View Full Version : making a exhaust work !!

bud firebolt
4th May 2006, 20:26

i'm looking for some formula's for exhaust lenght ( 2 in 1 ) and optimal diameters for my mate's drag xb
for drag use ( 6000-7800 rpm power )

@ the moment the exhaust is not good enuf to reach the max ( hp ) out off the engine
the 60 feet time's are good ( 1.4- 1.5 )
but the topspeed is still staying behind, still under 200 km/h ( 124 mph )
we need to get it over 200 to get under the 10 seconds.

i have seen the nightrider formula's but i would like to see more off theme,
i did some reading about savaging and intake track lenght, but i would like to put it into real numbers so we can see where the restriktion is

thanks, bud

4th May 2006, 20:42
This may give you some direction.


4th May 2006, 23:24
Bud ... I'm not willing to share my formulas and algorithms, but if you give me bore, stroke, and exhaust open event timing, I'll work up numbers for you.

bud firebolt
5th May 2006, 06:15
thanks, uncledaddy, good reading

thanks aaron,
the numbers bore 3-13/16 & stroke 3-13/16, Redshift 624's ( exhaust open 62 deg. , closeing 22 deg. duration 264/ 48 overlap )
we are running a little longer than usual intake lenght!

easy ( driver/owner ) & me are still learning about all the motordynamics involved for dragracing, but the feeling the used pipes are wrong ( to big ) to help the carb in the upper regions

gr, bud