Q: Is it possible to increase the horsepower of this engine to 260? or even 300? I’m a relatively new to all things airplanes as I have just been flying rental planes, but I just picked up a Velocity XL-RG and an O-540 from a Piper Cherokee. The Velocity requires at least 260 hp, but ideally if I could get to 300 hp safely I would like to do that. I would also like to add fuel injection.
Michael J. Baron
A: I’m afraid I’ve got some bad news for you regarding the horsepower for your O-540-B2B5 Lycoming engine.
This particular engine is FAA certified and rated at 235 horsepower at 2575 RPM and the compression ratio is 7.20:1. This engine was used primarily on the Piper Pawnee PA-24-235 and the Piper Cherokee PA-28-238. It was configured for a fixed pitch prop only.
When I research the genealogy of this series of Lycoming engines, I can tell you that since you’ll be using this engine in an experimental category aircraft, the best you can do horsepower wise is 250 horsepower.
Again, since it’s an experimental category aircraft, you could consider installing 8.5:1 compression ratio pistons and at 2575 RPM that should give you 250 horsepower, but that would be about it, and you’d be on your own as far as reliability, etc.
By changing the compression ratio, it actually falls in line and would be similar to the Lycoming O-540-A1D5 engine that is rated at 250 horsepower at 2575 RPM with the 8.5:1 compression ratio pistons.
I can’t emphasize enough that the most reasonable thing you can do to get the 250 horsepower is to change the pistons to a higher compression ratio, remembering that it’s done as an experimental configuration.
There are 260 horsepower O-540 series Lycoming engines, but they have many different components, such as the crankshaft making it uneconomical to try to convert your engine to that type of configuration.
The 300 horsepower engine is a completely different breed altogether and you can’t get there by converting your engine unfortunately.
Michael, I apologize for putting a damper on your project, but I’m certain there are other options that you’ll be looking at that will allow you to complete the project.
Wylbur Wrong says
I think that the picture being shown is a Turbocharged engine. The O-540 is not turbo charged nor has fuel injection.
So the picture used is not a Lycoming O-540-B2B5.
The question about adding horsepower is being asked of someone (Paul) that works in a certificated stock Lycoming world, but the question is really about operating the engine in the Experimental category. Paul is a really knowledgeable guy, but I question how much he dabbles in the Experimental area, and he sure can’t recommend that you get very far out of what Lycoming deems as acceptable. As Manny says, talk to LyCon. They can help with cleaning up the intake areas and flow matching the cylinders. They can provide higher compression pistons. You can retrofit an EFII electronic fuel injection and ignition to the engine. However, the biggest problem you’ve got, which Paul points out for you, is that you have a crank that is configured for a fixed pitch prop. I don’t know the specifics about this engine, but many Lycoming engines, and possibly this one as well can have a plug added internally at the tail of the prop shaft, and the front bushings changed to accommodate a constant speed prop. Of course your case has to have been configured to support the prop governor as well. LyCon should be able to help with all of this. Give them a call, but be prepared to spend some money. Or, you could sell that engine and look for a 300 HP IO-540-K. The Velocity aircraft perform well with the 260 hp engine. But they are exceptional when you put a 300 HP IO-540-K or a Continenal IO-550 on board.
The amendments that you kindly suggested require a total engine teardown — he would be way better to sell the engine and buy one that suits his horsepower requirements.
I agree with your suggestion about electronic ignition – that will not only pick up a few horsepower but will ensure better performance over the life of the engine.
Actually, Lycoming has a tool you can rent from them for inserting the plug into the back of the prop shaft without an engine tear down. They want a $2K deposit on the tool if you use it. Did that once when they shipped an IO-360 to us configured for fixed pitch when it was supposed to be configured for Constant Speed. They decided they would rather loan us their tool than pay shipping to replace the engine. But, as previously stated, everythinf else on the engine has to be the correct model for a CS prop as well.
Dave Acklam says
If you want constant speed on a fixed-pitch engine, for an experimental, you are better off getting an electric CS prop, than modifying the engine for a hydraulic one….
Even that has to be the correct model. Saw this recently when Continental shipped a Lycoming clone engine (IO-340) for use with an electric MT prop. It came with the small drive holes and drive lugs in the prop flange. The holes weren’t big enough to accommodate the larger drive lugs required for the MT prop. Continental ended up exchanging the engine as the crank had to be changed and they made the mistake.
But if the engine has the correct crank for the application (as I would expect with an IO-540), that’s certainly the easier route. Of course electric props come with a host of issues of their own. Slow response to changes and short electric motor life being the more irritating of them.
Manny Puerta says
LyCon in Visalia, CA flows aircraft cylinder heads. The increase in horsepower could be up to 10%. Worth a call to them…