Nascar / circle track exhuast ????????s

[ZROSSA]

Howdy all,

 

I have been looking here:

 

http://www.schoenfeldheaders.com/sbchevy.htm

 

and here

 

http://www.howeracing.com/exhaust/index.htm

 

and here

 

http://www.drgas.com/

 

I now am rather confused

 

I think the rules of different catagories of racing say what size and style of exhuast you can run. I was always under the impression that a v8 worked best with a twin system with a cross over or x- pipe. I get the feeling from some of the above places that a sigle pipe can work as well if not better in some aplications. I realize that these are race only systems but i feel that we should get our exhuasts as close to race spec as possable and then work on the noise. Can any of you offer some additional info. A single pipe would work well for the z if they can get as much power. What do they sound like? I am a long way from the circle fellows so i just dont have any idea.

 

Thanks,

 

Douglas

[johnc]

You're confused because you're hanging on to 1960s thinking...

 

Trans Am race cars use a single exhaust but the exhaust piping has a 8" x 24" cone shaped expansion chamber after the 2 into 1 merge. The expansion chamber and exhaust run throught the passenger compartment. A lot of the tricks that apply to two-stroke engines also apply to our four-stroke engines.

 

Its all about flow and velocity and there has been a lot of research in the past 15 years into intake and exhaust flow. What was trick on race cars in the 1960s is now only suitable for old pickup trucks.

[ZROSSA]

Fair enough,

 

Where do I go to find the new info? Howe racing in particular made a comment on one of there dual systems along the line of ' use this when the rules say you cant use a single'. This gave me the impression that they prefered the single system. The F1 guys use duals but then they dont have to deal with the 90 degree crank.

 

Need heaps more info!

 

Cheers

 

Douglas

[Z-Dreamer]

I wonder if these IMCA Lite Series or Modifed Adjustable headers could be made to work in V8 Z?

 

www.schoenfeldheaders.com/imca_mod.htm

 

Mark

[johnc]

Circle Track Magazine

RaceCar Engineering

MotorTec Magazine

SAE International

SAE Motorsports Engineering

[Z-Dreamer]

Again, anyone think that the IMCA Lite Series or Modified Adjustables would work in a V8 Z?

 

www.schoenfeldheaders.com/imca_mod.htm

 

Mark

[ZROSSA]

Z- Dreamer, those are all made to exit side ways. No way they will fit.

 

John, I looked at those links last night but didnt really come up with much i didnt know already. I am guessing that the rules for circle track racing say what size exhuast you run and these different aplications are to get the best performance within those rules.So it looks like equal length headers into a dual system with a x- pipe is close to the best you can do without using 180 degree headers.

 

Is there a formula that can be use to see where the best place to put the x-pipe is? I imagine it would be the same lenth away from the colecters as the lenth of the header tubes. After the x-pipe is the system still "in tune". By this I mean can i put the mufflers any where or should they be a certain distance from the x-pipe or collecters as well?

 

Cheers

 

Douglas

[pparaska]

I've read that the best place for the H- or X-pipe is where paint would burn off the head pipe.

This is usually somewhere in front of or under the transmission. But there's no room for that in a car like the Z. My X-pipe is just behind the tranny.

 

As far as muffler placement, one of those links said as far rear as possible. But that's for performance. As Mike C pointed out, having a tailpipe behind the muffler(s) helps to let the muffler(s) muffle. Hence, my post about adding something to the outlets of my rear-mounted mufflers.

[Guest Anonymous]

I think thats why we see such loud exhaust on our cars as well, because the muffler is at the end. Some mufflers prefer (flowmasters for one)to have 3' of exhaust at least after the muffler for proper sound. I suspect thats why a resonator in the system somewhere before the back muffler helps out quite a bit with the noise level.

 

Regards,

 

Lone

[johnc]

Douglas,

 

There was great article by David Vizard in a back issue of Circle Track Magazine about building pseudo expansion chambers in a dual exhaust setup. For some reason its not on Circle Track's web site and if you do a search on their site you get links to every magazine but Circle Track.

 

I did find it here: Vizard's Exhaust Tuning. Print it quickly becuase I bet this site goes away soon.

[ZROSSA]

Thanks John,

 

I have down loaded it the article. Missed page 3 and 5. Anyone else have them? I have seen this article somewhere else as well. Is it in some of his books?

 

Pete, I thought that the place where the exhuast changed color was where you cut the pipes off if you were running open headers. I think it should be a multiple of the primary pipe length. I have the formulas somewhere in my shed under a house lot of furniture. Bloody house still isnt finished so I can unpack.

 

Cheers,

 

Douglas