phantomjock
Member
Grumpy -
I am back to working on my beast, a 383, Weber-ized '78 Corvette Track-Car. As background - probably looking at 450 HP/420 QT, and will run a redline of 6500 RPM. The Torque curve runs fairly flat from 3000 to 5500 (390 and above) - again, that is all on paper and the curves and desktop dyno are posted elsewhere here..
I've read and re-read many of the postings here and elsewhere - a particurally good one :
viewtopic.php?f=56&t=185
And, I note with some interest you had recognized Jere Stahl's 360 degree headers. That is what I have started with:
Fortunately, I've set my engine back over a foot so I now clear the rack and pinion I've installed. The road race Canton oil pan I've installed also ensures under engine clearance for the header joins.The pic below, not my Corvette - but similar brings the questions forward.
I've significantly modified the headers. Now, all the primary's are now very close to the same length, and now exit as in the image above, that is to say, as side pipes and not under the car.
My Pics
The Stahl's are not a 4-2-1 configuration, that many of he online calculators use, but here is a snapshot of some of the results (using Desktop Dyno inputs from my engine):
pic - calculator My primary tubess are 1.625, so that checks prety close and the lengths are now all "relatively" close to 39-40 inches from cylinder head mount to first 2-1 merge collectors. But, These are not you "average 4-2-1 setup so that is why the questions...
The page I found the calculator on had the following pic for reference,
pic 4-2-1
and I've made some notes you'll see mine is not your average 4-2-1 setup, but maybe a 4-2-2:
I've checked Victory and other pages you've recommended in the past - but still come up needing some advice regarding what I should do for exhaust. I know we can "tune performance up/down" based on length of tail pipe - but I need a good starting point.
Should I keep the Stahl's flowing into 2 separate (duals) on each side - kind of like the Blue car above -
or merge them as they exit the frame into 2 singles (on each side)?
pic - CAD
Any recommendations on what diameter and length I might use for the tailpipe section? If I can get to 2 1/4 ID there are spiral/auger traps available - as I'll need to meet track side dB levels. And, naturally larger is possible too.
The calculators seem to suggest 2 1/4" - 2 1/2" for diameter might be close, and maybe 36 inches or so for length, but I need some advice and experience here. Should I join each side - or keep separate (duals)? In other words, should I try and do a 4-2-1 "like" setup - or make as a 4-2-2, and use a cone like "silencer" as you suggested in another thread?
Your thoughts, recommendations, suggestions are much appreciated.
Cheers - Jim
I am back to working on my beast, a 383, Weber-ized '78 Corvette Track-Car. As background - probably looking at 450 HP/420 QT, and will run a redline of 6500 RPM. The Torque curve runs fairly flat from 3000 to 5500 (390 and above) - again, that is all on paper and the curves and desktop dyno are posted elsewhere here..
I've read and re-read many of the postings here and elsewhere - a particurally good one :
viewtopic.php?f=56&t=185
And, I note with some interest you had recognized Jere Stahl's 360 degree headers. That is what I have started with:
Fortunately, I've set my engine back over a foot so I now clear the rack and pinion I've installed. The road race Canton oil pan I've installed also ensures under engine clearance for the header joins.The pic below, not my Corvette - but similar brings the questions forward.
I've significantly modified the headers. Now, all the primary's are now very close to the same length, and now exit as in the image above, that is to say, as side pipes and not under the car.
My Pics
The Stahl's are not a 4-2-1 configuration, that many of he online calculators use, but here is a snapshot of some of the results (using Desktop Dyno inputs from my engine):
pic - calculator My primary tubess are 1.625, so that checks prety close and the lengths are now all "relatively" close to 39-40 inches from cylinder head mount to first 2-1 merge collectors. But, These are not you "average 4-2-1 setup so that is why the questions...
The page I found the calculator on had the following pic for reference,
pic 4-2-1
and I've made some notes you'll see mine is not your average 4-2-1 setup, but maybe a 4-2-2:
I've checked Victory and other pages you've recommended in the past - but still come up needing some advice regarding what I should do for exhaust. I know we can "tune performance up/down" based on length of tail pipe - but I need a good starting point.
Should I keep the Stahl's flowing into 2 separate (duals) on each side - kind of like the Blue car above -
or merge them as they exit the frame into 2 singles (on each side)?
pic - CAD
Any recommendations on what diameter and length I might use for the tailpipe section? If I can get to 2 1/4 ID there are spiral/auger traps available - as I'll need to meet track side dB levels. And, naturally larger is possible too.
The calculators seem to suggest 2 1/4" - 2 1/2" for diameter might be close, and maybe 36 inches or so for length, but I need some advice and experience here. Should I join each side - or keep separate (duals)? In other words, should I try and do a 4-2-1 "like" setup - or make as a 4-2-2, and use a cone like "silencer" as you suggested in another thread?
Your thoughts, recommendations, suggestions are much appreciated.
Cheers - Jim
Attachments
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Stahl 360 cross over headers pairings.jpg71.9 KB · Views: 17
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Setup question.jpg129.9 KB · Views: 15
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Revised Left side Stahl Headers.jpg119 KB · Views: 18
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Revised Right Side looking to engine.jpg263.7 KB · Views: 15
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EXHAUST SIZING CALCULATOR.jpg119.2 KB · Views: 15
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421 exhaust system.jpg33.4 KB · Views: 15
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Header Priomary Length Calculations.jpg29.7 KB · Views: 15
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ExhaustTail Pipe from 360 headers.jpg31.4 KB · Views: 16
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My 4 into 2 into 2 xhaust system.jpg44 KB · Views: 16