Turbo question

If the TIT is too high, there is not enough fuel flow.

High TIT at high power when the engine is working
hard is very destructive. Should be 1350 or so.
To get that, you will have to set the pressures at the
absolute top end of what Continental recommends.

The electronic fuel flow restricts the flow a bit, requiring
even higher pressure, which is not widely recoginzed as
a problem.

Bill Hale BPPP instructor

If the TIT is too high, there is not enough fuel flow.
High TIT at high power when the engine is working
hard is very destructive. Should be 1350 or so.

Are you talking about a specific installation in a specific airplane ?
The red line for my TIT is 1750ºF. 1350ºF is way cold on my airplane. I
don't think I could possibly put that much fuel through it.
---
Ken Reed
M20M, N9124X

On Wed, 07 Jun 2006 00:24:02 GMT, Ken Reed wrote:

Just curious. Is the M20M the one equipped with the
turbo-supercharged Lycoming that was retrofitted with external oil
lines to cool the exhaust valve guides a la the TIGO-541?

If this is indeed the case, 1350 is only slightly cool on your
airplane, 1750 is way too darn hot.

TC

If the TIT is too high, there is not enough fuel flow.
High TIT at high power when the engine is working
hard is very destructive. Should be 1350 or so.

Are you talking about a specific installation in a specific airplane ?
The red line for my TIT is 1750ºF. 1350ºF is way cold on my airplane. I
don't think I could possibly put that much fuel through it.
---
Ken Reed
M20M, N9124X

wrote:
Are you talking about a specific installation in a specific airplane ?
The red line for my TIT is 1750ºF. 1350ºF is way cold on my airplane.. I
don't think I could possibly put that much fuel through it.

I believe recommended on the turbo Arrow is 1650F. [I could be off on
that, but that's memory.] Some systems do allow 1750 - but they have a
different metal for the exhaust.

For the problem itself - first off, as was said, make sure the fuel
system is set up correctly. You should be over 20 gph on takeoff
power. For cruise, do you have the cowling cooling mod? [I'm guessing
yours is an Arrow III.] That's the set of side vents (one on each
side) that were added. Most older turbo Arrows have had them added by
now, but not all.

The Merlyn Automatic Wastegate is a popular mod for that aircraft.
It's not a true automatic controller, but it is a durn site better than
the screw-in bolt that Piper installed. Having said that, the main
heat advantage it gives is down low. Up high it allows more power
(much more), but doesn't help with heat (with one exception below).
Some folks have installed an intercooler, but it really shouldn't be
necessary.

Now for that exception: If you *really* want the temps to come down,
reduce engine RPM. I cruise about 2300 or so, no more than that
certainly, at any altitude. However, without the Merlyn, you may have
trouble getting adequate power up into the flight levels.

Another option - run LOP. Then you can pretty much put the temps
wherever you want them. Again, though, with the fixed wastegate at
high altitude, you may not be able to produce the power you want.

And lastly, the most absolutely obvious (that is frequently
overlooked). Have your engine baffle system looked at by someone who
knows what he is doing. Very small leaks can make a huge difference.

For the problem itself - first off, as was said, make sure the fuel
system is set up correctly. You should be over 20 gph on takeoff
power.

I'm burning 27 GPH in take-off and climb.

For cruise, do you have the cowling cooling mod? [I'm guessing
yours is an Arrow III.]

No, I fly a Mooney Bravo. Sounds like you may have been discussing a
different (and specific) airplane and engine combination ?

Another option - run LOP.

Unfortunately, that isn't an option in the Mooney Bravo. I know about a
dozen owners and no one can run LOP. I ran LOP regularly in my previous
airplane, but this airplane/engine combination simply won't run LOP
smoothly and with reasonable temperatures.
---
Ken Reed
M20M, N9124X

Ken Reed wrote:
For cruise, do you have the cowling cooling mod? [I'm guessing
yours is an Arrow III.]

No, I fly a Mooney Bravo. Sounds like you may have been discussing a
different (and specific) airplane and engine combination ?

Sorry for the confusion. The original post said "I have a piper turbo
arrow with a TSIO-360-FB engine." and that's what I was going on.

The red line for my TIT is 1750ºF. 1350ºF is way cold on my
airplane. I don't think I could possibly put that much fuel
through it.

Just curious. Is the M20M the one equipped with the
turbo-supercharged Lycoming that was retrofitted with external oil
lines to cool the exhaust valve guides a la the TIGO-541?

Yes.

If this is indeed the case, 1350 is only slightly cool on your
airplane, 1750 is way too darn hot.

I don't run it anywhere near 1750º, but that is the red line for that
installation. I cruise at 1600º TIT and climb around 1450º. I don't
think I can get it down to 1350º.

At 1600º, at typical altitudes, RPM and MP, I get just under 210 KTAS.
---
Ken Reed
M20M, N9124X