Optimax Lightened & Balanced FW gives Rapid Acceleration!!!!

[Paul E]

The fact it's an Optimax makes no difference, you do not get more power with a lightened flywheel.

If I was in the UK I'd definitely take Dave up on his offer, and I'd love to be proved wrong and wouldn't be afraid to admit it. I stand by my view though that if the flywheel is the ONLY thing changed then top speed will remain the same. I can't try it on my own boat as my powerhead has to be 100% stock.

Coniston would be the ultimate proving ground, consistent water with zero tide or current flowing and a true two way average of a constant top speed.

[Banana Shark Dave]

Hi 2jz

I have this to say to BeyondHelp and in his very own words( post he wrote earlier this year on this forum) " OPINION IS NOTHING WITHOUT PROOF"

Hornet at the very start of this thread has told you it works and he purchased the Lightened and Balanced FW from me.

Prior to the day he came and collect the FW, I'd never met him in my life and I've only seen him once since as he was stood on a jetty in Lanstone harbour.
He isn't even on my FB, he has no reason to lie to you.

Would anyone like to come out an witness me making a video and changing the parts, so that I can't be accused of fudging the results????

I can pretty much go out anytime, weather permitting.

Just to be clear, you will only gain extra speed on a prop that doesn't reach the engines full RPM. Why is it so hard for people to believe that a 300xs engines power starts dropping off from 5000rpm and that turning a flywheel that is 4kg lighter is easyier for the engine, hence it manages a few hundred more revs!!!!!!

[Renegade]

Why did fitting the flywheel affect the slip of the prop?

[Toffy]

You guys talked about this before, did ya...
http://www.boatmad.com/forum/showthread.php?t=23515

A lot of info and even contradicting results info on the net, it's not all that easy so it seems. I found the following link very informative on how to best machine a flywheel (though this guy is a non believer)
http://www.w8ji.com/rotating_mass_acceleration.htm

I didn't get the chance to read this ('cause I needed to register the forum) , but it is said to be very informative as well.
http://www.byuboyz.com/forums/showthread.php?927

[Jizm]

Following this with interest as an owner and user of a 3.0L Optimax.

[OCRDA]

Paul.
Get A115ho flywheel lightened for Coniston !! We all know that real racing is all about acceleration, balance & handling it's only gay racing that relies on eventually getting upto 60mph.
Hopefully will have something to test still records week !!

[beyondhelp]

I'd rather it was "Opinion is nothing without FACT" as it sounds nicer and more definitive than "Proof" and if I died with that stamped on my grave, or as the only lasting thing people remembered of me I'd be a happy guy!

Dave, your offer is genuine I can tell but sadly I don't own a race boat to try it on myself. I may however give your thought some consideration on your own boat, but I'd put it under extreme control conditions using extensive data logging kit. Please feel free to do some back to back top speed tests with or without first so you can double check your own findings.

Just to be clear. My only interest in this whole discussion is the claim of 1-3mph increase in top speed - nothing else.

We all know that real racing is all about acceleration, balance & handling.

SO TRUE!!

[Toffy]

Originally Posted by beyondhelp

My only interest in this whole discussion is the claim of 1-3mph increase in top speed - nothing else.

Don't forget about those beers afterwards !

[Paul E]

If I can't have one for racing there's no point Bob, plus top speed won't change

I like gay racing with other gay boats of the same spec anyway 😘

A 300xs would be nice to try though, Dave V's f2 has done 98...

[Banana Shark Dave]

Beyond Help

I don't have access to data loggers, dyno testers and neither did generations of racers/testers and tuners before us. They made do with stop watches and measured distances as I do for acceleration times. I am fortunate enough to have two separate gps's both with tracking though.

I do find it offensive that you can sit there and say that the hundreds of hrs of testing, machining, polishing ect.....are wrong, that other people who have tried it and had the same results are some how liars.

But you can't even be bothered to spend a few hrs of your time, expenses paid to come and see for yourself. I think you need to climb out of your arm chair stop being an argumenative hater ( yes you dragged this post up which no one had commented on for weeks if not months) and see what's going on in the real world!

I can assure you I did not make these claims lightly. I have through the course of this year conducted hrs upon hrs of testing, going out almost everyday.

After fitting the light FW for the first time, it quickly became apparent I would have to re speed test every prop and I did!!!

So in short COME AND PROVE ME WRONG!!!!!!!

[beyondhelp]

Originally Posted by Banana Shark Dave

Beyond Help

I don't have access to data loggers, dyno testers and neither did generations of racers/testers and tuners before us.

Thats why the boating world is so far behind the automotive engine tuning world with regards to engine management etc. I'll offend half of boat mad here probably but I'll use examples of many people still thinking that carbs can outperform EFI. It may be the case that they DO but the reason for that will be the lack of system development or understanding in the EFI world.

My job demands entire control of what it is I'm doing where measurements may still be questioned but data can be shown to support what I'm doing.

I do find it offensive that you can sit there and say that the hundreds of hrs of testing, machining, polishing ect.....are wrong, that other people who have tried it and had the same results are some how liars.

Firstly I said its not personal, and are you seriously taking offence to the fact that NOT I, but the entire basis for which physics dictates power/energy/forces at work (again this is not MY opinion this is science fact) disagree with your findings.
That is NOT personal, how can I tell this to you in a way that it does not become personal, or offensive? Some people just resist education of any kind. There are groups of people who STILL believe the world is flat!!! http://en.wikipedia.org/wiki/Flat_Earth_Society but I'm sure your not one of them

So moving on, initially I just wanted to highlight the fact that top speed must have been caused by something else, just not the flywheel, though as already said many times, they may or may not have other advantages.

But you can't even be bothered to spend a few hrs of your time, expenses paid to come and see for yourself. I think you need to climb out of your arm chair stop being an argumenative hater ( yes you dragged this post up which no one had commented on for weeks if not months) and see what's going on in the real world!

Err I didn't say that. I said that I'd have a think about it but give you an opportunity to do more testing to be 100% sure you want me to do this. I'd also need to prepare a system to record the data etc.

I can assure you I did not make these claims lightly. I have through the course of this year conducted hrs upon hrs of testing, going out almost everyday.

After fitting the light FW for the first time, it quickly became apparent I would have to re speed test every prop and I did!!!

So in short COME AND PROVE ME WRONG!!!!!!!

Looks like I'm going to have to Because if your getting more speed, its not the flywheel so where is it coming from!!!

[Banana Shark Dave]

Ok, when suits you?? Weather permitting, I will make myself available anytime that suits you.

Luckily in the Solent you can pretty much always find somewhere to test, no matter what the conditions are.

I know that I'm right, simply because I speed and accelerate test every prop as it arrives. I own over 20 props at anyone time and they are constantly changing and when I swapped the FW over I tested a prop and noticed the speed had increased. I then retested every prop and every prop that was over pitched gained rpm.

I then sold that FW and had to put a standard one back on, it was horrible like driving a car with the hand brake on. Because I do a huge amount of propeller work ( at least 4 hrs every night), I quickly noticed a top speed loss.

Hornet has seen the same and so have other people I have sold them to. I have sold over 10 higher pitch, lightened and balanced rev4/bravo 1 props to these people. Everyone has reported a speed increase and I have adjusted props to suit for them.

I cannot currently get enough 2nd hand FW's to meet the demand and I don't advertise, sales are through word of mouth. So I must be doing something right!!!
Same with the prop lightening, seems I sell one prop to a particular area and then I get more orders from the same place. I get messages from people to say they have recommended me to there friends. Again I am struggling to buy enough 2nd hand props to meet the demand and I can't make them fast enough.

[2jz]

They are all true enough but its based on an object it self. None of your findings has taken into consideration the performance of motor that drives this flywheel and the forces it takes to get it there. this is where the problem comes in to play with us reading thread and the results. Now the motor is performing to its maximum ability @ 5000rpm 60mph with heavy flywheel you cant possibly tell us making the motor work load lighter with lightened flywheel its rpm would stay the same. the rpm would increase ex(5200rpm) so would mph because prop is spinning faster. Here is where you gain extra mph because you have increased the motor ability to turn that same prop @5000rpm to 5200rpm.

[beyondhelp]

Dave, I don't have any time until December now. I'm exceptionally busy during the days at the moment. I actually do want to help. If it teaches you or I a little something then great.

From what you say it should be immediately obvious the top speed gained by changing the flywheel, which makes it all the more interesting.

In order to control the conditions the flywheels would both have to be equally balanced. The timing checked in both cases - but optimax has a proper timing wheel doesn't it? Unlike early Carb Mercs, and the equivalent removed mass from the engine (flywheel) Would need to be added onto the engine in order for it to remain the same weight. This way we isolate the flywheel on its own and NOTHING else. In addition, air temp, pressure, engine rpm, throttle position, trim angle (if possible may be tricky), Tides, wind. Then in an ideal world the test should be blind and the driver should not be told which one is fitted to the boat. Then say 6 test runs should be carried out in each direction then stopped and repeated with the alternative setup. Then all the data would be analysed after and averages created to give a definitive outcome, with raw data also published for analysis by others... Its a big job, but actually the data may be of real use to you if we can also tie it in with anything else that may help you...



2JZ you seem to understand this less than I thought, or you are not reading what I say. I'll be honest worries me if you work in the same industry as I do.

None of your findings has taken into consideration the performance of motor that drives this flywheel and the forces it takes to get it there.

How have you missed this? I'm going to be very direct here. Do you understand that 'get it there' is acceleration? Its during this time the flywheel as an energy store is being "charged up". How can I make it any clearer that once you ARE there it takes NO more energy to keep a flywheel AT a given speed if it was 1kg or 10kg, other than once again, frictional air losses, if say the 10kg wheel was larger etc. So to say "get it there" means you are completely missing the point, sorry. The getting it there (quicker) is accepted with a light flywheel, but the entire 3 page thread is not about "get it there" its about what changes when the acceleration has stopped and load/resistance = engine power out. Aka terminal velocity.

Now the motor is performing to its maximum ability @ 5000rpm 60mph with heavy flywheel you cant possibly tell us making the motor work load lighter with lightened flywheel its rpm would stay the same.

Yes I can and I'll keep saying it, err actually no I wont as I don't think you understand the physics behind it and its not my job to teach that!

you have increased the motor ability to turn that same prop @5000rpm to 5200rpm.

No, you have decreased the time it takes to do that as your flywheel requires less energy to get it there, once its there and the rate of acceleration is zero it makes no difference...

[Toffy]

I live a bit too far away, otherwise I would love to join this upcomming test in december.

Beyondhelp, can you think of a reason why Dave sees topspeed gaines time and time again ?
So far you've explained why it isn't possible. But if the december-test proves there actually is a speedgain, that would leave us with a unexplainable result.

Walking the path of empirical physics isn't easy (first result, then theory) but ever so interesting. I still feel like we miss out on something here...

Greets, T.

[Banana Shark Dave]

Beyond Help

Ok the timing is on the FW. As for testing blind, that would be pointless, I can tell as soon as I touch the throttle if it has a Lightened FW. It revs hard and furiously straight away lol

The difference is unmistakably big, it's not like did it, didn't it, kind of thing.

You can charge up and down all afternoon with the stock flywheel, I'll just need one run!!!!

The only criteria is the prop used doesn't reach max revs with the stock FW.

I'm happy to go first if you want and then you can play to your hearts content or until the sun goes down. But you won't be the speed I set.

I have approx 20 props at all times, you can pick anyone you want. The slowest prop on the stock FW will beat the fastest prop on the stock FW when you put the lightened FW on!!!!!!

If anyone else (who has commented on this thread already) wants to come and have a try, your more than welcome.

[2jz]

Originally Posted by Toffy

I live a bit too far away, otherwise I would love to join this upcomming test in december.

Beyondhelp, can you think of a reason why Dave sees topspeed gaines time and time again ?
So far you've explained why it isn't possible. But if the december-test proves there actually is a speedgain, that would leave us with a unexplainable result.

Walking the path of empirical physics isn't easy (first result, then theory) but ever so interesting. I still feel like we miss out on something here...

Greets, T.

The reason why dave can see top speed gain time and time again is because the motor ability gain more rpm with lightened flywheel. beyondhelp is basing his findings on heavy flywheel and lightened flywheel reaches same rpm results is the same AND THAT IS TRUE IN HIS THEORY. Beyondhelp fails to understand that dave as gained couple hundred rpm with lightened flywheel which in turns = gained topspeed.


beyondhelp
A flywheel is quoted as a store of "angular kinetic energy". I will say again: You could have a 100kg flywheel on a 100hp engine, OR a 1kg flywheel, Other than the drag caused by weight of the heavier flywheel once up to lets say 6000 rpm and if you HELD IT THERE by applying the same amount of resistance to the energy out you would measure the opposing torque required to hold both engines at 6000 rpm as EXACTLY THE SAME. The flywheel makes NO difference once the engine RPM has stabilised.

"OPINION IS NOTHING WITHOUT PROOF" BeyondHelp

Three members have all said and proved quicker acceleration and gained top speed with their GPS system with lightened flywheel

Beyondhelp where is your actual proof to say we are wrong

[Banana Shark Dave]

I am wondering if Beyond Help is basing his theory on four stroke car engines!!!!

Beyond Help you do realise we are talking about two stroke engines with NO TORQUE??????

Do you have any idea how much your speed drops off the more people get in the boat??? Two Stroke outboards aren't like cars where they go the same speed with one or five people!!!!

Put 5 people in my boat and it's almost 8m long and you won't go over 40mph and that's a fact!!!!!

2JZ find me on FB mate!!! If you PM me I'll give you my email and I'll show you what I'm doing with props to really get some Speed and Acceleration out of them!!!!

[beyondhelp]

Ok last post on the subject. When its clear not even the foundation of forces or engine dynamics are understood, and a total blindness to even consider them there is nothing I can do to help.

But I will address a few final points which again are completely wrong, but I'm not going to post again answers to questions which I have already said several times.

Beyond Help you do realise we are talking about two stroke engines with NO TORQUE??????

I can't ignore this as its complete nonsense. Mercury specifies its 300sx 20inch mid as 300hp, 3160cc, 5400-6100 rpm.

Firstly lets calculate its torque. I'm going to give the engine 10% losses from the prop to crank shaft output. Many here perhaps would argue the transmission losses would be higher.

300x1.1 = Crank shaft power 330hp.

Lets take the middle of 5400-6100 rpm which is 5750 rpm.

Now we have RPM 5750, HP 330 and want to work the torque. That's easy.

Torque = Horsepower x 5252 / rpm, you can research that for yourself if you want to know why that's the case.

So, (330x5252)/5752 = 301lb/ft... Now to get to the figure we are interested in.... lb/ft per litre (so comparisons can be made)

301/3.160 = 95lb/ft per litre.

In order to compare this with another engine I need to find a 300hp 4 stroke non supercharged outboard. Mercury don't make one, so will use Yamaha as an example.

Most recent Yamaha F300 is 300hp at 5500 rpm. Its 4169cc.

Lets add the same losses, which again is 330hp @ 5500.

So, (330x5252)/5500 = 315lb/ft

Finally:

315/4.169 = 75.5lb/ft per litre.

So Optimax makes 20lb/ft more per litre than the most modern Yam 4 stroke...

2 strokes ALWAYS produce more torque than a similar 4 stroke, and it doesn't take a rocket scientist to see why.
For every 720 crank shaft degrees each piston in a 4 stroke would have completed ONE power cycle. In a 2 stroke each piston would have completed TWO power cycles, thus per litre of engine capacity would produce more torque...

One last comment on this, if you have a Banana Shark 770 rib with a 300xs on it and only get 40mph with 5 people, that to me doesn't sound right. I see people are getting 60mph with 250 verados.

Wonder what Banana Shark would have to say?

Anyway, enough from me now. Also I have had offer from another boat owner who I'm going to test on his boat with when I get a chance, who is non biased, and already has a well setup boat.

[Cookee]

Originally Posted by beyondhelp

One last comment on this, if you have a Banana Shark 770 rib with a 300xs on it and only get 40mph with 5 people, that to me doesn't sound right. I see people are getting 60mph with 250 verados.

Wonder what Banana Shark would have to say?

What would I have to say about what? I have met Dave on a couple of occasions and have had a number of email conversations about the boat and performance - he has dome way more work on props and flywheels than we have ever done and therefore you and he know more about this than I do - by the way I think you and Dave both make sense as in the theory is spot on as I understand it and if it goes quicker then it does!