i understand that there is a hidden gain in resonant pulse tuning and harnessing the negative pulse waves that get sent back up the primaries as the exhaust pulses travel down the pipe. I also saw Rotarygod posted a general forumla for calculating the ideal runner length to harness the resonant pulses. he stated that one can create a header w/ short runners to utilize the first resonant pulse wave or a long runner to utilize the 3rd or 4th pulse wave.

Im just not sure which is better for what im trying to acheive w/ my car. and im trying to figure out if there is more gain to be had w/ the long primary header, approx 94" each or the short primary header, approx 24" long.

im not going to do a street port or anything, i just want to put my power peak to work w/ my shift point at the redline so i can make best use of my torque multiplication before having to upshift.

i was originally fixin to just get the flange from mazdatrix and weld up my own equal-lenth header w/ 94" primaries and then collect it to a 2.5" exhaust and then splitting back to duals again.

can anyone explain to me why i should choose one header length over the other to best suit my needs?

EDIT; i forgot to mention, this is a stock port 90 GTUs.

thanks
Chris

 

I'd also likie to know about this (for a brideported 12A specifically) as it would influence my decision to go N/A ported if short primaries would do of turbo on my old school 323. There isn't as much room as a sev for twin long primaries and it is going to be quite a low car soon.

Cool thread flubyux2

 

can anyone offer an answer to this or post a link maybe? would be greatly appreciated

 

i wish someone with some experience w/ headers would chime in here. ive heard stories that the RB and pacesetter header lengths are too short. and that the "long" headers would actually join together midway under the car. Im half tempted to just make some adjustable header primaries and put the car on a dyno. i can get 3 runs for like $75... and then maybe i can try it shortened, then full length, then try to find out where the sweet spot is for a stock 8000rpm redline.

i dunno. i may just say ****-it and weld up some headers that join somewhere under the passenger seat.

 

In my experiance long headers(95-100in) work well on both stock and ported engines. Intake length is an important factor but I have yet to work out an intake-to-exhaust length rule of thumb. Basically I've had good success with long headers rather than short. From what I gather the n/a Mazda race cars back in the day started with short primaries and ended up using long.(pp's I belive)

 

I would suggest you contact Stan at SDJ. He has already done the research and builds one of the nicest headers that I have ever seen. He has been building rotary engines for many years, and has lots of real world knowledge.

db