so we built a d series ef for endurance racing and realize that we need our power band to be between 4-7k rpm's with good torque at lower rpms... efficiency is just as important as power, but not the ultimate deciding factor... specs are PM7 pistons, lightly surfaced Z6 head, valve springs/ retainers, fully balanced rotating assembly, ported and polished head/ intake, b series throttle body, S2 intake and a 4-2-1 header, we also have tuning capabilities ... my questions are on cams, i have a z6 and y8... and something like a 59100 or 59300 are in my budget... also on header design, is there one design that works better for my target rpm range, 4-2-1, 4-1 long tube, possibly a 4-1 "shorty" design... i have ability to built any of those designs... i know alot of you will say that i can run more rpm's, and we have basically overbuilt the engine for durability, remember this engine is run for 14hrs straight in a road race and we feel very comfortable limiting the rpm's to a stock level...

 

Anyone???

 

I have ran the 59300 hard on a stock z6 head for around 200 1/8th mile races over a summer and 10k of hard street driving, I would shift at around 7500rpms. After taking the head appart we could see a bit of wear but not dramatic.

I think you will be fine with that cam and your setup, and power increase will be noticable and reliability should not be a factor as long as the tune is right.

 

so we dyno'd the car today for reference.. 126whp with a y8 intake, factory exhaust manifold "header" and a bisi stage 2.4 turbo cam... its what we had, so we ran it... A/F was through the roof at 10.5 so it was running WAY to rich... obviously we will tune the car on the dyno after we make some changes... any suggestions on the header...

 

If you can afford it get Dave@SMSP to custom make a header for you he has alot of experience with the D series.

 

i have every bit of confidence that i can build a quality header, im interested more in what design will work better for torque and HP in the lower rpm range... 4-7k is my target rpm range...

 

Def go tri y if your redline is set low. My crappy b7 minime took 7.5k rpms at least every other day for 3 years and 1 of those was w the 59300. Tore it down yesterday and everything was still in great condition, even the flimsy stock rods! Did munch a z6 head and a piston with the zex cam but that was stock springs w pm3s, no tolerance for valve float as a z6 bottom might have had. oops
oh crap though this was new thread

 

You can google header primary length calculator to help determine what will work best for your engine. You’ll need all the cam specs, bore, stroke and a few other things but it’s a pretty good way to get a ball park. Honestly for what your doing something like a dc sports 4-2-1 would work great.