Lycoming IO 390 engine and Power Flow

[eshepardson]

With the recent STC for the Lycoming IO-390 for the Cardinal, any possibilities of your PF unit working with this powerplant? Am looking at the 390 for a replacement of a near TBO engine soon, and also want to install the PF at the same time, if not sooner.

Regards,

Eric Shepardson

[dtilman]

Originally Posted by eshepardson

With the recent STC for the Lycoming IO-390 for the Cardinal, any possibilities of your PF unit working with this powerplant? Am looking at the 390 for a replacement of a near TBO engine soon, and also want to install the PF at the same time, if not sooner.

The Power Flow Exhaust for the C177RG should fit and offer similar boosts in performance on the IO390 as it does for the IO360. We personally haven't done such an installation just yet, but we understand at least one of our deposit holders has the IO-390 engine on order.

From a Certification (a/k/a "Legal") stand point, it would be up to the installing IA (A & P with Inspection Authorization) to determine if the STC for the Lycoming engine and the STC for the Power Flow exhaust are ok together.

This is because most STCs modify the original configuration of the aircraft - as it was type certified. In the 30-40 years since that occurred, owners may have applied many different modifications to their aircraft. As it is impossible to check for every variable, most modifying companies (such as Power Flow and Lycoming) will do all of their required certification testing and evaluation using the basic type certified configuration. This covers the most bases and and keeps the costs as low as possible.

If the owner comes along later and adds a very simple modification, such as an exhaust fairing, the person signing off the aircraft installation can make a judgement call based upon their experience and knowledge as to if any conflict exists. Most people agree that as long as the exhaust isn't contacting the fairing, no problem exists and it will be signed off.

The same is technically true for the IO-390 engine, although it is arguably a little more involved than just adding an exhaust fairing.

Bottom line: If your IA is comfortable and will sign off the installation of the engine and PFS exhaust, it should be ok and approved because they are taking the responsibility for it.

Thank you for your question.

[RG_driver]

FWIW, my IA and I discussed the potential issues at length. He did sign off on a Power Flow exhaust on an IO-390. There have been no issues with the combination.

[dtilman]

Originally Posted by RG_driver

FWIW, my IA and I discussed the potential issues at length. He did sign off on a Power Flow exhaust on an IO-390. There have been no issues with the combination.

Excellent! Did you fly with the exhaust before you changed the engine? If so - Can you comment on what kind of performance gains you saw with the engine change and then the Power Flow or was it all at once?

Darren Tilman
General Manager

[RG_driver]

Unfortunately, no. I had already purchased the Power Flow and asked my IA to install it at the annual. He found a cracked head at annual, and on further teardown there were other signs of impending failure. The STC for the IO-390 in the Cardinal RG had just come out. Lycoming made me a great offer on a zero-time rebuild of the IO-390. I think my bird was the first in the fleet to get the STC'd IO-390, certainly the first with the IO-390 + Power Flow.

To top it off he discovered the source of a long-standing rigging problem and re-rigged the airplane, so there were 3 significant changes at the same annual. Not my plan, but that's life.

So I can't give meaningful before and after numbers. I can say that the airplane climbs much faster. I've been flying this airplane for 18 years and the performance is markedly improved. It's fairly routine to maintain >1000 FPM at cruise climb airspeeds with full tanks and me flying alone.

Cruise is also better, I used to plan on cruise of 137 knots at 2400 RPM and full throttle. The tuned induction system on the IO-390 seems to work well, I see manifold pressures at altitude that I never saw with the IO-360. I've been keeping the power high during break-in but I have to back it off in bumpy conditions to stay below the top of the green arc at 142 knots.

Once I have some more time on the engine I'll take it higher and try to get some decent cruise and fuel burn numbers; for now I'm staying low and above 72% power whenever I can.

I'm very pleased with the combination and would recommend it for any RG. My IA called the Power Flow the single best performance enhancement I could make; he was right. The IO-390 is a great improvement over the IO-360, more than the 10 HP difference suggests.