Information on 4-2-1 header design

[Sam_Q]

thanks for the info, I have heard about this book, I heard its like the resonance bible. Any ideas where to get it? ebay USA has one on there

[madmont]

You could always try using the pipemax1 programme to calculate your pipe sizes
This link might work
http://f1.grp.yahoofs.com/v1/sERcReQ...w/pipemax1.zip
its so old it runs in dos
here is a nice little article on extractors for 4 cylinder engines
http://www.mgparts.co.nz/extractor.html

[nick.parker]

thanks for the info, I have heard about this book, I heard its like the resonance bible. Any ideas where to get it? ebay USA has one on there

Amazon.com for $20US....

I think I might just have to buy this book as its too hard to guess what results can be expected from different setups. I have seen this 'secondaries should be half the length of the primaries' rule mentioned a few times, but its not much use without some backup statement of why this works! I have also tried a couple of programs that suggest the secondary length should be longer than the primaries, up to 1.5x longer, in one case on that MG link in the last post the guy is saying up to 60" for the secondaries....still I guess thats on generally low revving engines..

At the end of the day, the longer the lengths of pipes before differnent exhaust runners meet, the lower the frequency at which "cylinder filling killing" interfence will occur. But perhaps also higher rpm scavenging will be less effective to....

Regards, Nick

edit: for some reason I cant enter data correctly into that pipemax app

[oldcorollas]

thanks for the info, I have heard about this book, I heard its like the resonance bible. Any ideas where to get it? ebay USA has one on there

UNSW has a copy.

[Sam_Q]

UNSW has a copy.

whats UNSW?

[bobob]

University of New South Wales?


http://www.unsw.edu.au

[madmont]

The pipemax programme would appear to be more for larger capacity v8s the smallest 4 cylinder you could apply it to is about 2 litre . It works ok provided you fill in all the parameters

[Enchanter]

I got a copy from my local library, there is actually a use for these places

I have recently found from a respected source that if there is a small step from the exhaust port into the headers (about 1mm) it will help with the power when out side of the designed tuning of the extractors due to it acting as an "anti reversion step".
If the 2" primaries mentioned earlier have a step from the exhaust port into the extractors this may explain the good lower torque mentioned.

[roadsailing]

my mate has 2 inch secondaries, i would not suggest using 2 inch primaries!