under boost a switch opens the race fuel solenoid valve (pressure switch), and the higher fuel pressure in the race fuel setup closes the back flow valve in the low octane fuel circuit so the engine is running on race fuel only. Low the low octane setup still runs, but returns all fuel to the main tank.

Off boost, the race fuel solenoid is turned off. Fuel supply then flows through the low octane fuel reg to the rail. High octane fuel still circulates through the high octane reg, but it all returns to the high octane fuel cell.

Considering how dam complex fuel systems are in most skylines these days, I don't see this as being any worse. Also, you could do away with the need to run really big injectors, multiple pumps and E85, and just go for a ULP race fuel like Martini 116 octane.

You would use less fuel by volume, and have higher octane fuel and only be using the race fuel when your on boost.

Any thoughts... ? Discuss...

[Manuel Kasko]

I kind of skimmed this but I'm sure the ecu would have to be quiet complex with being able to swap maps etc

Unless content sensors can handle this?

[GTRNUR]

I'll add, you could put a 2-3 second delay on the switch back to low octane easily enough to stop low/high octane fuels mixing during gear shifts too...

[GTRNUR]

I kind of skimmed this but I'm sure the ecu would have to be quiet complex with being able to swap maps etc

Unless content sensors can handle this?

Perhaps if your using MAF sensors... but really who does these days.

Any MAP sensor based setup could tune this.

[zebra]

how fool proof is it regarding snapping the throttle open to overtake etc?

for me it would come down to the few thousands bucks it would cost to setup would buy a shed load of E85 and/or PULP

[Manuel Kasko]

Pretty interesting stuff hey.

How does the sensors work with swapping the tune etc

Do you have 2 different tunes and it adjusts between them or is it one complete tune that works on both fuels

[GTRNUR]

how fool proof is it regarding snapping the throttle open to overtake etc?

for me it would come down to the few thousands bucks it would cost to setup would buy a shed load of E85 and/or PULP

The volume of the fuel rail would need to be consumed before making reasonable boost, but every turbo car has at least some lag initially. Once your into the boost zone, its not an issue.

Using ULP low octane and a ULP race fuel has a very similar calorific value, so that transition back to low octane when getting off boost wouldn't cause too much of a glitch.

Using ULP and switching to E85 is another story because it would go rich just as you got off the throttle for a moment when fuel mix switches back to ULP.

[DVS JEZ]

U could set it up. Very interesting and outside the box

[XRATED]

The only way I see it happening is with 2 totally seperate fuel systems and two sets of injectors.

Or

Don't drive so fast...

[GTRNUR]

Pretty interesting stuff hey.

How does the sensors work with swapping the tune etc

Do you have 2 different tunes and it adjusts between them or is it one complete tune that works on both fuels

In theory a MAP tuned ECU would do it transparently with one map, so a D-jetro power fc would do. No crazy sensors or anything required. Using 2 fuels with similar calorific properties would make it easier to setup, and would make any transition a lot smoother and easier to tune for.

The issue is that you have to use LOTS of e85 to make power so the tank has to be larger. Using a full blown race fuel makes sense as you can use a smaller tank. Evening using 98 in the second tank is worth considering, or 98 with 10-15% methanol perhaps...

[GTRNUR]

The only way I see it happening is with 2 totally seperate fuel systems and two sets of injectors.

Or

Don't drive so fast...

Do you have an explanation to backup that opinion? Where is the problem?

Everything is impossible until you put in some effort to making it work.

[zebra]

I have seen it done, but not switchig via MAP

just a switch and an output on the ECU, hit the switch, switches on the race fuel setup and off you go, flick it back again and back to PULP

not as fancy as your idea, but imo more fool proof (the car in question had the boost control setup to match the fuel map it was using

[Nee-san]

Honestly man, you're probably better off keeping a single tank and fuel and then having duel maps, one for economy, one for power.

[wedge_r34gtr]

The plumbing at the rail would use seperate fuel delivery from two regulators.

Interesting idea.

Would it be easier to run two fuel rails, two sets of injectors (e.g. nismo plenum can be set-up for this). It would allow a more exact transition between the two fuels and the ecu could be tuned accordingly to totake into account the changing calorific value.

[DVS JEZ]

Neesan there is not advantage to that. Nur's point is a dual fuel, 1 for race fuel 1 for normal octane. Only uses the race fuel on wot basically

[GTSBoy]

I agree with using 2 fuel systems. Otherwise, as stated above, you'd risk transitioning to boost and needing high octane juice whilst low octane stuff was still coming out the injectors.

[KiwiRS4T]

I think one fuel system and one tune would be most efficient. With lower grade fuel you are going to need bigger throttle openings and more gear changes. I have a quite noisy exhaust and no WOF at the moment so I tend to drive around off boost most of the time and can still easily keep up with the traffic and my fuel consumption is lower than it has been for ages! But whenever I want I have the power of the GT3540 on tap.

[The Dan]

I can see a wheel being reinvented

[ARTZ]

really, i just see an idea that while interesting in theory is self defeating in practice...

i mean he complains about having to carry extra e85, but is prepared to add extra fuel tanks to carry race fuel which Im pretty sure is illegal anyway..

as for complex fuel systems, well a surge tank and larger lines is hardly complex and is nowhere near as complex as this crazy get up is going to be..to make it work would most definately need twin rails and twin injecotrs, otherwise by the time your fuel rail floods with the race fuel you want its already at 7000rpm and knockin its head off..add to that the weight of the system your running...

i guess if you want a 1000hp street racer with good fuel economy there is some merit to be had here, otherwise it seems completely pointless

Anyways, if you think it is worthwhile go for your life but personally i think it is MUCH easier to carry a few jerry cans of e85 in the boot

[ARTZ]

haha. Ok .i forgot to watch the video...i see you are talking about 1000+hp street cars and yep all makes sense now...