Racing Fuel---to mix or not to mix

[Wendell #1303]

I'm running a VW 1835 with unknown compression. The previous owner says to run 50-50 110 octane and 92 octane, and that it will run cooler that way rather than 100% race fuel. I always thought racing fuel would just allow the fuel to ignite at higher compression or more advanced timing. I thought it wouldn't make a difference if you had too much octane rating. Would it really run hotter with 100% race fuel?

[lstrong]

a lot of people "mix" fuels together but they really don't mix.Different fuels have different specific gravities and won't mix together.It creates hot spots in the combustion chamber that could lead to engine failure.I have had some discussions on various forums with chemists on this subject and the only answer I have ever gotten was "don't do it"

[lstrong]

just run what ever octane that keeps it from pinging and watch the oil temp.

[amr126]

in reference to questions above, does that mean your better off with octane booster, since additives are the only thing raising the octane? I've never heard of fuel mixing causing trouble due to incompatability. I'd just like a little more explanation.

[lstrong]

just use a racing gas with the proper octane.try 100 octane and go from there.check your spark plugs often for signs of pre-detonation.Also,most octane boosters are crap.they say 5-7 points of octane but they are really only adding .5-.7 points of octane.
The best octane booster for the money is berrymans b12 carb cleaner.It has toulene,xylene and other octane adders in there for a fraction of the price.google the ingredients.You will be surprised. your still only going to gain 1-2 points with that though.Just use racing gas,it is safer

[redmist]

A 50-50 mix will almost certainly yield a different octane rating from each mix. Petrol when refined doesnt yield the same octane rating each time. Additives such as Toluene are added to raise the octane rating to a pump saleable octane. Dilute these additives by mixing fuels and you may end up with a high octane rating one batch and a low octane rating the next. Simply put, if you want maximum performance, don't mix fuels.

[bajaxp]

I know that some 76 stations sell 100 octane 'racing gas' that is expensive, but not as much as drum race gas.

Also I have seen guys run very high octane race gas in standard engines and found out that they make less power. This is due to the race gas burning so slow in the lower compression engine that it actually mostly burns in the first part of the header pipe. This is obviously not a problem in a high compression engine.

You might want to do a simple compression test and call an engine builder such as FAT and ask them some opinions on your results.

[bajabird]

I just spoke with Greg at Fat. I have an 8:1 fat motor in my prerunner and have lots of race fuel to burn. He said "no problem using better gas in the motors" "just dont run lesser quality in the high compression motor". As for mixing fuels. No problem, I can mix mexicos magna with the sunoco 110.

Thank you for starting this post. I feel more comfortable running my race fuel in the prerunner now. Though it is a huge waste of money!

[Chase 2]

a lot of people "mix" fuels together but they really don't mix.Different fuels have different specific gravities and won't mix together.It creates hot spots in the combustion chamber that could lead to engine failure.

Whaaaaat??? That is not even close to correct. All Gasoline range fuels are blends of hundreds of compounds in the C5 to C12 range. Those compounds typically include Benzene, Toluene, Ethyl-benzene, Xylene, Pentane, Heptane..... and on and on along with each company's own additives. The specific gravity of the gasoline is dependent upon the ratios of those compounds and has nothing to do with their ability to mix. To go further to imply that the inability of two gasolines to mix such that they burn at different rates in the combustion chamber is complete bull. Besides complete mixing in the fuel cell/ gas tank, the atomization of the fuel in the carb or injectors will effectively blend your supposedly non-mixable fuels.

Now, it is possible that there could be a race fuel that has an additive that could be incompatible with other gasolines, but that is far, far from what you are saying here, and I've yet to see it.

I've been running blends of pump gas and race gas for years with great results and no problems what so ever.

[Ramsey_ElWardani]

I ran four different fuels in this years Baja 1000, anything I could beg, borrow or steal, and couldn't see a difference in AFR or EGT. They mixed well over the bumps, shaken not stirred.

[bajabird]

Ramsy,,, who knows what I got put into my car......

You said four different fuels:
1. anything you could beg
2. borrow
3. steal

was the 4th purchase? hehe

[Wendell #1303]

Since I posted this thread I've talked to several other people who have mixed fuels in the past and had no problems. One guy runs oval dirt tracks up in Santa Maria and he says everybody on that circut runs 50-50 110 racing gas and 92 pump gas. Thanks for all the input.

Wendell

[RWilliams]

Im no expert but Ive been running mixed fuel for 5 years in my sand rail and never had one engine problem. Mixing helps with calming down the octane and the budget, especially when race gas is so expensive.
Speaking of that where does everyone buy race gas, Ive been going to SOCO or a little station in El Cajon it varies from $7.50-$8+ per gal anyone know of a cheaper place??

[Wendell #1303]

I buy it from Silvas in Oxnard. It runs about $8 a gallon, but I get it in 5 gallon cans. The cans are sealed so they won't every leak and they're handy to throw in the toy hauler for the trip out to the desert. Plus you have a can afterwards! Whoppee deedle, huh? Really it's handier than the way I used to get it (in bulk).

[lstrong]

Whaaaaat??? That is not even close to correct. All Gasoline range fuels are blends of hundreds of compounds in the C5 to C12 range. Those compounds typically include Benzene, Toluene, Ethyl-benzene, Xylene, Pentane, Heptane..... and on and on along with each company's own additives. The specific gravity of the gasoline is dependent upon the ratios of those compounds and has nothing to do with their ability to mix. To go further to imply that the inability of two gasolines to mix such that they burn at different rates in the combustion chamber is complete bull. Besides complete mixing in the fuel cell/ gas tank, the atomization of the fuel in the carb or injectors will effectively blend your supposedly non-mixable fuels.

Now, it is possible that there could be a race fuel that has an additive that could be incompatible with other gasolines, but that is far, far from what you are saying here, and I've yet to see it.

I've been running blends of pump gas and race gas for years with great results and no problems what so ever.

If you don't mind ,Chase 2,would you read through a thread on another site about mixing fuels.I think they were able to explain my points better than I did.Let me know what you think.

http://www.trx450r.org/forum/index.php?showtopic=42532&hl=mixing+race+gas

[Chase 2]

Lyle,

IMO Mr. Bad Habit is just wrong. The two different fuels will indeed mix. As pointed out each of the fuels being combined are already mixtures of various compounds. They will not separate into two independent fluids allowing his so called gulp of bad fuel effect.

I totally agree with Mr. Chuck’s 06 450 in his explanation of combining the two fuels.

I think Bad Habit is taking quotes from Ticeman out of context and using them to support his beliefs with out fully understanding what he is quoting. I’m not even sure that Ticeman is all that correct either.

Ticeman seems to think that unless you are a petrochemist you will destroy your motor by mixing fuels you don understand, and if you don’t do your mixing in laboratory setting you are going to screw every thing up. Look, if you take what is represented to be 114 octane and combine it with 92 octane the result may not come out to be exactly 103 octane, but hey come on is the fact that its 102 or 104 octane really going to make that much difference?

The QUOTE(Ticeman @ Oct 6 2004, 09:54 PM) regarding mixing fuels appeared to have been plucked from a previous discussion regarding using high octane aviation fuel rather than high octane race fuel. AV gas has additives which you don’t want to run in your car or bike. AV gas will mix with regular pump gas and with race gas, but it will still contain the “undesirable” additives.

The other quote from Ticeman had to do with blown motors and a rant regarding how he feels that MTBE was causing two stroke motors to fail due to incompatibility of two stroke oils with MTBE. Well we’ve all been running MTBE containing fuels here in California for some time now & I haven’t heard of massive numbers of two stroke failures. But, that is besides the point, MTBE and two stroke are much more dissimilar than pump gas and race fuel, and even if MTBE & two stroke oil were incompatible, that doesn't support an argument that pump and race gas would be incompatible.

I think that GPracer 2500 on the last page pretty much summed everything up just fine.

[lstrong]

I can agree with his summation as well.I personally won't mix fuels because I don't know if the additives in each fuel are compatible.I know plenty of people that mix their fuels with success and I have one friend in particular that wont do it ever again(he thinks he holed a piston because of mixing fuels).To each his own.

[hammer down racing]

I know a drag racer that runs a VP fuel that I don't remember what the octane is. It is an oddball octane that VP makes by blending an octane higher and an octane lower to make the octane rating my buddy needs. I think the octane is 111 but I'm not sure.

[classicboats@gmail.com]

I ran 110 low lead aviation fuel in my boat for 10 years. I would run it in my other toys as well. I have also mixed it.

[Perfect Race]

I have been using and mixing race gas for many years in my VW's with no problems. It is a good way to get rid of old and questionable race gas and the cars seem to run better and cooler on it.