Hey, that's what I was going to say! Hehe, I have run 140 in my 250R before just for fun (a friend had it for is race ski). It lost most if it's low end, wouldn't idle, and was hard to start, even in the middle of summer. Boy did it sound like it had a wicked porting job though.

Don't run the race gas unless you have a high compression engine that needs it (or if you have your timing too far advanced )....

 

I geuss you guys are right, seeing how I've only been drag racing for about 13 years and been building engines for around 15 years.

 

Please explain further.

Higher octane fuel is a "deader fuel" and does not explode as easily, this is the property that makes it desirable to run in a high compression engine to avoid detonation (that is, the uncontrolled, compression induced, pre-ignition of the fuel/air mix).

Do not confuse the octane rating with the specific energy of the fuel...

There is plenty of documentation on the web if you are interested.

Here's a link to a great article on the subject http://motorcycle.com/mo/mcnuts/rt-fuel1.html

 

A fuel's "octane" rating is the amount of the fuel that is made up of chains of at least eight (hence OCTand) hydrocarbons. These longer chains take longer to burn, which extends the length of time of the explosion in the cylinder, and allows the engine to develop power through more of the power stroke. Lower octane fuel contains more shorter chains, which combust more rapidly, explode faster, which causes the pinging, because your peak explosion is happening too early in the power stroke. So, higher octane fuel burns slower. Whether or not it burns hotter or cooler I couldn't tell ya, my engine doesn't seem to heat up any faster or slower when running high-octane fuel.

Absolutely any engine, low or high compression, will benefit from higher octane racing fuel, but higher compression engines will benefit MORE. During the summer my friend's and I fill up at the airport with 100 octane Aviation fuel, because it gets rid of the pinging in the hot temperatures, runs stronger, and gives the exhaust a nice sweeet smell.
As far as I know racing fuel won't hurt anything, other than the fact that of course your developing more power so there is more risk of snapping a connecting rod or something like that.

Just thought I'd stop all the myths right now.

 

BOB 4X4,im with you on this one.From EVERYTHING that I have read and learned thru the yrs about Octane,we are both correct.Why dont some of you expert Octane folks in here read some things posted and written by EXPERTS in the feild of Octane.Use the Internet if you like,than say thanks BILL for setting us straight.Motorhead,especially you.You are so wrong making a statement like, any engine,high or low compression will benifit from higher Octane.You are SO wrong.Asfastasu could take an education to.====BILL

00 Xplorer 400cc 4x4
Dont waste your money on higher Octane if you dont need it.

 

Bill: Have you ever USED high octane fuel? I'll bet you buy Regular at the gas pump because you think it runs just as well as Premium? Grow a brain. Or better yet, just TRY IT FOR YOURSELF! A high compression engine, like a race engine, benefits from high octane, we agree on that, correct? Alright, now I've got an '86 Ford Bronco that I've put a 460 engine in with 8.5:1 compression, I'd call that relatively low, and the difference between even regular and premium is noticeable, and when I put Avgas in it (~100 octane), it makes a HUGE difference! Firsthand experience bitch, you can't beat it. Now, before you go and read some damn book to prove me wrong, just take your POS datsun out and put some premium fuel in it for christs' sake, it'll thank you for it.

 

MEATHEAD,before you call me a bitch,do yourself a big favor and go a few posts up to the one that 86atc250r wrote.Please go to the link he suggest that we read,you'll than see,you owe me an apology.
FOR THE REST OF YOU,The real advantages of racing fuel comes from the fact that they will tolerate higher compression ratios [due to the octane rating]and thus indirectly produce more power since you can now build an engine with a higher compression ratio.

The BOTTOM line here is that,in a given engine,a fuel that does'nt knock will produce the SAME power as most expensive racing gasolines.

BILL,
00 Xplorer 400cc 4x4

If you want to come in second ''FOLLOW ME''

 

Actually there are some "issues" running 100LL avgas in high performance engines or regular automotive engines for that matter. If you think about it, it is formulated for airplane engines that turn very low rpms, and there are some other problems with it as well that I can't remember at this point.

Do a search in Dejanews and you will find quite a bit of info on the subject, and why it's not a good idea.

FWIW, I have a Toyota Celica for a daily driver, not a race machine by a long shot, but it is a very refined 4-valve high rpm motor. It will ping on 87 octane, will not on 89, and begins to feel like it is losing power with higher grades, so I run 89. I have not verified those comments with anything but the seat of my pants, so take it for what it's worth.

I do know for an absolute fact that my stock compression 250R runs much, much better on pump gas than race fuel.

 

Bill: If you think you know more about the subject than my college chemistry professor, then your welcome to dilute yourself with whatever information you want, just don't go spreading your stupidity to the masses.

What I said is true, the technical reasoning in my post is accurate, I dare you to find any information that says otherwise. I never said whether or not racing gas was healthy for an engine, I said higher octane gas will produce more power in an engine. I say this from experience, as I have yet to see a vehicle that produces LESS power on high octane fuel than it did on low octane.

If you can prove me wrong with solid figures like dyno runs by a major publication, instead of just talkin out your *** as you have so far done, then I might give you a little more credit. Thus far all you have done is say I'm wrong, and that I need educated, yet you don't say why or where I'm wrong. I think your the one that needs to educate yourself. Just because a fuel can run your car without pinging doesn't mean there isn't a fuel out there that will produce more power. Just think about it yourself, use your own head for once (that's that big growth on your neck with the hole you shovel the food into).

 

Also, just for reference, my best friend has owned an all original '64 Pointiac Catalina with a 389 for over six years, and has run 100LL Avgas in it 90% of the time he's owned it. To this day the original engine, no work whatsoever, has about 140,000 miles on it, and still shows no signs of aging, doesn't smoke, knock, anything. So, if running Avgas is unhealthy for a car, it must not be bad enough to kill off his tired 389 after running the stuff for six years. Firsthand experience. Don't always trust what you read in books, it's almost always from a biased source.