Anti-Reversionary Exhaust

[Zach Gomulka]

Fabs, (or anyone else for that matter), do you have the August 1979 issue of HotVW's? Page 42-43, if you could scan it please?

I've always been been intriged by Jim Feuling. The man built a W3 Harley motor that was similar to a radial engine, a turbocharged Oldsmobile 4 cylinder making nearly 1200hp, and more importantly for us a 2232cc (92x84) ACVW engine with his own 16 valve cylinder heads, one venturi per valve, and anti-reversionary exhaust. This mill is reported to have produced 470hp on alcohol, naturally aspirated.
But for now I am curious to learn about this anti-reversionary exhaust "technology" in the previously mentioned HotVW's.They take the closest look at this technology that I have ever seen, but it still leaves much to be desired! It works by reducing the amount of exhaust that is pulled back into the combustion chamber during the beginning of the intake cycle during valve overlap. Naturally, the larger the cam, the more benificial it is. Claims were 25% increase in power at 2500rpm and 12.5% at 5500rpm. That's something that I could get on board with!

What do the VW engine experts think about this? Does it work? Or was Feuling a crack pot?!

[Jon]

Some claims there is more to exhaust than just good looks... 
Burns Stainless is a company that should be able to do some calculations for you...

[Neil Davies]

I've seen something similar in an old Hot Rod "All About Engines" magazine I think. Seemed like it could work, but expensive to make. Bigger gains on big diameter headers?

[Airspeed]

I was/am surprised nobody used that set-up, but I found out it is (or was?) patented by Jim Feuling...
His paper on the anti-reversing primaries is open-source and can be found on the www. I made a print-out some years ago...
Its actually very simple and sort-of easy to construct yourself 
His heads (HD) had the exhaust port on the bottom of the head, cross-flow design. Can you say 'type 4-style' ? 

[Zach Gomulka]

I was/am surprised nobody used that set-up, but I found out it is (or was?) patented by Jim Feuling...
His paper on the anti-reversing primaries is open-source and can be found on the www. I made a print-out some years ago...
Its actually very simple and sort-of easy to construct yourself 

Where is it? I've looked with no luck...

[Jon]

http://www.wikipatents.com/5165231.html

[speedwell]

here we go  & pm sent

[cpalma]

Was just thinking, will a stepped header not have the same effect as this one has?

[Jon]

Has anyone seen anything like this in formula one? They are usualy pretty quick on the uptake... it could obviously have something to do with high revs or stuff like that...

[RFbuilt]

hmm interesting...

if i may share.. based on experiences on a different platform/brand engines , i think the anti-reversion chambers  work well and is/was good for steady state rpm and low rpm engines ?  on planes or boats maybe?    im not sure and certainly dont want to say j.fueling is wrong.. but sum1 could possible research on that?  as im also curious..

cpalma - stepped headers  work nice on engines ive tried (non vw aircooled)  , supposedly it gives abroader torque curve and a fatter powerband  ,      but as we know... alot of things  work and dont work  for aircooled vw.. but works for other motors.. namely inline4's 

very interesting topic i may say... hopefully some of the guru's  can comment or critic the points i mentioned as i wana learn more...

maybe Mr.Ratto has sumthing to share?  yuhooo!   hehe



 

[eugene]

Anti reversion works according to Larry Widmer-Endyn.
....
I’ve discussed the fact many times about exhaust header overlap and I feel that it’s still a necessity, whether your header uses anti-reversion chambers or not. The header primary tube must be larger than the exhaust port exit, period.
....
from hire:
http://www.theoldone.com/articles/badtothebone/

Check the antireversion chambers on this header..




And i have seen something similar also on an F1 engine- on youtube maybe . I think it was an renault.

[Jon]

I have heard of using mismatched header/exhaust port to stop reversion... but newer seen the "trap" before... can't wait until the big boys show up in this thread