Just wondering if any of you have dynoed with pump gas and with race gas with the same mods to see the difference the fuel makes in HP.

 

You understand without a tuning change the difference is negligible. Race fuels may make slightly higher HP numbers, but not significantly without retuning the car, its the anti-knock properties of high octane fuel that make the car perform, you retune to increase cylinder pressures <wether it be via more timing or more boost>. Also high octane provides a larger measure of safety when the car is hot to prevent detonation.

 

With Supras race gas can make a HUGE difference on the dyno as it makes the engine run more quietly thus the knock sensor doesn't retard the ignition as much.

The FD has a shitty knock feedback system (the Power FC has no knock feedback) so the difference it very little. As stated above it will allow for a more boost or a leaner tune due to the anti ping properties.

 

At low boost levels race gas will make LESS HP due to slower burning in the combustin chamber which is why it is more resistant to detonation.
John

 

So the main reason I asked was because a performance shop just opened up next to my house here in town. They are selling race gas for like $7 a gallon and was trying to figure out it were actually worth it to go try a tank full....

 

if youre going to the track dont fill up w/ a full tank.... that just makes it heavier..... but race gas will help if you up the boost just pray that you dont up the boost too much and somethin doesnt blow....

 

Race gas is also often leaded (the 110 that I can buy here is), so if you're still running a catalytic converter it will foul it up quickly. It will also hasten the demise of your O2 sensor.

That's not to say that running 5 gallons of race gas at the track every so often is going to foul everything up, but if you do it often enough you'll be in the market for a midpipe or new cat, and a new Oxy sensor for sure.

 

that's an interesting way to put it...Nahh, it would be for running it at the track once a year or something like that.

 

if you really want to do something like that run avgas from your local airport much much much cheaper it is usually 100LL just dont forget to add some marvel mystery oil or two cycle oil because 100LL does not have good lubricating qualitys

 

Don't just buy 110LL and assume its the same because its not. You have to look at all the data i.e. octane, burning speed, energy value, cooling effect, specific gravity, etc. Believe it or not there is a reason why good race gas is more expensive than av gas. I recomend VP gas myself

 

WTF? Anti ping properties? Anti knock? The only thing loading up on anything higher than 93 is going to do is make your wallet empty more quickly. If you had a motor that ran with out knock, or very little knocking, and with out tuning/raising boost, bringing up the octane rating isn't going to do squat. In fact, it should make you LOOSE power since it takes MORE compression to ignite it. It will ignite later in the compression stroke, thus the rotor/piston will be closer to TDC, or in extreme cases, already at TDC. If you're not going to be running more than ~13-15psi, 93/94 should be fine. (that's what I'm running...no issues whatsoever). Maybe you can go more, but I personally wouldn't risk it. Take a look see at...http://www.howstuffworks.com/question90.htm

And since I know I'm going to get flack, no, I didn't just read this either. Simple chemestry and physics.

 

I G N O R A N T

Why not use 89 octane in that case? Why do race cars use race gas?

 

I can't stop laughing!

 

I would assume because race cars are tuned more aggressively, so have a higher rate of knock. He was saying that (loosely quoted) "cars with no knock or very little knock don't need it", which is correct. Normally aspirated cars with high compression don't need anything better than 89 because they aren't highly tuned. Add any sort of forced induction or changes to the combustion in the engine and you increase the need for more knock retardant gas.

 

That's great. Coming from an 18 yo kid, I expect nothing less. How 'bout giving me an argument to back up your wonderful point. If you don't have one, then don't bother to post and go back to popping zits.


DaedelGT

Do you think that race cars use it 'cause they're running high enough compression with timing advanced enough that they might actually need it? And obviously some don't even use it, rather use alcohol, nitro (maybe not so much anymore), etc. I DO use 89, in my daily driver. If you were running boost low enough you could use 89 too. Obviously you need 93 in the FD as the compression due to boost is high enough to warrant it. You have room to play, that's why you can still use 93 when bringing up the boost. That's all I was trying to say.

In general...

Saying that there's an "anti knock" property isn't correct. I'd like to know what this "property" or ingredient is. Let's see how much more power you get running 93 as opposed to 89.

 

We are spefically talking about forced induction cars.

Sorry for the ignorant comment, you are apparently not so. I didn';t really read your post.

 

Yup, The only reason why you would use higher octane is for tuning or forced induction.

Gas isn't going to improve horsepower by itself.
Unless you advance/tune the car for the higher octane gas then it will not take advantage of the raised knock/detonation level.

A N/a doesn't need high octane because it is not as prone to knocking detonating like a forced induction application is.

The Race cars use Race gas/methanol/etc cause it increases those things. Methanol/nitro burns hotter as well(friend put a cap full in his goped and melted the piston to the block).
Those cars are incredible anyways. They aren't meant to last very long so they do crazy stuff like push it to the very limits. So they raise the safety/knock level with the fuel to go even father.

An example was that in Super Street they had a crazy FD. It was doing like 400 HP on 91 but on race gas it was pushing 600(i think) with more boost.
The higher octane allows you to up the boost while retaining the safety margin.

I probably contradicted myself somewhere in there or something but oh well.

 

Negatory. The vast majority of unleaded racing fuels (with RON of 108 or higher) burn just as quick or quicker than pump fuel, due to the large amounts of oxygenate and volatility additives. And the price isn't all that high, not as bad as the leaded race fuels, which I see no reason for unless you're pumping unreal boost levels (and have jettisoned your cat and 02 sensor).

It'd be great to see some dyno tests on some of the better unleaded race fuels now available on the market to see if there's a power boost. I'm not advocating running race fuel unless it's truly warranted, but we did some dyno tests with some unleaded race fuels in motorcycles (sportbikes) with no other modifications whatsoever, and several boosted power by 2-3 percent.

 

Pharg...$7.00 a gallon is pretty damn expensive for race fuel. What brand and octane is it? It's got to be leaded race fuel if they're charging that much (and even then, I used to buy Sunoco Maximal Red leaded race fuel-- which had the highest RON of any race fuel a few years ago-- for $5.75 a gallon).

 

Mix your Sunoco with Toulene, or Xylene (10 20 or 30 percent) and you will have race gas, at various octane levels. Either chemical can be purchased at local chemical houses for usually less than $5 per gallon, and a 55 gallon drum for less. these are the octane increasing parts of "race gas". You can even mix in small amounts of mineral spirits for injector cleaning. The only problem when using high octane fuels is what has been stated before that you must tune with more agressive parameters for more power increase. The drawback is that you must run the good fuel in every tank with that state of tune.

 

Mix tolulene with Sunoco Maximal Red? Why? It already has tons of tetraethyl lead (highest of any race fuel a few years ago) for an RON of 122. Anything more and the stuff will burn slower than wet marshland. (I take it you're talking about regular pump gas)

The other problem is that tolulene is toxic as hell. Nasty stuff. Continual contact with your skin or breathing fumes will get you sick as a dog.