Sealing the Cowl: Re: REFLECTOR:Re: Exhaust system

[Scott]

Jim,

Are the holes in the cowling that the exhaust exits out of sealed real 
well?   That made a huge difference for me.  Also all the little places the 
aluminum baffling poorly meets the engine, like the engine mounts, 
etc..?  And you do have the aluminum spreaders that are fastened to the 
tops of the cylinders?

I've heard of the "fat lip" modification for the scoops but never got that 
far.   The fuel line sounds like an easy way to try it out.

What kind of engine analyzer are you using to monitor EGT's/CHT's?   Does 
it have a Find first/last Peak function?

Scott

At 09:21 PM 12/10/2003, you wrote:
><... I would say the tape may ... have reduced my CHT's by 5 degrees ...>
>I kind of suspected as much with mine.  I'll do a good test when I get my 
>new exhaust
>since I'll have one side taped and the other side not.
>
><... got my CHT's down by being extremely anal about sealing up the 
>cowling and
>running LOP ...>
>I redid the baffling and sealed stuff up really good - MUCH better than I 
>found it -
>and I still have CHTs hovering around 400 (375-400-375-425) - and I'm 
>running LOP too
>(that would work better if I had electronic ignition - maybe for Christmas 
>:o).
>
>My CHT probes are on the bottom of the heads, close to exhaust port, but 
>also on the
>upwind (cooler) side of the head so I don't know what the temps are on the 
>top of the
>heads.
>
>Another factor I've heard of is air leaking out the cowl seams where they 
>join the
>wings and fuselage.  I don't know how to quantify those losses (or even 
>verify that
>they're a problem) much less how to prevent them.
>
>I was told to put a fat lip in my armpit scoops and that would improve 
>flow.  Fellow
>said to split a piece of 1/2" OD fuel line or neoprene tubing and put it 
>over the
>scoop lip, duct tape it on, try it and see what I get.  Sounds like a 
>stretch, but
>I've heard of this type of thing before in similar circumstances.
>
>Don't know where else to look for that 75 deg I need to be comfortable ... 
>Jim S.
>Jim Sower
>Crossville, TN; Chapter 5
>Long-EZ N83RT, Velocity N4095T
>
>Scott wrote:
>
> > I have an updraft IO360, straight back SS exhaust.
> >
> > I tried it with and with out tape.  I would say the tape may, and I am
> > stretching here,  may have reduced my CHT's by 5 degrees.  I took um
> > off.  I want to be able to see my exhaust pipes when I'm poking around
> > under the cowling and I've heard they do shorten a systems life, and at
> > $800 a pop I don;t want to shorten that one to much.
> >
> > I'd say I got my CHT's down by being extremely anal about sealing up the
> > cowling and running LOP.
> >
> > I have a hard time keeping them above 300 degrees now that's its winter.
> >
> > Scott
>
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