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

[discopotato03]

I just have to wonder at the value of anyting like a 1000 hp street car . I wouldn't want all that stuff in the boot for safety reasons and if you got pulled over and checked out theres no hiding it .

Better I think to use one higher volume fuel system and set up a flex fuel capable computer eg a Vipec and ethanol sensor . That way you can vary the amount of ethanol you throw in and even use power kero (91ULP) as a basis though I don't know why you'd bother .

Anyway the risks are safety , yours , and if anything screws up detonating your engine which isn't cheap to fix . I believe its possible to build an engine that can make lots of power and still be tuned to give good fuel consumption - for the engines size - when driven sanely .

Whatever you build will cost money and then the saving on fuel concept goes out the window .

One thing to note in that RX7 was the "auto" trans and the tall final drive gearing , that could sort of work with a higher stall converter if it had a lock up mechanism for highway driving . They had the huge advantage of a turbocharged 7 litre V8 which in a light car can light em up easily .

I very much doubt that thing gets good fuel economy and the build cost must be huge .

[Deano 1]

i think its stupid, If u cant afford to put the right fuel in a 1000hp street car..... than u shouldnt own a 1000hp street car.... simple as that, performance cars use expensive fuel.... i understand dual maps on 98/e85 as e85 is not available everywhere so it would get you out of trouble, trying to cheap out on fuel because your to tight to put the right stuff in, is just stupid....

[GTRNUR]

I can see a wheel being reinvented

Nothing wrong with trying to make a better wheel. I've done that more than once before.

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

Leaded fuels are illegal. ULP high octane is perfectly legal, as is running a fuel cell in the boot (at least it is in QLD). It requires a blue plate for the second tank, that is all.

I live more than 2200km from the nearest E85, so it was never a consideration for me nor was I complaining about it. Frankly e85 is not a good option for duel fuel anyway as you use too much of the stuff to make power. I believe Piggaz told me his car drinks 10~14lt minute to make over 400kw. 3.7lt/minute of 98 octane ULP can produce the same power, and a high octane fuel would do it even easier.

I estimate the average billet fuel rail wouldn't hold more than 60ml of fuel. At 3000 RPM/WOT/no boost my motor will empty that fuel rail in less than 2 seconds. Add a delay for the transition back to low octane when off boost and there is no problem there. That's not complex, its maths and a little engineering.

There is no doubt that the NRE cars are utterly mental, but the point you should have taken from what they do is that it is possible. That is all.

If there is any truth to predictions that fuel prices will exceed $2/litre in the not too distant future, duel fuel setups begin to make a lot more sense. Unless you'd rather be driving a hybrid.

[discopotato03]

I wouldn't think $2/L is someting you'll see in the near future , but if it did it may make the viability of locally produced ethanol more economic .

Something else to think about if you want to run lower octane (cheaper) pump fuel is water or water/alcohol injection . Its much easier/cheaper to supress detonation by adding charge cooling only when you need it rather than running a higher octane fuel all the time .

From memory one of Mafias original reasons for using WMI was that he couldn't get pump 98 easily in his neck of the woods at the time .

[Rolls]

just use water meth injection, only comes on on high boost, advantages of running better fuel.

or get a flex fuel setup so you can fill up with E85 when you want then switch back to 98 halfway through the tank

[StevenCJR31]

Use LPG as the "cheap" runaround fuel, no need for a second map on the ecu and the gas has a higher octane than 98

[Piggaz]

Frankly e85 is not a good option for duel fuel anyway as you use too much of the stuff to make power. I believe Piggaz told me his car drinks 10~14lt minute to make over 400kw.

Haha. That number gets higher and higher. 1500 cc worth of injector per cyl. It's about 9.5 IF you hold it flat for 1 minute. No idea where you can do that though. I'm sure it could be leaned off a tad.

[GTRNUR]

Ah... Short term memory loss. I knew it was a lot though.

I already have a basic WMI system on the car although Im using it with 98 octane. I'd want to switch to a direct port progressive setup to get more accurate cylinder distribution if I were to run it with 91 octane. Perhaps the answer worth considering right there.

[ARTZ]

Who the hell runs 91 octane in this day and age..its hardly goin to give you better economy ..

[ARTZ]

Also you mention emptying your fuel tail in 2 seconds ..I have a reasonably large twin entry rail and I'm pretty sure it would hold more than 60ml, intact I would guess at least twice that..Also a well sorted 1000 hp car at WOT is going to hit limiter in well under 2 seconds.. Sure it's a small margin for error, but it could be a really big error..

I don't know, I'm sure it could work but not sure I'd be comfortable using it automated unless it had twin dedicated fuel rails.. Or it would have to be a manual switching..This means you have switch it on in advance, which means you may as just get out and fill your tank with race fuel..I mean when have u ever needed an extra few hundred hp that quickly.

[Cowboy1600]

I kinda like the idea, but just how much fuel would you have to use before the initial investment in the fairly complex setup would pay for itself?

Let's say it costs you $2k to setup (considering equipment, labour and tuning).

If it was simply 91 vs 98 ($0.15 litre difference generally), that's about 13,000 litres of fuel you would need to burn throught the 98 nozzle to essentially pay back the initial cost. If you add something to your fuel which bumps it to say $3/litre that's more like 1,700 litres which is getting on 10,000ks which is a whole lot of Ks considering it's WoT type driving (ie. track day or traffic light GP).

That said, I still like the idea, just not as a way to save money on fuel. I like it from the same perspective as switchable E85/98 maps - only taking it to the next level. E85 is a bitch to get so I'd be more inclined to have a 10L drum of C16, or something to that effect, in the shed and keep 10 litres in a "switch to" tank in the boot. Drive around on 98 all day and when you know you're going to want the power and safety of a high octane fule, flick a switch and run the car for a minute before sinking the loud pedal.

[Cowboy1600]

Oh yeah, and Water Methanol Injection.

Problem very close to solved At least for a non-1000hp car.

[discopotato03]

How can you get power from 91 octane fuel ? Low octane fuel burns more readily that high octane fuel , the major difference is that one is harder to ignite than the other which is why it resists detonation .

Its probably getting narrow focused but if I was doing an RB25 head today it would be a Neo one because these were getting into the ULEV era of RBs and they probably had chamber and piston crown designs that better resisted detonation than earlier versions . Low emission/low consumption engines needed better chamber and port cooling from water jackets to deal with hot spots that promote detonation - particularly in lean burn situations .

If you can beat detonation in other ways it reduces the need for high octane fuels and richer AFRs .

[GTRNUR]

Good point. The NEO heads are essentially the apex of the development of the RB platform. For the most part all that was done with the Rb26 heads since 1989 was camshaft development.

Forget about 1000hp cars too. Every 1000hp RB out there tends to break either itself or everything else around it when they are driven. Try 500-600, becase that at least will be reliable enough to be daily driven, and not an utter bitch to drive in traffic.

Most of the KM's I do in my car are done below 2500 rpm. This is where most of my fuel is consomed. Factor in an 8.2:1 compression ratio and there is no reason 91 octane won't work just fine. The motor doesn't start to run at 0 vacuum until about 110 in 6th, which is about 2400 rpm. And thats perhaps 2/5th throttle, so not even close to full load.

[STATUS]

We had a soarer in that ran 3 fuels via a Link ecu... all automated.. was a cool setup and the brain child of VB (sau member)

349rwkw (ish) on LPG injection for daily duties

379rwkw on BP 98 for long trips to extend range

and over 400rwkw on E85 for making smoke.

[DVS JEZ]

Must have been an expensive setup,

[ARTZ]

Yeah by automated Trent do you mean it would switch fuels automatically at a desired rev point..?

Cause I believe that is what NUR wad hoping to do..as apposed to just having a dash switch to change..

I'm just not sure automatically switching fuels in the rail mid rev is a great idea..however if you had twin rails and an ecu programmed to switch to secondary injectors at a desired revpoint or throttle position, would be much safer

[Cowboy1600]

And now I watch the vid on the OP

They essentially have a souped up WMI which is full of C16. Two entirely separate fuel systems, a "91" for cruising and then the "C16" when boost kicks in. Seems overly complex for the gains it would no doubt give (because car still runs a 50/50 91 to C16 mix).

[GTRNUR]

Yeah by automated Trent do you mean it would switch fuels automatically at a desired rev point..?

Cause I believe that is what NUR wad hoping to do..as apposed to just having a dash switch to change..

I'm just not sure automatically switching fuels in the rail mid rev is a great idea..however if you had twin rails and an ecu programmed to switch to secondary injectors at a desired revpoint or throttle position, would be much safer

Load switched based on Manifold vacuum, not RPM was my idea.

And having re-thought how it could be done, the back flow valves can be eliminated if the fuel supply is fed from a three way 3/8" solenoid (same as a boost control solenoid, but fuel rated). This would eliminate any cross-fuel system contamination.

[GTSBoy]

......everything has to flow through the rail back to the tank unless you're running some sort of dead head system......