So lately I've been thinking of running race gas

[Kennay]

The engine in my ski is a 84.5mm 760 engine with a 62t/64x topend. I guess I will be using a b pipe of sorts and dual 46's.

I'm thinking of getting pump domes, and some race gas domes when I want to run it. Normally I'm annoyed by having to pay out the ass for 110, but I'm wanting the low end power.

Will I notice a large difference between pump gas @ 185, vs 110 at 230-240?

Anybody think it's worth it? How much will it affect engine wear and the need for rebuilds?

 

[Matt_E]

Pump gas on a 62T cylinder with 185psi cranking compression is a bit iffy.

Other than that, I am interested in responses.
With gas prices as crazy as they are, might as well go higher.

 

[Kennay]

Pump gas on a 62T cylinder with 185psi cranking compression is a bit iffy.

Other than that, I am interested in responses.
With gas prices as crazy as they are, might as well go higher.

Well maybe not 185, but the upper realm of what you can safely run with 93 on this thing.


And what did you mean by "With gas prices as crazy as they are, might as well go higher"

I just woke up and am a little slow on the uptake. :beerchug:

 

[Matt_E]

I meant that if you're going to pay over $4/gal for Premium, might as well go to $6/gal for Race gas.

Also, the 760 cylinders have lower pump-gas safe compression, for a couple of reasons. So what is deemed safe for 701 cylinders, is not necessarily safe for 760's.

 

[HBCwatercraft]

lol, was doing that this summer with my 790cc,240psi vp110,ur going to regret it..every 2 hrs is 50 bucks not fun,i was spending 140 bucks a weekend not include the oil.remember a high comp engine eats bendix and starters.also get a ign timing becomes a factor ADVENT made my starts alot easyier.go 200 psi run 50/50 ur not going to see the diff in perf between the two and more run time.if u dont run a ign piston life exhaust side becomes a issue(roll down on the piston top)due to timeing,detenation ect.

 

[Matt_E]

Holy run-on sentence.

 

[SUPERTUNE]

Get a new Pro-Digital MSD-TL ignition before race gas, one time purchase and setup and will give you a race gas hit off the bottom. (very close if running a std Superjet ignition)

 

[Hydro3131]

I meant that if you're going to pay over $4/gal for Premium, might as well go to $6/gal for Race gas.

Also, the 760 cylinders have lower pump-gas safe compression, for a couple of reasons. So what is deemed safe for 701 cylinders, is not necessarily safe for 760's.

Huh..in sweden we pay $7,3/gal for premium :crying:

 

[Kennay]

Get a new Pro-Digital MSD-TL ignition before race gas, one time purchase and setup and will give you a race gas hit off the bottom. (very close if running a std Superjet ignition)

I wish! If I could afford that, I wouldn't even be using this 62t cylinder to start with

 

[kevbo]

Race gas is now for the "money no object" crowd. You should have a fully modified engine with a programable battery ignition to go along with that fuel.

 

[D-Roc]

i agree, get all the big bolt on items first and then if you need to spend more money and running cost, bump the compression. good carbs and a msd TL are great investments, make good hit and smooth power delivery even on a 701 without the hole reliablilty issue of high compression

 

[750SX]

Think about it. Overtime you will spend as much extra on race gad, than if you would buy a sweet set of carbs/intake or ignition. Running 230-240 psi isn't going to make your crank last any longer either.

 

[thegoldenboy]

I wouldn't. How good of a rider are you? Does your ability warrant the use of race gas? I think a 760, .5 over with 46mm carbs will hit well enough for 99% of riders on 91-93 octane.

Just seems pointless. I'm not good enough to warrant race gas, I don't want the headaches of changing domes/carb settings, so I wouldn't consider this unless you plan to run race gas setup 100% of the time.

 

[Kennay]

I wouldn't. How good of a rider are you? Does your ability warrant the use of race gas? I think a 760, .5 over with 46mm carbs will hit well enough for 99% of riders on 91-93 octane.

Just seems pointless. I'm not good enough to warrant race gas, I don't want the headaches of changing domes/carb settings, so I wouldn't consider this unless you plan to run race gas setup 100% of the time.

Not that great :sadwavey:

Good points everyone, I don't think I am going to dabble with it until later on, if then.

 

[crammit442]

Not very many people run compression numbers as high as you mentioned. 205-220ish is the norm on race gas. If you need more than that on a fully built motor, something is wrong with your setup. Compression numbers much higher than that are covering up a builder's inadequacies in other areas. And I agree about the TL.

 

[BombThreat]

I meant that if you're going to pay over $4/gal for Premium, might as well go to $6/gal for Race gas.

So are you saying that race gas prices don't go up as with normal fuel? Last Summer it was approx $6.29/gallon with Premium @ approx $3.39

This is all in hindsight b/c we are in different places but if your getting race fuel for $6 a gallon when premium is $4/gallon your one lucky SOB!

 

[Kennay]

The prices here on 110 don't seem to go over 6 a gallon.

 

[Odd Duck]

Last weekend we paid almost $10 per gallon. Mark mixes 1 gal race per 4 of premium for his ski.

Kennay, if you don't have a pipe on your ski yet, I'd say you've got a ways to go before you should consider higher compression and race gas. If you can't afford a TL, you probably can't afford higher compression yet and the consequences of it - race gas, higher maintenance, more breakage, etc. I'm with the boys, do carbs, pipe and etc way before you up the compression.

 

[Kennay]

Pipe, carbs, and whatever else is going on all at once. The boat itself is in the middle of a build, and the engine is just sitting there waiting for goodies.

 

[Odd Duck]

Wow, nice. Wait and see what you've got with the new parts before you get too cranked about going to race gas, then. It really does add a whole other level of expense. We've had boats we had to run full race gas and we're back on pump gas for the most part, now. My hubby does mix 1 gal race gas per 4 gal premium for his boat only. The others are all just pump gas. Soooo much easier and cheaper.