REFLECTOR:INTAKE COMBUSTION AIR

Scott reflector@tvbf.org
Sun, 14 Sep 2003 07:19:58 -0600


I am just about finished with my change over from a 4-into-1 exhaust to the standard 4-into-4, side by side system.   Two pipes on each side of the engine exiting straight back. Have been test flying, redid the cowl once, and have been redoing the baffling. 

Before the change I had a heat problem in the summer.  Would have to level off every 2 or 3 thousand feet in a climb and reduce power to cool things off, and couldn't run at full power in cruise .  

Now, I am a HAPPY FLYER!!! 

Yesterday, after getting about 85% of my baffling experience complete I took off, couldn't wait.  It was about 85 degrees,  at 6500ft.  Not a good cooling environment.  Continuous climb to 12,500 at about 1000 ft a minute, it was bumpy with some wave action so it varied between 500 and 1500 ft a minute.  Cyl head temp's at the highest were 345, oil temp just touched 215 when I leveled off.  Right after leveling off oil temp dropped to 210 and started a slow reduction to 203, cyl temp's slowly dropped to 330(that was the highest cyl), the lowest cyl was 300.  The cool down when I leveled off was at a high power setting, just lean of max egt, 2720 RPM.  I was indicating about 155-160 knots, about 180 true.

This is an IO 360 C1C  with a single oil cooler in the nose, both oil lines in the same duct, updraft cooling.  I still have a few more holes to plug in the baffling to gain a bit more cooling air over the cylinders.  I have turning vanes in my oil cooler duct and have Kooler fines on my oil filter.  I think I might wrap some of the exhaust tubing to cool things down just a bit more. This can make a huge difference in an updraft system.

Scott

> From:  Tom Martino
> On most of the Vs Ive seen ...  all of the air to the engine comes
> in from above through the naca vents.  The air is then directed
> over the  cooling fins of the cylinders.   There are also 2 ducts
> that divert some of that air.  One duct goes to oil cooler and the
> other duct provides combustible air for the  engine.
>
>
> I have been wonderings if the  engine would run more efficiently if
> I put a separate air intake scoop (low  profile) on the lower cowl.
>  This  looks as if it would provide a more direct and cooler flow
> of air.  And it wouldnt divert any of the  cooling air away from
> the cylinders.
>
>
> And while on the topic of cooling  ... is it really necessary to
> have two oil coolers?  Is the one up front good  enough?
>
>
> I saw one  Velocity that had  only one (up front) then had tiny
> side vents along the fuselage which directed  air into the ducting
> that carries the oil lines.
>
>
> So is there anyone using just one  oil cooler up front and not the
> one ion the engine compartment?   I would appreciate any insight
> into either of these topics.