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Author Topic:   2-stroke vs. 4-stroke: More data
jimh posted 09-08-2002 08:09 AM ET (US)   Profile for jimh   Send Email to jimh  
More data is available on the performance of 2-stroke and 4-stroke engines on identical boats. In this case, at the 225-HP level. Based on tests originally run by Bass & Walleye Boats Magazine, Evinrude is posting these numbers on their website:

BOAT: 2300#, 20-feet fiberglass

YAMAHA 225 HP 4-stroke
TOP SPEED = 56.5 MPH
ACCELERATION = 0-30 in 8.7 seconds
CRUISE = 28 MPH @ 3500 RPM
ECONOMY = 5.0 MPG

EVINRUDE 225-HP FICHT
TOP SPEED = 59.8 MPH
ACCELERATION = 0-30 in 5.7 seconds
CRUISE = 28.6 MPH @ 3000 RPM
ECONOMY = 4.5 MPG

HONDA 225 4-stroke
TOP SPEED = 52.4
ACCELERATION = 0-30 in 10.7 seconds
CRUISE = 27.7 MPH @ 3500 RPM
ECONOMY = 4.7 MPG

The numbers show the FICHT 2-stroke to be the fastest engine, and it is also much faster to accelerate to 30 MPH. The HONDA is noticeably slower.

Fuel economy of the 2-stroke is down about 20% from the Yamaha 4-stroke.

Source: http://www.evinrude.com/evinrude/web/jsp/241000.jsp?Params=N.US.0.0&pid=001

Peter posted 09-08-2002 09:43 AM ET (US)     Profile for Peter  Send Email to Peter     
Very interesting. The differences between all of these engines at their respective "best cruises" would appear to be even less than stated in the test report if the measurements were made on a substantially same worked performed basis.

For example, if they were all tested at the same speed achieved at the Evinrude best cruise, both of the two 4-strokes would consume more fuel per hour but it appears that they still might be a little better. Alternatively, if the Evinrude was tested at the lower speed of either of the two 4-strokes best cruise, it should consume less fuel per hour, although the test data seems to suggest it still might be a bit more. Where the Evinrude seems to outperform its 4-stroke companions in fuel consumption is at high speeds above about 50 MPH.

The Evinrude might be a better choice for the bass boaters that run their rigs at high speeds more frequently or for a longer duration if fuel consumption at high speed is a concern for the bass boaters. Based on the fuel consumption data, the Evinrude also looks like it might be the better choice for the troller. The 4-strokes might be the better choice for the cruisers.

I don't know why they don't show the results in a graphical format. It would be very easy to spot where each of the motors perform their best relative to the others. differences.

jimh posted 09-08-2002 09:50 AM ET (US)     Profile for jimh  Send Email to jimh     
OOPS! The fuel economy of the FICHT is only down about 10% from the (best) 4-stroke.
David Jenkins posted 09-08-2002 09:59 AM ET (US)     Profile for David Jenkins  Send Email to David Jenkins     
Is it possible to compare 2-strokes and 4-strokes by noise output in decibels at various rpms? Quietness (and reliability and near-odorless operation and ease of starting and reduction of vibration) are more important to some people than top-end speed and fuel consumption. Is it possible?
Peter posted 09-08-2002 10:16 AM ET (US)     Profile for Peter  Send Email to Peter     
Noise and vibration at various engine speeds should be objectively measureable. "Near odorless" and ease of starting are a little more subjective. From an ease of starting basis, the EFI 2-strokes are as easy to start as the EFI 4-strokes. Leave the control in the neutral position and just turn the key.
jimh posted 09-08-2002 11:22 AM ET (US)     Profile for jimh  Send Email to jimh     
Sound pressure levels (SPL) can easily be measured. Unfortunately, this data is not often recorded or published.

Reports of SPL readings are subject to "weighting". Raw SPL numbers are often then curved to help correlate the measured levels with perceived levels. The human ear is less sensitive to lower frequency sounds. This has an effect on the perception of sound by human ears of the noise produced by a 4-stroke engine.

The 4-stroke engine has only half as many power strokes (at a given crankcase speed) as a 2-stroke. Therefore, the fundamental frequency produced by the 4-stroke engine is about half that of a 2-stroke. Even if the two engines produced identical SPLs, the human ear will perceive the 4-stroke to be quieter.

FISHNFF posted 09-08-2002 10:10 PM ET (US)     Profile for FISHNFF  Send Email to FISHNFF     
I remember a TrailerBoat Magazine comparison of a 150 Merc DFI, Evinrude 150 Ficht, and a Yamaha 150 HPDI. Some were under-propped, some were over-propped. This showed in top speed and acceleration. In this test of the 225's, all were over-propped (the Yamaha about right on with 5900), the Honda the most, which may yield a slower acceleration. I still would like to see torque measured on these motors.
Just my .02

FISHNFF

newt posted 09-09-2002 08:20 AM ET (US)     Profile for newt  Send Email to newt     
I honestly can't say I relate to the smoke, startup, and noise issues with the 2s motors. Granted, I have not logged the hours on the water that you veterans have, but here are my observations so far with a Merc 90 hp 2s motor.

The only time I even see smoke (and I am still on double oil) is at start up and warm up. While cruising or puttering I dont see or smell anything.

At cruise, the wind in my ears drowns out the sound of the motor anyway, so how would a 4s help with noise? (except at idle or trolling speeds maybe?)

Startup is simple. Prime, push the button and slide the throttle forward, crank with the choke button in, and throttle back when she catches. Easy.

I have no regrets about saving $3-4000 bucks.

PS, 0-30 is about 4-5 seconds. Maybe I should install seat belts. :)

Bigshot posted 09-09-2002 11:21 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Once again.....you guys are comparing a DFI to a 4 stroke. Compare one(either DFI or 4s) to a carbed 2 stroke and see the difference. The DFI is designed to compete with 4 strokes in both efficiency and price but with better performance. Unfortunately they have not been able to prove better reliabilty, or that they are reliable at all.

The "Boating magazine" report did show decibels and the Mercury 4 stroke was the champ, then Honda, then Yamaha 4s, then Ficht, then Optimax. Ficht was also most expensive next to Honda. Mercury being the cheapest. Ficht and merc had the best warranty, Yamaha prorates and basically sucks.

Peter posted 09-09-2002 01:52 PM ET (US)     Profile for Peter  Send Email to Peter     
What's wrong with comparing carb'd 2-strokes, EFI 2-strokes or DFI 2-strokes to each other or to 4-strokes? For some transoms, they are all viable choices one could make.

The original topic subject matter was "Fuel Economy: 2-Stroke vs. 4-Stroke." I read this thread as an extension of that. I don't believe that anybody is arguing that a 4-stroke isn't more fuel efficient than a carburated 2-stroke -- they clearly are.

The only published comparisons that I really put much faith in are the ones done by independent sources that accept no advertising or otherwise have no interest in the outcome of the results. Powerboat Reports is the only publication that I'm aware of that meets that standard.


Bigshot posted 09-09-2002 04:04 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I agree but it seems that they are comparing a DFI to a 4s only. Remember when DFI came out and they compared it to carbed 2s? The results were amazing. Now what we need is for someone to compare a merc 225, merc 225efi, merc 225 Opti, and a merc 225 4S. Same can be done for Yamaha. Now that would shed some light on the whole argument.

Problem is...if you have a 1989 Yamaha 200 and want to repower, comparing a DFI to a 4s helps make your decision but what do they do compared to your 200 Yamaha or a new Yamaha 2002s. Joe is gonna go to the Yamaha dealer and say I want to repower....what do you have and what will it cost. Now Bob can say well Joe, if you repower with a 200 carbed, you will burn 10gph at 4k, spend 1k more and get the efi which will burn 9.3 and start easier, etc. Get the DFI for another $2500 and she will burn 7.8 and be even performance wise but much quieter etc. Go for the 4 strioke for yet another $1000 and burn 7.5 but performance will be XYZ compared to the 2s. Now that is the type of info the consumer needs.

What I try to do here is show people what MY Montauk did with a 90 Yamaha 2s and now with a 70 Zuki 4s. What are the pitfalls and performance figures and what do I burn GPH wise. I get at least 3 emails a month asking me If I would recommend the 70. I tell them what I know and even include the downfalls like a slower top speed and holeshot, more weight, etc. If that is acceptible for them, then yes I recommend it.

lhg posted 09-09-2002 04:55 PM ET (US)     Profile for lhg    
For what it's worth, as an aside, I saw figures from Mercury that indicated in 2001 model year, 70% of their engine sales were 2-stroke. In 2002, this figure has evidently dropped to 60%, with 4-stroke and Opti accounting for the rest. I don't know the breakdown between Opti and 4-stroke, but this would be a difficult comparison because the Opti's are for big boats and 4-strokes for smaller boats. I think in the smaller HP ranges, the 4-strokes are coming on strong.

We still don't know yet whether the DFI's are a dead end or not. It's too early in the game to tell, but they're putting up a good fight, and seem to out perform the best of the large 4-strokes so far. But with the possibility of supercharged 4-strokes out there, the DFI's may not last. My guess is once Mercury brings out their new 4-stroke high HP line-up, the price of Opti's could drop.

Am I correct in assuming that air pollution wise, the new 4-stroke outboards (and all I/O's and Inboards) are really no cleaner than the old muscle car engines of the 60's. Do they have any emission controls on them at all? So relative to our cars, they're still real air polluters?

Bigshot posted 09-10-2002 09:56 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Got to be better than the muscle cars, etc. If honda is using a v6 accord engine without a catalytic converter, it can't be that bad to the environment.

I don't think the EPA is really worried about emmisions as much as the oil slicks the 2 strokes leave behind.

If you run my Zuki on muffs, it is not much louder than in the water. therefore I believe it has a muffler systemm and little exhaust is run through the prop into the water.

kglinz posted 09-10-2002 11:07 AM ET (US)     Profile for kglinz  Send Email to kglinz     
I have been reading the posts about 2stroke/4stroke with much interest. I am repowering after 163 hours of use because of reliability concerns.I don't care much about 2 MPH or .1 MPG. How many hours of use are you guys getting from V6 Outboards.I am planning to replace my DFI 225s with the new Merc/Yamaha 4 Strokes and hope to get 1000 hrs from them.
Salmon Tub posted 09-10-2002 11:41 AM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
Bigshot, I am not sure how it is around the rest of the country, but here in California, the history of the pollution scenario went like this. We have lots of people and lots of cars. The higher ups decided that gas should be oxygenated. Then they decided that a new additive - MTBE was to be put in gas, it helped the fuel burn more completely on cold days. All gas in California now had MTBE. Then they find out that this stuff gets in to ground water and is deadly for everything. Then they realize that in 2 stroke outboards, that may not fully burn off all the fuel, this may be the same as just pouring the new gasoline into the water - oh no - very bad. They then decide to make the stiffest regs in the country regarding outboards. Once this is in place, they then decided to eliminate MTBE. It is slowly going away now. The intro of MTBE raised gas at the pump by 10 to 20 cents, you know re-tooling, blah, blah, blah. Can't buy cheap gas out of state. The elimination of MTBE raised gas prices another 10 - 20 cents, re-tooling, cost of bringing in gas from out of state, blah, blah, blah. In reality it is: Check, check, check, checkmate.
jimh posted 09-10-2002 12:57 PM ET (US)     Profile for jimh  Send Email to jimh     
In his July address to investment bankers, Brunswick CEO Buckley said the MERCURY outboard product mix was now 41-percent low emission engines. This is considerable growth from last year when the product mix was 34-percent low emission.
Bigshot posted 09-10-2002 01:39 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Like i said Tub....gas slicks in the water.

My guess is just that it has to be addressed and if they were THAT concerned they would have mandated Cats on I/O's etc. I think the MTBE(we had that crap in NJ) is a big reason and I personally am glad to see it go. CA has always been a pain in the butt with their own set of rules but hey.....you don't have to live there ya know:)

I on the other hand live in the last of the lawless states. We do not even have inspection or emmisions here....yet I have a 4 stroke.

jimh posted 10-09-2002 09:47 PM ET (US)     Profile for jimh  Send Email to jimh     
Here is an excellent article, written by an author with some credentials, of just this topic: 2-stroke versus 4-stroke outboard engines.

His observations are very astute. I don't recall anyone else with an analysis this acute:

http://www.boatmotors.com/outboard/outboard_motor_article.html

SuburbanBoy posted 10-10-2002 01:15 AM ET (US)     Profile for SuburbanBoy  Send Email to SuburbanBoy     
Why not put these engines on a dyno? That would eliminate the problem of optimizing the prop and engine height etc. Somewhere I have a video of my old Black Max on an outboard dyno. While it was executed in fire drill fashion and not the model for others to follow, the concept was sound. Use the dyno to help reduce home field advantages.

BTW, if (big if) I ever find the video, what is the "Acrobat" of the digital video world? Some day I could post it. You might howl as much as my old Merc did. It was a hoot.

sub

Peter posted 10-10-2002 07:50 AM ET (US)     Profile for Peter  Send Email to Peter     
Jim, thanks for leading us to that article. It gave me a nice explanation of why the fuel consumption of the 4-stroke 225 wasn't much different than the consumption of the 225 2-stroke EFI at higher speeds. Seems that direct fuel injection could be key to improving the somewhat lackluster 4-stroke performance but such improvement won't come without an additional weight penalty.

I agree with Surburbanboy -- seeing the raw results from a dyno comparision would be very interesting as well.

jimh posted 10-10-2002 08:49 AM ET (US)     Profile for jimh  Send Email to jimh     
Volkswagon is making a turbo-charged direct injection (TDI) diesel engine for their cars. Some owners are reporting almost 60 MPG with this engine.

See http://www.tdiclub.com/ for more details.

dgp posted 10-10-2002 09:21 AM ET (US)     Profile for dgp  Send Email to dgp     
jimh, I own a TDI and I consistently get 47 MPG combined city/highway driving. In the rest of the world the TDI badge means turbo-diesel-intercooled but here in the US VW is downplaying the diesel because of the mid-70's GM automotive diesel fiasco.
The "Wall Street Journal" recently had a story about the TDI and the tdiclub http://www.dieselforum.org/inthenews/WSJ_091002.html
Bigshot posted 10-10-2002 09:46 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Jim they have been making that engine since 97 or so....great engine. If I ever digress enough to be seen in a Bug, I would get the TDI.
dgp posted 10-10-2002 09:53 AM ET (US)     Profile for dgp  Send Email to dgp     
I have the Jetta (4 door sedan model) but you can get the TDI in the Beetle, Golf (2 or 4 door flange back) or Jetta.
Bigshot posted 10-10-2002 09:57 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I just figured out something. The reason I and most areso impressed is because we went from a carbed 2 stroke to 4 stroke. If I went head to head with a similar montauk with a 70 Jouhnson 2 stroke, I think the results would amaze some. If I did it against a 75hp Ficht, I may want to sell my engine. I agree the DFI is the way to go but I don't own one. He keeps talking about weight and price in that article. Last time I looked the Ficht and Yamaha 225 4 stroke are close in both weight and price.
kglinz posted 10-10-2002 11:17 AM ET (US)     Profile for kglinz  Send Email to kglinz     
I think this 2 Stroke / 4 Stroke thing could got on for ever. DFI is a great system. It was just put into production in outboards before all the problems were found and solved. Blam the EPA. Same thing happened to cars about 1969. Gas mileage and power went away. I think all outboards will go 4 stroke. I can think of 3, 2 stroke auto engine in the last 50 years. Saab & BMW had some in the 50s and Suzuki had 1 in a SUV in the 70s.
jimh posted 01-30-2007 10:57 PM ET (US)     Profile for jimh  Send Email to jimh     
[This discussion was revived after a being dormant for four and a half years by a new participant who wished to append to it some complaints about a particular brand and type of motor. These comments have been removed and the discussion closed to further comment. Please do not revive ancient discussions. If you have some urgent need to post your opinions on current motors and their performance, please feel free to start a fresh discussion. Thread closed.]

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