[midway64]

what octain is safe for 15-1 race motor

[bigchief468]

I use 112 and it runs the same as 114.

[WARPed]

a lot has to do with chamber design, iron head - old e heads - KRE - CV-1 all have different octane requirements at the same Cr.

[Vengeance Race Engines]

Originally Posted by midway64

what octain is safe for 15-1 race motor

We have used C-14 at 15.1, but there's a lot more to it than just Octane rating.

[craigs69]

Be aware that not all race fuel manufacturers use the same octane rating in their advertising. Some use the Research Octane rating, while others use the Motor Octane rating. I personally feel that the Motor Octane rating is more accurate, and is always the lower number of the two. Another misconception is that VP Racing Fuel's C-12 is 112 octane. It is actually rated at 108 Motor Octane. Never assume that VP's fuel numbering system is a true representation of octane numbers. Some are, while some aren't.

I was a VP fuel distributor here in northern Wisconsin from 2005 - 2012. As a general statement, I would say that C-14 (which is actually 114 Motor Octane) would serve you well, however, your engine builder would be the best guy to make a recommendation. Like WARPed and Vengeance Race Engines said, there are many factors that need to be considered other than just compression ratio. My suggestion would be to determine your actual fuel requirements, and then talk to a technical representative from one of the fuel companies about your needs. Just like engines, the octane rating in fuel isn't a clear cut science either. Many race fuels are blended with different additives that will allow you to run a lower octane rating than a competitors fuel. For expamle, VP uses Coolinol, which is an additive that help reduce detonation by cooling the intake charge. I saw that first hand with some of my former customers who ran C14 for years, but switched when another brand became the official sponsor of their series. After fighting detonation issues while trying to run the official fuel sponsor's 114 octane rated offering, they gave up the contingency money and purchased C14 from me to solve their problem. I am certainly not implying that VP is better and will solve all of your fuel related problems, as there are many great fuels available for purchase today. I'm just highlighting the fact that you can't just shop fuel based on octane numbers. Call the tech line at the fuel manufacturer of your choice and discuss your needs.

Here is a link to some good information about octane:

http://www.vpracingfuels.com/page469659.html

[midway64]

KRE motor was told to run 114 I'm using c14 and c15 both showing motor octain of 114 or 115 fuel guy tring to sell me late model plus from vp show's good to 15-1 but only has a motor octain of 113 ???????? very pricy stuff but I wanna race

[craigs69]

Late model plus may work and it used to be considerably less costly than C14. Since I gave up distributorship in 2012, I haven't seen any price lists so I can't speak for today's pricing, but Late Model + used to be close to 40% less costly and C14. I had a lot of off road racers switch to it when it became available. It's claim to fame was that it ran cooler than C14.

One thing that I did learn quickly while selling VP fuel is that I was not an expert on engine fuel requirements, so please don't take what I say as the gospel. I would definitely leave that to the engine and fuel guys. All I can do is pass on real experiences that I had with customers over the 7 years that I sold it.

[Vengeance Race Engines]

Originally Posted by craigs69

Be aware that not all race fuel manufacturers use the same octane rating in their advertising. Some use the Research Octane rating, while others use the Motor Octane rating. I personally feel that the Motor Octane rating is more accurate, and is always the lower number of the two. Another misconception is that VP Racing Fuel's C-12 is 112 octane. It is actually rated at 108 Motor Octane. Never assume that VP's fuel numbering system is a true representation of octane numbers. Some are, while some aren't.

Here is a link to some good information about octane:

http://www.vpracingfuels.com/page469659.html

Good info Craig.

Advertised Octane Ratings are the last thing we look at when choosing a Fuel for a given combination, and even then it wouldn't be the deciding factor.. A lot of power can be found or lost with the right type of fuel for a given combination and it isn't the Octane that does it.