REFLECTOR: IO-540 Engine Plenum & lower baffles

Ron Brown romott at adelphia.net
Tue Aug 30 07:38:06 CDT 2005


Keith,

I have seen all four methods used.  I used stainless because I saw how the 
fins rubbed holes in our 172's baffles with 3000 hours.  Mark Machado laid 
up fiberglass on tape laid up on the cylinders.  I believe this is one of 
the factory trainers now.  Regarding the gap at the bottom of the cylinders, 
I copied the layout on a 180 hp - parallel valve in a Beech Sundowner - this 
gap was only 1.5" wide.

I agree with Bob Wood, the air must be forced to go through the fins.  My 
angle valve IO360 runs nice and cool - even while on the ground.

Oh and keep the gap between the back of the cowl and front of the prop tight 
too.  Mine is 1" except for relief at the top and bottom to allow the cowls 
to come off.  I cut away just enough to allow the cowl to slide up/down the 
prop blade using a rag to protect the finish on the prop.

By the way, I do have the top NACA inlets.

Ronnie

----- Original Message ----- 
From: "Keith Hallsten" <KeithHallsten at quiknet.com>
To: "'Velocity Aircraft Owners and Builders list'" <reflector at tvbf.org>
Sent: Tuesday, August 30, 2005 1:32 AM
Subject: RE: REFLECTOR: IO-540 Engine Plenum & lower baffles


> This is timely as I am working on the plenum for my IO-540 (260 hp) right
> now.  It appears that the factory plenum leaves a HUGE hole on the front
> side of cylinder #6.  I assume that this needs to be covered with a 
> separate
> piece, laid up on tape on the cylinder and attached to the rest of the
> plenum with screws.  Is this right, or am I missing something?
>
> Also, I see Ron used stainless steel for his lower baffles.  I've seen
> others use aluminum.  A friend building a Cozy told me his "factory"
> instructions call for laying up 2-bid in red RTV, then attaching that 
> (after
> cure) to the plenum with screws.  Dave Dent advised me to lay up the 
> RTV/bid
> directly onto the cylinders wet, and let it cure/bond right on to the 
> edges
> of the cooling fins.  Anyone else want to make a suggestion on lower 
> baffle
> installation?
>
> Keith Hallsten
>
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Ron Brown
> Sent: Monday, August 29, 2005 7:05 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Engine Plenum
>
> Correct.  The 2 bid gap filler lays on the case rather than butting up
> against it.
>
> The cylinder wraps (on the bottom of the cylinders) holds the plenum down.
>
> See http://home.sprintmail.com/~romott/page55.html
>
>
>
> ----- Original Message ----- 
> From: "Scott Derrick" <scott at tnstaafl.net>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Monday, August 29, 2005 6:48 PM
> Subject: Re: REFLECTOR: Engine Plenum
>
>
>> Ron,
>>
>> So you put a kind of "foot" on the plenum so the sharp edge wasn't riding
>> on the case?
>>
>> How did you hold the plenum down?
>>
>> thanks,
>>
>> Scott
>>
>> Ron Brown wrote:
>>
>>> Scott,
>>>
>>> I did use the factory plenums but I taped up the engine with duct tape
>>> where the plenums meet the engine case.  Then I laid up two bid from the
>>> plenum onto the tape to make a tight fitting seal - but did not use any
>>> silicone. I think the silicone gets used when folks are having cooling
>>> problems and have to get an airtight seal.
>>>
>>> My IO360 runs very cool with the set up I have.
>>>
>>> Ronnie
>>>
>>>
>>>
>>> ----- Original Message ----- From: "Scott Derrick" <scott at tnstaafl.net>
>>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>>> Sent: Monday, August 29, 2005 5:09 PM
>>> Subject: Re: REFLECTOR: Engine Plenum
>>>
>>>
>>>> Its hard to believe that nobody here has built their plenum with an
>>>> improvement over the method shown in the manual?
>>>>
>>>>
>>>> Scott Derrick wrote:
>>>>
>>>>> I was fitting the plenum on my TSIO520 today,  cutting and filing to
>>>>> get it as low as possible to allow room for a partially modified upper
>>>>> standard cowling.   After I shortened the upper deck manifold and
>>>>> rerouted some of the injection lines I got it as low as practicable.
>>>>>
>>>>> Now I would like to make the edges that contact the engine more
>>>>> "rubbing" friendly with some kind of silicone edging, it would be nice
>>>>> to have something that slipped over the edge like door seal stuff.
>>>>> What are people using?  I know I can cut Silicone baffle strips and
>>>>> glue and rivet but I thought there might be something a bit more cool
>>>>> looking.
>>>>>
>>>>> I looked on the Velocity site and the gallery and the only thing I saw
>>>>> was siliconing(as in gluing) the edges to the engine(YUCK).
>>>>>
>>>>> Also how are people attaching the firewall, runner to plenum assembly.
>>>>> The manual has a direct connection which has no slip joint to
>>>>> accommodate the engine moving around.
>>>>> Also regarding the runners to the firewall, the manual has us using 
>>>>> the
>
>>>>> cowl screws to hold the runner to the firewall. I'm still toying with
>>>>> the idea of a groove for the cowl to slip into and doing away with all
>>>>> those screws.   Any other suggestions?
>>>>>
>>>>> I searched my email archives and came up with nada on "plenum" in the
>>>>> subject line.
>>>>>
>>>>> Pictures are of course are greatly appreciated.
>>>>>
>>>>> Scott
>>>>> _______________________________________________
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>>>>>
>>>>>
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>>>
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>
> _______________________________________________
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>
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>
>
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