Perhaps the most desirable mod for a 231 that makes it more like a 252 is an intercooler. One system— the Turboplus—has been highly recommended by M20K owners and it comes from Turboplus Aircraft Systems in Gig Harbor, Washington. Turboplus says it was the first company to bring intercooling for GA singles and twins in the early 1980s and there are thousands of Turboplus intercoolers and induction systems in use today.
The company says its M20K intercooler kit can yield a max speed of 241 MPH at 24,000 feet, and 170 knots true airspeed at 10,000 feet and 65 percent power, with the added benefit of lower cylinder head temperatures. The STC’d kit for the Mooney M20K is $5995 and the estimated installation labor is around 18 hours.
“My conclusion is that the Turboplus intercooler provides much improved intake manifold cooling and an increase of 3 inches in available manifold pressure at altitudes above the 13,500-foot critical altitude, while providing significant performance benefits across the board to the hot-running, non-intercooled engine in the 231 M20K,” reader Geoff Lee said of the system. He’s documented the installation in a well-written tech guide that’s available at themooneyflyer.com/issues/2019-MayTMF.pdf . That’s a link to The Mooney Flyer www.themooneyflyer.com , the official magazine of the Mooney community.
In my past experience flying turbocharged Mooney's, I would see temps pushing 400
degrees, climbing at 110kts. I now notice differences of more than 50 degrees cooler. On a
standard day, temps can be as low as 290 degrees in the climb.
Great product with friendly service.
I'm a firm believer in Turboplus Intercoolers!
- Jon Martin, February, 2018
ATP, CFII and A&P
Turboplus Intercooler NACA Duct
The biggest change I've noticed is the CHT drop. It has dramatically expanded
my performance climb options, especially on hot days.
- John Cuyle, January 2018
The things are just too simple, durable, and effective to need a lot of parts. In eight years of ownership I have had mine cleaned once and that's it, and its 15 years old. In the meantime, it just works, and keeps my engine cool.
Thank you for your most
excellent contribution to GA.
- J. Lunseth, October, 2017
The Turboplus is not that hard to install. My AP and I did it in a little more than a
day. The heater box mod is very simple. Everything else is very straightforward. I would think the NACA duct in the
Turboplus installation will deliver more cooling air than the blast tube design. At cruise
altitudes I frequently see over a 100 degree drop between CDT and IAT.
- Mooneyspace, October, 2017
I am the proud owner of a M20K/231 with a Turboplus intercooler. The plane performs so
well with the intercooler, on average it cools the air about 75 degrees going into the
engine. I can see a difference in CHT's and it runs so smooth. Thanks for making such a
- Mike Haley, December, 2017
Picked up my Turboplus Intercooler at KTIW today on the way down to Reno. The quality shows
in the craftsmanship. I can't wait to have it installed.
Thanks for coming out for a personal delivery, Jeff.
- mooneyspeed , September, 2017
Mooney M20K Charge Air Temperature Chart
I’m extremely happy with my TurboPlus Intercooler. I frequently see 95+ degree drop across the intercooler at cruise in the high teens. Manifold pressure has dropped about 2” to achieve the same performance.
- CaptRJM, January, 2018
I have one in my 231 and used it to fly around the world. The Intercooler
definitely reduced operating temps. I installed it about 15 months ago and since have
put about 500 hours on it. Not a glitch. I am amazed at the reduction in IAT, typically
50C-60C at altitude. My IAT rarely goes above 120F. It is a great companion to
the Merlyn waste-gate controller. Critical altitude for me is now about 21,000'.
I whole-heartedly recommend your intercooler.
- Brian Lloyd, June 2018
I highly recommend every 231 owner to Turboplus their engine.
- John D. Beer, October, 2017
We now enjoy performance that almost matches the “252” and for
about $90,000 less. This modification has proved invaluable.
- Mark Whitcomb, October, 2017
Last Year I bought a Turboplus intercooler kit from Jeff Shapiro for my Mooney M20K 231. First, the delivery was very fast and second he gave me a special price for me as member of MAPA. When I unpacked the kit, I was very happy about the really great quality of all the parts. Welding, tolerances and so on. I installed the kit in two days and it was a great pleasure to do. The fiberglass work at the cowling is also very easy, but needs a little bit of trim.
When I had finished all that work and the final adjustment of the TCM injection system, I went flying to see what it will improve. First was, that the intake air immediately cooled down about 30 deg. Celsius in the takeoff run. I operate my Mooney from a 750 meter asphalt strip. After takeoff, in the climb it was cooling by 45 deg. Celsius and raised to 55 deg. in higher altitudes. I think the NACA duct is at the optimum position. Much better and more efficient than by the 252 model, because it gets directly cool air from the outside and not via the cylinders inside the cowling on the right side in the engine compartment.
In cruise I have now much cooler cylinder head temperatures , mostly about 320 deg. Fahrenheit with 75-85 percent of power. I was flying now for approx. 9 month with the intercooler and in every phase of flight it is a really great improvement in performance and in cylinder temperatures!!
So finally I think that is one of the best mods for a 231 model.
D-EMLL Mooney M20K, June 2019
The Turboplus Custom Designed NACA Duct for your airplane provides the most efficient airflow systems to your Intercooler assembly and to the turbocharger. The direct airflow system into the intercooler are proven to be the most effective and efficient way to supply ambient air right at the intercooler installation. NACA ducts are used worldwide in passenger jets, NASCAR, high performance automobiles and in the aerospace industry.
The Turboplus Mooney M20K, 231 intercooler system provides ram air through their custom designed NACA duct that directs ambient air through the custom designed intercooler assembly. The NACA duct creates no drag.
YOUR Mooney 231 can now achieve speeds up to 241 MPH.
Turboplus Aircraft Systems, Inc. is the only general aviation aftermarket intercooler kit manufacturer to offer a Five-Year warranty on their intercooler system.
Turboplus Aircraft Systems, Inc. will ship your order to your home, business or any FBO shop of your choosing. Don't fly to us when we can ship to you.
The Turboplus intercooler gauge allows you to continuously monitor your
NEVER INTERCOOLER FLY WITHOUT ONE
Estimated installation: 18 hours
Paint match: 3+ hours (if required)
STC: SA2154NM Intercooler System Installation - Mooney M20K
It is highly recommended:
To record the critical engine altitude, oil and cylinder head temperatures and fuel flows at given power settings before the intercooler installation. After installation, another “flight test” ensures that engine and aircraft performance adhere to Turboplus Aircraft Systems, Inc. high standards. Post modification flight test data provides a direct "Before and After" comparison of the dramatic improvement in aircraft performance and engine operation. For your convenience, we supply the pre-flight and post-flight performance documents.
Turboplus Aircraft Systems Inc.
4117 35th Ave NW Gig Harbor WA 98335
Now FAA-PMA APPROVED!
Copyright 2017 Turboplus Aircraft Systems Inc.