Mohr performance header
baz:
Quote from: Neil Davies on March 16, 2022, 23:12:51 pm
Quote from: baz on March 12, 2022, 21:23:31 pm
You're right in that bespoke is the only way if wanting to extract the most from your own particular combination. Ive been hunting all over for info on the mohr system but can't find anything, I guess that tells me that they aren't very popular in the scene. Not to say they don't work but as pointed out to me they may work very well with a particular combination of parts particularly cam and heads.
I guess building a system is the way to go. Gotta find someone local who can build exhausts first though as its beyond my capabilities.
Whereabouts are you Baz? Turbo Thomas is good, based in Redditch if I remember correctly.
Hi Neil I'm back in Ireland since 2018.
PPRMicke:
How to calculate a primary pipe
A good guess is 500 ° - 550 ° C. A good starting point for the primary pipe diameter from the top is 5 - 10% larger area than the exhaust valve. Where the primary pipe enters the secondary pipe (collector), it should be the same area as the exhaust surface of the exhaust valve at full lift or larger. Sheath surface = Valve diameter x pi x valve lift. To calculate the length of the secondary pipe to an engine with even ignition sequence and get the secondary pipe negative pressure pulse to return at the same time as the next primary pipe pulse will be used the formula: secondary pipe length = secondary pipe tuning factor (900000) x root out (average exhaust temperature + 273) to.
Primary Pipe length = primary pipe tuning factor (205800) x root out (average exhaust temperature + 273) / rpm to which the primary pipe is to be tuned.
Sometimes it's easier to believe in something and buy something you believe in
And test in dyno
/// Micke
Neil Davies:
Quote from: baz on March 17, 2022, 07:30:18 am
Quote from: Neil Davies on March 16, 2022, 23:12:51 pm
Quote from: baz on March 12, 2022, 21:23:31 pm
You're right in that bespoke is the only way if wanting to extract the most from your own particular combination. Ive been hunting all over for info on the mohr system but can't find anything, I guess that tells me that they aren't very popular in the scene. Not to say they don't work but as pointed out to me they may work very well with a particular combination of parts particularly cam and heads.
I guess building a system is the way to go. Gotta find someone local who can build exhausts first though as its beyond my capabilities.
Whereabouts are you Baz? Turbo Thomas is good, based in Redditch if I remember correctly.
Hi Neil I'm back in Ireland since 2018.
I'd got a feeling you were. Rich does have (or certainly used to) the back end of a Beetle set up in his workshop complete with mock up motor so that he can build a system to order. Worth a call?
andrewlandon67:
Quote from: PPRMicke on March 17, 2022, 15:43:23 pm
How to calculate a primary pipe
A good guess is 500 ° - 550 ° C. A good starting point for the primary pipe diameter from the top is 5 - 10% larger area than the exhaust valve. Where the primary pipe enters the secondary pipe (collector), it should be the same area as the exhaust surface of the exhaust valve at full lift or larger. Sheath surface = Valve diameter x pi x valve lift. To calculate the length of the secondary pipe to an engine with even ignition sequence and get the secondary pipe negative pressure pulse to return at the same time as the next primary pipe pulse will be used the formula: secondary pipe length = secondary pipe tuning factor (900000) x root out (average exhaust temperature + 273) to.
Primary Pipe length = primary pipe tuning factor (205800) x root out (average exhaust temperature + 273) / rpm to which the primary pipe is to be tuned.
Sometimes it's easier to believe in something and buy something you believe in
And test in dyno
/// Micke
Now THAT's the kind of science I'm looking for! My next question is - what are those equations spitting out? Is it supposed to be length in MM, or volume, or something else entirely?
PPRMicke:
Quote from: andrewlandon67 on March 18, 2022, 16:03:57 pm
Quote from: PPRMicke on March 17, 2022, 15:43:23 pm
How to calculate a primary pipe
A good guess is 500 ° - 550 ° C. A good starting point for the primary pipe diameter from the top is 5 - 10% larger area than the exhaust valve. Where the primary pipe enters the secondary pipe (collector), it should be the same area as the exhaust surface of the exhaust valve at full lift or larger. Sheath surface = Valve diameter x pi x valve lift. To calculate the length of the secondary pipe to an engine with even ignition sequence and get the secondary pipe negative pressure pulse to return at the same time as the next primary pipe pulse will be used the formula: secondary pipe length = secondary pipe tuning factor (900000) x root out (average exhaust temperature + 273) to.
Primary Pipe length = primary pipe tuning factor (205800) x root out (average exhaust temperature + 273) / rpm to which the primary pipe is to be tuned.
Sometimes it's easier to believe in something and buy something you believe in
And test in dyno
/// Micke
Now THAT's the kind of science I'm looking for! My next question is - what are those equations spitting out? Is it supposed to be length in MM, or volume, or something else entirely?
Length in mm on primary
There is a very good simulation program called pipemax
Too bad you do not read Swedish because we have a forum like Like crazy guys like me who exchange ideas about high-level engines (www.savareturbo.se
/// Micke
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