Success with Subaru STI

[rv6ejguy]

Randy Crothers in WA has been test flying his 7A recently, equipped with an MT prop, Gen 3 gearbox, custom turbo in place of the supercharger and an aftermarket ECU replacing the OEM ECU.

He's showing 170 knots true at 7500 MSL at 42 squared (4200 rpm and 42 inches MAP). At 10,500 MSL he's showing 175 knots true at the same power setting. Total fuel burn was 13.77 gallons for the 1.4 hour flight for an average of 9.83 GPH including the climb and descent. Turbine inlet temp was 1620F.

Aircraft does not have gear intersection fairings in place at this time.

Not too shabby so far. Some more tweaks to come with aerodynamic and cooling system cleanups should give a few more knots.

Kudos to Randy, a talented guy who does all his own work and tuning and did not give up on the STI dream.

[frankh]

A great performance numbers!

Frank

[rv6ejguy]

I'll see if we can get a link to the takeoff video I've seen. Takeoff and climb is quite impressive and it sounds great.

[osxuser]

Coolant temps acceptable range? How hot was the OAT?

[rv6ejguy]

All temps are pretty cool but I suspect OAT was as well. It's winter in Washington State right now. Cooling mods are coming soon as it is highly doubtful that cooling would be adequate in the summer months with the current setup.

Many of the STI guys are fitting custom radiators now. There is good sharing of info on one of the Sube dedicated forums now so we hope the process of getting all the bugs out will progress somewhat faster than it has for the last couple years.

Randy was the first to take the big step of turbo and new ECU and get it flying. Several others are following suit.

[Danny7]

that's great ross. keep us posted as he gets hours, always good to hear how it is working from someone with the engine running on his plane.

[airguy]

Wow - those are some good performance numbers indeed. I'll be really interested to see the cooling mods and how that all comes out with summer temps.

It's almost enough to make me reconsider a Lyclone IO360 for my bird. Good thing I've got about a year to watch from the sidelines before it's time to write a check....

[Randy]

Hi all,

Mt STI package is working much better after changing to the turbo charger and the SDS system. Part of this involved getting rid of the throttle by wire setup and that in itself made a big difference. The Subaru ECU was making too many adjustments for airplane use. Logged data showed the timing moving all over the place. With the SDS system I have a mixture knob and full control of the programming of the timing etc. and the timing is stable, not jumping around like it was.

The end result is the engine has a bit less power, but more margin to detonation and that is a trade off I can easily live with and over time I will be able to get that power back.

No sense reporting on temperatures in the winter, no problems at all but no test either. I am in the process of ordering larger ratiators and a new oil cooler. Not looking forward to that fiberglass work but I know the changes are needed for summer time temperatures.

It is kind of fun to tell someone you were running at 45 square at 10,000' and watch them absorb what I said...

In my mind it is a bit early to claim success. My goal has been to achieve lycoming performance with this smooth modern engine. That will take more time to prove out but I am very happy with the way it is working for me at the present time.

Randy C

[Randy]

I forgot to mention that I sent that little video clip to Ross as I don't know how to link to it here. We will just have to bug Ross to make it available.
Randy C

[rv6ejguy]

Here is the link to the takeoff video on YouTube: http://www.youtube.com/watch?v=om1GU...e=channel_page

Turn up the sound and enjoy.

Gotta like that climb angle in the last 4-5 seconds.

For sound comparisons here is a takeoff on my EJ22 turbo 6A at 38 inches and 4800 rpm: http://www.youtube.com/watch?v=kjNsb...e=channel_page