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 Post subject: Re: Exhausting exhaust?
PostPosted: July 14, 2015, 12:41 am 
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coneeng wrote:
Several of the questions asked here are covered in articles on our Technical Assistance section of our website. And even if they aren't specifically for the engines used in your cars, you may find useful info in some of the seemingly off-topic articles. Here's a link to tech: http://www.coneeng.com/tech_assist.html



Thank you for that suggestion!

coneeng wrote:
One thing I would caution builders/designers on, I actually have many people make similar comments. If you have a motor that makes mostly torque, you can't just change to a "top-end" style exhaust and suddenly make horsepower instead of torque. The exhaust is the finish of what was designed into the motor. The exhaust can't contradict the basic nature of the motor without making changes to the motor itself. What you end up doing is just designing an exhaust that doesn't deliver the optimal performance of the designed motor. Hope that makes sense?


Strangely, yes it does. Recalling vaguely my failed attempt at calculus, you're saying that my idea to reshape the power curve will mostly likely end up simply reducing the area under the curve, reducing the peaks and not producing correspondingly more power at the upper limits. Which does sound very plausible.

I'll be around for, at the very least, the flanges, and probably a couple of 3 into 1 collectors. Thanks again!

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 Post subject: Re: Exhausting exhaust?
PostPosted: July 14, 2015, 12:50 am 
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While I'm at it, I finally made contact with a friend who, before he had health issues, was a top engineer both at Walker and Wescast (last I checked, Wescast was the world's largest supplier of exhaust manifolds and turbocharger housings).

His comments:

Quote:
Exhaust manifold tube diameters are a contentious subject. I am NOT of the "free-breathing" school. I've repeatedly reduced tube diameters beyond what OEM engineers thought possible, and had the data to prove it. But the goal was cost reduction, weight reduction, and most importantly, thermal mass reduction. None of those matter much to you in this case, I suppose.

For the engine you mention I'd start with 38.1 OD 1.4 to 1.8 wall 321.

Very important: mandrel bend the pipes, do not press bend! Bend radii of 2D if can get it. Never less than 1.5 D.

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 Post subject: Re: Exhausting exhaust?
PostPosted: July 14, 2015, 5:13 am 
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Jegs and the like do a diy header kit with flanges at very reasonable costs.

http://www.jegs.com/c/Exhaust-Headers-M ... 7/10002/-1

Just saying :)

Bob

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 Post subject: Re: Exhausting exhaust?
PostPosted: July 14, 2015, 4:40 pm 
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geek49203 wrote:
I've seen lots of posts here about mufflers and building headers.

While researching the building of my headers and the choosing of my muffler, I started reading up on optimal header/exhaust design -- ie header feeder tube size/length, proper pipe diameters, etc.

Quite frankly, I don't see too many ways to optimize our exhausts other than tube diameter and muffler type? I mean, we have to run our header feeder tubes fairly long to get outside of the frame, right? and the straight back exhaust design pretty much means that the thing is one veryyyyyy long header collector?

Anyone here have any background or expertise on how to do a bit of exhaust tuning beyond mufflers and tube diameters?
The bible for "The scientific design of exhaust systems" was written by Philip H. Smith. It's well worth the price if you don't have a copy.

http://www.amazon.com/Scientific-Exhaust-Systems-Engineering-Performance/dp/0837603099

It's a lot more than than just diameter & mufflers. You also need to tune the intake to maximize the affect of a tuned system.

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 Post subject: Re: Exhausting exhaust?
PostPosted: July 14, 2015, 8:44 pm 
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This thread on first time construction is 20 some odd pages long now. Some of the people contributing here do the best work around, front line NASCAR etc. This pointer is well into the thread but there are some good pictures at this point and useful comments. Not sure how an 8 translates to your 6, but it won't hurt to look this over...

Geek, considering the events you've covered you would know some of these people or their cars...

Quote:
http://speedtalk.com/forum/viewtopic.php?f=1&t=41836&start=390

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 Post subject: Re: Exhausting exhaust?
PostPosted: July 14, 2015, 9:00 pm 
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Marcus --

Thank you!

I'd love to get the IndyCar V6 engineers from Honda or Ilmor (Ilmor builds the Chevy engines, shhhh, it's a secret!) help me out too, but in the past they've been very sensitive about their exhaust work. They get real cranky when I have my camera out and the engine covers are off, for instance. And of course, theirs goes into 2 turbos, and I'm thinking I'm not likely to do that.

Will be reading that thread for sure.

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 Post subject: Re: Exhausting exhaust?
PostPosted: July 15, 2015, 5:21 am 
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olrowdy_01 wrote:
geek49203 wrote:
I've seen lots of posts here about mufflers and building headers.

While researching the building of my headers and the choosing of my muffler, I started reading up on optimal header/exhaust design -- ie header feeder tube size/length, proper pipe diameters, etc.

Quite frankly, I don't see too many ways to optimize our exhausts other than tube diameter and muffler type? I mean, we have to run our header feeder tubes fairly long to get outside of the frame, right? and the straight back exhaust design pretty much means that the thing is one veryyyyyy long header collector?

Anyone here have any background or expertise on how to do a bit of exhaust tuning beyond mufflers and tube diameters?
The bible for "The scientific design of exhaust systems" was written by Philip H. Smith. It's well worth the price if you don't have a copy.

http://www.amazon.com/Scientific-Exhaust-Systems-Engineering-Performance/dp/0837603099

It's a lot more than than just diameter & mufflers. You also need to tune the intake to maximize the affect of a tuned system.



I will grab one of those books and have a read, there may be some useful info in there. Being realistic most of us here are only trying to package a free flowing exhaust system that miss various fixed objects on route to the side of the car. Once built there are not many that will be looking to eek out the last few HP and alter what they have made. You would probably need many hours on a dyno and chop around dozens of systems long before getting a noticeable performance gain.

Bob

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