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1. 04:52 PM - Re: merlyn conversions (Scott Dickey)
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| Subject: | Re: merlyn conversions |
--> Commander-List message posted by: "Scott Dickey" <jdickey@radictech.com>
Hi Everyone,
Here are some answers to the last two posts about the Merlyn conversion:
Barry - 1525-187 is my plane, N222LE.
STC SA01212SE - Merlyn Shrike 320 conversion and 7200 lb GW increase. In
order to be eligible for this installation, the engines must have been
modified under STC SE01211SE, conversion to TIO-540-AE2A(MC). This basically
adds the turbo, exhaust system, and up exhaust cylinders. Also, the
conversion requires Hartzell HC-C3YR-2UF/FC8468()-6R props (compact hub).
This conversion basically takes the Malibu engines and lots of accessories
such as the alternator, oil cooler, remote oil filter, pressurized mags,
etc. and utilizes them in the Commander. There are lots of small advantages
like the remote oil filter (oil change 20 minutes) and a vernatherm
mounted in the cooler, not in the impossible to access oil filter adapter on
the back of the engine. No engine mount changes are necessary and it also
includes two Weldon nacelle mounted fuel pumps in lieu of the sump mounted
ones. The nice part is the Malibu engines are very well supported so parts
like mags, vacuum pumps, etc are readily available. The turbo system itself
is very simple and it's designed for low maintenance. The wastegate is
manually actuated but it is slaved off the throttle linkage. The first 75%
of throttle travel doesn't move the wastegate but after that the wastegate
starts closing. There is no wastegate controller to break and there is a
massive pressure relief valve in the induction line so overboosting is
basically impossible. The turbo is mounted up high so there is no need for
an oil check valve or scavenger pump. The oil drains freely back into the
case. It also comes with a really cool electronic tach made by Hickok
(analog face, but electronic everything else). It runs off a Hall effect
sensor on the mag so there is no tach generator to worry about and so far it
is super accurate.
The turbo operated best below about 21,000 feet although it will make 42" @
2500 RPM up to around 21,000 or 22,000. At that altitude and at full power,
however, the wastegate is fully closed and I'm told the servo inlet temps
start to rise. Pull the power back to 35"/2400 (climb setting) and the servo
inlet temps come back down. I cruise at 28" and 2200 which is about 65% and
it will maintain that well past 21,000 which is the highest I've flown it so
far. 65% at 21,000 yields about 195 KTAS in my plane. Down at 12,000 -
14,000 the same power yields about 180 KTAS. Fuel burn at 65% is about 17
GPH/side at 100 degrees ROP. I'm going to start experimenting with LOP but I
was waiting for the engines to fully break in. Cooling is good, with all my
CHTs under 410F @ 65% @ 21,000. CHTs are lower at lower altitudes.
Note: The 320 conversion is technically rated to 300 HP continuous (38") and
320 HP (42") intermittent. I think the reason for this had something to do
with not having to do as much flight testing for a 300 HP continuous rating.
This is probably why the FAA didn't require a time limit on the 320 HP, just
saying "intermittent" was enough.
V speeds are a little different due to the heavier GW and higher power.
Vso 62 KCAS
Vs 67 KCAS
Vmc 69 KCAS
Vyse 104 KCAS
Vy 110 KCAS
As I mentioned before, there is also a STC to turbonormalize the
IO-540-E1A/B5 (290 HP). I believe the same STC allows turbonormalizing of
the IO-540-M1C5 to 300 HP if you have that engine. The latter also requires
the compact hub props so if you have neither the M1C5 engine nor the compact
hub props, it is an expensive way to add 10 HP/side which is why no one has
done it so far.
Hope this helps.
Scott
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