Turbo chargers

[prkaye]

I don't know anything about turbo-chargers... are they something that can be "added-on" to an existing engine? For example, if I put an O-320 on my plane, and then later on decide I want to fly higher, can I simple slap a turbo-charger in there, or would this constitute a serious modification requiring taking the engine off, etc ?

[frankh]

Serious as in if you get it wrong you will blow your engine up!...Or destroy it through detonation.

I would only do this if there was a proven bolt on kit out there that already has all the engineering done.

Expect your engine to have a shorter life in any case.

I'd go the simpler route and bolt on an (I) O360.

Frank

[rv6ejguy]

You probably wouldn't have to remove the engine but you will need to keep some things in mind:

The turbo will have to be low mounted so you will need a scavenge pump to return the oil to the sump.

It needs to be intercooled so you need a place to mount that plus inlet and exit ducting for it.

The turbo needs to mounted solidly, you can't hang it off .035 or .049 exhaust tubing. You need slip joints on the header tubes. You will need space for a 2.5 inch exhaust pipe to exit the cowling.

You should have a wastegate. If separate type, this needs its own exhaust pipe also.

This will add a minimum of 30 pounds to the firewall forward weight. If you have a Hartzell C/S prop, C of G will be a concern probably.

If you are carbed and blow through, you need a boost referenced fuel pressure regulator to maintain FP differential above boost pressure and the pump to feed it plus a way to vent to bowl to boost. If you are injected, mods to your control unit may be required.

If your CR is below 8 to 1, you can probably safely normalize on 100LL. If you plan to boost more than a couple psi, you need to watch spark timing.

Cooling requirements will be higher due to the higher thermal load. Watch CHTs and oil temps.

You must watch the TAS at high altitudes and flutter margins.

These are all reasons why you don't see too many turbos on RVs.

[Walter Atkinson]

Add this one:

If you are injected, you will have to change injector types to include an upper deck reference line.


This is no small feat of engineering. It took GAMI/TAT almost two years to properly engineer the turbo for the Cirrus. It was FAA Certified yesterday! And, remember, they know what they are doing. They already have turbo STCs on other airplanes.

Walter

[mcphersn]

Talk to Jeff Neilsen, if you can catch him. His supercharged RV-6 is unbelievable.

Miller McPherson
RV-6 770+ hours

[Guy Prevost]

There's a fella in Texas with a Turboed RV8. He calls it Grezdlitnin. There's a sport pilot article on it somewhere. He's also been to LOE a few times.

Guy

[gmcjetpilot]

Originally Posted by prkaye

I don't know anything about turbo-chargers... are they something that can be "added-on" to an existing engine? For example, if I put an O-320 on my plane, and then later on decide I want to fly higher, can I simple slap a turbo-charger in there, or would this constitute a serious modification requiring taking the engine off, etc ?

By the way your phrased "slap on a turbo-charger" and the fact your building a RV-9A, my guess is you have not flown a turbo charged plane or may be even a RV yet? I don't know.

Besides $$cost$$, weight and complexity, to take advantage of turbo charging you need to fly at high altitudes, which require you suck O2, all the time. Do you have experience sucking O2 for hours? It's not fun, dries the nose out and you need to fill tanks, etc. etc. Than there is Vne. You can fly higher and faster but you will run into Vne, which you can consider is based on TRUE AIRSPEED, not indicated. Van publishes a single Vne indicated. However the "real" Vne drops about 2 mph indicated for every 1000 ft altitude.

Hot engine? As you climb the air is thinner. Thinner air means less cooling. Compressing induction air (turbo) and maintaining higher HP at altitude means a HOT running engine. This is why they have inter-coolers. When you compress air you heat it. You are stuffing this pre-heated air into an engine that is getting less cooling air. An inter-cooler BTW adds even more complexity, weight and cost. Bad news is cowls on RV's are small and tight, for speed, right. There's not a lot of room for the turbo, much less an inter-cooler. RV engines are also not cantilevered off the firewall far, meaning its crowded behind the engine as well, where some aircraft stuff their turbo.

Have I convinced you? Look if you want extra altitude performance, start with more sea level HP and keep your plane light. I don't know much about the new IO340 (170HP) engine, but it may be a good match. It keeps the weight down, gains a little HP boost, both a win win. It would allow higher service ceiling without running dangerously up against the Vne, but you still may have to watch it.

PAIN IN THE BACK SIDE
With a normally aspirated (not turbo-ed) engine the HP drops to protect you from exceeding Vne. There are some good threads on this and Van has published his admonishment against Turbos in RV's. Can it be done? Yes. Is the RV-9A a good match? No, of all the RV's it is the least suitable in my opinion, for one weight. I have flown several Turbo planes as a commercial pilot, flight instructor and they are pain's in the back side. They seem to be in the shop a lot. Fortunitly I did not have to pay for maintenance since I was being paid to fly them. The clubs C210T (turbo) was in the shop every 50 hours for major work on the exhaust or inter-cooler.

HOW HIGH DO YOU NEED TO FLY?
The RV is plenty fast and efficient with out a turbo. That is the beauty of it. Trust me flying real high where you can't see much loses its thrill after a while; RV's are plenty happy at sufficiently high altitudes. A 160 HP RV-9A already has a service ceiling of 19,000 (gross wt) and 24,500 ft (solo). Now service ceiling is NOT a practical altitude to fly at, you are just hanging on the prop, but 5 or 6 thousand feet lower is doable on a standard day. So you can easily cruise at 13,000-14,000 feet any time at gross weight and up to 18,000 feet solo! You know you have to be on a IFR flight plan above FL180. Above 12,500 to 14,500 ft for more than 30 min you need O2. Above 14,500 you need O2 100% of the time. So the RV-9A is no slouch in altitude performance. SO if you want to suck O2 than you can still climb to nose bleed altitude without a turbo. The 170HP IO340 would add slightly to the altitude performance. The RV-9 has a good wing for altitude, but its weight. Don't make your RV heavy. You will regret it. The lighter the more "RV like" your plane will fly. Weight affects takeoff distance, climb rate, max altitude and landing distance. Also the handling is heavier and not as nice. A turbo does nothing super practical for you in a RV, but can and has been done a few times. Your choice. Good luck.

[cobra]

How much HP do you really need in an RV-9a? Adding more HP doesn't add a lot of speed, at least not as much as a bit of streamlining might, but it can increase climb rates and use a lot more gasoline in the processes.

If you want much more than the recommended 160 HP and want to keep weight close to Vans recommendations, you certainly do not need a super/turbo charger to achieve it. Turbos do give a bunch of power, but they also add a lot of potentially damaging heat that is more difficult to dissipate high up in thin air, especially with air cooling.

My recommendation if you are serious about needing or wanting more power, consider a Rotary (Renesis) engine; around 200 naturally aspirated HP at the O-320's weight (around 350 lbs fwf), and gain all the other inherent rotary advantages along the way (durability, reliability, low costs, smoothness, etc). Rotaries have the best power:weight Ive seen so far in a small package.

[Jconard]

No turbo...too muc weight and complexity.

I know!!! lets add a car engine....thank goodness we kept it simple.

And, mike, all engines in an airplane rely on air for cooling...either through a radiator, or otherwise.

[airguy]

Having looked at this issue for the last couple of years and run the numbers on it, I can't see putting a turbo on a 100LL engine for an RV. I would, however, install a turbo'ed diesel in a second, with water cooling. That eliminates the heat problem, and higher HP at altitude will go a long way to overcoming the added drag of the radiator. You still have to watch Vne at high-power cruise, but more an issue of situational awareness than anything else.

Deltahawk and Thielert are high on my list, and if I can get one by the time I'm ready to hang an engine, you can bet your house and kids I'll have one.