Has anyone ever run a Knisley exhaust vs a stock exhaust for 0-470 on dyno and got a real world comparison on HP increase?

Just curious cause just overhauled my 0-470-U/TS and it made 262HP @ 2600RPM with the stock exhaust the shop that built it had. I have an AWI built Knisley exhaust and could tell a difference when I installed it on my original L motor. With hindsight I should have taken the shop the Knisley to run it on the dyno with. It don't really matter but it'd be interesting to know

Can you post a photo or description of the dyno they used? I have never seen a dyno set up for aircraft use, for that matter all too few shops that do engine overhauls even have a test stand & test clubs so that they can properly run in a fresh engine.

Hotrod,

I didn't take any pictures when I drove the 470 up. Had Custom Airmotive in Tulsa do the overhaul. It was a really interesting setup, they have two test cells/dyno's. They may have pics on their website

Skalywag wrote:.... I have an AWI built Knisley exhaust and could tell a difference when I installed it on my original L motor....

I'm kind of confused. Knisley & AWI are both certified aircraft exhaust repair shops, and competitors. I assume they each have certified repair station licenses or parts mfr authority (or both). As far as I know, they both just overhaul (or build new) stock exhaust systems. I don't see a high-performance or hotrod exhaust system for Cessnas listed on either of their websites. I don't get the "AWI built Knisley exhaust" comment either, since as far as I know Knisley does their own work.

AWI does knisleys work (as far I knew at one time).
It is definetly better than stock in quality and performance even if not stated so. Imo of course. It at very least deletes the step down (restriction) right at exit point.
Sure woulda been cool if you could of got a stock vs the other dyno read for sure. (;

Hotrod,

I have Knisley designed and STC'd exhaust built by AWI, technically it's overhauled and thus cheaper. Maybe they melted some old stuff down but it was all new stainless.

Way better design than stock Cessna IMO, and the stock pipes fit inside the Knisley. It's a sleeved design vs bolt/clamp

Skalywag wrote:Hotrod,
I have Knisley designed and STC'd exhaust built by AWI, technically it's overhauled and thus cheaper. Maybe they melted some old stuff down but it was all new stainless. Way better design than stock Cessna IMO, and the stock pipes fit inside the Knisley. It's a sleeved design vs bolt/clamp

If you get a chance, maybe you could snap a pic next time the cowl's off and post it here?
I have the earlier dual exhaust on my 53 model: 3-into-1 on each side. Sounds good, like a 6 cylinder Harley, but dunno how restrictive it may or may not be. It might be pretty cool to have the same thing but without mufflers (or without the flame tubes in the mufflers).

Knisley Exhaust

I wonder if anyone makes a hotrod system for the early C180 with the dual exhaust?
Seems like a natural, a 3-into-1 with no mufflers-- just a straight section where the muffler is now to clamp on a heat muff for the carb heat, maybe with heatsink studs welded on.
I seem to recall someone posting a photo of some sort of 180 exhaust (Leading Edge?) like that a while back.
Here's the stock exhaust off mine. Standard 193-55 system, modified to 4 bolt flanges for my K engine.

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