High compression...What fuel??

[pistonbroke800]

So this year i decided to big bore my XP. It is a sled head racing 860 with a 14:1 RKT head. I mostly ride around Golden but i do make it out to Revy and Sicamous a couple times a year.
My engine builder says i am safe to run premium pump fuel from 5000' and up. If i am below that he said to add octane booster. I have never really been a beliver in octane booster it kinda seems like a joke to me for whatever reason. I want to have the peace of mind that i am using good fuel.
Now all you guys running higher comperssion engines. What do you use for fuel? Premium with some AV gas added? Premium with C12? Just premium?
Thanks in advance for any info

 

[Slamnek]

I seem to remember someone on here say that anything over 13.5:1 to add race gas. I'm gonna guess that the 860 would be close to a 50/50 mix. I would not even think about octane booster.

 

[CUSO]

If BJ says run premium at elevation, then run it. Always keep an eye on your EGT's...
Lower elevations, go with the real deal, a couple of gallons of c12 in the tank should be safe... again, compare your EGT's with your plug readings, and use that as your baseline.

 

[takethebounce]

When you say your engine builder, are you reffering to BigJohn from SHR? As CUSO mentioned, if John is saying its safe, then so it is.

If your engine builder is anyone other than BJ, get ahold of John from SHR and ask what he recommends for his 860 set up. He and Kelsey from RKT spend many hours for r&d for these kits and know what works.

This info is usully given long before you even purchase the setup because they want to know where you ride and what fuel you will plan on running.

The problem with Revy is the elevation of the stagging area, or any low elevation staging areas. Another problem sometimes if you are running marked gas from Sicamous or Revy is it is not always as fresh during early season. They sometimes have left over stuff from the summer and when the boaters leave the fuel sits in the tanks until sledders buy it up.

On a side note, I'd be really interested in seeing how you like this build once winter comes, it is something I have been interested in but haven't had the cash to do.

 

[pistonbroke800]

When you say your engine builder, are you reffering to BigJohn from SHR? As CUSO mentioned, if John is saying its safe, then so it is.

If your engine builder is anyone other than BJ, get ahold of John from SHR and ask what he recommends for his 860 set up. He and Kelsey from RKT spend many hours for r&d for these kits and know what works.

This info is usully given long before you even purchase the setup because they want to know where you ride and what fuel you will plan on running.

The problem with Revy is the elevation of the stagging area, or any low elevation staging areas. Another problem sometimes if you are running marked gas from Sicamous or Revy is it is not always as fresh during early season. They sometimes have left over stuff from the summer and when the boaters leave the fuel sits in the tanks until sledders buy it up.

On a side note, I'd be really interested in seeing how you like this build once winter comes, it is something I have been interested in but haven't had the cash to do.

That is a really good point abou the fuel quality. I guess you really dont know 100% what you are getting from the pump. Maybe i will start the season with a couple gallons of C12 mixed into the tank just for peace of mind. Then as the season goes on just lower the mix and keep an eye on things.
Again another good point about stagging elevations. That is one thing ubert the years i have never looked at and i really only have a ball park idea of what the different spots i ride are.
Once we get going in the season i will try to do a little update on the new motor.

 

[pistonbroke800]

Oh i forgot to mention that the builder is Big John

 

[pfi572]

Have RKT 860 with 14:1 head and running from 3400 ft to 6000 ft and run 2 gallons of 110 with no problems,
Main jetting is 480, ecm update,2007 needles in middle postion.boyesen reeds,dyno port y and pipe.
1200 miles on engine.

 

[takethebounce]

Just remember with octane booster, if you are inclined to use these products, they package them to make the consumer believe they are purchasing something that will increase the octane greatly in fuel.

This is wrong! If you have an octane booster that says it increases your octane by 7 or 8 points, those are .7 or .8 so 91 would be increased to 91.7

Not much of an increase. The additive boosters basically lower the BTU of the fuel so you don't get premature detonation. :d We hate when that happens!

Just an FYI, the base elevation of Revy is around 500m. So lets call it 1500 ft. You have a lot of riding to get to the 5000' mark. Golden staging areas are as low as 2500-3000 ft in mid winter. Again, lots of riding to get to the 5000' and above, and you won't often top out over 7000'.

Then you can get into the arguements of should you mix leaded race fuel with non leaded pump gas. Lots of people do it. But did they ever figure out the leaded fuel issue in Canada? I am assuming so, lots of people are still buying it. You might be looking at buying more 110 than you originally thought.

 

[DaveB]

I've been running AV gas (LL100) for years with no issues. 14:1 I use 50/50 around home and 70/30 in Revy. (70% Shell 91 and 30% LL100)

 

[glengine]

I have built lots of those 860 kits and what i recommend is mixing in 1.5-2 gallons of VP C111 or C12 per 5gallon jerry can. I go by the 5 galloon jerry can just because it's easier to mix it up in there and then you aren't guessing what your ratio's are. There are people that run av gas in there sleds, myself i'm not a fan of it at all due to the fact that is designed to be ran at 10,000+ft and it is extremely dry fuel.

 

[pistonbroke800]

Thats a good idea with the jerry cans. What is the difference between VP111 and C12? What are the disadvantages of using AV gas because it is a dry fuel. The reason i ask is that i can get Av gas easily from a bulk dealer i know in olds and i dont really have a line on race gas. Not saying its hard to get but Av gas would be more convenient if its worth it.

 

[DRD]

"There are people that run av gas in there sleds, myself i'm not a fan of it at all due to the fact that is designed to be ran at 10,000+ft and it is extremely dry fuel."

What do you mean?
The most load an airplane will see is is taking of and climbing. Normal flight elevation is normally less than 10,000 feet. After 12,500 FAA requires supplemental oxygen for the pilots or a pressure cabin. Most of the little planes bombing around have neither.
What do you mean by dry? What affect does it have on a 2S?

I run straight 100LL in my 14.5 triple, never had any problems.

 

[CUSO]

AWWW MAN,,,, Another

AV GAS THREAD!!!

Look whacha did Dave.... Just look!!

 

[DaveB]

I know, I know....DRD and I must be weird to run that horrible fuel that only works on airplanes....but for me its about presenting that money saving option since AV costs 1/4 what race gas costs. Naysayers are generally those who have: a) never run it, or b)sell race fuel.

 

[cdnsleddog]

Oh no, not again....

 

[pistonbroke800]

Lets just be happy it didn't turn into a can thread lol

 

[team dirt]

I have built lots of those 860 kits and what i recommend is mixing in 1.5-2 gallons of VP C111 or C12 per 5gallon jerry can. I go by the 5 galloon jerry can just because it's easier to mix it up in there and then you aren't guessing what your ratio's are. There are people that run av gas in there sleds, myself i'm not a fan of it at all due to the fact that is designed to be ran at 10,000+ft and it is extremely dry fuel.

Been running AV gas for years in some pretty big iron, very consisten and safe fuel to use, My rule of thumb for compression is 13.5-1 pump gas is out. You will detonate and squeak a piston anything below 5000'. You might not even notice the detonation on your egt but might see your water temps come up substantially. Dont cheap out, you will regret it in the end.

 

[Modman]

The problem with Revy is the elevation of the stagging area, or any low elevation staging areas.

Gotta agree there. Some areas not too bad, Revy starts really low, I think bottom of Boulder is 1300 ft. The top is only 6300 ft. Again, as team dirt said, watch the water temp, once you start detonating you will see the temp start to increase. Go easy on the trail coming up and down. Good fuel is cheap insurance.

 

[pistonbroke800]

Alright so im am going with AV/Premium mix. Only question is how much of each to stay safe?

 

[Modman]

Alright so im am going with AV/Premium mix. Only question is how much of each to stay safe?

Won't tell you what to run because that's up to you, but I mix 50/50 with
VP 110 and pump gas 94/91 for 13.5:1

I can probably get away with 70% pump and 30% race gas, but like I said, fuel is cheap insurance.