Straight piping? - Snowmobile Forum: Your #1 Snowmobile Forum
http://www.snowmobileforum.com
Go Back   Snowmobile Forum: Your #1 Snowmobile Forum > Snowmobile Tech / Mod Center > Engine / Drivetrain


» Sponsors





Reply
 
LinkBack Thread Tools Display Modes
Old 06-06-2011, 10:01 PM   #1 (permalink)
Live To Ride
 
deezy's Avatar
 
Join Date: Sep 2010
Location: Iqaluit, Nunavut
Posts: 194
Straight piping?

Hellooo.

Starting my summer project shortly, and its going to be a drag sled.

I just have a question about straight pipes because I realize that many many drag racers set up their sleds with nothing but a 2-3 inch diameter pipe directed to the side as the exhaust pipe, one for each cylinder.

what are the gains if any of doing this to a drag sled?
is it bad in any way?

might be a dumb question but Im not going to try and make some without a real reason, lol

thanks
__________________
I drive a snowmobile
deezy is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 06-07-2011, 01:29 AM   #2 (permalink)
Super Moderator
 
BC_Dan's Avatar
 
Join Date: Jan 2004
Location: oregon
Posts: 12,455
Straight pipes on a two stroke can be dangerous to the engine. Because of the design of the engine, the intake ports and the exhaust ports in the cylinder are both open when the piston is at bottom dead center. Some of the unburned fuel actually enters the cylinder and exits with the exhaust gas, but because of the length and shape of the pipe, at the exact moment the raw fuel/air is leaving the cylinder, a pressure wave rebounds from the restriction in the pipe and shoves the fuel back into the cylinder to be burned.

If you have a straight pipe, there will be no rebound and your air/fuel mix will be lean, which could cause excessive heat and melt holes in the pistons. If you make the fuel mix rich enough to be safe, your fuel mileage will go south, and your emissions will go up. You will also have really lousy performance at lower RPM. Carbs are designed around the tuned pipe, it will take you a long time (and probably a few rebuilds) before you find jetting requirements to keep the engine safe and still give power.

A tuned pipe eliminates all that and gives you more power to boot, as all the air/fuel mix is burned with no waste.
__________________
2007 Dragon RMK 700 155", 2008 RMK 600 155", 95 Prowler 550 2-up, Really OLD AC Cheetah

http://www.avalanche.org/accidents.php
BC_Dan is online now   Reply With Quote
Old 06-07-2011, 03:45 PM   #3 (permalink)
Live To Ride
 
deezy's Avatar
 
Join Date: Sep 2010
Location: Iqaluit, Nunavut
Posts: 194
Thanks Dan once again!

Yeah, I wasnt sure but it did feel like straight piping would feel sort of 'wrong',
I just wanted to check because it would have been nice to have at least one freebie component to the sled! haha.

Ive also seen people running twin/tripple pipes but without the stingers, is that just as bad? or sort of like a half way type of thing?
__________________
I drive a snowmobile
deezy is offline   Reply With Quote
Old 06-07-2011, 11:56 PM   #4 (permalink)
Super Moderator
 
BC_Dan's Avatar
 
Join Date: Jan 2004
Location: oregon
Posts: 12,455
There may be a bit of benefit from stingers, but would be easy to tune around (if there was.) The stinger mostly muffles the sound a a bit. Without stingers, a sled would be uncomfortably loud! Noise is not important when drag racing, wear hearing protection
__________________
2007 Dragon RMK 700 155", 2008 RMK 600 155", 95 Prowler 550 2-up, Really OLD AC Cheetah

http://www.avalanche.org/accidents.php
BC_Dan is online now   Reply With Quote
Old 06-08-2011, 03:25 PM   #5 (permalink)
Super Moderator
 
RJ Gleason's Avatar
 
Join Date: Feb 2005
Location: Groton NY
Posts: 32,210
Dan, stingers are the small tips on the ends of the pipes, silencers are a packed attachment or open box attached to the end of the pipe outlet.
__________________
Old Cat Rider
'93 Wildcat 700EFI
w/ Comet 108 Pro-4 clutch & 01 ZR skid

'90 Wildcat Project in progress.

Vintage (sorta)
1980 Indy Trail 440 (for sale)
1980 AC Pantera (donor engine to the 90 wildcat)


http://www.dcdrifters.net/


Worshipful Master; F&AM Dryden Lodge# 472
http://www.masonicdryden472.org/

Rules of this forum are strictly enforced!
RJ Gleason is offline   Reply With Quote
Old 06-08-2011, 05:22 PM   #6 (permalink)
Super Moderator
 
kccats's Avatar
 
Join Date: Dec 2006
Location: Northern IL
Posts: 19,523
Stingers are the same as the silencers.
kccats is offline   Reply With Quote
Old 06-14-2011, 07:08 PM   #7 (permalink)
Polaris All The Way!!!
 
cam615's Avatar
 
Join Date: Jan 2010
Posts: 657
Quote:
Originally Posted by BC_Dan View Post
Straight pipes on a two stroke can be dangerous to the engine. Because of the design of the engine, the intake ports and the exhaust ports in the cylinder are both open when the piston is at bottom dead center. Some of the unburned fuel actually enters the cylinder and exits with the exhaust gas, but because of the length and shape of the pipe, at the exact moment the raw fuel/air is leaving the cylinder, a pressure wave rebounds from the restriction in the pipe and shoves the fuel back into the cylinder to be burned.

If you have a straight pipe, there will be no rebound and your air/fuel mix will be lean, which could cause excessive heat and melt holes in the pistons. If you make the fuel mix rich enough to be safe, your fuel mileage will go south, and your emissions will go up. You will also have really lousy performance at lower RPM. Carbs are designed around the tuned pipe, it will take you a long time (and probably a few rebuilds) before you find jetting requirements to keep the engine safe and still give power.

A tuned pipe eliminates all that and gives you more power to boot, as all the air/fuel mix is burned with no waste.
krikey where do you learn all this?
__________________

Last edited by BC_Dan; 06-15-2011 at 12:06 AM. Reason: language
cam615 is offline   Reply With Quote
Old 06-15-2011, 12:06 AM   #8 (permalink)
Super Moderator
 
BC_Dan's Avatar
 
Join Date: Jan 2004
Location: oregon
Posts: 12,455
I stayed at a Holiday Inn Express
__________________
2007 Dragon RMK 700 155", 2008 RMK 600 155", 95 Prowler 550 2-up, Really OLD AC Cheetah

http://www.avalanche.org/accidents.php
BC_Dan is online now   Reply With Quote
Old 06-15-2011, 06:39 AM   #9 (permalink)
Super Moderator
 
kccats's Avatar
 
Join Date: Dec 2006
Location: Northern IL
Posts: 19,523
And Years and Years of failures! Personally I've been sledin since 69-70! Been wrenchin since 72!
kccats is offline   Reply With Quote
Old 06-15-2011, 10:10 AM   #10 (permalink)
Registered User
 
eli346's Avatar
 
Join Date: Feb 2011
Location: MI,thumb area
Posts: 1,215
Quote:
Originally Posted by kccats View Post
And Years and Years of failures! Personally I've been sledin since 69-70! Been wrenchin since 72!
Does that mean you didnt have to fix your sled for 2 years?!
__________________
1989 arctic cat jag afs 440(small project)
1990 yamaha phazer 2

The new money pit
eli346 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Powered by vBadvanced CMPS v3.2.2

All times are GMT -5. The time now is 06:56 PM.



Copyright SnowmobileForum.com

Search Engine Friendly URLs by vBSEO 3.6.0