Understanding Reversion
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Seasoned HDF Member
Joined: Aug 2008
Posts: 5,078
Likes: 2,150
From: Ohio
Understanding Reversion
Came across a good video while checking out S&S carb tuning, the video is targeting many areas of exhaust, drag pipes mods, exhaust reversion explained and showed in simple forms, it is worth 11 minutes of your time.
Little while back put a thread out on tuning a monster on how they like fuel in the rich 12.0 AFR range rather than the basic 13.2 but a monster also needs a large exhaust. Have ran into the large exhaust has the ability to pull air (reversion) back into the engine when moving and throttle closed causing AFR's to go into the lean 16.0 range and cause a spit out the carb when hitting the throttle quick after the condition described. So when you hear big engines and street manors, it is true about taking some patience to repair side effects of horsepower on the streets but can be done.
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Seasoned HDF Member
Joined: Aug 2008
Posts: 5,078
Likes: 2,150
From: Ohio
Ok, I'm a dummy that is intrigued on how exhaust reversion can affect AFR's when tuning with equipment, this also affects engines with junk TD's, junk 2-1's. drag pipes just happen to be used as a extreme example of reversion characteristics. Tuning exhaust is just as important as tuning a carb so another reason why watching how AFR is effected by changing restriction backed by electronic equipment can be useful to some, if a Dyno tuning god is watching this video then yes it would be for dummies, non of us on here are a tuning god and can learn any chance we get.
Lolly pop's and bolt installs have came across this board before, thought this would helpful to those trying to make exhaust work. Personally have made adjustments to Propipes with more and less restriction that can move a torque area up or down but also requires a fuel change along with the more or less restriction exhaust changes. My current 3" baffled exhaust in the large engine is effected by reversion because of it's design for horsepower, have had to make adjustments caused by the reversion, not convinced reversion characteristics during tuning is for dummies
Lolly pop's and bolt installs have came across this board before, thought this would helpful to those trying to make exhaust work. Personally have made adjustments to Propipes with more and less restriction that can move a torque area up or down but also requires a fuel change along with the more or less restriction exhaust changes. My current 3" baffled exhaust in the large engine is effected by reversion because of it's design for horsepower, have had to make adjustments caused by the reversion, not convinced reversion characteristics during tuning is for dummies
Ultimate HDF Member
Joined: May 2006
Posts: 6,590
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From: Ohio
Hey, don't get me wrong, I thought that was a great video. They explained reversion so well even a dummy could understand.
You learn something new every day. I did.
You learn something new every day. I did.
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Outstanding HDF Member
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From: North Florida
Ok, I'm a dummy that is intrigued on how exhaust reversion can affect AFR's when tuning with equipment, this also affects engines with junk TD's, junk 2-1's. drag pipes just happen to be used as a extreme example of reversiake eto make adjustments caused by the reversion, not convinced reversion characteristics during tuning is for dummies
No offence intended.
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Thread Starter
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Seasoned HDF Member
Joined: Aug 2008
Posts: 5,078
Likes: 2,150
From: Ohio
My bad, put so much energy into the complex art of tuning I didn't keep a open mind.
