Ok I got a killer deal on some 109 Web cams, looking into a high compression piston, OK at 11:5 to 1 I can run Pump gas, at 13:1 I gota run race fuel 108, the question is how much notable TORQUE differance is there?

 

I will wait for someone with more dyno testing experience to accurately answer the torque question. I will say though that I would go to the 13:1 if for no other reason than the fact that you are going to be running 109's. Hopefully you have a port job that really understands the 109's or they really cost a lot of bottom end to give you better top end. The higher compression will give you more torque from bottom to top which should help your cam configuration to be more ridable. When I was running the 109's the 13:1 compression seemed to help a lot. The biggest thing I did though was run lower gears. Lower gears is a common bandaid for a late torque curve. 109's have really good top end though.

If I had to guess, I would say 1.5 to 2 lbft average torque increase from just the 13:1 compared to the 11.5:1. Most 13:1 pistons are significantly lighter than the 11.5:1 so it will seem like a bigger difference because it is quicker revving.

BTW, how is your sleeve install coming? Will this be a 720 piston or stock bore?

Ron

 

I am still waiting from Kurt @ Millennium to call me back with the Yay or Nay on being able to do the 105MM alum nikisil cylinder. I do agree after measuring the wall thickness that it like putten 10 lbs of poop in a 5 lbs pail, I wonder why Bombardier made such a thin wall casting??? my LT500 has more meat in its walls, like triple the amount.

Nope no piston yet, But there are some killer deals on some 13:1 pistions right now (100mm and 105mm) and better in cost than the 11:5 to 1.

Mike said its a yeahh! cost for alum sleeve with coating is $400.00. ok what piston hummmmmm??

 

Ok went with the 120.00 CT piston 13:1 as I figured I dont trust california 91 pump gas I always mixed some race juice in the mix, I figure with a thicker base gasket I can get close to 12:1 and run a half and half mix. The question do you that run 11:5 to 1 run straight 91 pump or do you ad a little reace fuel to pertect from pinging?

 

Erbs, at altitude I run my 12-1 on pump. Our 14-1 on 100. I would run 110 in the 14-1 at sea level. If you go down to 12-1, I would mix to about a 100 octane level.

I call Bu!!**** on anyone who says 109's loose a significant amount of bottom end. All bigger cams give up alittle to gain a litttle, but to say 109's loose alot of bottom end is ludicrous(spelling?). IMO, they are the best cam on the market for there money. And again thats just my opinion.

 

 

MY dad and I were fighting over who would take them off of his hands when he upgraded......He actually offered half off [img]i/expressions/face-icon-small-smile.gif[/img]

 

 

I have a hard time following your logic. Why buy a 13:1 and reduce it to 12:1? Why not run race gas and leave it at 13:1. I thought you wanted more torque????

 

OK DSNUT, I bought the 13;5 to 1 because it was cheaper than the 11:5 to 1Piston, I did not want to run straight race fuel, so at 12:5 to, I can run a mix of half and half, my LT500 runs on the same mix and so does my sons Blaster.