SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: SLCKREG on January 11, 2008, 08:23:26 AM
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Does an intake have any effect at all on reversion? I bought a vic jr to replace my single 4 tr, the other day I read what sounded like the tr would be less likely to have that issue?
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Can't Imagine why Kreg ,did you read something otherwize? :-\ Tom
Kreg check this article out,might be helpfull T
http://www.jetboattech.com/pages/header_tech.html
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So that's what reversion is. Thanks. ;)
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I wish could remember where I read it. It made no sense to me either? Maybe they were talking about reversion inside the intake manifold (air/fuel) I don't know. Oh well nevermind.
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Over on performance boats, there is a thread on carb spacers, post #8 says something about putting a sheer plate on a tr to prevent reversion??? Then says something about it would be worse on a single plane than the tr. BTW wtf is a sheer plate?
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SLCKREG,
Yea, I think thay are talking about reversion in the intake. It seems like the t ram would less prone to problems from reversion due to its longer equal length runners. The vic jr has shorter runners for the middle cylinders so reversion would have more of a chance of disrupting air/fuel flow in the plenum.
This is just my thoughts, and is not based on any real knowledge of anything ::) ;D.
btw, how is the Daytona coming ? we like pics ( hint hint ;) ). heres a link to your boats project thread, in case you cant find it any more >:D .http://www.socaljetboats.com/index.php?topic=1874.0
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It can affect the signal to the carb. A plate made for that purpose is available through some of the aftermarket places. I know Magnafuel offers them. I don't know how much help it will be on an aveage HP motor.
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You get reversion in both the intake and exhaust. How much is dictated by the cam overlap.
In the exhaust, it is only an issue if you start sucking in water from the lake. It also helps create the sound of the engine, and earlier opening of the exhaust valve causes some of the combustion at low rpm to happen in the exhaust pipe - this is where the lopey sound comes from.
In the intake, it dilutes the fresh intake charge, and causes the mixture to be off at lower RPM's. You compensate by running the mixture richer at idle, giving the stink smell and blowing unburnt hydrocarbons out. This is why big overlap cams are not used with anything that requires a smog check. As the mixture is mostly diluted by its own runner, really a TR / single / dual doesn't have that great of an impact on it.
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Thanks for the info guys. I'm not bolting on the vic jr until I can gps the boat this spring. That way I'll get a direct comparison. I'm to dumb to post a pic but Tom (jbp) said he'd put some up for me all I had to do was ask. The transom has been un-swiss cheezed and painted, got exaust tips in today. harness is comin, back seat made(not upholstered, ect. I know pics. :P I'll shoot Tom some pics monday. Thanks again KREG.
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Greg send me the pics I'll post them up this afternoon Tom
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Thanks Tom. My dial up from home is so friken slow it would take 1/2 hour for 1 pic, I'll shoot you some tomorow from work. I'll call you monday I was able at the end there on hot boat to post is it that much different here? I hate to bug ya for something I ought to be able to do. Anyways thanks again Tom. One last reversion question for anyone, well I thought putting on the vic jr would make my boat more "driveable" at lower r's, better throttle response ect. Once the boat is warm it's all good, but ideling out of the harbor(wakeless) when it's cold good luck.