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The technical adventures of Dr_C
- Thread starter Dr_C
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Here are some views of the sleeves. The bearings are ordered. New design of exhaust system (noice approved without substantial loss of power) is underways with one oval carbon muffler underneath the engine and one tri-oval on the side. Tomorrow I'm off to Germany to shop an exotic engine for a new, long term café racer project! 
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Beware! Off topic post follows! Sensitive readers might want to close their eyes until I say OK!
Here is the power plant for my coming cafe racer project!
OK!
Here is the power plant for my coming cafe racer project!
OK!
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Whoa.
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OK now that my eyesight has come back. What is that?
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There is a brief history at: Hedlund Motorcycles
This engine was produced in the mid/late 60s. Nils Hedlund also made a DOHC speedway engine and later a V2 at 1000cc for sidecar mx. In total there was 205 engines made of all types. Mine is #205 and has never been started yet!
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Cleaning out stuff in the workshop. Lots of sacrifices to the holy mother of acceleration!
Some of the small pieces of metal lying around here, have had bad consequences, whereas this little thing has not!
Some of the small pieces of metal lying around here, have had bad consequences, whereas this little thing has not!
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Constructed and assembled a feed -04,650 who saved motorblocket.Vevpartiet is boven.Tom -03 is preferred
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In the meantime, somewhere in the outbacks in Scania, new exhaust components arrives. Lower sound level - same power! Large dia tubing and two mufflers in series. Custom delivery by "PJ Engineering". But calm down! I WILL manufacture end caps and tubing for the first oval silencer under the engine and up to the tri-oval (!) on the side of the bike.
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Dr C, on the ducati 1198 engine Ive found 35mm outlet x2 with db-killer doesnt take any hp away but brings noise down by 3db.
The 570 ice racer Doma exhaust came with exactly that diameter killer too on half the cc and no loss in the dyno, just a lot quieter.
You likely know this already, just telling what I found.
The 570 ice racer Doma exhaust came with exactly that diameter killer too on half the cc and no loss in the dyno, just a lot quieter.
You likely know this already, just telling what I found.
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Seems right! I have no dyno results to prove it, but my 888sp5 didn't suffer much from dB-killers either.
The Supermono needs to come down 10dB, so I have had to almost plug the exhaust with modifications to the dB-killers. The bike didn't like that at all, but the marshalls were happy! [emoji52]
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10db, wow thats a lot Was it super loud before or why? You are racing swedish tracks and supermono as far as I can tell?
Was it super loud before or why? You are racing swedish tracks and supermono as far as I can tell?- Joined
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The 1198 research may be valid for you, did 152hp per litre on a dynojet 250i SAE correction, and no loss with 35mm outlets.
All there is to it is a short sleeve and a ring ID 35.
Easily passes 95db driveby. Hope it helps
All there is to it is a short sleeve and a ring ID 35.
Easily passes 95db driveby. Hope it helps
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You are correct! Swedish, Finnish, Norwegian and Danish tracks. Easter will be spent manufacturing a new exhaust system from the primaries and downstream. Kind of a tradition for me... I tried dB-killers but they didn't do the trick. After modifying them I got down to a level that the marshalls could accept (not 95 dBA...). Anyways now it will be a large tubed system including 2 mufflers. The first will incorporate a small chamber in the front end, and have an oval shaped perforated tube. An it will be good looking!
Jag är visserligen från Skåne, men engelska verkar lite onödigt..
Jag är visserligen från Skåne, men engelska verkar lite onödigt..
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Been plumbing all Easter. New exhaust system which hopefully reduces noice instead of power...
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Finally the new exhaust system is complete! I would REALLY like to show my competitors this view this season!
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Damn. That's so nice looking I'm sure they'll be tempted to let you pass!
Is the exhaust system based on theory or experience and heuristics? Got any links to reading material or discussion forums on it? (I'm quite keen on DIY loudspeakers and nice sounding exhausts - and resonance and filtering and such in general! - and like to chew on a bit of theory when I can find it)
Is the exhaust system based on theory or experience and heuristics? Got any links to reading material or discussion forums on it? (I'm quite keen on DIY loudspeakers and nice sounding exhausts - and resonance and filtering and such in general! - and like to chew on a bit of theory when I can find it)
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Thanks, Tourist!
Exhaust system design is funny enough the area where there still is some "black magic" envolved! That means all is not completely understood, explained in formulas and simulating softwares are still somewhat incomplete. I have used to run my data in the sw "Pipemax", to get a hint on where to start with the design. This time I have been in contact with my machinist brother-in-law, who happens to be involved in the Koenigsegg engine design. A former drag racer with a doctors degree and doing research at the local university. He has done different exhaust designs and tested them in 70 (!) dyno runs. The result has formed the base for formulas better complying with the practical results. This system is mainly based on his calculations. Also Gordon Blair has a lot of theories on the matter, which the sw "GT Power", which most car manufacturers are using, is based on. Fx we ended up with primaries ending after 812mm...
Skickat från min sk smartphone med pilligt tangentbord och irriterande spellcheck.
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I wanted to understand exhausts as I plan to build my own. Came to the conclusion that I need to build myself a dyno first. ..
It is very interesting but when I realized how the 4 stroke really works I also understood that the exhaust, at best, is a compromise, and that my brain is not enough to calculate it and that I have to start at an established design and empirically go from there.
To read about how you do it Dr_C is very impressive and interesting!
It is very interesting but when I realized how the 4 stroke really works I also understood that the exhaust, at best, is a compromise, and that my brain is not enough to calculate it and that I have to start at an established design and empirically go from there.
To read about how you do it Dr_C is very impressive and interesting!
