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Posted: Sun Jul 16, 2006 5:34 pm
by VermilionX
oldschoolorange wrote:ypu can get 100 at the pumps at some places in the states cant you?
you said above 12... my bike has 12.5:1
does that mean it will somewhat benefit?
anyway... i can't waste money on racing fuel... im barely hanging here in terms of spending money, i need to find a new job or i'll never be able to afford trackdays and future upgrades.
but like zoo said... he gave a company that sells race gas outside of the race track.
Posted: Sun Jul 16, 2006 5:36 pm
by jonnythan
VermilionX wrote:oldschoolorange wrote:ypu can get 100 at the pumps at some places in the states cant you?
you said above 12... my bike has 12.5:1
does that mean it will somewhat benefit?
anyway... i can't waste money on racing fuel... im barely hanging here in terms of spending money, i need to find a new job or i'll never be able to afford trackdays and future upgrades.
but like zoo said... he gave a company that sells race gas outside of the race track.
If the engine doesn't knock running whatever you're running now, there is zero benefit.
The compression ratio itself isn't important. What is important is the absolute pressure obtained in the cylinder. 95 octane will autoignite at a certain absolute pressure, whereas 110 will autoignite at a higher absolute pressure. This resistance to burning allows the engine to be tuned to deliver more compression. If you generate too much compression, the engine will knock. If it's not knocking, there's no benefit.
Posted: Sun Jul 16, 2006 11:17 pm
by macktruckturner
^^^ what he said.
Higher octane simple resists autoignition (knocking) more. For all intents and purposes ignition is near instant upon proper spark and compression for all grades - broken down to the most scrutinizing levels, the higher the octane rating the slower the flame front moves. This is where the earlier timing comment comes in. As with all things, you never get something for nothing - and when you get the ability to run higher compression w/o autoignition, you need to give more spark sooner in the power stroke in order to fully burn your fuel charge.
It was mentioned that you can gain as much as 5HP on a dyno w/ race gas.. provided you tune for it. The same can be said for just about any grade of fuel, if you tune for it. If your bike is designed to run 87 octane, and you give it a tank of 110 - you'll actually lose power without some serious tuning. It'll smell nice though.
Posted: Mon Jul 17, 2006 1:19 am
by Stratus311
I agree, 110 won't do much for you. Although if I could afford to pay $6/gallon all the time just for that sweet, sweet smell then I would.
It might be leaded
Yeah it's leaded. We used to run 118 in our Honda CRX drag car a few years ago. Ofcourse it also had a 60-1 standard turbo with a 4" inlet, 4" downpipe, 1600cc injectors and about 26 psi boost with 7.7:1 compression on a single-cam 1.6L. Put down 570hp and 480ft lbs at the wheels with that setup.

Posted: Mon Jul 17, 2006 1:53 am
by roscowgo
It's not going to do anything unless your engine is specifically set up for it.
Octane formula-PDF
If your motor pings, or is predetonating. move up an octane rating. otherwise. leave it the heck alone.
Posted: Mon Jul 17, 2006 2:49 am
by VermilionX
you know...
my question was not whether it will work on my bike or not guys?
im just asking how much difference it makes to those that have experience w/ it.
but thanks anyway.
Posted: Mon Jul 17, 2006 2:54 am
by scan
VermilionX wrote:you know...
my question was not whether it will work on my bike or not guys?
im just asking how much difference it makes to those that have experience w/ it.
but thanks anyway.
It will make no difference.
Posted: Mon Jul 17, 2006 2:55 am
by jonnythan
VermilionX wrote:you know...
my question was not whether it will work on my bike or not guys?
im just asking how much difference it makes to those that have experience w/ it.
but thanks anyway.
The gas doesn't make a difference.
Increasing the compression ratio on the engine, however, does. That's what you should be asking about.
Posted: Mon Jul 17, 2006 2:56 am
by VermilionX
thanks.
another question, what is the minimum compression ratio for that gas to be effective?
you mentioned 13:1 on the car and you said it needs higher than 12:1.
so is 12:1 the minimum for it to be effective?
Posted: Mon Jul 17, 2006 3:03 am
by jonnythan
VermilionX wrote:thanks.
another question, what is the minimum compression ratio for that gas to be effective?
you mentioned 13:1 on the car and you said it needs higher than 12:1.
so is 12:1 the minimum for it to be effective?
First: I don't think there's an easy way to answer that question, as it depends highly on the engine, intercooling performance, etc.
Second.. what an odd way of going about it. It sounds to me like you want to use high-octane fuel in your bike, and you're curious about how the engine needs to be tuned in order to use high-octane fuel. What seems more logical to me would be to ask how to get a certain level of performance increase out of your engine, and, if that involves increasing engine compression ratios for more HP, what octane rating must be used to achieve the desired performance. The way you're going about this makes it sound like you care way more about having the "110 octane" to throw around than actual performance.