The Straight Dope

Go Back   Straight Dope Message Board > Main > In My Humble Opinion (IMHO)

Reply
 
Thread Tools Display Modes
  #1  
Old 03-21-2010, 06:29 PM
Johnny L.A. Johnny L.A. is offline
Charter Member
 
Join Date: Jan 2000
Location: NoWA
Posts: 48,692
Doper pilots: Lycoming O-320 vs. Continental O-300

Except for dad's Skylane, I've only flown behind Lycoming engines. Dad's Skyhawk was a 172L that was built two years after Cessna switched from the Continental. AIUI, the Continental O-300 has a TBO of 1,800 hours, vs. the 2,000-hour TBO of the Lycoming O-320 -- and there are two fewer cylinders to overhaul. The O-320 has five horses over the O-300 (comparing the 145 and 150 hp ones), and is more fuel-efficient to boot. It seems to me that the Lycoming wins.

Which do you think is the better engine?
Reply With Quote
Advertisements  
  #2  
Old 03-21-2010, 07:01 PM
Broomstick Broomstick is online now
Charter Member
 
Join Date: Mar 2001
Location: NW Indiana
Posts: 18,804
I have two criteria I use to evaluate engines:

1) Reliability
2) Fuel efficiency

I've flown behind Lycomings, Continentals, Rotaxes, a Rolls Royce, and a couple I don't remember the names of (at least one rotary? Odd number of cylinders in a circle). I've had 1 Lycoming and 1 Continental quit on me - in both cases it had nothing to do with the engine itself but with something connected to the engine.

I've heard a number of people claim Lycoming is superior. Maybe it is, given the numbers you gave. But from the reliability standpoint they both seem about equal to me.

However, if the Continental O-300 is the 150 hp 6 cylinder one - MUCH less engine vibration while in flight, it is a notably smoother ride than a 4 cylinder.
Reply With Quote
  #3  
Old 03-21-2010, 07:03 PM
Johnny L.A. Johnny L.A. is offline
Charter Member
 
Join Date: Jan 2000
Location: NoWA
Posts: 48,692
Quote:
Originally Posted by Broomstick View Post
However, if the Continental O-300 is the 150 hp 6 cylinder one - MUCH less engine vibration while in flight, it is a notably smoother ride than a 4 cylinder.
I thought of that. (Yes, the Continental is a six.) But I don't have a frame of reference for that.

Oh -- technically, I've also flown in front of Lycomings too, as they're aft of the cockpit on R22s and Schweizers.
Reply With Quote
  #4  
Old 03-21-2010, 07:12 PM
Broomstick Broomstick is online now
Charter Member
 
Join Date: Mar 2001
Location: NW Indiana
Posts: 18,804
I've flown a Continental 145 hp 6-banger in a very old C172 - VERY smooth ride.

I've flown the Lycoming 4 cylinder O-320 150 hp, too.

So, my statement regarding a smoother ride was based on experience. If it's important to you that might be a deciding factor. If not, probably fuel efficiency.
Reply With Quote
  #5  
Old 03-21-2010, 07:14 PM
Johnny L.A. Johnny L.A. is offline
Charter Member
 
Join Date: Jan 2000
Location: NoWA
Posts: 48,692
The deciding factors are paying off my mortgage, paying off my car, and possibly winning the lottery!
Reply With Quote
  #6  
Old 03-21-2010, 07:15 PM
Duke Duke is offline
Guest
 
Join Date: Jul 1999
My dad worked on the Lycoming O-320's descendants, so....the Lycoming O-320 is clearly a better choice
Reply With Quote
  #7  
Old 03-21-2010, 08:21 PM
Magiver Magiver is offline
Guest
 
Join Date: Apr 2003
Lycoming O-320 - Dry weight: 244 lb 150-160 hp
Continental O-300 - Dry weight: 268 lbs 145 hp

Let me think, which engine offers 15 more hp, gets better fuel economy, and weighs 24 lbs less.

I put one of these in my Piper colt. Guess which one it was.
Reply With Quote
  #8  
Old 03-21-2010, 08:55 PM
Sam Stone Sam Stone is offline
Charter Member
 
Join Date: Jun 1999
Posts: 25,525
I don't know of any real differences in reliability between the two, other than the slightly shorter TBO on the continental (which doesn't necessarily mean anything). However, the Continental will likely be more expensive to maintain - two more cylinders and the shorter TBO raise the cost of ownership.

As others have said, the six-cylinder engines are generally smoother (although there's some engine-to-engine variance due to balance quality). I flew a Stinson 108-C with an old Franklin six banger in it, and it was the smoothest, most vibration-free airplane I've ever sold.

All that said, I'd go with the Lycoming, if for no other reason than that it's a much more common engine, so mechanics will be more comfortable with it and parts are more available and all that.
Reply With Quote
  #9  
Old 03-21-2010, 10:42 PM
Llama Llogophile Llama Llogophile is offline
Guest
 
Join Date: Apr 2002
Ask a mechanic who has worked on both.

The guys in my shop take a dim view of Continentals. They say they need top overhauls much more often than Lycomings. Sometimes in a startlingly short amount of time.
Reply With Quote
  #10  
Old 03-22-2010, 03:05 AM
Magiver Magiver is offline
Guest
 
Join Date: Apr 2003
Quote:
Originally Posted by Mach Tuck View Post
Ask a mechanic who has worked on both.

The guys in my shop take a dim view of Continentals. They say they need top overhauls much more often than Lycomings. Sometimes in a startlingly short amount of time.
The Lycoming favors the left bank of cylinders because of the way the oil passages are set up to feed the top end through the pushrods. You can probably address this more but I believe it's the O-320H model that does the best job of keeping things oiled/cooled.
Reply With Quote
  #11  
Old 03-22-2010, 11:14 AM
Johnny L.A. Johnny L.A. is offline
Charter Member
 
Join Date: Jan 2000
Location: NoWA
Posts: 48,692
This is good stuff. It makes me wish I could afford a flying-thing. (But then, I always wish that. )
Reply With Quote
  #12  
Old 03-22-2010, 12:24 PM
ElvisL1ves ElvisL1ves is offline
Charter Member
 
Join Date: Jul 2000
Location: New England
Posts: 32,612
The fewer parts, the more reliable. Go with the four over the six. Unless you can get the six cheaper.

No big deal either way.
Reply With Quote
  #13  
Old 03-22-2010, 04:07 PM
Magiver Magiver is offline
Guest
 
Join Date: Apr 2003
Quote:
Originally Posted by ElvisL1ves View Post
The fewer parts, the more reliable. Go with the four over the six. Unless you can get the six cheaper.

No big deal either way.
The cost of the engine should not be the driving financial force. One of the reasons I upgraded from an O-235 to an O-320 is that the O-320 was cheaper to overhaul by a significant amount. It was cheaper to buy and overhaul the O-320 than it was to just overhaul the O-235. I believe that may have changed since I've done it but at the time it was ridiculous what things like pistons rings cost for an O-235. But since the engine was in demand for home-built airplanes it was a no-brainer to sell it and swap in a bigger one.

Things to understand about the O-320. If you want the 160 hp setup the engine has to spec out first (I think it's the tolerances for the crank). It's not a given that you can do the upgrade. And if you're swapping between a Continental and a Lycoming there will certainly be different motor mounts, exhaust systems, propellers, spinners, and everything else that is specific to the motor.

Last edited by Magiver; 03-22-2010 at 04:09 PM..
Reply With Quote
  #14  
Old 03-22-2010, 05:02 PM
Llama Llogophile Llama Llogophile is offline
Guest
 
Join Date: Apr 2002
Quote:
Originally Posted by Magiver View Post
Lycoming O-320 - Dry weight: 244 lb 150-160 hp
Continental O-300 - Dry weight: 268 lbs 145 hp

Let me think, which engine offers 15 more hp, gets better fuel economy, and weighs 24 lbs less.

I put one of these in my Piper colt. Guess which one it was.
What kind of performance do you get from your Colt with that engine? I fly Colts every so often, but have only been behind the 108 hp engine.
Reply With Quote
  #15  
Old 03-22-2010, 06:02 PM
Magiver Magiver is offline
Guest
 
Join Date: Apr 2003
Quote:
Originally Posted by Mach Tuck View Post
What kind of performance do you get from your Colt with that engine? I fly Colts every so often, but have only been behind the 108 hp engine.
I had to go with the 150 hp version but I raced a Cherokee 140 and won (I did have a weight advantage). The 108 version would take a long time to climb to 12,000 feet and then wallow when it got there. It's basically a Tri-Pacer without flaps so 7-800 fpm climb is about right. It doesn't have enough elevator to stall so the extra hp allows you to fly at a ridiculously steep angle which puts your weight on the seat back.

What is most notable is the larger prop. it acts like a speed brake when the engine is pulled to idle. You can push the nose over and really drop like a rock without hitting VNE.
Reply With Quote
  #16  
Old 03-24-2010, 07:25 AM
Anne Elk Anne Elk is offline
Guest
 
Join Date: Dec 2005
Broomstick said;(at least one rotary? Odd number of cylinders in a circle)

I think you mean radial. Flying behind a rotary motor would mean either a Mazda auto-to-aviation conversion, or a Sopwith.
Reply With Quote
  #17  
Old 03-24-2010, 04:30 PM
Broomstick Broomstick is online now
Charter Member
 
Join Date: Mar 2001
Location: NW Indiana
Posts: 18,804
Radial

It was a W670 series Continental engine - 7 cylinder radial (let's here it for log books and N-number databases with engine information).
Reply With Quote
  #18  
Old 03-24-2010, 06:50 PM
Anne Elk Anne Elk is offline
Guest
 
Join Date: Dec 2005
Quote:
Originally Posted by Broomstick View Post
Radial

It was a W670 series Continental engine - 7 cylinder radial (let's here it for log books and N-number databases with engine information).
Cool! Every time I've seen an old rotary engine running there was somebody standing by with a fire extinguisher. Just in case.
Reply With Quote
  #19  
Old 03-24-2010, 07:04 PM
Johnny L.A. Johnny L.A. is offline
Charter Member
 
Join Date: Jan 2000
Location: NoWA
Posts: 48,692
I saw an original Sopwith Camel flying with an original rotary engine once. It was incredibly
Reply With Quote
  #20  
Old 03-24-2010, 07:53 PM
Broomstick Broomstick is online now
Charter Member
 
Join Date: Mar 2001
Location: NW Indiana
Posts: 18,804
Would love to fly a really old bipe like a Sopwith or a Jenny.

Unfortunately, I'm not at all current in anything, much less something from the dawn of aviation. Nevermind the unlikelihood of getting such an opportunity.
Reply With Quote
  #21  
Old 03-24-2010, 10:23 PM
Richard Pearse Richard Pearse is offline
Member
 
Join Date: Aug 2001
Location: Kiwi in Adelaide
Posts: 8,078
Quote:
Originally Posted by Johnny L.A. View Post
I saw an original Sopwith Camel flying with an original rotary engine once. It was incredibly
I was going to say that I'd seen a rotary engined aeroplane flying but after doing some research it looks like I was mistaken.

What I saw was a Bleriot XI which has a 3 cylinder "W" engine. Still cool though.

As far as Continentals go, I've flown behind just one as far as I can tell, a 100hp Rolls-Royce built 0-200-A fitted to a PA-18 Cub. It didn't stop on me in 50 hours so I guess that's good!
Reply With Quote
  #22  
Old 03-24-2010, 10:42 PM
Richard Pearse Richard Pearse is offline
Member
 
Join Date: Aug 2001
Location: Kiwi in Adelaide
Posts: 8,078
I tell a lie, I've flown behind a couple of Continental IO-520s in a Beech Baron. They didn't stop on me either, and there's double the chance of a failure in a twin!

On the subject of vibration, this can be influenced by things other than the engine. I've flown a Britten-Norman Islander and a Shrike Commander, both were fitted with Lycoming IO-540 engines but the Shrike was a lot smoother than the Islander.
Reply With Quote
  #23  
Old 03-25-2010, 06:19 AM
[Undecided] Adrian [Undecided] Adrian is offline
Guest
 
Join Date: Sep 2008
Quote:
Originally Posted by Anne Elk View Post
Broomstick said;(at least one rotary? Odd number of cylinders in a circle)

I think you mean radial. Flying behind a rotary motor would mean either a Mazda auto-to-aviation conversion, or a Sopwith.
Or some gliders capable of self-launch, which use a Wankel engine.
Reply With Quote
  #24  
Old 03-25-2010, 07:27 AM
Richard Pearse Richard Pearse is offline
Member
 
Join Date: Aug 2001
Location: Kiwi in Adelaide
Posts: 8,078
Quote:
Originally Posted by [Undecided] Adrian View Post
Or some gliders capable of self-launch, which use a Wankel engine.
That'd be what some models of Mazda have as well, but it appears that some Wankels are purpose built for aircraft rather than being a Mazda conversion.

Last edited by Richard Pearse; 03-25-2010 at 07:28 AM..
Reply With Quote
  #25  
Old 03-25-2010, 08:26 AM
IdahoMauleMan IdahoMauleMan is offline
Guest
 
Join Date: Sep 2008
Quote:
Originally Posted by Johnny L.A. View Post
Except for dad's Skylane, I've only flown behind Lycoming engines. Dad's Skyhawk was a 172L that was built two years after Cessna switched from the Continental. AIUI, the Continental O-300 has a TBO of 1,800 hours, vs. the 2,000-hour TBO of the Lycoming O-320 -- and there are two fewer cylinders to overhaul. The O-320 has five horses over the O-300 (comparing the 145 and 150 hp ones), and is more fuel-efficient to boot. It seems to me that the Lycoming wins.

Which do you think is the better engine?
What an awesome thread. In the SDMB, no less. I'm getting an erection. Makes a man want to come back to the message board again, and post from time-to-time.

Not much to add to the discussion above, other than I've flown behind both and owned a number of planes. If your primary concern is cost of ownership and not hair-splitting about performance or vibration, then the biggest variables will be in your control and I would worry less about the actual engine type. Unless of course you are getting something that is truly going out of style, like a Franklin.

Fly the plane regularly (1 hour or more at least once/week) change the oil and filter as soon as it starts to darken, preheat under 40F, do the analysis every 3rd or 4th change, keep the prop balanced and in good condition, and keep the major engine components on a PM schedule. If you do all that, my experience is that the TBO will become (almost) meaningless.

Drop back in and give us a Pirep the next time you take it up.

Last edited by IdahoMauleMan; 03-25-2010 at 08:27 AM..
Reply With Quote
  #26  
Old 03-25-2010, 08:45 AM
[Undecided] Adrian [Undecided] Adrian is offline
Guest
 
Join Date: Sep 2008
Quote:
Originally Posted by Richard Pearse View Post
That'd be what some models of Mazda have as well, but it appears that some Wankels are purpose built for aircraft rather than being a Mazda conversion.
Yes, I know. The ones in the gliders have 37kW and weren't intended for cars, but for motorcycles.

By the way, in Europe there is quite a lot of interest in Diesel engines for aircraft, which can fly on kerosene as well.
Reply With Quote
  #27  
Old 03-25-2010, 01:48 PM
Johnny L.A. Johnny L.A. is offline
Charter Member
 
Join Date: Jan 2000
Location: NoWA
Posts: 48,692
Quote:
Originally Posted by IdahoMauleMan View Post
Drop back in and give us a Pirep the next time you take it up.
I would if I had one!

I don't have an aircraft, and won't be getting one in any sort of foreseeable future. I was just curious about the engines.



Errata: Dad's Skyhawk was a 172K, not an -L.
Reply With Quote
Reply



Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 05:03 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Send questions for Cecil Adams to: cecil@chicagoreader.com

Send comments about this website to: webmaster@straightdope.com

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Publishers - interested in subscribing to the Straight Dope?
Write to: sdsubscriptions@chicagoreader.com.

Copyright 2013 Sun-Times Media, LLC.