Evil Aviator

Yes, but the problem is that most of the posts on this forum discuss AFR rather than lambda, and most of the members of this forum are reading AFR on their meters rather than lambda.

True, lambda makes more sense to an engineer, but the general public prefers the dumbed-down AFR reading.

grantmac

What about running a toulene injection set-up? Sort of similar to water injection but raising the octane? I've seen something similar to this with LPG on the internet and according to their tests it worked rather well.
Grant

Turbo 3

iTrader: (3)

Running a secondary fuel tank and/or system is and has been done before. The great and mysterious Kevin Wyum, for instance, had a secondary fuel tank with race fuel that comes on at a certain boost/throttle level. That was with his original FD, don't know what he has at this time.

You could introduce the secondary fuel via separate fuel injectors for instance.

LPG is used as an octane boost for diesel engines.

C Rock999

Down here is shitty california the highest is 91 octane. Is it possible to achieve 100 octane out of a mixture of toulene, if so, what percentage must i run?

Thanks,

Chris

yelwoci

Just to controversial here!
I don't think that Octane Boosters are the way to go with rotary engines.

In fact with my racer (Grp1 1982 RX-7 12A big bridge ports) I tryu to use the lowest octane I can get. I think the Le Mans engines used 84 octane.

If you consider what the high value RON/MON anti-knock properties are trying to do, it is to a limit contrary to what teh Wankel needs.
In a reciprocating engine, pre-detonation can co-incide with the piston rising or stationary. In the Wankel the working/thrust surface is always 'running' away.
What matters, provided we don't have explosive detonation, is the flame front speed. This is of paramount importance for the fuel companies and entirely focussed on reciprocators.

I believe that the Wankel needs a faster but consistant flame front for maximum thrust/power. Toluene and Xylene, though explosive, retard the flame front when just burning.
What we want is an accelerant, though not to the point of explosion.

When racing they insist on pump fuel so I have wondered if a small amount of diesel, in similar ratio to the pre-mix oil, might work as it has a high flame speed once its burning.
The other option is adding Oxidants, which the Petro companies already do.
This amy also explain why leaking water seals make the motor appear to run better. At very high temperatures water breaks into radicles/hydroxyl ions which assist burning.
In racing it is normally legal to use anything that was Homologated on the car. Like the Scandinavian cold start option on the RX series (water+ethanol......alcohol fast flame front....radicle better burn........Ah Moriarty.a word!)

sbd

The low octane/fast burning fuels are highly desirable for NA rotary engines. Not so for force induction ones, where by rising the charge density compression pressures are significantly higher.
Reading through the initial article I think there is an aspect, which is not covered. Assuming the author uses toluene without any additional modifications/tuning of the fuel system (a Porsche and Audi V8) by adding toluene to the fuel he effectively leans the mixture.
As Evil Aviator says most fuel metering systems are volume based. So having in mind the higher SG of toluene of 0.87 and SG for petrol of about 0.75 (0,72-0,77), we can calculate that for the same volume of liquid, 16% more mass of toluene is delivered. The λ for toluene is 11,5 and for petrol 14,7. Therefore if for certain volume of petrol when λ=1 AFR is 14,7, for the same volume of toluene AFR is 14,7/1,16= 12,67 which is λ = 1.1, meaning leaner mixture by 10% from stoich.
Based on the above calculations and assuming no modifications of the fuel delivery system, apparently every 10% toluene added to pump petrol lean the mixture by 1%. Under certain circumstances especially when running stock EMS, this could be considered additional “free” though negligible performance gain.

yelwoci

This gets very complex

Compare Toluene with Ethanol with has λ = 9 but has a lower SG.

yelwoci

You might like to look at the following link while you waiting for you razor blades to rust over before slashing your wrists!

http://www-g.eng.cam.ac.uk/energy/No...5/Lecture1.pdf

13btnos

iTrader: (1)

Did you read through this whole post? This is in reference to forced induction TURBO engines and not N/A-naturally aspirated engines like your 12A with big bridge ports. Please read through the post before you jump down someones throat. So your telling me you would run the lowest octane say 84 octane, like the Le Mans engines that you referenced, with a high boost motor. Hell the threshold of pump gas with 92 octane is 20psi boost max and that is with excellent tuning not good tuning but excellent tuning! You are the one that needs to do some reading while you are waiting for your razor blades to rust over before slashing your wrists! I guess all the big racers, with turbocharged engines, running VP C16 or Methanol which have a slow burn and high octane rating are all wrong and you know better. LOL. Yeah right.

yelwoci

Please forgive but I don't flame anyone unless I mean to and its in CAPS!
I just found a highly detaled discussion on fuel and thought I'd share it.
I have a 12A NA race car and a TII road car.
Both engines can tolerate much higher flame speed fronts than reciprocating engines. What does change howeveris the timing.
My racer runs about 30 deg BTDC with normal 95RON fuel, if I found ways to create or source sub 90 octane a session on tyhe rooling road would be in order.