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

[motorvator]

Pah you and your simplistic calculations, you're just as bad as that Newton fella.

It's a boat you see and physics doesn't apply here.

[Zander]

Originally Posted by Paul E

Prop slip calcs have NOTHING to do with lightening flywheels.

Can we please separate lightened props and lightened flywheels!

The way modern engines make their horsepower (torque instead of rpm) make the way you prop boats change. I can ping small props off the limiter easily and go nowhere, I can also add pitch and keep adding pitch and still attain similar rpm simply by propping to where the engine produces the most power and torque. As the pitch increases the speed increases to a point. Adding a lighter flywheel to my 'over pitched' prop of choice will improve acceleration, not top speed. Lightening the propeller and making it more efficient will make it easier to spin (in water), in theory adding more speed and rpm.

I can also see 3-4mph difference in peak speeds on any given day simply by changing direction, or by bumping the trim slightly, making any actual increases or decreases pretty subjective.

+1

Just read the whole thread and it´s.... Interesting but I have to agree on what Beardy said here.
Here in Sweden when we race "only" E-tec H.O and Optimax Pro Xs´s (115 and 150) we noticed that the Pro Xs REALLY likes high pitch propps. To use all that torque is the key. E-tec likes abit more rev but not nearly as much as a old yammie 90 or XR2.
( My gen2 200XS will rev like a pro tho )
Since we are not allowed to have lightend flywheels in racing I dont really know if it makes a different.
However, when making the propp lighter, you also making it thinner. That is the most bennefit from lightening the propp IMO. Less drag is more important than the weight in this case.

My 5 cents.

[2jz]

Originally Posted by motorvator

Pah you and your simplistic calculations, you're just as bad as that Newton fella.

It's a boat you see and physics doesn't apply here.

Lol maybe paule/racefan can understand above quote better lol
YOUR OPINION IS NOTHING WITHOUT PROOF.
1)have you tried lightened flywheel =NO
2)has anyone said they bought dave lightened flywheel and the finding are wrong=NO
3)have provide a lot of your BS opinion=yes:-)

[Paul E]

Originally Posted by 2jz

Lol maybe paule/racefan can understand above quote better lol
YOUR OPINION IS NOTHING WITHOUT PROOF.
1)have you tried lightened flywheel =NO
2)has anyone said they bought dave lightened flywheel and the finding are wrong=NO
3)have provide a lot of your BS opinion=yes:-)

I've seen two people on this thread who have one, and their new found top speed can quite easily be attributed to something else. I've also seen some bullshit numbers you provided, and still won't say where you got them from! David's own test numbers have huge variation and inconsistencies

[motorvator]

Originally Posted by 2jz

Lol maybe paule/racefan can understand above quote better lol
YOUR OPINION IS NOTHING WITHOUT PROOF.
1)have you tried lightened flywheel =NO
2)has anyone said they bought dave lightened flywheel and the finding are wrong=NO
3)have provide a lot of your BS opinion=yes:-)

Lol, you're an excitable chap aren't you!

A lot of my bullshit opinion? I've made one post trying to enlighten you to Newtons laws of motion. You know, the stuff that scientists use to explain the universe and everything. But obviously you know better.

Dave and I know each other well enough to have a discussion and I let him know my opinion as to why he may be seeing the results he is.

So jog on matey.

[2jz]

Originally Posted by motorvator

Lol, you're an excitable chap aren't you!

A lot of my bullshit opinion? I've made one post trying to enlighten you to Newtons laws of motion. You know, the stuff that scientists use to explain the universe and everything. But obviously you know better.

Dave and I know each other well enough to have a discussion and I let him know my opinion as to why he may be seeing the results he is.

So jog on matey.

Hey im sorry if reply wasn't clear and you misunderstand it.I agree with everything you said but reply wasn't meant for you mate. Im also talking with Dave to get two of my flywheel lightened

[Paul E]

So where did your figures come from?

[Banana Shark Dave]

paul the prop slip calculators are a useful guide but not even close to 100% accurate. They are also really dependant on the accuracy of the information given to them.

For example they don't make it clear you need to add another 1" of pitch for cupping. How does that work, I have props with slight cupping and I have props with loads of cupping. I have several PowerTech props that come with enormous cupping straight from the manufacturer, do you add an inch for those or is it included in the manufactures measurement of pitch. I have several bravo 1 21 props, if I put them on the pitch gauge, everyone is different!!! Some are nearly 22's!!!

It doesn't tell you you need to add 2" of pitch for 4 blade props. What do you do with progressive pitch props???? You are taught when you re pitch a prop only between 1/3 and 1/2 of the prop has to be at the new pitch. You simply cannot bend the prop closest to the hub when you re pitch. So what do enter for for a 4 blade progressive pitch prop that has been re pitched from a 23 to a 24 with lots of cupping???

So in short 2JZ's testing is probably exactly as he says. The bulk of the pitch on a progressive pitch prop is the advertised amount, however the higher you Rev it the higher the pitch gets!!!

All of the people on here that are adamant that Lightened FW's don't rev higher, why isn't one of you prepared to come testing????

Could any of you people care to explain why the 300xs engine makes 20hp less than the 300x??? Mercury clearly say it's because the 300xs has a belt driven air compressor. So it's ok if you add something to 'drive train' ( call it what you like) to accept that uses power, but you can't accept if you remove something you get power back??? Strange Way of thinking!!!!!

I have news for you I have now lightened the compressor wheel its on the 'drive train' the amount removed isn't huge and I'm not going to conduct lots of tests.

I shall do a few runs with a couple of different props, but I'm around 6.5kg removed off the weight the 'drive train' has to turn before its pushing props around!! i do know one thing for sure, it's never gone as fast as it does now!!!

Once you used a Properly lightened Rev4 or Bravo 1 that's 2.1kg lighter than stock and has had the exhaust tube/defuser trimmed to match the boat and remove the stern lift, you'll never go back!!!!

[Paul E]

Originally Posted by Banana Shark Dave

paul the prop slip calculators are a useful guide but not even close to 100% accurate. They are also really dependant on the accuracy of the information given to them.

Pretty sure it was me that told you that a week or so ago on Facebook!! If the inputted data is right then they are 100% accurate, maths doesn't lie!! (Neither does physics)

Originally Posted by Banana Shark Dave

It doesn't tell you you need to add 2" of pitch for 4 blade props.

You don't do that to fudge numbers on a slip calculator. That's a general rule for if you're changing from a 3 blader to a 4 blader, reduce 2" of pitch to keep the same rpm. Prop slip calcs give a fundamental reason for that, 4 blade props slip
less than 3 blades! Not rocket science.

Originally Posted by Banana Shark Dave

So in short 2JZ's testing is probably exactly as he says.

He hasn't said where he plucked those numbers from, but I can guess...

Originally Posted by Banana Shark Dave

All of the people on here that are adamant that Lightened FW's don't rev higher, why isn't one of you prepared to come testing????

For one I live in Guernsey. For two I can't run a lightened flywheel in my class anyway. For three, as Beyondhelp says until you have 100% controlled environment and test conditions any gains can easily be attributed to other things.

Originally Posted by Banana Shark Dave

Could any of you people care to explain why the 300xs engine makes 20hp less than the 300x??? Mercury clearly say it's because the 300xs has a belt driven air compressor. So it's ok if you add something to 'drive train' ( call it what you like) to accept that uses power, but you can't accept if you remove something you get power back??? Strange Way of thinking!!!!!

The compressor does rob power, the flywheel does not. The compressor is subject to friction, which turns some of the energy inputted into heat and sound. The flywheel is an energy store, and doesn't lose any of the kinetic energy supplied from the pistons and crank. All of it's energy is transferred back to the crank and pistons, and via the driveshaft to the propeller. The flywheel is not a part of the 'drivetrain', neither is the compressor. Aside from the compressor, the 300X and 300XS are also quite different engines using very different technology. If you were to make the gearbox more efficient, then you'd absolutely gain horsepower at the prop.

You can't also claim that one of your modified Bravo 1s or Rev 4s will transform any boat!

[motorvator]

Dave you do realise the difference between the compressor wheel and the flywheel surely?

The compressor itself is there doing work. The energy used is transferred to the air that is being compressed which in turn is released witghin the combustion process. Not totally efficient as there are large losses to heat in the process.

Lightening the compressor wheel will have exactly the same effect as lightening a flywheel. Improve acceleration but no difference to the net power output of your motor.

[2jz]

After testing, the 300X made exactly 326*hp stock with the XS making 306 hp. They both made over 300 ft lb of torque however the X rev'd to 7000 with more after peak power (over-rev) than the larger displacement XS. This explains the larger top speed numbers we have all seen from the X. The good news is the XS can be made to run with and beat up the X with bolt on parts. This is possible while still retaining the 4.5 gal per hour fuel savings enjoyed running the XS. You may wonder why the 3.2 is less powerful than the 3.0 liter? It is simple. The air pump. This air compressor pump is basically a dead single cylinder being drug along for the ride to push air and fuel into the direct inject chamber (also called parasitic drag). This is an awesome design however; nothing is free. It takes 20 hp to run that pump. Once the 3.2 XS is upgraded with level 1.1 spec, the XS becomes a contender to the X while still saving almost 5 gal per hour. DBR.Inc

[2jz]

DBR Mercury 300 XS Level 1.1 Kit: http://youtu.be/HbzhBgSBoKM

Paule/beyondhelp here are your test results and you pay close attention to video you will see motor has lightened flywheel on during testing.
This shows Dave's finding are 100% TRUE

[Paul E]

Alongside ECU and Intake mods!!

[Paul E]

Originally Posted by 2jz

DBR Mercury 300 XS Level 1.1 Kit: http://youtu.be/HbzhBgSBoKM

Paule/beyondhelp here are your test results and you pay close attention to video you will see motor has lightened flywheel on during testing.
This shows Dave's finding are 100% TRUE

I just watched that whole video. What the hell makes you think that those results are from a lighter flywheel?? You're dumber than I thought!

[2jz]

Originally Posted by Paul E

Alongside ECU and Intake mods!!

Do you see any cowling on motor while on dyno=NO
Dyno shows motor revving to 6800rpm that is what ecu is for stock is 6400rpm

if you want to get technical compare dyno results up to 6400 rpm you can clearly see power differences between both

[Paul E]

Originally Posted by 2jz

Do you see any cowling on motor while on dyno=NO
Dyno shows motor revving to 6800rpm that is what ecu is for stock is 6400rpm

if you want to get technical compare dyno results up to 6400 rpm you can clearly see power differences between both

What's included in the 1.1 DBR kit then? A flywheel and a cowl vent? Get real!!

[Paul E]

The flywheel is actually an optional extra, because it adds no power!

[racefan]

Originally Posted by 2jz

DBR Mercury 300 XS Level 1.1 Kit: http://youtu.be/HbzhBgSBoKM

Paule/beyondhelp here are your test results and you pay close attention to video you will see motor has lightened flywheel on during testing.
This shows Dave's finding are 100% TRUE

That's actually quite interesting. The level 1.1 kit comprises of the following:

ECU recalibration upgrade optimizes fuel, oil and ignition curves and trims. This re calibration has been a year in development and raises the rev limit to 7000 rpm and increase torque and hp by 25.
Aluminum anodized velocity stack
300X style intake vent
lower exhaust gas temp that increases gear case life
Easy to understand instructions with templates for mounting vent and air temp sensor
Optional Billet custom flywheel (optional @$1000 additional charge)

The lightweight flywheel is advised as " the optional billet flywheel and pick up more acceleration and high rpm engine balance for greater reliability."

(you see that. light flywheel (optional) gives more acceleration, but the kit works with out)

So, to get approx an additional 25hp, which equates to 3-4mph, you have to do all the above modifications.

Or you can just buy a lightened flywheel from Mr Webber, and you achieve identical results as the Dave Bush Racing kit.


Some one needs to tell Dave Bush to stop wasting his time, and buy a lathe.

[Paul E]

This is quoted directly from the DBR website, in the product info for the 1.1 kit in the video.

"Add the optional billet flywheel and pick up more acceleration and high rpm engine balance for greater reliability. We strongly recommend balancing (on any flywheel) as we have seen failure due to out of balance modified steel wheels. If you lighten yours...balance it. The lighter the flywheel the harder the acceleration. We have found the perfect weight to inertia ratio to gain the most acceleration and also retain stock idle and shift characteristics."

NO mention of additional speed from the optional flywheel. The additional speed and rpm in the 1.1 kit are from an ECU remap, repositioned sensors and a new intake kit for both the motor and cowl. Pretty sure Dave Bush knows his shit.

[racefan]

Originally Posted by Paul E

You're dumber than I thought!

Which makes him the perfect customer for a flywheel purchase