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delusional

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I've heard rumors that it's not uncommon to significantly overclock an O-200 to get a bit more power. Not just racers, but even certificated aircraft.

Is that right? And if so, how much more power can be had without greatly increasing other risks like shortened tbo?

What would the other implications of doing so be?
 
0 200

In the midget racer era when many of the racers were flown cross country, a typical cruise r/m was 2900. The two Cassutts that I flew I ran around 2800 for cross country and full power as needed for acro. Typically 3000 to 3500 for acro depending on the prop. These engines seem to hold up better at high rpm/low manifold pressure than at low rpm/high mp in a Cessna 150
 
jrs14855 said:
In the midget racer era when many of the racers were flown cross country, a typical cruise r/m was 2900. The two Cassutts that I flew I ran around 2800 for cross country and full power as needed for acro. Typically 3000 to 3500 for acro depending on the prop. These engines seem to hold up better at high rpm/low manifold pressure than at low rpm/high mp in a Cessna 150
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Rated power of 100 is at 2750, so is it safe to assume that at 2900 the power would be around 110hp? Is there any way to reliably get up to around 115-120 without sacrificing tbo below , say, 1000 hours?
 
0 200

The big jump in performance for the racers in recent years comes from a tuned exhaust, usually a four into one. High compression pistons are available but the custom pistons run around $325 a PIECE. C85 pistons can be used for a modest increase in compression ratio but will probably require custom relief for valve clearance. Flowing the cylinders, without removing huge amounts of metal, at around $1k.Gapless piston rings should also help. Some have had success with modified cams, but if the cam doesn't work, tearing down the engine to replace the cam is expensive. Typically a high compression c90/0 200 will run 1000-1200 hours depending on how hard you run it. People have been doing the hot rod mods on the c90 dating back at least to the early sixties, probably longer. The guy in Denver area that sells the Cassutt Plans/kits has a wealth of information on these engines.
 
just trying to explore all avenues here

Most 9 builders go with O-320, which has many advantages, but is overkill for flatland flying without oxygen. And I might very well go that way despite that fact.

The thought that prompted this post was simply that if Van got very respectable performance with a o-235 and a FP prop, that sounds good to me. But the 235 is not still in production as I understand. Maybe with a CS prop, or possibly even FP and some other mods to get up to the same performance as Vans prototype the O-200, which offers much better support from TCM etc. Other advantages lighter, and probably lower burn.

Am I way off base here?
 
delusional said:
Am I way off base here?
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Yes, I think you are! From the O-235 perspective new engines are certainly available from Lyc, although nothing new from Lyc is ever low priced. Installing an O-200 in an RV-9 is going to be a lot of work - you will need a new engine mount and all the firewall forward fittings. One of the most time consuming will be an air box. You may also have an aft cg problem that may negate the weight saving from a light engine with the need to add ballast. Getting the right prop could also take a few iterations.

Racers often turn over 4000 rpm at Reno, but I have no idea what they have to do to get that rpm, or the life of the engine. Certified airplanes would never be approved to run at over the certified max rpm (2750).

Look at all the implications of the change you propose to figure if it is worth your while.

Hope this helps, Pete
 
Richard,

Are you talking about the O-200 for your -9? As mentioned above, I wouldn't do that. If you want a small engine, go with the O-235. Parts are easy to come by and the O-200 & O-235 weigh almost the same.

Van's does make a longer engine mount and cowl for the small engines, so that isn't an issue.

You can install high compression pistons in the O-235, which bumps the HP to around 125 and this is a Lycoming approved change.

However, when you look at the numbers, the cost of an O-235 is about the same as an O-320. I would only put the O-235 in it if someone gave me a good one for a VERY good price. I went this route and installed an O-290-D2 (135 HP) in my -9 and liked the combination. After destroying that engine in a prop strike, I'm replacing it with an O-360 (180 HP), so this should be very interesting.

Having said all that, go with the O-320. It is best to stay "common" when talking about engines.
 
fuel burn?

Thanks to all who have responded.

I understand the initial price of the o-235 is not significantly different from an 0-320, and i like the broad availability of support for 320. But if it would reduce hourly operating cost, even by only a few bucks per hour, one or two gallons/hr (at what price?) , and inrease payload that sounds worthwile, again for flatland performance off longer, paved runways and don't care about the 10-15 knots penalty.

What would be other disadvantages to the 235? Can I get a brand new one with f.i.? Where? How about Vans support fwf? I think someone mentioned the mount is different, longer, which to my mind sounds a bit easier since you have more room between the engine and the firewall, no?

Serendipitously, perhaps, the 235 is the only engine I have much firsthand experience working on. I removed for overhaul and reinstalled one on a pa12 many years ago, under the tutelage of an A&P, and yes I realize that was a piece of cake compared to what's ahead of me...
 
Richard,

You are correct, the extra two inches behind the longer mount makes access back there easier.

The price is almost the same for new O-235, O-320, & O-360 engines but the used prices are different.

This is reflected in the sale price of RV's with smaller engines. Max return on investment is made with the O-320, not an O-235 or O-290.

As for Van's support, they do support the smaller engines, sort of. They make a longer mount and cowl, as I said above, but the rest is a mix. Go through the engine section of my web site, listed below, for details of what it takes to install an engine that is slightly different.

After trying to save some cash by putting a smaller engine, if someone gives you an O-235, sell it and but an O-320 (or O-360).

After trashing my O-290-D2 I have elected to replace it with a slightly larger engine.
 
The o-200 is an awesome little motor, there is no doubt of that.

I don't think you'll see what you want out of it though. We estimate that our Reno motor put out about 135hp at 4200rpm, with forged pistons, flow work, some proprietary port work, and complete carb polish job, and a very tuned stock intake system. Cam. We had about $35k into that motor over two race seasons.

That said, at those levels we get about 15-25 hours out of one.

I'd say look at the IO-240? Weight would be better suited, HP would be spot on, Injected (LOP?) and you can do race/performance work to it as well.

Talk to Chris at Pacific Continental Engines if you are serious about putting together a hopped up 4 cylinder continental. Their shop knows as much or more about these engines as any other shop... I can promise you that.

http://www.pceonline.com/
 
N941WR said:
Richard,

Are you talking about the O-200 for your -9? As mentioned above, I wouldn't do that. If you want a small engine, go with the O-235. Parts are easy to come by and the O-200 & O-235 weigh almost the same.

Van's does make a longer engine mount and cowl for the small engines, so that isn't an issue.

You can install high compression pistons in the O-235, which bumps the HP to around 125 and this is a Lycoming approved change.
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It was approved, but in this configuration rarely makes it to TBO. The 118hp version was the most powerful that still remained relatively "bullet-proof."

However, when you look at the numbers, the cost of an O-235 is about the same as an O-320. I would only put the O-235 in it if someone gave me a good one for a VERY good price. I went this route and installed an O-290-D2 (135 HP) in my -9 and liked the combination. After destroying that engine in a prop strike, I'm replacing it with an O-360 (180 HP), so this should be very interesting.

Having said all that, go with the O-320. It is best to stay "common" when talking about engines.
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I'll second this position - if the airframe is rated for a 320, use a 320. You can ALWAYS throttle back, and if you're happy buzzing around at 55% you'll save gas. You CAN'T add extra power for a go-around that was never there to begin with...
 
I don't need to decide yet, luckily

I just wish we had some more options. Not that the 320 variants are horrible but something a bit more fuel-efficient yet with real good support would be very nice. Like if the o-290 were well supported, or even a 140 hpish, lightweight, geared Rotax variant (imaginary so far, I know).

I'm years from finishing and I worry that the availability and price of fuel between now and then will make even 7gph seem a serious burden. Some realistic diesel options, maybe? Practical single-lever power would also be attractive, maybe some day...

Sorry for all the hand-wringing. Maybe some more options will appear by the time I have to choose...

Thanks again for the guidance.
 
More fuel efficient?

delusional said:
I just wish we had some more options. Not that the 320 variants are horrible but something a bit more fuel-efficient ...

I'm years from finishing and I worry that the availability and price of fuel between now and then will make even 7gph seem a serious burden. ...
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I think it a falasy that smaller engines are more fuel efficient! If you want to go slow just pull the throttle back:D In my (then 150hp) 6A I used to fly regularly with 160 hp & 180hp 6s. Going places we'd fly for 2 hours together (all going the same speed) in basically a straight line. The larger engined airplanes always consumed less fuel than me (by 1 gallon an hour), they had better take-off performance and climbed faster. Above 10K their climb was much better than mine. Airplanes with a c/s prop consumed less still and performed better. I'm told that 200hp airplanes consume even less.

So flying at a given speed a larger engine seems to burn less gas. If you want to burn less gas at O-235 speeds get an O-320 with fuel injection and a c/s prop and fly at O-235 speeds with the rpm down, mp up and running lean of peak (with a good engine monitor).

Pete
 
penguin said:
I think it a falasy that smaller engines are more fuel efficient!
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It's a fact................sometimes my 0360 powered 6A meets or exceeds the fuel efficiency of a 0320 powered 9A, when we both fly at slower speeds. Sometimes not. However, I have better climb performance and top speed. Besides, I don't like airplanes that don't respond to density altitude well..........because of anemic sized engines...

L.Adamson --- RV6A
 
O-200 Mods

If you want to Mod the O-200 and still reach 1800hr TBO this is what I would do. Call Lycon and order ported and Polished TCM cylinders with 9/1 compression pistons (about $1250 ea.) Install TCM P/N 530788 C90 cam and matching followers. Lightly blend/polish intake tract. Balance rotating assembly. Set timing to 26 Top, 28 Bottom, BTDC. Use 2900 Rpm as redline. This setup makes ~110hp. Be advised that the O-200 in factory trim is really an 85-maybe with luck 90hp engine. Factory power ratings for engines certified under the CAR's are very optimistic. As for installing this in an RV-9 I would recomend a more powerful engine. (O-290-D2 or O-320) Good luck, Russ
 
IO-240 maybe?

That sounds like just the ticket in terms of the right compromise between power and efficiency. Significantly more power than 118hp, but light still and even possibly FADEC!

But, I fear negligible support from Vans. I'd be a trail blazer, unless someone else has already done that?
 
delusional said:
Are you saying you can get down to 5gph cruise with a o-360? I know it's feasible with a o-235.
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Oh sure. I get around 150 MPH at 5 GPH in my O-360/ RV-6. Super economy cruise. Sure is quiet at that setting too. I admit, I don't use it often.
 
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