Header matching/porting - exhaust gases?
#1
Sorry, can't remember what the technical term is here but I remember from the dim & distant past that matching headers to the exhaust port precisely can lead to worse exhaust extraction from the cylinder - having a 'rim' (?) err, mismatch where the header is a larger diameter can reduce the exhaust sucked back into the next cycle. Which is a good thing. For one, more exhaust gases left over from the previous cycle increases the liklihood (how do you spell that???) of knocking.
Just thought I'd bring this up as a popular pastime at the moment seems to be porting headers for an easy (& cheap ) performance increase. And this might help?
Or am I barking up the normal-aspirated tree here? It was some time ago.
Just thought I'd bring this up as a popular pastime at the moment seems to be porting headers for an easy (& cheap ) performance increase. And this might help?
Or am I barking up the normal-aspirated tree here? It was some time ago.
#3
Aha, I noticed this on F1 engine.
I assume enlarging the headers to bigger than port has a similar effect too.
I also remember reading in A Graham Bells "Four stroke engine tuning in theory and practice" (library copy, excellent, might buy a new updated copy) that he found a larger overlap on one side of a rectangular port helped. I think it was the bottom edge, closest to the smallest bend rad of header.
Paul
I assume enlarging the headers to bigger than port has a similar effect too.
I also remember reading in A Graham Bells "Four stroke engine tuning in theory and practice" (library copy, excellent, might buy a new updated copy) that he found a larger overlap on one side of a rectangular port helped. I think it was the bottom edge, closest to the smallest bend rad of header.
Paul
#4
Ah-ha. OK. One sided.
So I presume that this is all a bit 'advanced' at makes such a small effect that, well, it's not really worth it? As soon as it has anything to do with F1 the advances seem to be, well, 'technical' as opposed to useful.
Or does it just mean it doesn't really matter if we get a bit carried away with the angle-grinder?
So I presume that this is all a bit 'advanced' at makes such a small effect that, well, it's not really worth it? As soon as it has anything to do with F1 the advances seem to be, well, 'technical' as opposed to useful.
Or does it just mean it doesn't really matter if we get a bit carried away with the angle-grinder?
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fatboy_coach
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18 June 2016 03:48 PM