Karting Forum

Rotax Promotion

It is currently Thu Nov 20, 2008 1:55 am

All times are UTC + 8 hours




Post new topic Reply to topic  [ 10 posts ] 
Author Message
 Post subject: Rotax exhaust
PostPosted: Wed Jul 02, 2008 11:02 pm 
Rookie

Joined: Wed Jan 23, 2008 4:09 am
Posts: 6
Location: UK
We've recently completed some back to back testing of exhausts and found one really, really bad exhaust that costs several tenths on track (quite a surprise how significant). All exhausts had an intact cone (inner tube) and fresh wadding. All sealed with silicone at the join. The poorly performing one had a dent in the tube immediately below where it joins to the engine and this is the only obvious difference between the tested units.
I checked with our engine builder who said some exhausts just didn't want to perform and it was usually either a collapsed internal cone/pipe or more likely due to inferior internal welds. Unfortuantely other than on-track, the only way to find out is to cut the pipe open which is terminal for the component.
Anyone else had any similar experience?


Top
 Profile  
 
 Post subject: Re: Rotax exhaust
PostPosted: Thu Jul 03, 2008 9:34 am 
Site Admin
User avatar

Joined: Tue Jun 19, 2007 1:38 am
Posts: 1071
Location: Malaysia
Interesting observation. I haven't tested different exhausts myself but I can see how that could be an explanation for some "mystery" problems. Not many would think of switching out the entire exhaust when troubleshooting engine performance.


Top
 Profile  
 
 Post subject: Re: Rotax exhaust
PostPosted: Thu Jul 03, 2008 4:16 pm 
Rookie

Joined: Wed Jan 23, 2008 4:09 am
Posts: 6
Location: UK
I think this issue may be a more significant performance issue than it appears. I would really like to hear of anyone else finding any significant performance variation on-track with different exhausts. Also what age of wadding seems optimum.
In the top level Rotax series in UK (Super 1) I have never, ever seen any top team go to track with a new wadding (you can clearly hear a newly wadded exaust) so I think the general rule seems to be that new is not best. There was a fashion for assembling exhausts with double wadding but this is now outlawed.
My engine builder believes there is an interaction between exhaust and power valve which is important for bottom end performance.
Is there a commercially available power valve sensor for the Rotax engine?


Top
 Profile  
 
 Post subject: Re: Rotax exhaust
PostPosted: Thu Jul 03, 2008 9:39 pm 
Site Admin
User avatar

Joined: Tue Jun 19, 2007 1:38 am
Posts: 1071
Location: Malaysia
I might just take a few exhausts to the track and start testing ;).

miles wrote:
Is there a commercially available power valve sensor for the Rotax engine?

Sensors are available for PI, Unipro, and Alfano. I use a Unipro and the sensor. Been meaning to write up a bit on it for ages now but just haven't done enough with it yet to write anything worthwhile.


Top
 Profile  
 
 Post subject: Re: Rotax exhaust
PostPosted: Thu Jul 03, 2008 10:07 pm 
World Champion
User avatar

Joined: Sat Jul 07, 2007 11:25 pm
Posts: 731
Location: P1
Mikko Nassi wrote:
Been meaning to write up a bit on it for ages now but just haven't done enough with it yet to write anything worthwhile.

anything will do for me.. :|

_________________
Karting Spammer


Top
 Profile  
 
 Post subject: Re: Rotax exhaust
PostPosted: Tue Aug 12, 2008 9:08 pm 
Rookie

Joined: Tue Aug 12, 2008 8:43 pm
Posts: 4
I ve been out for the same trouble
It give me a big headake until i switched pipe with a friend and .........WOW
After the test i went straight home and put my pipe under the saw
But when i cut the 180 pipe of i didnt found anything that looks wrong ??
When you read the regulations i see it is alot of +- 5 mm on every section on the pipe
So in the total it could be 15 mm longer or taller ????

I am looking forward to see if anyone got a answere to this

Thanks


Top
 Profile  
 
 Post subject: Re: Rotax exhaust
PostPosted: Tue Aug 12, 2008 9:48 pm 
Rookie

Joined: Wed Jan 23, 2008 4:09 am
Posts: 6
Location: UK
I just bought a brand new exhaust, tried it back to back with the one (and only) good exhaust we retained, and found it was USELESS!!! I have spoken to my engine tuner who says the only way to find out what is going on is to cut the pipe and inspect, there is great variation in manufactured quality. But that then renders the exhaust useless - so pointless. The only way is to track test and keep the good ones.
At the last Super One UK Rotax round, officials removed the exhaust from one of the leading contenders on the dummy grid and substitited their own selected exhaust. So someone knows there is a difference.

Biggest item of contention in UK at present is slipping clutch, which lets the engine rev higher before engaging and so gains pull out of slow corners.


Top
 Profile  
 
 Post subject: Re: Rotax exhaust
PostPosted: Wed Aug 13, 2008 10:46 pm 
Rookie

Joined: Tue Aug 12, 2008 8:43 pm
Posts: 4
Hmm slipping the clutch what do you mean ?
And now when you find a pipe that works and one who doesnt
Please try to see if you can find any diffrent meussre everything you can

Or is it someone who know the secret ???


Top
 Profile  
 
 Post subject: Re: Rotax exhaust
PostPosted: Thu Aug 14, 2008 12:58 am 
World Champion
User avatar

Joined: Sat Jul 07, 2007 11:25 pm
Posts: 731
Location: P1
miles wrote:
Biggest item of contention in UK at present is slipping clutch, which lets the engine rev higher before engaging and so gains pull out of slow corners.

Tho its a problem with the KF class only??

_________________
Karting Spammer


Top
 Profile  
 
 Post subject: Re: Rotax exhaust
PostPosted: Thu Aug 14, 2008 8:08 am 
Rookie
User avatar

Joined: Tue Sep 11, 2007 3:33 pm
Posts: 13
Location: Malaysia
We had a similar problem with a new exhaust on round 5 (junior class). Had to revert to an old exhaust with new fiber and walla !

_________________
V8


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 10 posts ] 

All times are UTC + 8 hours


Who is online

Users browsing this forum: No registered users and 0 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
forums
All submitted content in these forums, either graphical or textual, is the copyright and responsibility of the content creator.

Karting News | Karting Forum | Picture Gallery | Karting Calendar | Kart Tips | Kart Tracks | Contribute | Advertising | Links

phpBB SEO