Tuned vs Not-Tuned Headers ???
Thread Starter
Racer
Joined: Sep 2005
Posts: 484
Likes: 0
From: Redwood City CA
Tuned vs Not-Tuned Headers ???
Yes it's another header question, & Yes I did a search....
1. Can some one explain to me what a Tuned Header is ???
2. are they better then a Un-Tuned Header ???
3. If so, then why ???
thank You................
1. Can some one explain to me what a Tuned Header is ???
2. are they better then a Un-Tuned Header ???
3. If so, then why ???
thank You................
Team Owner
Joined: Jul 2002
Posts: 22,267
Likes: 15
From: The light that never warms.
St. Jude Donor '12
Racers have always made a big deal about tuned header lengths. And with a race engine that sees limited RPM variance, it is probably worthwhile.
Interestingly, primaries that vary might be better on the street. Each one will be tuned to a little different RPM, and therefore work better over a wider RPM range.
Course, the problem has always been that people want what the racers use, not what really works better on the street. Tri-Y headers are a perfect example. Ever since racers started using four-into-one collectors, that's what has sold best. Even though tri-y actually works better for low end power. Which is exactly what you need, on the street.
Interestingly, primaries that vary might be better on the street. Each one will be tuned to a little different RPM, and therefore work better over a wider RPM range.
Course, the problem has always been that people want what the racers use, not what really works better on the street. Tri-Y headers are a perfect example. Ever since racers started using four-into-one collectors, that's what has sold best. Even though tri-y actually works better for low end power. Which is exactly what you need, on the street.
Thread Starter
Racer
Joined: Sep 2005
Posts: 484
Likes: 0
From: Redwood City CA
Racer
Joined: Apr 2007
Posts: 269
Likes: 1
From: Anniston BAMA
Much can be argued on this topic.
Heres my viewpoint.
An internal combustion engine is nothing more than an air pump.
The easier air flows through it the more effecient it is. Always work from the back of the exaust system forward. Remember, you can't put 10 LB in a 5 LB bag. You have to match what comes in the front end to what shoots out the back end. From my expriance a tuned exhaust is one where exhaust gases are scavanged out (sucked out) based on the exhaust valve timing, causing pulses that pull burned gases out of the combustion chamber when the piston is on the exaust upstroke. A properly "tuned exhaust" or header is one that is calibrated to the exhuast pulses of the engine.
Thats about as detailed as I can get now. A basic "how it works" thang.
This would be a critical concern an a compitition car, maybe a street racer. Probley not if you are doing a street car.
just my observation, wait; I got 2 cents!!!!
Heres my viewpoint.
An internal combustion engine is nothing more than an air pump.
The easier air flows through it the more effecient it is. Always work from the back of the exaust system forward. Remember, you can't put 10 LB in a 5 LB bag. You have to match what comes in the front end to what shoots out the back end. From my expriance a tuned exhaust is one where exhaust gases are scavanged out (sucked out) based on the exhaust valve timing, causing pulses that pull burned gases out of the combustion chamber when the piston is on the exaust upstroke. A properly "tuned exhaust" or header is one that is calibrated to the exhuast pulses of the engine.
Thats about as detailed as I can get now. A basic "how it works" thang.
This would be a critical concern an a compitition car, maybe a street racer. Probley not if you are doing a street car.
just my observation, wait; I got 2 cents!!!!
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by OTS_UFN
Much can be argued on this topic.
Thats about as detailed as I can get now. A basic "how it works" thang.
Thats about as detailed as I can get now. A basic "how it works" thang.
RACE ON!!!
Instructor
Joined: Sep 2006
Posts: 161
Likes: 0
From: Yorkville IL
You forgot one VERY important factor. The tuning of a particular engine, especially a given displacement, takes place within a narrow RPM range. You totally ignored engine speed in your discourse. The exhaust tuning is done to optimize the scavenging at a specific engine speed.
RACE ON!!!
RACE ON!!!
If you look at a few different types of engines... starting with a 1 cylinder racing motocross bike, exhaust tuning is EXTREMELY important. Without it, half the fresh mixture goes straight out the tailpipe. With it, you can double the horsepower, in a very narrow rpm range.
Very important on a drag race motor too, primary size and length, and collector size and length play a big role in the engines power and power band.
Even a nascar engine, running between 7500 and 9500 rpm with a partial exhaust and no mufflers, finds considerable power in exhaust tuning.
Stick on a full exhaust, mufflers, cats, and an expactation for the engine to behave from idle to redline, and (lack of) backpressure matters a lot more than any "tuning."
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