air/fuel

[Fast Fred]

i 've been told that the air fuel mix of alkys is about 1/2 that of gas through the same carb.
so to say if i had a moda that ran good on gas, made the jets 1/2 the size in the same carb and ran on methonal i'd be close?:cool:
any body,
thanks
FF

[John (Taylor) Gabrowski]

You need in the area of twice as much methanol by volme as gasoline in the air fuel mix where it was just gasoline and air before, lube not factored in for 2 strokes. The octane on alcohols varies from just over 105 in ethanols to some 140 in methanol, I recall. Octane can vary by purity of the alcohol, very pure is one thing but add water and the anti-knock figure goes up being its actual octane. The higher the octane the slower the burn, the more BTUs built up on slowly the more power you get. All Alkys are oxygen bearing where gasolines are not until gasohols came along.

There are probably a host of guys hanging around here that can give you jetting references or ideas on rejetting gasoline carbs bigger but to say it is 2X bigger would be very global where an ajustable high speed needles are concerned but for a OMC, Tillotson or Minkuni or Kehien carbs there is a whole learning curve because of all their innards. I am used to what Carter Model Ns (and that is newer to me) than Vacturis in using Alky mixes and they have those twist them needles controlling the fuel to the air taken in. Tuning alky is not abrupt to changes in jetting as gasoline is by a long shot. That is why you used to see ALkys melt down pistons after the second lap or 3rd lap in 5 lap courses (used to be) in what some one thought was the best setup with Alky only to find out they were just a little lean and seized pistons or in cases melted a hole in the crown. It sneaks up on them. Anyone else???

[Mark75H]

Most of John's post is correct, with the exception of this
The higher the octane the slower the burn, the more BTUs built up on slowly the more power you get.

Knock resistance and flame speed are not 100% correlated. Slow pressure rise does not create more power. Power is solely dependant on peak pressure and correct crank angle at peak pressure. Alcohols have lower BTU content than gasoline.

The fuel air ratio he describes is a good rough starting point

[Freddie Webb]

If your gasoline, high speed jet is correct you should be able to multiply times 1.6 and that will be really close. For example, .062 x 1.6= .0992 .062 would be your high speed gasoline jet and .093 would be your alcohol jet. I do not know what carbs your running but you need to make sure the needles are viton and all gaskets are alcohol resistant.

[Fast Fred]

dose Nitro % in to the mix change any thing?
thanks:cool:

[Skoontz]

When you boost nitro in blown a fuel motor, yoy change timing accordingly to best respond with the fuel. We used a wet/dry thermometer to determine the humidity in the air, which would in turn tell us how much pop the engine could drink. Changing very subtley by adding a hotter plug can cause superchagers to blow off the manifold. In the old days of front engines, that in itself caused alot of burn victims and deaths from the supercharger hitting the drivers.

Word of wise...Be careful with nitro, and you're best hooking up with a crew cheif who has experience with it to learn from. Last note here....Plan on ALOT more money spent per run.

[Roy Hodges]

dose Nitro % in to the mix change any thing?
thanks:cool:
Ask someone who has used blenzall. it comes in a pint can
has nitro,alcohol , racing castor oil , and whatever else it needs. ) i do not think with this mix , that you have to change anything . one can /gallon of gas. The can I still have is ALMOST a pint (15 3/4 oz.) But this tom cat piss is not cheap, if it's still available . It is supposed to be a 15% power gain, immediately .

[Fast Fred]

i looked for some, no dice, i need a case:eek: :cool:

[jphii1]

Hey Fred CLICK (http://www.google.com/search?hl=en&lr=&q=blendzall+castor+octane&btnG=Search) It's Blendzall, maybe that's why you had a hard time finding it. When we were racing F1 & F2 bikes either Blendzall or Castrol R were all we used. I never saw the octane booster before, but I think I'm gonna try it too.

[jphii1]

Actually their website is http://www.blendzall.com/

[Fast Fred]

i looked over thare, but didn't see any thing that looked like NITRO JUICE for gas,:eek: can we make some?, Sure we can:cool:

[Mark75H]

I don't think nitro is legal under any race sanctioning body. Why are you looking for it?

[Skoontz]

Contact sales@pricechemical.com

They are in Kenedale Texas. Since gas requires about 15 parts of air to burn, nitro burns alot slower, and will only require 1.9 parts of air to combust. Fact is, it burns so slow that quite often it not all has burned when the exhaust valve opens. It is still on fire when it pushes out the pipe, and, thats why the exhaust shows fire on a fueler. If you are not careful with fuel, your engine can develope hydrocity, by not burning enough fuel when it hits the chamber. Since fuel is liquid, the liquid, unburned can cause heads to blow apart, and rods to bend. There is a starter chart below for jetting






% Nitro in Methanol Jet diameter
increase over Methanol
per volume


0% 1.0

10% 1.12

20% 1.22

30% 1.32

40% 1.41

50% 1.5

60% 1 .58

70% 1.66

80% 1.73

90% 1.8

100% 1.87

[Tim Chance]

I tried running nitro at one time in a 250cc Konig. It was a premix with methanol and castor oil and 25% nitro. I went bigger with the jets and changed the timing and maybe cc's on the heads. I will say all three times I tried it I was in first place when I blew up. I ended up using what I had left in my lawnmower. I think that that little Brigs and Straton could mow down a hay field if I wanted and it smelled good too (makes your eyes burn though).

[russhill]

Freddy,

Gasoline burns at about 21,000 BTUs per gal, menthanol about 12,000. This is based on 50 year old info and 50+ yo memory. So anyway, you can get a lot more kapush out of alcohol at the same temperature. Of course it take more. (Gasoline is a pretty good fuel - particularly that I used to buy in Kingsburg)

Aren't you sorry you brought it up?

Russ

[Ron Hill]

Fast Fred isn't Fast Freddy Hauenstein.....

We always called my brother JUNIOR...when he'd screwed up...

This Fast Fred ain't never been to Kingsburg...

Why not tell the wstory about the time you were inspecing the STOCKS at Bakersfield, because the Old Man was at like McKeesport, PA for the alky Nationals.... "That hot sun sure melts plastic"...

[Skoontz]

There is one other thing that you might want to try, which fuel engines have used for years. Dual distributors, one is timed first, the second one fires a milisecond later to help blow the fuel before the exhaust opens. With a 2 stroker, you got yer basic open holes when the piston drops, so, I'm thinking this system would allow you to blast more pop without the issue of hydrocity.

[Fast Fred]

Freddy Hauenstein
No i am not that Fred. i do Know of him, did get some roundabout info from him, on a Moda i've been workin on.
He would be one of the Grate Ones.:cool:

my self, got some trophys, none like the ones he's got, guna be Takin a Shot
at the Kilo, Marthon, and if my wallet's got any thin left, Endro.

[Fast Fred]

Aren't you sorry you brought it up?
getin some good stuff, :cool:

[Mark75H]

I don't think nitro is legal under any race sanctioning body. Why are you looking for it?I'm still wondering ??

[jphii1]

The only place I know for a fact it is legal is in ODBA Unlimited & Pro Fuel.

[Master Oil Racing Team]

It used to be legal in the alky division both NOA and APBA and AOF I thought. Is it not legal in the Pro division anymore.:(