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

[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 done 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!

[Banana Shark Dave]

Beyond Help, I still don't know what your name is, isn't it about time you introduced yourself???

Firstly I have never conducted speed tests with 5 people on the boat. Whenever I have had that many on the boat there's been kids and I havnt been going silly fast. However I can feel a huge difference in the boat and I would be surprised if it went much faster than 40. But that's neither here not there.

Ok regarding the well set up boat and testing. I have a stock FW, a FW that is at the correct weight not to stall on Tick Over and the Lightest Stock FW I have ever seen at 4516grams!!!! Unless you buy a FW from me I fail to see what you are going to achieve on someone else's boat. Simonsmotorsport FW are 2kg heavier than mine, so the results arent going to be the same. However I notice on there website they are claiming 1-3mph speed gain. If this wasn't true, someone in the US would sue them!!!! After all the U.S. is compensation crazy!!!!

I have over 20 props several are the same, but in various states of modification, from stock standard, to 2150 grams lighter than stock. In order to conduct this test you need a slightly over pitched prop, if it already hit's the limiter then it will accelerate faster but won't go quicker!

Biase doesn't come into it, the difference between stock and lightened is just so great. It's like getting on a 600cc motorbike or getting on a 1000cc motorbike. There both fast, just one is very noticeably faster than the other!

Everynight I spend at least 4hrs working in my garage with props or FW or developing new ideas. I'll be the first to admit that not everything works, In fact something's are a total disaster. Recent Mercury High five propeller modifactions spring to mind :/ a Bravo 1 prop I thinned to much in the rear hub, exposing the "1" that was recessed also wasn't a great move. With the welder on the lowest power setting trying to weld this back up was a total nightmare :-/

However instead of sitting in my armchair criticising other people's work and doing naf all, I always have ago!!! Over the years I have made all sorts of things from Flying Fish ( came 2nd at the bird man of Bognor), to the Worlds Fastest Motorised Bar Stool ( couldn't afford to get Guiness to verify this, it was going to cost about 5k, however if your doubting my claims, it still runs come and have ago at that as well......I'm lightening the FW first though haha), to building Racing Lawn Mowers, I've built my own Off road car, a CBR 1100 powered kit car................the list go's one and on.

The point is I am a DO'er not a Groaner!!! So why don't you Do something!!!!! Rather than keep bothering me???

The Only way your going to prove me wrong is to come and have ago, in my boat. That way there's no disputing the findings!!!

I'll even buy you lunch in the Folly and a pint if you want one.

[cybergibbons]

The idea that two strokes have no torque seems to come from motorbikes - it's a misconception I have often heard.

I don't understand what difference between a four stroke and two stroke in this argument though.

To increase the top speed of a boat, you need more power. There is no doubt about this.

A flywheel doesn't consume engine power at fixed RPM. It requires more power to accelerate a heavy flywheel, but at fixed RPM they are exactly the same.

You can tell that a flywheel doesn't consume power because the only place that significant power could go is heat and flywheels don't generate heat.

I don't understand the dynamics of boats that plane, so I can't say how much extra power you would need for 4mph of top-end gain. It's going to be more than 10hp though. That's 7.5kW of extra power, the only place where that could have been wasted before is heat. There is simply no way that much heat is being generated by a flywheel.

[cybergibbons]

Originally Posted by Banana Shark Dave

Simonsmotorsport FW are 2kg heavier than mine, so the results arent going to be the same. However I notice on there website they are claiming 1-3mph speed gain. If this wasn't true, someone in the US would sue them!!!! After all the U.S. is compensation crazy!!!!

US consumer protection law is terrible. People can sell products making all sorts of claims and get away with it. To sue them, you'd need to spend an awful lot of time and effort gathering robust data, and then you'd only really be able to claim limited damages.

[Toffy]

Still think you guys should go out and test this thing together.
Like Cookee says you both make sense.

Long shot but I still gonna mention it.
Could it be that a standard flywheel isn't as balanced as a lightened flywheel ? Therefore a standard flywheel generates a bit more heat and frictional losses and eats up a bit more power compared to the balanced flywheel... I find it very hard to believe myself this would totally explain the speed- and rpmgains, but it's the only true difference I can think of for now...

If the above is true, then only balancing a flywheel would lead to speedgain, not making it lighter.

[Renegade]

With respect Dave, you did state put 5 people in the rib it wont go over 40 mph 'fact'.

[Sam1cats]

I would just like to quote a few facts about this Process of lightning flywheel You say You Tune cars than what about this I raced bat boats for a few years with 5.7 V8 This is going a little bit away from the subject of flywheel But does make a lot of sense When you put less oil in an engine But just enough for it to Pump what do you think happens When the crankshaft is not smothered With oil. The RPMs are raised with ease As there is nothing to slow the crank Shaft down And this leads to the same process, As a Flywheel It takes horsepower to spin a crank in the oil And it takes horsepower to spin a heavy flywheel So by making the flywheel lighter You increase horsepower At higher rpm Which means you rev higher Which equals more Speed Not saying that you don't understand engine's But I've been doing engines in boats for 20 years And I can assure you I know what I'm talking about So I suggest you just stick to your Chipping which you do To your cars Just keep in Mind when an outboard leaves a factory specially Mercurys They are highly tuned already As mercury engines are the highest performance outboard on the market So I think if you do not understand how outboards work Then I don't think you should Disagree with some of the best people out here I can assure you Lighting the flywheel will make a big difference In the right application.

[Paul E]

LIGHTENING A FLYWHEEL DOES NOT GIVE YOU MORE HORSEPOWER.

It allows you to reach a given rpm quicker but it has zero influence on how much horsepower is made. A flywheel does not rob an engine of power, it is merely storing kinetic energy the engine has made via internal combustion. Anyone that claims otherwise cannot then claim to know about engines.

[cossie69]

Less engine oil means lower compression resistance faster engine but shorter life thats all nothing to do with oil on crank buddy ! as for FW better acceleration no top end gain at all thats just from personal experiance, still a good mod

[Sam1cats]

Right not going to keep on having an argument But a flywheel takes hp To spin .So if you lighten Your flywheel You will gain horsepower But you do lose torque But you don't always need torque at the top end To gain speed

[Paul E]

Wow so now you gain horsepower AND lose torque? 😐

[cossie69]

Torque =acceleration, bhp = top end, fw improves torque not bhp Fact hence better acceleration

[beyondhelp]

Hahahah honestly. I really don't know what to say to the posts above. I'm actually laughing out loud at how LITTLE seems to be understood here.

Made my day! I share Pauls fustration or perhaps its plain disbelief!

Wow just wow!

P.s. sam1cats your oil issue you are referring to is known in the industry as windage... but it has nothing to do with flywheels.


pps not aimed at you cossie, you are on the right lines

[maz928]

Firstly well done Dave for sharing your finding with us on such an interesting subject.

Anyone who races or has raced or even just wants there boat to go just a bit faster spends most of the time thinking and going out testing to get that extra
1mph or 100 rpm.You know who you are......Ive spent over ten years trying to find the edge within the rules !!!.

I've met many 2 stroke engine turning over the years and the very BEST of them had one thing in common they always kept an open mind to engine tuning and tried many things which went against common theory's on engine tuning many of which didn't work but every now and again came across something that worked.

Dave has come crossed something that has worked to give him a bit extra speed so I say well done Dave and he's also prepared to share his findings with a day out in his boat .... Top guy

Looks like Dave's has changed the way his engine delivers the torque through better acceleration and thus allowing him to pull a larger pitched prop and gain some top speed.

I came across this web site www.uucmoterwerks.com/flywheel/
Look at performance effects of a lighten flywheel...worth a read.

Open minded people never stop learning ......

[Banana Shark Dave]

OMG YOUR FRUSTRATED!!!!!!

It's really simple it works!!!!!! You have been offered countless chances to get in the boat and prove me wrong.

You still have the chance, if your not prepared to take it, I can only assume you know you will be proved wrong!!!!!!!

[cybergibbons]

There are so many people in the tuning industry that don't even understand the basics like power and torque. Making engines work better is really quite formulaic and understood - the people that make it out to be a black art or that it requires an open mind don't understand the subject matter well enough. You can make gains by making random changes, but it's far easier to understand what is going on beforehand.

The linked page about lightened flywheels has some sense but perpetuates some common misconceptions. The lightened flywheel means that less power is needed to accelerate the flywheel. There isn't any more power under steady-state conditions though. It's just not possible.

The analogy of carrying a light weight and a heavy weight to the top of a hill is a good one. The heavy weight is harder to carry to the top. Once they are both there though, it makes no difference. And you can't carry either one higher than the top of the hill regardless.

[pro-rig]

Stick it on a dyno and compare the 2, simples

[cybergibbons]

Exactly.

There are a few services companies down that way that have dynos. Why not get it on one of them?

[Ciao]

I went down this road before the Guernsey 3B World Championships in 1986 - (Wooden Stapley Catamaran / Yamaha 90).

I tested, slightly better acceleration - No improvement on top speed.

I sold the light weight flywheel to a fellow 3B competitor in Jersey.

Slightly better acceleration - No improvement on top speed. (Phantom 16' race deck / Yamaha 90).

He then sold the "Hot Potato" onto someone else.

It became a game of Pass the Parcel with no end result.

[Paul E]

Originally Posted by pro-rig

Stick it on a dyno and compare the 2, simples

At a constant rpm the power will be identical.