Anti-Reversion Headers

General engine tech -- Drag Racing to Circle Track

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Re: Anti-Reversion Headers

Post by nitro2 » Fri Jun 12, 2015 4:21 pm

I hate to say it, but while all these types of discussions can be interesting and indirectly go on for years/decades, the technology to simply measure what's going on and get the answers has been around for several years. If you want to know what happens at some A/R device placed somewhere in the exhaust (or intake) just put a couple sensors in there and it's case closed, then build something else and see what it actually does (as opposed to theories/discussions/more theories), and so on. Life is short :(

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Re: Anti-Reversion Headers

Post by modok » Fri Jun 12, 2015 8:07 pm

The technology to measure it is now accessible, but not new at all.
Pressure traces were taken back in the 60's. Then and now the same problem exists. Reading philip H smiths book has lots of of data, but provides NO understanding of why a header is designed the way it is, and suffers greatly from much tail chasing trying to develop a working theory. They were not able to develop merged headers because not able to decipher the highly complex pressure traces. if you give average joe a pressure trace, he still don't know WHY it is doing what it does, or what to do about it. This device could be a tool in the toolbox. If adding it does something......then it could mean several things, which you'd have to narrow down, but better than nothing.

Yesterday i skimmed a thread where MR nitro2 had a pressure trace with spikes in it, and not sure why, I think I know. It's essentially what my first post in this thread was trying to communicate. But since i didn't see any pictures of the setup I'm not totally sure.
I bet no man alive can look at a pressure trace, and imagine what the exhaust system looks like entirely. I have only a rough idea, that he was taking a pressure trace upstream of a taper.
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Re: Anti-Reversion Headers

Post by nitro2 » Sat Jun 13, 2015 1:25 pm

modok wrote:The technology to measure it is now accessible, but not new at all.
Pressure traces were taken back in the 60's. Then and now the same problem exists. Reading philip H smiths book has lots of of data, but provides NO understanding of why a header is designed the way it is, and suffers greatly from much tail chasing trying to develop a working theory.

In reference to Philip H. Smith's book from decades ago, I read that when I was 15, and you're right it was highly underdeveloped on the understanding side of things. Except for nostalgia reasons, I wouldn't even consider cracking that book open now.

You are also right that "no man alive can look at a pressure trace, and imagine what the exhaust system looks like entirely,". There are numerous designs that make more or less the same thing happen, which are by simple logic obviously not optimal.

If you look through a few more threads you will find the (checkmark) trace exhaust that we developed. It is a design that generates a greater suction magnitude and duration than any exhaust trace ever submitted to us, and over a pretty decent rpm range.

Assuming one has little or no experience with exhaust pressure traces, then the simplest way to use the sensors is to install the sensors on whatever you currently have to see what you've got to start with, then do another test trying out whatever change or theory you have in mind. The data is then there in black and white for each and every change you wish to make. You can see what every change did, instead of guessing, and learn from that. The more you learn the simpler it becomes. Some people don't want to learn, but some people do.
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Re: Anti-Reversion Headers

Post by vannik » Sat Jun 13, 2015 1:48 pm

As Nitro says it should be a simple matter to put a pressure transducer up and down stream of an anti-reversion device. Why does no-one do this? Or has the results been kept secret by the people that has done it?

It is a pity that the single pulse and pulse generator equipment at QUB no longer exists - it would really be interesting to see if the major effect is on flow or pulse shape/amplitude/phasing.

What Nitro should have said is that the measuring equipment has only been available at a reasonable price for the last 10 years or so. Yes, it has been available for much longer but at extreme prices.

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Re: Anti-Reversion Headers

Post by Kevin Johnson » Sat Jun 13, 2015 2:12 pm

vannik wrote:...
It is a pity that the single pulse and pulse generator equipment at QUB no longer exists - it would really be interesting to see if the major effect is on flow or pulse shape/amplitude/phasing.

...
https://www.youtube.com/watch?v=QcxFgKHkrz0

What could possibly go wrong.

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Re: Anti-Reversion Headers

Post by Fendermate » Sat Jun 13, 2015 5:16 pm

I agree, seeing something and guessing why is no substitution for actual measurements and mapping. In my 'shade tree' testing, back in the 70's it was frustrating. When I tested intake pressures, I had the most accurate (and expensive) gauge I could find and all I still got was high activity that couldn't be measured. Why it was there I could only guess, but I still took my chances and tried something. I was lucky that the results were positive but it could of gone bad very easily.
Today, the tools are out there.
Can you folks do me a favor?
I've developed a resource library for the Automotive Service Industry. Yeah, I know it's not focused strictly on racing, but then again, where do most of our enthusiasts come from? It is also focused on this industry, here in BC to start (that's two strikes).
What I'm looking for are links to resources I can catalogue to benefit everyone who's looking. I've started a Racing group of links and am setting it up under the Tech Center/ Tech Resources to start with on the site at http;//www.asbn.ca and will create further detailed site directories as needed. The tools, equipment and performance parts makers will be added to their respective categories.
Feel free to check it out. It belongs to all of us, so any suggestions and additions are welcomed.
Yes, Elston, Endyn and TFX have been added. These are great.

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Re: Anti-Reversion Headers

Post by Kevin Johnson » Sat Jun 13, 2015 5:26 pm

That sounds like it should be under a separate thread because a casual search will not bring it up otherwise.

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Re: Anti-Reversion Headers

Post by modok » Sat Jun 13, 2015 7:54 pm

nitro2 wrote:
In reference to Philip H. Smith's book from decades ago, I read that when I was 15, and you're right it was highly underdeveloped on the understanding side of things. Except for nostalgia reasons, I wouldn't even consider cracking that book open now.

[/b]
Wow, I think I was 15 also.
Some want to learn......and some don't. I mentioned the book as a way to determine who is who. Was hoping for more takers.
I would make exception for those under 25, because the internet replaced libraries to a degree, so they may have missed it.
Tired of hearing about conspiracies and secret technology.......... Nobody knows, because nobody cares. You probably know better than anyone!

For other readers:
Today I would recommend those interested to "play" with simulation software, such as Lotus, to gain basic understanding, it helped my considerably.
But I didn't have that when i was 15, so I read that book and SAE papers, and everything that I could get my hands on.
Without a basic understanding, there is no way to explain what any exhaust system does and does not do.
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Re: Anti-Reversion Headers

Post by vannik » Sun Jun 14, 2015 2:59 am

Was hoping for more takers.
Funny thing - I was also about 15. And I still have it. I also still have "Tuning for Speed" by PE Irving.

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Re: Anti-Reversion Headers

Post by modok » Sun Jun 14, 2015 3:57 am

High five!
I think we will have great discussions in the future.
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Re: Anti-Reversion Headers

Post by steve cowan » Sun Jun 14, 2015 5:02 am

to modok and fender,i have read this thread a couple of times now with great interest, i dont have an opinion on the subject but i have a couple of questions.i purchased smith and morrison book-scientific design of exhaust and intake systems this year and have read sections( Q ? do you guys think it has merit in todays technology of heads and intakes etc or is it out dated or do you think the theory is set in stone,the reason i ask is i am interested in exhaust power gains for myself,i dont work in the industry but i have enjoyed drag racing steet/strip vehicles for 3 decades now and in between my 60 hours a week working highrise construction i am in my home workshop trying to make the most of all the parts i have,i enjoy the research and the data to go with testing and i only have one handbrake in the car ( NO WIFE) what i am trying to say is it worth the effort for a person like myself to fabricate headers,mufflers, x pipes, h pipes, terminator boxes,anti reversion mufflers etc etc or just go buy the latest and greatest so called performace devices available at the time,thanks for your thoughts in advance.

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Re: Anti-Reversion Headers

Post by modok » Sun Jun 14, 2015 6:32 am

The book contains a large amount of real world data, and engines still have pistons, valves, and run on gasoline...........so it's still relevant.
But useful? Probably not in a direct way.
For most popular engines there are already intake and exhaust systems on the market that are better than I can hope to make, and there is also a lot of junk out there too. The more you know, I think the easier it will be to tell which is which.
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Re: Anti-Reversion Headers

Post by joe 90 » Sun Jun 14, 2015 6:39 am

The biggest problem here is that everyone keeps going on about flowbenches.

As I keep mentioning.......a flowbench works at 1PSI constant flow.
An engine does NOT.

So why would you want to keep on thinking about it as the best and only tool for the job.
Wrong theory used.......wrong tools used for the job.
Need a bigger hammer?

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Re: Anti-Reversion Headers

Post by MadBill » Sun Jun 14, 2015 8:17 am

vannik wrote:
Was hoping for more takers.
Funny thing - I was also about 15. And I still have it. I also still have "Tuning for Speed" by PE Irving.
Mark me down for membership as well. Smith, Irving, Campbell, etc., although I was about 5 years older than you guys when they came out. Smith's writing style irritated the hell out of me at the time; I should revisit to see if it still does...
Felix, qui potuit rerum cognscere causas.

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Re: Anti-Reversion Headers

Post by Kevin Johnson » Sun Jun 14, 2015 9:02 am

Bought my copy from Dave Bean, IIRC.

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