ordengineering
Automotive
- Nov 17, 2008
- 9
I want to discuss about exhaust header length for normally aspirated motor,
my motor was 2.2L, 86mmx95mm 15:1 cr, pro 3 camshaft (310ish adv duration, 270ish @ 1mm duration) and individual runner carbed 50mm twin weber with ventury 48mm.
some of those Honda guys out there, he was Don Flores from DFE give me a rule of thumb for building header with 45mm inside diameter pipe.. I made the primarry length 70cm / 27.5 inch..
those motor was run madly
It made brutal power 308whp @ 8400rpm, peak tq @ 7.600rpm… even my driver cant handle it. It spin everywhere from 1st-3rd gear…. On mt 24.5x9.5
but I know my dastek dyno was a lot inflated…. I guess it was only 260-270whp in sae..
I plan to built another header for this motor.
Now I’ve seen that so many race header fabricator using shorter length about 45-50cm (I just guessing the lenght by viewing the picture on Honda-Tech.com), they were such as Bisimoto, RMF, etc.
And RMF design with shorter header like that promising lot more HP than the old (long primarry) version.
Is that true that the shorter primarry made more power than the long primarry?
But if I see the header picture, it was only 45-50cm length. Based on rule of thumb (such as graham bell, jim mcfarland) calculation, that kinda length with big camshaft like pro 3 (270ish 1mm exhaust duration) would make power above 10.000rpm.
I plan to built another header for my 2.2L motor but I don’t have any clue about how is the best length for my setup. and I hope anybody here that have a bit similar setup with me feel free to tell me about their 2.2L motor header sizing (inside diameter and length). And with an explanation about the correct length sizing formula.
Please teach me more guru…
Regards
Odie Rachmat
my motor was 2.2L, 86mmx95mm 15:1 cr, pro 3 camshaft (310ish adv duration, 270ish @ 1mm duration) and individual runner carbed 50mm twin weber with ventury 48mm.
some of those Honda guys out there, he was Don Flores from DFE give me a rule of thumb for building header with 45mm inside diameter pipe.. I made the primarry length 70cm / 27.5 inch..
those motor was run madly
It made brutal power 308whp @ 8400rpm, peak tq @ 7.600rpm… even my driver cant handle it. It spin everywhere from 1st-3rd gear…. On mt 24.5x9.5
but I know my dastek dyno was a lot inflated…. I guess it was only 260-270whp in sae..
I plan to built another header for this motor.
Now I’ve seen that so many race header fabricator using shorter length about 45-50cm (I just guessing the lenght by viewing the picture on Honda-Tech.com), they were such as Bisimoto, RMF, etc.
And RMF design with shorter header like that promising lot more HP than the old (long primarry) version.
Is that true that the shorter primarry made more power than the long primarry?
But if I see the header picture, it was only 45-50cm length. Based on rule of thumb (such as graham bell, jim mcfarland) calculation, that kinda length with big camshaft like pro 3 (270ish 1mm exhaust duration) would make power above 10.000rpm.
I plan to built another header for my 2.2L motor but I don’t have any clue about how is the best length for my setup. and I hope anybody here that have a bit similar setup with me feel free to tell me about their 2.2L motor header sizing (inside diameter and length). And with an explanation about the correct length sizing formula.
Please teach me more guru…
Regards
Odie Rachmat