MCXpress Turbo Kit - Headgasket "t" and safe boost

[kip]

It was a bender kit...... of the 7-8 bender turbo kits i am aware of up here in minnesota, this is the only one that had problems,, and those problems go back to the dealer.... the sled was a great looking warrior, the guy said he had been trail riding for a couple days, and decided to runt it at the speed run that day,, the dealer suggested he could flip up the boost switch to high... 10lbs.approx. if he added some octane booster...... THAT WAS THE MISTAKE>>> the installer had tweaked up the factory set high boost setting by a couple pounds... not sure what type of octane booster or ratio the guy was using.... but when the boost goes up, it pays, does not cost to run race fuel...

 

[sledheadgeorge]

Whats the max boost run on the bender units?

 

[kip]

stage II... the turbo can produce about 14-15 indicated pounds of effective boost... that to say the turbine is maxed out .... that relates to approx. 260hp.... now you can produce a higher boost number on the guage, but you will not make any more hp... my stageIII unit is capable of 25lbs of boost, yet it has not been run at that level yet...Terry at Bender as run it 22lbs on the dyno which put out 360hp.. he suggested that he did not run it any higher since i had been paid anything at that point..... such a kidder.... anyway we will race the sled at 22lbs until the end of the winter then turn it up at the last race.... Terry said his sled put out 398hp at 24.5lbs of boost with the same set up i have....

 

[kip]

Bender stage II in high boost mode, installer told the fella that he could run pump gas with octane booster.... No question it was the installers fault....

 

[HYERUP]

Detonation is actually increased with a thicker head gasket!
Here's some interesting tidbits directly from the Bender site...

Stock Headgasket--While it has been common practice in the turbo motorcycle industry to install a thicker head gasket to lower compression, it's the last thing we want to do in a snowmobile application. Though it does lower the compression, it also increases the squish which will have the opposite affect of what is trying to be accomplished; reducing the chance of detonation. Many think the since the RX-1 and the Vector are motorcycle engines, we can look at what the motorcyclists are doing for ideas. But in most cases the differences between snowmobiles and motorcycles more than outweighs the similarities. If any of you have every been fortunate enough to have driven a turbo charged R-1 of FZ-1, you know that it is almost impossible to drive one of these bikes at wide open throttle for more than a second or two. (Even in Montana where there are fewer speed limits).

A snowmobile is the exact opposite. We all love leaving our favorite trail for that lake blast, to feel the sensation of our arms stretched to the limit. We also desire to be able to return to the trail, to ride back to the lodge or restaurant, and start all over in the morning. The addition of a thicker head gasket is not the solution, and is in fact a cheap and dangerous way to reduce compression.

 

[Turbo Tim]

Mc express seems to like thicker headgaskets .............

 

[Buckeye]

Mine too. I put 1800 miles on last year with no problems. Why do the other sellers offer the head gaskets? Maybe Jeff could explain how a thicker head gasket increases detonation.

 

[ken_climb]

Bender's just trying to knock the competion any way they can cause they just don't make as much power, Period!

 

[Silverbullet]

I think that there is some merrit to the thicher gasket thing. Yamaha spends a ton of time and money developing the squish area on their engines (that's why you can run regular gas). I think that the reasons for changing that head gasket is that it's WAY cheaper than changing the pistons to lower compression. And in theory, with everything being equall the low comp pistons will make more and safer power than the thick gasket will.

 

[Buckeye]

I agree with the benefits of low comp pistons vs. just a thicker head gasket, but I don't see the thicker head gasket increasing the chances of detonation. Alot of us have gone to pistons and thicker gaskets. I believe it will enable me to run higher boost and still be safe. To a point ofcourse.

 

[Turbo Tim]

I'll bet there has been more engine problems from engines with the stock headgasket than there has been from engines with a thicker gasket ...........I ignored benders advice about the headgasket because it simply did not make any sense........Thicker headgasket = less compression which means more boost is possible , I have the 0.54 cometic gasket and run mine hard all day on the weekends at 11 p.s.i w/ no problems .........I wouldn't dare do that if i had the stock headgasket .

 

[Buckeye]

I'll bet there has been more engine problems from engines with the stock headgasket than there has been from engines with a thicker gasket ...........I ignored benders advice about the headgasket because it simply did not make any sense........Thicker headgasket = less compression which means more boost is possible , I have the 0.54 cometic gasket and run mine hard all day on the weekends at 11 p.s.i w/ no problems .........I wouldn't dare do that if i had the stock headgasket .

What octane gas are you running at 11#'s?
How do you like the GP-1 exhaust?

 

[spray25]

Bender's just trying to knock the competion any way they can cause they just don't make as much power, Period!

I'm not sure I'm clear on this........... do you like bender or not?

 

[ken_climb]

I know light'n up EH! Hows yours work'n Ray since the piston mod? Everything good? ripp'n it up or what?

 

[Turbo Tim]

"What octane gas are you running at 11#'s?
How do you like the GP-1 exhaust?"


...........I run 100 LL exclusively in the frt mount & in the rear mount , we have an airplane so the tank in the back of the truck comes in real handy for the sleds

I think the gp1 is just right w/ a turbo , maybe a little on the loud side but I like it that way , Don't have to worry about noise regulations riding in Alaska!..........