O-540 question

[Chad Meeks]

I'll start with Happy Thanksgiving!

I'm a Continental guy, but I've seen a few guys build an aircraft engine utilizing an O-540 lower end with a GTSIO io-520/550 top end. That sounds impressive.

My question is, if I wanted to build an engine like this, what model O-540 lower end would I use, and would that be a large or small journal crank?

Like I said above, I've only had, and still run Continental engines For 30 years. I've always loved the E-225 with the IO-520 top end.

 

[John Fenner]

There were a few "lyconentals" built back in the racing days, pretty sure they were on narrow deck cases, mainly 4 cylinder based, they ran ok, lots of work to build up such of an engine.
Keep in mind that GTSIO heads are the worst flowing for naturally aspirated/ carbureted applications.
The E225 with 520 jugs is the great match up if tuned and say blueprinted, 12:1 forged pistons, cam timing advanced to 114° lobe center, other little tricks, why reinvent the wheel?

 

[Chad Meeks]

John, I appreciate your feedback. I recently (within the past 2 months now) saw a video of an o-540 with the GTSIO cylinder inverted and installed... they guy who owned it stated it was "rank". So, that kinda peaked my interest in building one.

 

[Slidin Gator]

For the effort and cost to add 5% displacement I would opt to add 7.4% and build a Lycoming 580. You get the longer lycoming stroke and an even larger 5.319 bore vs 5.25 Continental. Better flowing cylinders and you can purchase new loaded for $1,900 each. I’m sure the case needs to be opened up, the stud pattern is unknown to me.

Some bore and stroke figures for comparison:

Bore x Stroke

Lycoming
540
5-1/8 x 4-3/8

580
5.319 x 4-3/8

Continental
520
5-1/4 x 4

550
5-1/4 x 4-1/4

 

[Chad Meeks]

For the effort and cost to add 5% displacement I would opt to add 7.4% and build a Lycoming 580. You get the longer lycoming stroke and an even larger 5.319 bore vs 5.25 Continental. Better flowing cylinders and you can purchase new loaded for $1,900 each. I’m sure the case needs to be opened up, the stud pattern is unknown to me.

Some bore and stroke figures for comparison:

Bore x Stroke

Lycoming
540
5-1/8 x 4-3/8

580
5.319 x 4-3/8

Continental
520
5-1/4 x 4

550
5-1/4 x 4-1/4

Wow, that's interesting.. Slidin Gator, I appreciate the feedback