[Tom Vaught]

Years ago, Bert Straus campaigned an Astre in Gas and Pro Stock called "Chief Chilly Willy"

The car was campaigned with both a RA-IV engine and a RA-V engine at different times.
One of the unique features of the car was the "stub" header exhaust design.

The normal exhaust runner was cut off and a 2" long stub was custom made for the "high port" exhaust port design in the heads. Larger tubing headers slipped over the top of the stubs and was held on by beefy springs between the headers and the heads. The whole exhaust system could be removed in about 5 minutes.

But that was not the "magic" in the exhaust design. The "stub" design allowed any exhaust reversion to escape from the system without contaminating the next charge coming into the cylinder. The "stub" design also allowed a very good "Stepped Header" to be built for the engine for high rpm.

You ever think about going down that path?

Might be some extra HP there. You put a lot of effort into your oil pans, why not look at exhaust header designs.

Tom Vaught

Warren Johnson saw a set of Bert's "stub" heads at Norwalk one year when he was there and immediately recognized them. He has nothing but good things to say about the design apparently and about Bert Straus.

[GOAT490]

Sounds very interesting. Any pics?

[BruceWilkie]

Anti-reversion cones off the port?

...Snowmobile exhaust pipe springs hold things together quite well.

[Tom Vaught]

Some History:

a) 351 Cleveland engines, 351 429, etc used to have an exhaust port like a Pontiac that had a 180 degree type bend in the head from the exhaust valve to the exhaust port flange.

b) Cleveland race guys would chop off the exhaust runners (like the CV-1 convertible port mod) and add plates to the side of the cast iron heads that made the ports a "High Port" Exhaust. http://www.pricemotorsport.com/Exhau...ort_plate.html

You ported the roof of the head to match the roof of the plate and filled in the bottom dead air section of the port. The headers bolted on to the plates Like a small block chevy headers do.

Bert Straus did it one better as he chopped off the ports, raised the exhaust ports, added extension "stubs" to the high port exhaust, and SLIPPED HEADERS ON THE OUTSIDE OF THE STUBS (with clearance around them).

So yes, Bruce the stubs were the anti-reversion cones, but the normal anti-reversion headers still trap the burned exhaust inside the header pipes by their sealing flange to the heads so it was still possible to back flow some exhaust into the combustion chamber. The slip on headers and stubs let the bad gases out of the pipes.

Not a STREET exhaust system but definitely a proven design for a race car.

I recently saw a post about it being a pain in the aze to get header bolts installed and torqued in race cars with big tube headers. This design would fix that deal and could provide some additional power.

The other benefit would be the removal of the exhaust ports on a CV-1 head (convertible exhaust) would allow adding the extra head bolts to the head/ block in a vertical manner using a common bridgeport mill.

Tom Vaught

You could do the mod on RA-V heads or any aluminum head easily.

Tom Vaught

[BruceWilkie]

Thanks for the link Tom.

Anti reversion for either side of the head has always intrigued me. Guess I need to start looking at current "state of the art" as its been a real long time since I've read anything on it. 2 stroke race exhausts seem to be all about expansion and anti-reversion.



As I mentioned snowmobile exhausts are usually held on with springs and do a great job. (exhaust systems can get a tad heavy and are subject to severe shock loads along the trail.)
These 2 links show springs and typical mount.

http://www.denniskirk.com/jsp/produc...fCatId=&mmyId=
Available in many lengths/tensions

http://www.denniskirk.com/jsp/produc...fCatId=&mmyId= A typical ball mount

There are non ball mounts where the pipes fit over a stub/flange. Pretty similar to the ball mount though.(just doesnt have the flanges)

This is just basic mount stuff. Its highly effective, holds up well, and way easier than messing with bolts(as long as you have a strong spring tool).

[taff2]

In a tuned length header wouldn't the reverse pulse that goes back up the primary pipe be negated,or compromised if there was a 'leak' at the manifold joint? Or would the fact that there are less reversion gases in the chamber outweigh the loss of the reverse pulse, I wonder?
I have an old magazine article on the Chief Chilly Willy car,very forward thinking for it's time,I had thought about building a similar car but using a Vega as a base because I haven't seen an Astre over here.

[tom s]

Tom,over the years I have seen a few sets of V heads done that way.Dudy Difus(spelling) did them,I owned a head that had been cut but never finished which I sold to Nunzi.Tom

[Tom Vaught]

Originally Posted by taff2

In a tuned length header wouldn't the reverse pulse that goes back up the primary pipe be negated,or compromised if there was a 'leak' at the manifold joint? Or would the fact that there are less reversion gases in the chamber outweigh the loss of the reverse pulse, I wonder?
I have an old magazine article on the Chief Chilly Willy car,very forward thinking for it's time,I had thought about building a similar car but using a Vega as a base because I haven't seen an Astre over here.

I do not think that contamination of the cylinder is beneficial in any system.

On an intake system you can tune the pulse wave to improve the power in a small area of the curve, everywhere else you lose on the deal.

On an exhaust system you want the burned gases to leave the chamber and all new fuel and air gases to take up all of the space in the combustion chamber. If you can reduce the dilution of the intake charge there will be more power.

Tom Vaught

[cgeise]

I have "heard" of stubs being put inside the primary pipe where you would never see it - a 2 1/4 pipe off the head my have a 2 in inside for maybe 2 or 3 in - you have a step - and and anti reversion set up all in one -