Matt
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Subaru Cam Sprockets - 2005/10/11 10:28
I'm trying to find aluminium Cam gears. Not for the weight savings so much, as the hard plastic ones are very brittle, and one chip shatters them, leaving the valves to fend for themselves. If anyone has any info on manufactures of these, or info on if they are any good, I'd love to see it.
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ryanrlamothe
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Re:Subaru Cam Sprockets - 2005/10/11 12:35
JUN makes some of the best Subaru parts in the world. They are not cheap, but are not low quality either.
I would contact Rallispec and talk to them about JUN Cam Gears for your Subie. They list them as an engine building option on their website, such as:
http://www.rallispec.com/sub_enginevalve.htm
Also, here is another link with some prices for the JUN parts:
http://www.upgrademotoring.com/performance/jun/raccamssprocket.htm
If anyone else knows of another manufacturer or retailer, please feel free to let everyone know.
Thanks.
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Matt
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Re:Subaru Cam Sprockets - 2005/10/12 15:08
I looked into the cam gears for the subaru ver 6 motor. Apparently becasue of the unusual design of the gear, they are hard to copy, so there are not many aftermarket options. The JUN setup is adjustable, but it is steel, and likley heaver than I want, in top of being a 2 piece construction, par of wich being the origional sprocket. It would appear, though i havent used it, to add weight and keep the same likleyhood of breaking.
The stock subaru main pulley is heavy, but it has a built in harmonic balancer. Light aftermarket peices do not. While i couldn't tell you exactly how a harmonic ballancer works, I'm sure it goes a long way to taking that nasty vibration out of the crank.
So, much like the header system, and the in dash 6 disk and tape player, it seems the the guys at the subaru factory have trumped the aftermarket market.
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ryanrlamothe
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Re:Subaru Cam Sprockets - 2005/10/12 15:49
How much harmonic balancing does the crank pulley do? My understanding is that the boxer engine design is inherently balanced on it own. 
Also, I thought the Subaru header aftermarket system is alive and well. You can find both turbo and normally aspirated headers from a variety of top notch racing/aftermarket companies.
Post edited by: ryanrlamothe, at: 2005/10/12 15:53
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Matt
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Re:Subaru Cam Sprockets - 2005/10/12 16:46
As far as headers are converned, the Stock subaru ones are about as good as it gets. The cas Iron holds in a lot of heat, so there is not much pressure loss from cooling before the turbo. The design shoots gas to the turbo in a smooth, and short path. Stainless aftermarket Headers can lose a lot of heat before the turbo. It's also tough to get smoother bends than the existing setup. You can improve the setup, but it is very expensive, for not much gain. There is a great article about this at Cobb Tuning. http://www.cobbtuning.com/tech/exhaustdesign/index.html
For naturally aspirated engines, I'd bet there is a lot of room for improvment, but I am no expert on NA motors.
I've heard people say you don't need to balance a Boxer motor, but I've never heard anyone in the know say it. I can's imagine how a spinning wheel with 4 differently weighted appendages swinging around could be inherantly ballanced, even if it does work vertically opposed. When I put my hand on my motor, i feel a vibration. The ONLY person I would ever trust enough to take out my harmonic balancer would be a fuji engineer, and they seem to have left it in there. So... I don't know an answer to this one.
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ryanrlamothe
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Re:Subaru Cam Sprockets - 2005/10/12 17:04
Yeah, I used to post on the Cobb forum for years before too many people turned it into crap and all of the old time Subaru tuners stop posting there. Cobb Tuning does make excellent hardware and software systems for Subaru's.
There is also debate on the usefulness of equal length headers and turbo's, but as I understand it the new Subaru Legacy 2.5GT contains an equal length header from the factory, so that is an interesting point. As far as cast iron is concerned, you are correct, it is the best for turbo applications as it can absorb and dissipate heat much better than other metals. I have also been interested in the twin-scroll turbo setup, which I am not sure if it is just the exhaust collector and turbo inlet or a little more involved.
I was doing some more research on the harmonic balancer built-in to the crank pulley. Apparently, this is more of a vibration damper than a harmonic balancer, since the 4 cylinder boxer engine always has opposing cylinders firing at the same time, but the engine accessory belts cause the actual vibration. In either case it is not a good idea to replace it with a pulley which does not contain a dampener.
Interesting. Any other thoughts or comments on these?
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Matt
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Re:Subaru Cam Sprockets - 2005/10/12 17:12
I've had a Cobb built engine melt on me, and when we took it apart, there was some funny buisness going on. i heard other horror stories, so I don't really trust Cobb's machienery, but their knowledge is spot on.
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ryanrlamothe
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Re:Subaru Cam Sprockets - 2005/10/12 21:47
Interesting, I've heard both thumbs up and thumbs down on Cobb Tuning. Cobb Tuning seems to have a sharp divide of work they've done while in Texas and work they've done since they moved to Utah. If you had an engine melt on you, that is a definite thumbs down.
If you have any specific details on what funny business they were doing inside of your engine, that would be great to know, I do know that Cobb Tuning built and maintained David Higgins Subaru engine when he was competing in his Subaru in North America.
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Parker
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Re:Subaru Cam Sprockets - 2005/11/04 17:26
Matt,
I'm not sure what it is exatly you are looking for, but I would try Crawford performance in CA. WWW.crawfordperformance.com
Parker
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Matt
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Re:Subaru Cam Sprockets - 2005/11/05 11:36
I was trying to find a cam pulley (sprocket??) I've seen them used for different things, so I'm second guessing what name to use here. I'll just say that the timing belt actually makes contact with them. 
With their location on the front of the motor, I've been having the bad luck of cracking a lot of them, and losing my timing, which busts valves. I was thinking that a nice aluminium pulley would crush, but not shatter, making it more likley that my valves wouldn't bend. I'd still have to rebuld my motor after pulley crushing crashes, but atleast I wouldn't have to buy as many valves. 
JUN makes adjustable Cam sprockets, but thay seem to be made out of cast Iron and the usual subaru cam matierial. I might be mistaken, and I'd love to hear from anyone who's actually handled a JUN Sprocket, What are they made of? 
I'll definilty take a look at what Crawford has to offer. He seems to be very cutting edge. I feel like I've heard stories of Doug's motor blowing up, but i can't recall when, maby Pikes? whick is an odd event. I can't remember an even't I've been to that Doug has had engine problems, except Ojobwe in CDP2. Didn't Crawford build the VTcar Gumball Motors? and they are stupid fast.
Either way I don't want to get into adjusting my cam timing just yet, I just don't want to keep losing my timing altoghter.
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