On 22/01/2010 22:11, jimpuglise@comcast.net wrote:
>
> EGT and CHT are all you will need to be careful of. I am in the
> middle of installing a 3300 in mine; am going the Sensenitch prop as
> John has. One of the secrets seems to be the amount of twist in the
> prop near the hub, so that it throws a lot of air into the cooling
> ports. This is why the Senesenitch is recommended. I don't know
> anything about the Whirlwind. Ther are several Jabs. flying in the US
> with excellent performance. Many of the problems have been in monos
> or with VP props.
>
> Jim Puglise A-283.
>
Carburation affects cooling. The carb needs air going straight in
evenly, a smooth elbow into the carb doesn't work, different air
velocity across the inlet which causes different mixture in the front
and rear cylinders, (I'm thinking aloud here) could be that turbulent
flow is needed. A plenum that feds straight not curved seems to work
better. A box with in and out tubes @90deg works. Turbulence might help
evaporate the fuel droplets spraying into the inlet manifolds. Drops
won't go round corners.
There's a guy in UK who worked this out, Anthony Higgins but I don't
have his contact details, (@#%$^&windoze crash :-( Rally driver and
Europa builder. Are you there Tony?
Tony helped cure an overheating Jab 6, I spent hours on it and failed.
Which reminds me, I recommend you fit a fuel bleed back downstream of th
engine driven pump. Pump is bolted to the engine and will get hot, fuel
vaporisation is a possibility. One accident due to this suspected, not
yet proven. Fuel was Avgas.
Graham
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