Has anyone ever tried 9:1 (or somewhere around that ratio) compression pistons in a O-200...experimental of course. And if you have, how does the performance stack up to a stock motor? Also, did you see any negative effects why you wouldn't want to do that again?

Roger

I think I asked this before, but....

Is there something similar to the Sparrowhawk for an O-200? Is the Sparrowhawk STC for the aircraft type, or the motor?

I've heard that you can run C-85 pistons in an O-200 for higher compression. You do have to machine a bevel on the top edge of the piston. Also, I hear that Klaus Zavier (sp?) of Light Speed Ignition sells hi-perf stuff for small engines. I don't know how legal any of this stuff is for certificated airplanes however.
From what I understand, the O-235 sparrowhawk mod is a different Sensenich prop and a remarked tach. Good for 125 horsepower at 2800.

Eric

From the Light Speed Engr'g website: "With a recommended compression ratio of 9.4:1, 115-120 horsepwer can be achieved at rated rpm". $1050 for 4 pistons, some fitting work required.

Besides modifying C85 pistons, I know of several companies that manufacture pistons. Along with the ones mentioned above, High Performance Engines in La Verne, Ca. also offer some nice pistons. I think theirs are around $ 600 per set of four.

What I'd really like is someone that has actually run them in an O-200 for awhile and can describe what type of performance gain they achieved.

Gaining performance through higher compression is nothing new and in-fact lots of people pump up there HP this way. Just look at the Lycoming O-320, people put in 8.5:1 for an increase to 160 HP and I know of a number of people that even put in the 10:1 pistons from the Lycoming heli motor for even higher gains.

As I mentioned above, this is experimental territory and as far as I know, no STC is even remotely available for this modification. You would think with all the Cessna 150's out there, someone would have STC's higher compression pistons years ago....when you probably could have achieved a stamp of approval from the FAA. I really dought you could do this in these times with all the B---S--- the fed's make you jump through .

Roger

Roger S wrote:As I mentioned above, this is experimental territory and as far as I know, no STC is even remotely available for this modification. You would think with all the Cessna 150's out there, someone would have STC's higher compression pistons years ago....when you probably could have achieved a stamp of approval from the FAA. I really dought you could do this in these times with all the B---S--- the fed's make you jump through . Roger

It's not as hard as it sounds for the engine. Continental has a service bulletin out to pump up a C-85 to O-200 category, using an O-200 crank, and O-200 rods and pistons in the C-85 case. And, as I recall there were mods available to the O-200 also. Many, many moons ago I pumped up the C-85 in my T-Cart on Edos using Ritter cam, O-200 crank, rods and pistons. Made a big difference in performance.

But... Don't know about specific STC to apply that engine to the C150.

Gump

I think C-85 cranks are getting hard to find. I know there is an STC for putting an O-200 crank in the C-85. A guy named Randy Thompson has the STC. He can be found on the 120/140 forum. I assume the STC is for the engine and not the airframe.

Get a hold of any of the Formula guys, they can tell you all about pumping up an 0-200

Gump wrote:I pumped up the C-85 in my T-Cart on Edos using Ritter cam

Tell me about this cam...is there a STC or something?

a64pilot wrote:I think C-85 cranks are getting hard to find. I know there is an STC for putting an O-200 crank in the C-85. A guy named Randy Thompson has the STC. He can be found on the 120/140 forum. I assume the STC is for the engine and not the airframe.

The crank is getting hard to find. When I rebuilt my C-85 I had a good crank but I wanted more ummph so I sold the crank for enough to buy the STC and a brand new 0-200 crank...and I'm glad I did.

I don't remember who i bought the STC from, must have been Randy Thompson cuz I bought it from the guy who developed it, but I asked the guy if it really made a difference and he said it does for sure...but no promises about hp output. He did say that it would make 130 hp at 3000 rpm, but redline is 2575.

The STC was for the engine and it didn't matter the airframe.

Jon

I know I just mentioned this on another thread but that's okay.

whee wrote:

Gump wrote:I pumped up the C-85 in my T-Cart on Edos using Ritter cam

Tell me about this cam...is there a STC or something?

This was about 20 years ago, and we got it from an engine shop in the midwest that specialized in high performance grinds. Mr Scout is right in that the Formula guys who race behind the O-200s are the ones to ask who's doing the cool grinds now. It's been years since I've even heard of a Ritter cam. Thing worked well though, and ours was supposedly putting out about 125 HP.

I am using 9.5/1 lightspeed pistons. Had Klaus at Lightspeed port my cylinders and balance my rods. Using a 588 cam and 4 into 1 exhaust. Have it on floats in Canada in the summer and it is really a performer. Also balanced the crank and did a dynamic on the prop. Smooth as a elect motor.

My 0-200 will turn 3100 WOT straight and level with a 76AK2-40

Klaus' pistons are 9.4.
I run NFS 9.5 at 28° BTDC for a 9.76% increase in power and torque throughout the rpm band. Cruise fuel burn on 93 octane mogas is 4.3 gph.
No downside that I've noticed.

Zzz wrote:I think I asked this before, but....

Is there something similar to the Sparrowhawk for an O-200? Is the Sparrowhawk STC for the aircraft type, or the motor?

The Sparrowhark applied to the Lycoming O-235.

We were not allowed to do very much cam grinding in Formula One. They had a "nearly stock" cam profile that they would measure your valve lift against, with a proper gauge. They also measured compression ratio using the cylinder volumes, so you could not use tall pistons or a stroker crank. Some of the F-1 engine builders were convinced that a cam profile with LESS lift/duration was better, with the cam JUST meeting the max lift over a very short period of time, was the key. I heard it referred to as "trap compression ratio", where the amount of time the valves were open was letting some of the compression ratio out. The reason was that the engines were not turning fast enough to make the bigger cam profiles really work like they do in hi-po engines, so cutting your losses in another area of cam lift was the better method in a low-performance engine like an O-200 turning "only" 4000 RPM.

If you want an instant 5-10% improvement in power and economy for your EXP O-200 (or almost any other airplane engine) put in one of the better electronic ignition and fuel injection systems. Some of these are or will soon be certified.