2,4ltr N/A twin spark exhaust build

[Wally]

Hey guys,

Its been a while since I posted a topic here, but I was inspired by Mark his exhaust build on his 2,9ltr and I was thinking along those lines as well for exhaust primary options.
I have this idea for a VERY long time to build in this anti reversion boxes, after I saw the Feuling engine some 15+ years ago and looked up his and the many other patents before him about this subject. Since I am not gonna sell or produce this, I think (and hope) he would be ok with that.

Engine to try this on is my freshly rebuild (ahum) 102x74 engine with the Pieper billet twin spark heads and type 1 exhaust port orientation:



Since the other spark plugs are on the bottom of the heads and all type 1 market options have their 1 and 3 primaries run exactly there, I cannot use any of those and have to make something of my own anyways..


I'll keep the thread updated when exhaust parts are here and when I have figured out how things will be running (not a fixed idea yet).
Some smart oldtimers here already know what I want to do, but I have not seen it done IRL so far, so I am exited

[Steve Arndt]

For reference of others google
"Feuling anti reversion"
also google
"Hytech anti reversion"

[wreck]

would an equal length stepped tuned header with the the correct sized and length collector , not draw the next slug of exhaust gas into the header , not allowing it to get drawn back into the cylinder ?

David Vizard's book on cylinder heads promoted the exhaust as having as much draw or more on the incoming charge as the piston dropping in the bore ,if it is tuned correctly .

It will be interesting to see real world testing ? are you putting the turbo on the back burner for a while ?

[Wally]

would an equal length stepped tuned header with the the correct sized and length collector , not draw the next slug of exhaust gas into the header , not allowing it to get drawn back into the cylinder ?

Possibly, but would just a step or two be enough resistence against the complete reversion event? Or: how much extra volume and resistence in the "wrong way" would the stepped header need to achieve just that?
Its difficult to know and for us near impossible to test all these theories.

I would even think - theoretically of course - you could run less duration when you can counter the reversion process enough? Or reasoning the other way: torque would be better, especially in the lower/mid revs, without reversion effects having their negative effects?

David Vizard's book on cylinder heads promoted the exhaust as having as much draw or more on the incoming charge as the piston dropping in the bore ,if it is tuned correctly .

I can see that theory working indeed.

It will be interesting to see real world testing ? are you putting the turbo on the back burner for a while ?

Yeah, even with the low CR.
Turbo will not be on the back burner for long though; I only want to test this exhaust idea and see what the engine with this cam makes n/a and then all the turbo junk gets bbolted on again. All the turbo anxcillaries are heavy though! I do like the engine bay better n/a tbh, but the power with just a few psi boost is so much more, that it will be boosted shorly after.
The ultimate goal is still doing a 10-second 1/4 mile with the car.

[Wally]

also google
"Hytech anti reversion"

Nice one! I wasn't aware the Honda scene (Hytech) was doing this. Very cool to see some further reference, tnx!

That google search also came up with this cool page with schematic enclosed exactly what I want to do:
https://crateinsider.com/using-anti-rev ... ree-power/

[Eddie010]

The ultimate goal is still doing a 10-second 1/4 mile with the car.

Yessssss … Go fo it...

[MegaRookie]

Very nice project Walter! I am also very curious what it will do as an NA engine.

When you wrote about a 4-2-1 with a twist I first thought about you were going to use twinscroll turbo's as y-collectors so you get a twin- twinscroll turbo to compound setup with another big twinscroll turbo. I guess 30psi will also work as anti reversion

Enjoy the build!

Mark

[Wally]

Started with test ftting and tack welding the anti-reversion chambers in place.

[wreck]

looking good . What did you use for the chambers .
slightly off topic but not . something I was thinking about last year was an anti reversion chamber/damper on the intake manifold . It also could be a tuned length to get the reversion pulse back to the valve at a desired rpm , or made adjustable and coupled to an linear actuator ,it would be just like a variable intake manifold .

[Wally]

looking good . What did you use for the chambers .

Stainless steel (tapered pieces I bought online)? Seriously: what exactly you want to know?

slightly off topic but not . something I was thinking about last year was an anti reversion chamber/damper on the intake manifold . It also could be a tuned length to get the reversion pulse back to the valve at a desired rpm , or made adjustable and coupled to an linear actuator ,it would be just like a variable intake manifold .

I agree: The intakes encounter the same reversion issue as the exhaust path. Imo, thats why injection is so much better: carbs really get confused when the pressure wave gets back to them and can often be seen as the famous stand-off above the stacks.
But indeed: variable intake length manifolds are being used by many big car companies, also the Porsche 3,6ltr aircooled boxer engines use it in their intake plenums as pressure wave tuning. Not something easily made for our cars I think.
Some anti-reversion measures have and can been taken though in our more simple parts, for instance: I run manifolds with a noticebly larger bowl just under the TB (or carb if you use those). AFAIK, those wider bowls (think mine are a little over 55mm, while I only use 48mm) in the OK-products manifolds (other german shops sell these as well) are there just for that reason.

[Clatter]

Nice. Love it.

Anyone remember Cyclone AR headers from the 80s for V8s?
Tried to find an ad online but couldn't.. Will see if I can't find a pic.
They used to have a cone at the head, right at the exhaust flange.

For that reason I always thought that's where any of these AR things (cones?) would go..

Anyone know why they have moved 'downstream' as of late?

[Wally]

Engine runs as of today

[Wally]

Since its shaped in a 'V' from the heads to the first Y section, I think I call it the 'V-tech' exhaust
Those of you that know me, probably get why this is so funny

Inspection today, so on the hoist/ramp, what do you guys call this?


Yes, I ordered the damper a little bit too big, so it sticks out a bit, but its only temporary.

[MegaRookie]

Very nice Walter! Its nice weather to be on the road!

Can I ask you what sizes you used for the primary, second, third and damper?

Enjoy!

Mark

[Wally]

Can I ask you what sizes you used for the primary, second, third and damper?

Enjoy!

Mark

Of course, no problem; I have very little “secrets”
- 42mm : out of the head into AR chamber
- 44,5mm (1 3/4”) : exit AR chamber
- 50,8mm (2”) : 4 into 2 part
- 63,5mm (2,5”) : 2 into 1 to silencer
All sizes are external. 1,5mm wall thickness 304 stainless. Head exhaust diameter is actually 40mm, but I didn’t bother too much about that 0,5mm radius as the 42mm pipes fitted my CSP flanges so perfectly.
I hope to load up and bed-in the rings this WE as I might be able to an opening in the dyno schedule coming week at my local ‘friendly dyno/aircooled shop’. You know the one Mark