Limits of Compresion and Fuel !

[PancakePete]

I put my brother inlaws ski together after sitting for 2 years. He has been so busy and did not get around to it... So we finally did.

Local place does not have Race fuel anymore.

He is 230 comp. in motor, can he get away with 100 oct. low lead AV gas?

I run AV 100 low lead in my 205 comp. motor.. Is he pushing it too much?
I did not know what to tell him !:question:

 

[douglee25]

I put my brother inlaws ski together after sitting for 2 years. He has been so busy and did not get around to it... So we finally did.

Local place does not have Race fuel anymore.

He is 230 comp. in motor, can he get away with 100 oct. low lead AV gas?

I run AV 100 low lead in my 205 comp. motor.. Is he pushing it too much?
I did not know what to tell him !:question:

Whoa baby! 230 psi compression? Are you sure the gauge isn't broken? I would say that even at 100 octane, you're still going to be too high. Can you lower the compression with a different head?

Doug

 

[Matt_E]

I wouldn't even try. 230Comp sounds like 115octane and higher.
But there are more factors than compression, so I don't know.

 

[FL-cracker]

^^^^^Thats just insane!

 

[Matt_E]

yeah, rotaxgrenade runs pump gas in his 220psi blaster motor.

just dont hold it wipe open!

edit: of course the safe answer is to just post here and say NO.. but, you know that, and still posted, so.. my comments are just 'FYI' ;-)

I hear you. I ran 195psi on 91 all season long last year.

 

[PancakePete]

Gauge is fine !

We wont to ride today. I know mine is fine with 205 psi and 100 AV gas.

So I am guessing 230 is to much for 100...

What is the minimum octane to run in 230 motor :banghead:

 

[Matt_E]

It depends on more than just compression. Is that a stock or aftermarket ignition? What's the timing?
What's the porting? What pipe?


(Not that I can give a better answer with all this info, but these are the factors the pros always mention)

 

[douglee25]

Gauge is fine !

We wont to ride today. I know mine is fine with 205 psi and 100 AV gas.

So I am guessing 230 is to much for 100...

What is the minimum octane to run in 230 motor :banghead:

I don't think you can put compression and octane rating in a linear relationship. There are may factors like timing, load on the engine, size of the rider, prop, etc that all factor in. As mentioned before, you can read plugs to determine if detonation is occuring, but the engines grenade quickly before you even know it.

Doug

 

[gimmick]

What is the minimum octane to run in 230 motor :banghead:

Depends where timing is. Retarded timing = safer to run lower octane.

 

[Jr.]

230 is too much for AV gas, unless the is absolutely no high rpm use. that is a full race gas combo.
as for yours being safe at 205? Not really !! If you rember correctly on how I set it up & also instructed you no high rpm runs, that is the only way it would live!

 

[guiness92]

I would try to lower the compression a bit, sounds sketchy and I personally wouldnt take the chance. What kind of head is on it? can you change the domes?

 

[PancakePete]

I think !!!!
Its a
750 kawy
with:
2 over bore ?
44's
ported
factory pipe
stock ignition
r&d head
I think thats it

I tuned it last night... seems like its rippen.. we could richen it a bit,
But I think that gas might play a factor. He wants to run AV and I told him let me ask first...

 

[PancakePete]

230 is too much for AV gas, unless the is absolutely no high rpm use. that is a full race gas combo.
as for yours being safe at 205? Not really !! If you rember correctly on how I set it up & also instructed you no high rpm runs, that is the only way it would live!

i dont get on the 6 mil ADA precious ! I ride it like I stole it... JK
All the Super mod motors like my other... Dont pin any of them !You know me better than that !
Thank you all for the info. I will Tell him dont run it on AV.

Paul the ADA will be ok with Av right... I though it was ok ?

 

[Superjet3]

i dont get on the 6 mil ADA precious ! I ride it like I stole it... JK
All the Super mod motors like my other... Dont pin any of them !You know me better than that !
Thank you all for the info. I will Tell him dont run it on AV.

Paul the ADA will be ok with Av right... I though it was ok ?

My guess is if you dont hold it wide open you will be fine on 205 with av gas.

IM running 200psi on Sara's ski with 93 and it's fine.. Guess she is light enough that she really dosent put a load on the motor. Or my Snap-on gauge is incorrect.

 

[douglee25]

My guess is if you dont hold it wide open you will be fine on 205 with av gas.

IM running 200psi on Sara's ski with 93 and it's fine.. Guess she is light enough that she really dosent put a load on the motor. Or my Snap-on gauge is incorrect.

Damn bro! You got balls to run that ski with 93 octane!:cool2:

Doug

 

[njfl]

I'm running close to 220psi and 100 Low Lead on my ADA and Pat Bogart similar on his Lamey. As Chuckie (Team Scream) pointed out in a separate post, it has a lot to do with the dome machining which changes the squish behavior and can allow for higher than typical compressions to be run. Here's the post:

http://www.x-h2o.com/threads/5589

 

[douglee25]

I'm running close to 220psi and 100 Low Lead on my ADA and Pat Bogart similar on his Lamey. As Chuckie (Team Scream) pointed out in a separate post, it has a lot to do with the dome machining which changes the squish behavior and can allow for higher than typical compressions to be run. Here's the post:

http://www.x-h2o.com/threads/5589

Very true. Good post from Chuckie in that link.

Doug

 

[njfl]

I put my brother inlaws ski together after sitting for 2 years. He has been so busy and did not get around to it... So we finally did.

Local place does not have Race fuel anymore.

He is 230 comp. in motor, can he get away with 100 oct. low lead AV gas?

I run AV 100 low lead in my 205 comp. motor.. Is he pushing it too much?
I did not know what to tell him !:question:

Sorry Pete, I pointed out in my last post that it might be possible in some motors, but if you don't know for sure with your brother inlaw's motor who did the work and if they considered squish, etc. then you should not run it.

There is a guy in Wall, NJ who has really good pricing on VP fuels. He sells to a lot of guys for Wall and Englishtown so has volume pricing if that helps:

Mike's Performance Center
(732) 280-4848
2200 Belmar Blvd.
Wall, NJ 07719

 

[Mark44]

I feel sorry for that crank that poor crank.

Brapanimal. A person that runs over 200 psi of pressure in his motor and doesn't care about the feelings of the crank.


Mark44

 

[PancakePete]

Sorry Pete, I pointed out in my last post that it might be possible in some motors, but if you don't know for sure with your brother inlaw's motor who did the work and if they considered squish, etc. then you should not run it.

There is a guy in Wall, NJ who has really good pricing on VP fuels. He sells to a lot of guys for Wall and Englishtown so has volume pricing if that helps:

Mike's Performance Center
(732) 280-4848
2200 Belmar Blvd.
Wall, NJ 07719

Word. Klotz is my sponsor and I can get really hooked up from them. He just wanted to ride last minute and did not think about gas... A-D-D thing. I will have to order some for him... Thank you !:biggthumpup: