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Author Topic:   Two-Stroke vs. Four-stroke Performance test
Sammy posted 01-29-2003 09:48 AM ET (US)   Profile for Sammy   Send Email to Sammy  
With all the discussion and debate surrounding 2-stroke versus 4-stroke outboards, the following comparison test information seemed interesting enough to post for further thought/comment/discussion. There is also mention of a possible change or revision in the process for determining HP and weight standards and capacities.


The article was part of an on-line news letter that I recieve - quotation marks were added by me to mark beginning and end of the copy. It's interesting that the organization/group/company conducting the test was not identified - nor was the hull, make(s) of the outboard(s) or weather conditions. Your thoughts, opinions? sammy

Chap posted 01-29-2003 10:08 AM ET (US)     Profile for Chap  Send Email to Chap     
Some additional info.;f=6;t=000752;p=

Sammy posted 01-29-2003 10:29 AM ET (US)     Profile for Sammy  Send Email to Sammy     
Don't know if thats the same test or not, but it sounds somewhat similar.
kglinz posted 01-29-2003 10:47 AM ET (US)     Profile for kglinz  Send Email to kglinz     
I must agree that the "High Tech" 2 Strokes run strong,but its like the Tortoise and the Hare. I'll catch up while you're changing your powerhead.
Bigshot posted 01-29-2003 11:05 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I have read that before and I must say it "could" be an urban myth. Reason being it was definately geared to make 2 strokes look good but does not state the boat type or engine type or who did the comparo and what props were used and what redlines were on those engines. For example a 225 4s with a prop geared to run 5500 that has a 6k redline has a bigger pitch than a 2s propped to run 5500 that redlines at 5250 or 5500. 2nd is that I have been on the same boat with different engine setups both 2 and 4s and it is NOT that drastic. My bud has a 23 seacraft with twin 130 yammies and he switched to twin 115 suzi 4s. He lost 1 mph top and 1 mph cruise and both setups plane the boat on 1 engine. He also dropped 30hp with the 4 strokes. Now I do not know what kind of rig was in this test but to run high 30's with a single(on a twin setup) is unheard of unless way over powered. Even then the 4s would get it on plane if the test is true. If 4 strokes were that lame do you REALLY think people would buy them? Do you really think they suck that bad at performance when my 70 4s almost matches the performance of my 90 yammie 2s? PULLLLEEEEZE!
weekendwarrior posted 01-29-2003 11:17 AM ET (US)     Profile for weekendwarrior  Send Email to weekendwarrior     
One common theme that I'm picking up on (someone tell me if you notice the same) is that the smaller 4-strokes appear to be closer to a drop-in 2-stroke replacements than the larger 4-strokes. What I mean is that the replies that I read from owners of motors in the 50HP range (myself included) are completely satisfied with the hole shot, fuel economy, top speed, etc.. But when reading about the larger motors (which I have no personal experience with) I keep hearing how the hole shots are slower, top speed is slower, fuel economy is roughly equal, etc.. It would seem that hours between rebuilds would be the only major advantage with the big motors. I must admit that I am quite surprised.

Is anyone else noticing this same theme?

A side note; I would like to see some video from these "tests" with 2 different motors on the back of the boat. Neat idea for testing, but a nice mpeg would really bring it into perspective.

acassidy posted 01-29-2003 12:46 PM ET (US)     Profile for acassidy  Send Email to acassidy     
You know if you read the comparison reports on the Trailer Boat magazine, and the Bass and Walleye magazine, they say the same thing that is said here. The bigger 4 strokes do not have the low-end torque that the 2 strokes do. And in some cases did not achieve the same high top end. Of course both magazines where very careful about how they reported it, to not offend the manufactures, but it is there in black and white. Also reported is that some of the fuel injected two stroke have better mpg @ mid range. Even one the tests were between Yamahas 2s and 4s 225 hp. You will not see the magazines giving reports like this though, unless they are looking to loss endorsers ($). I feel that the 4 strokes will catch up. 2 stokes have 70 years of research and development, the 4 stoke only have 20 years. Archie
Arch Autenreith posted 01-29-2003 01:04 PM ET (US)     Profile for Arch Autenreith  Send Email to Arch Autenreith     
Unfortunately I know far more about bikes (dirt) than ob's. In that arena 2 strokes have been legislated into retirement by 2008. (I think that's the date.) Much of it was b/c of mis-information (noise, pollution, etc.) but it happened anyhow. It's a done deal unless it's overturned for some reason but there seems to be little opposition.

4-strokes have made amazing gains in the past 5 years or so. The current crop are the best ever of course.

The handwriting must be on the wall as I see it. 4S is the wave of the future even though 2S's seem to perform equally well in most if not all respects. Including pollution. Just me thoughts.

weekendwarrior posted 01-29-2003 02:19 PM ET (US)     Profile for weekendwarrior  Send Email to weekendwarrior     
I too am involved in the dirt bike area, I ride a YZF426 (4-stroke). This is the source of some of my puzzlement over the boat motors. In the dirt, the 4-stokes typically are somewhat larger displacement (400-450cc 4-strokes are raced in the same class as 250cc 2-strokes) however compared to the 2-strokes, the 4-strokes have an amaizing power spread with incredible torque from right off idle and pull incredibly hard all the way to the rev limiter. The peak HP numbers are in the ball park with the 2-strokes but but the power curve is definitely much wider on the 4-strokes. Weight is not THAT big of an issue. I belive my 426 weighs about 20# more than a comparable 2-stroke, newer 4-strokes are even lighter. I am puzzled that the 4-strokes marine engines don't follow this same basic path, both in terms of weight and in terms of power (i.e. not THAT much heavier and wider power curves). I guess they just need more R+D?

And as was said above, I can't believe that the larger 4-strokes are THAT bad or they wouldn't be catching on like the are.

PMUCCIOLO posted 01-29-2003 06:17 PM ET (US)     Profile for PMUCCIOLO    
So, now the question for me is: Do I buy the F60 or 70 Yamaha? I'm going to plunk down the cash next week.
Arch Autenreith posted 01-29-2003 07:51 PM ET (US)     Profile for Arch Autenreith  Send Email to Arch Autenreith     
You're right, Paul. It is so confusing. For some darn reason Dick and Bigshot convinced me of 4strokes. But I could change my mind in a heartbeat for no apparent reason at all.

For my Montauk the Merc 60 4S (F60, right?) would do the job for me. But only if I get a fair price. (I'm too cheap to pay retail for anything.) I still have to let the ol' oil burner die it's own death first.

Whalerdan posted 01-30-2003 08:25 AM ET (US)     Profile for Whalerdan  Send Email to Whalerdan     
The way this test was done makes me wonder if they would have gotten different results if they swapped (left to right) sides the motors were mounted on would they get the same results. Seems like the prop torque could cause one to plugh more if it was mounted off center. Isn't this ONE of the reasons you want counter rotating prop on a twin?

Maybe I'm all wet, but just thinking out loud.

jimh posted 01-31-2003 11:55 AM ET (US)     Profile for jimh  Send Email to jimh     
Although the results cited don't surprise me, this alleged test seems quite contrived.

The test technique seems very labor intensive, having to install and remove several engines on the same boat's transom. Since this is a twin engine set up you would have to connect tie bars and other rigging to get the two different engines connected.

In addition, new controls, throttle, and shift cables would have to be installed, unless the engines were of the same brand and had compatible control cables.

In all, it seems a bit far fetched. I'd say this story is probably apocryphal.

VMG posted 01-31-2003 05:50 PM ET (US)     Profile for VMG  Send Email to VMG     

...ya know, Jim, I've been hearin' that one at the bait shop every weekend. I was always wonderin' what they was talkin about when they was talkin about them apocalyptic albacore. Now I know it was apocryphal albacore. Mercy Bo-cups, bubba for the inlightment.

SuburbanBoy posted 02-02-2003 05:03 PM ET (US)     Profile for SuburbanBoy  Send Email to SuburbanBoy     
After reading the supporting article using the link supplied by Chappy, I am convinced that the fella who wrote "O Brother Where Art Thou?" had a hand in this story.


minimontauk posted 02-02-2003 08:51 PM ET (US)     Profile for minimontauk  Send Email to minimontauk     
I am a complete powerboating novice, but I was shocked at how much unburned oil comes out of a 2-stroke engine idling with a hose and ears. I really had no idea. Multiply that amount of pollution by the number of recreational boaters in my area (Cape Cod), and the death of local shellfish beds is a no brainer. If the 4 stroke engine is less polluting, as I've read, we should all switch over when we can. There's no good reason not to apply the same kind of pollution controls and fuel efficiency technology we all take for granted in our cars to our boats. No holier than thou here, I suppose I'll run my 96' Johnson 48 HP till it croaks, but my next engine has got to be a little more environmentally friendly.
lhg posted 02-04-2003 04:23 PM ET (US)     Profile for lhg    
Paul - I think you should buy the Yamaha 2-stroke 70, since if you buy the Yamaha 4-stroke 60, you'd be getting a Mercury powerhead painted gray! Why not the black EFI version?

But seriously, I just read that Bombardier is about to begin a massive advertizing blitz promoting Evinrude 2-stroke DI (Their new name for Mercury DFI/Yamaha HPDI instead of Ficht) as superior to 4-stroke technology. Why not, they have nothing else (that they manufacture) to promote, and with the new Merc supercharged 4-stroke in the wings, 4-strokes will gain even more sales. But they will not be all wrong. It is now apparent and confirmed that the current crop of highly popular Honda/Yamaha 225 4-strokes can't keep up with an Optimax or Ficht 225. Even Mercury, temporarily buying and selling the Yamaha 225 in black, takes a cheap shot at Yamaha by saying in their new 2003 catalog that a 225 Optimax will clearly outperform the black 225 4-stroke in all but fuel economy, and even that is close. But the word is that the new in-line 6 supercharged 2.6 liter 4-stroke coming out this Fall will outperform all of them.

I have also been seeing, even on new Whalers, a resurgence of the conventional Mercury EFI technology, in the 200-250 HP ranges. The super quiet reliability and high power output of these engines is still in demand evidently, and a lot are being sold. And Mercury now basically has this market to itself. I think it's unfortunate that 2005 will be it's last year, especially as I drive the interstates watching all the smoke from diesel truck exhaust.

kglinz posted 02-04-2003 05:15 PM ET (US)     Profile for kglinz  Send Email to kglinz     
Those trucks are coming under emission controls. This will include retrofits of current engines in some cases. Even stationary and heavy equipment engines are covered.

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