What kind of gas to run???

[LIVE2RIDE Powersports]

I am going to be running a Westcoast head on my 701. I am going to use the race domes i have for it. It for a freestyle engine.

What octane can i run? I was told to use 110 throught it for best results, but i dont want to spend 100 bucks a day running it.

Can 110 be diluted with premium?

 

[tor*p*do]

psi? porting? what bore and size domes?
more info would help to get a reasonable answer:fing02:

 

[Waternut]

Yes you can dilute 110 with 93 but as stated before, let us know more about the setup.

 

[LIVE2RIDE Powersports]

I have 2 sets of domes. 29cc and 33cc. My cylinders have been ported by a friend that built race skis back in the day. He is also doing work on my pistons when they come in. It will be bored one over from standard.

I'm wanting atleast 190+ psi. I will be running a stock cdi with adjustable rev, stock 650sx pipe mod on my fx-1, 650sx pump, 46+ carb.

Hope that helps

OH and the port job. He calls it a 3 step. The said he bought the template from watercraft factory, I think.

 

[Waternut]

Well I run 93 gas on 195 psi in my 750 but I would definitely call that running on the ragged edge of deto. The engine is ported and I'm running total loss. I don't ever run full throttle except for a split second though.

Not trying to be a jerk but I feel compelled to state the obvious... Wouldn't asking your friend who ported your engine and ports many race engines be the guy to ask about octane requirements for your ski?

 

[LIVE2RIDE Powersports]

Well I run 93 gas on 195 psi in my 750 but I would definitely call that running on the ragged edge of deto. The engine is ported and I'm running total loss. I don't ever run full throttle except for a split second though.

Not trying to be a jerk but I feel compelled to state the obvious... Wouldn't asking your friend who ported your engine and ports many race engines be the guy to ask about octane requirements for your ski?

Ya, he actually told me to run straight 110 or 112. But i didn't know if it would hurt to mix with premium. I dont want to spend 100 bucks a day riding. If i had the money i would say its totally worth it. But im hurting like everyone else and wanted to see my options. Thanks

 

[Waternut]

I'm sure there's a gain running that kind of compression but I can't justify the hassle and extra money associated with having to run race fuel every ride. I can deal with the hassle of having to charge my battery every ride due to total loss but that's, without a doubt, an OMG improvement. I can't see 190psi vs 210psi being anywhere near an OMG improvement.

 

[Speedfreak]

I would run straight pump gas on 200 PSI of compression with no porting but with "step 3" porting (what ever that is) I would run straight race fuel. And would still not hit WOT for more than a few seconds. Detonation is caused by heat and without WOT you won't be building enough heat to hurt anything. (If it is properly tuned)

I am a big advocate for pump gas on super high compression but I would be scared of that. I run 50% mix 93 and race fuel in my stroker with 210 PSI but the motor was built by a freestyle guy just for that. NOT by a guy that built race motors.

And if I am not mistaken isn't 29cc domes on a 701 about 230 psi of compression.

 

[Waternut]

And if I am not mistaken isn't 29cc domes on a 701 about 230 psi of compression.

Sounds about right assuming you're running o-rings. I had 28cc domes on a westcoast head using a regular head gasket and it produced about 175psi. :shrug:

 

[snowxr]

If you can't afford the race fuel why are you even building your engine that way? Sounds like you didn't think too far into the future when you made that decision.

 

[LIVE2RIDE Powersports]

If you can't afford the race fuel why are you even building your engine that way? Sounds like you didn't think too far into the future when you made that decision.

I can always come up with the money to ride, not worried about that. Its just the fact that i could be using that money somewhere else.

And i was wrong, they are 26cc domes.. What comp will that bring?

 

[yamanube]

Race gas is going to be a PITA, I would find some different domes.

 

[LIVE2RIDE Powersports]

Race gas is going to be a PITA, I would find some different domes.

I have a few different sets of domes. I will find something. hey Yamanube pm me ur number please. i lost it.

 

[Speedfreak]

I had a compression chart for a 701 and 760's but I can't find it. But I would guess if 29's are near the 230 mark then 26's would near the 260's or 280's. I wouldn't even attempt to start that motor with 26's.

Also squish band and dome shape has a lot to do with detonation. But remember that with a ported motor it will move more air when the ski is running. The dynamic compression could a lot different that the static cranking compression therefor detonation could come on strong at a lower RPM. (Someone correct me if I am wrong) All of those figures need to be figured into the engine as it is built. SO that leaves it all to your engine builder.

 

[Aircraftsalz]

Isn't all that high compression hard on the crank? When I use to race we would replace cranks every year due to running higher compression motors (240-250 PSI) . I like 195-210 on 50/50 (93) & Avgas or straight avgas. just my .02 , cheaper gas rocks when your riding every weekend!

 

[LIVE2RIDE Powersports]

Thanks guys. I am going to talk to Paul this week and see what his thoughts are since he is the builder. I don't want to have to replace the crand every year, i do have a spare crank if needed. I will keep u guys up to date and let u know the specs soon.