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apparently there is no such beast as a pipe or pipes that can improve on the stock pipe...

...but i still refuse to believe that...

I WANT A SET OF TWINS FOR MY 440...PLEASE...LETS ALL PUT OUR HEADS TOGETHER AND DISCUSS THIS ONE!!!!!!!!!!!!
 

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crank shop 440 twin race pipes,also you can mod the stock pipe
 

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dyna-tek racing said:
crank shop 440 twin race pipes,also you can mod the stock pipe
[snapback]700997[/snapback]​
Crank shop still can't make a single or twin pipes to make any more power than the stock pipe for the 440 motor.
 

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The stock pipe has a stinger reducer in the end of the pipe that is 1.175'' id and you can get better top end power by boring it out to 1.250'' and or 1.375'', 1.250 for stock cyl's and 1.375 for ported cyl's. the crank shop twins only work on drag motors,but someone asked so i answerd.
 

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dyna-tek do you lose any bottom end with that pipe mode? Is the sled more finicky or any drawbacks? Does it make the sled sound a little better? I am interested...
THanks TJ
 

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dyna-tek...can you put together a post with some details on how to go about doing this?? Pics and stuff would be great.
 

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dyna-tek...can you put together a post with some details on how to go about doing this?? Pics and stuff would be great.
X2

Otokiak ...

Rankin Inlet, NU
CANADA
 

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If you look in the outlet of the expansion chamber you can see the reducer in there, we did the earlier ones by cutting off the tail section boring to specs and reattaching it to the pipe,if you have a good machine shop locally they may be able to get the whole pipe in a ficture and do it without cutting it off, boring it to 1.250'' will loose a little bottom end,most of the pipe mod motors we put larger carbs on to make a total power package,the small loss of bottom end is passed over by the mid track and top speed you get . when boring out to 1.375'' we ported the cyl's and installed 40mm carbs , the original 440 pipe is designed for tight course snowcross that is why it is so small to get the pipe to heat up fast and have better acceleration,for the guys wanting to do cross country or lemans racing we had to do things differently.
 

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dyna-tek racing said:
If you look in the outlet of the expansion chamber you can see the reducer in there, we did the earlier ones by cutting off the tail section boring to specs and reattaching it to the pipe,if you have a good machine shop locally they may be able to get the whole pipe in a ficture and do it without cutting it off, boring it to 1.250'' will loose a little bottom end,most of the pipe mod motors we put larger carbs on to make a total power package,the small loss of bottom end is passed over by the mid track and top speed you get . when boring out to 1.375'' we ported the cyl's and installed 40mm carbs , the original 440 pipe is designed for tight course snowcross that is why it is so small to get the pipe to heat up fast and have better acceleration,for the guys wanting to do cross country or lemans racing we had to do things differently.
[snapback]704482[/snapback]​
This is awesome info.
I have limited knowledge on expansion chamber design, but do you have dyno numbers that demonstrates this?!?

I never would have thought increasing the stinger diameter and reducing back pressure would increase your peak HP. I know a few guys have done this with the 800 mods to make them "trial friendly". The flip side of doing this was that peak RPM for which it made hp was reduced.

I wonder if this would be the case for the 4-4-D pipe?!??
 

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Dyna-Tek Racing knows something we don't. Please share your insight.


I'm no "expert" but, as I understand it, Stinger diameter is crucial to the pipes operating temperature and hence the power production. Normally a smaller stinger will improve top end power because the exhaust gas temperature (EGT) will increase which will have the effect of a shorter pipe length (more torque). If you go too small on the stinger then power will suddenly start to drop in the corners and the motor will begin to overheat. A bigger stinger will have the effect of spreading the power band but, the engine will not make the same peak hp. The speed at which pressure waves travel is greatly affected by temperature: higher temperature means faster wave speed. As a result, expansion chambers can be tuned for higher RPM resonance, by increasing the average temperature of the exhaust gases inside the pipe.

I suppose the 800 mod pipes were a bad example as these bananas supposedly make peak hp @ 9000 RPM, but are tuned to run @8400 - 8500 RPM in snow-X. Todd I think you know by example of people trying to run these 800 mods in X-country events and burning down their motor! Super small stingers! But the thing about these pipes is you CAN afford to change to a larger stinger to decrease the RPM and spread your power band. With the 4-4-D pipes, power dramatically falls off the power band after 8400 RPM with a hot pipe. You can't afford to loose too much RPM. I also think these 440 pipes are remarkably reliable given the small stinger diameter. Not sure how you would gain HP & top speed by moding to a lager stinger (unless you adjust length as well)?

http://www.dootalk.com/forums/index.php?showtopic=61948&hl=

Am I missing something Dyna-Tek?!?
 

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peak rpm is lowerd to 8100 rpm's, we initially came up with this pipe design following in the 500 series three design on the consumer sleds, which at lower compression ratios ,larger carbs and a larger stinger diameter gives the motor a broader tourqe curve and better overall drivability,the same theoretics played well into the 440 motor as it is very similar engine in design,while horse power increases arent huge (generally 3-5)the power curve is wider and alot easier to tune to,detonation seems to be reduced in motors that are run on the edge.sometimes you just get lucky when experimenting.
 

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That combo should work well and be a great trail motor to boot,my wife and kid rode this week end and she rode my moded 440 and she got 115 miles out of 8 gals of fuel,14.4 mpg,granted we were only doing average 40-50-mph but i about [email protected]#t myself when we filled up together,maybe a fluke maybe not.
 
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