unequal length tri-y secondary merge points.

[PrettyCoolWagon]

With respect Dan,

I don't want to begin with OEM anything, even though those are decent at the wheels numbers for an ecenomy engine pushing 1200kg+ 4wd drive tain

• I want to know what the exhaust port diameter is
  How to calculate resonant lengths, for a certain engine at certain rpms
  I want to use brand new mandrel bent tubes to try this idea out.

If it's shit. I'll cut them up and make something more conventional.

[knightrous]

I don't want to begin with OEM anything, even though those are decent at the wheels numbers for an ecenomy engine pushing 1200kg+ 4wd drive tain

• I want to know what the exhaust port diameter is
  How to calculate resonant lengths, for a certain engine at certain rpms
  I want to use brand new mandrel bent tubes to try this idea out.

Have a play with this then.
http://www.mez.co.uk/mezporting/exhaust_length.html

Punch in your figures, get your numbers, make it and see what the results are.

[oldeskewltoy]

With respect Dan,

I don't want to begin with OEM anything, even though those are decent at the wheels numbers for an ecenomy engine pushing 1200kg+ 4wd drive tain

• I want to know what the exhaust port diameter is
  How to calculate resonant lengths, for a certain engine at certain rpms
  I want to use brand new mandrel bent tubes to try this idea out.

If it's shit. I'll cut them up and make something more conventional.

np on respect...

I can help with one of your questions... The outlets on the early 4AF head are about 25-27mm and in my case very poor indeed




Just for chit chat sake... There is another problem with the F head exhaust... port #1 crowds the oil drain... and because of it port #1 is partially blocked...

[PrettyCoolWagon]

Thanks knightrous, I did see that calculator in recent days and that's where I got to the edge of my knowledge so far.
I was hoping people might know some of the input info required for that calculator??


Dan,
Thanks for the port diameters, ..if I remember correctly ^^that head^^ you ported is 1st generation 4afe whereas the 7afe and 2nd gen 4afe use a head with an improved port design.