8 Maniac

iTrader: (1)

I dont know if I'd say they tried to BS us... if they were BSing, they should have tried BSing the wheel power numbers... it doesn't matter what amount of power is made at the flywheel really. The only problem is we knew their method of calculating flywheel power was off.

Revolver

Gawd.

I thought Mazfix made it perfectly clear he's not trying to BS anyone and nor is he trying to sell something at this stage. Build a bridge.

Let's hope he takes Brettus' advice and starts a new thread so people can actually discuss the kit rather than beat their chests about how damn clever and clued up they are.

rx 8speciale

iTrader: (3)

U guys are a bunch of arrogant mtf that dont understand nothing. The op clearly was not trying to bs anyone. Lmao with ur comment paulsoner and gang

Charles R. Hill

iTrader: (7)

Powertrain losses in the M/T RX-8 are usually around 40 h.p. (stock flywheel) and about 25 h.p. (light flywheel). To use percentages is erroneous and the aftermarket tends to do this because of a misunderstanding of the OEM's operations.

8 Maniac

iTrader: (1)

First off, I'm hoping that was intentional. Otherwise, proper english dictates that you should have said "don't understand anything".

Second, you're the arrogant one. Once a few people reiterated what paul said and clarified why he posted it, you simply devolved into insults without providing anything useful. Paul was actually helping Mazfix out by pointing out that they will have problems if they don't review information they post before they post it. Similar to how most people would expect a newspaper to proof read and spellcheck their articles before they get published. It makes perfect sense to advise them for their future benefit in a rational and composed manner like paul did. If you disagree with that, then you're either being stubborn or stupid.

Good day sir.

skc

Archie and Mazfix have been avid supporters of the RX8 community in Australia with two outings at the Nationals.Their car was also used in a test against other modified cars for a magazine article (I think an excerpt can be found on the forum).

I have also witnessed the car around the track many times over the last three years and it works flawlessly. I have also seen it on track days where two drivers have had the car running back to back sessions.

The kit is on numerous cars and to date I have not heard one complaint.

Mazfix has also contributed greatly to the advancement of rotaries in the local community and should be commended for his efforts.

zoom44

yes they should be commended. AND they should fix errors when they make them. they did. move on. everyone.

zoom44

oh i love this debate

It's not one or the other Ray its a bit of both there's a basic loss of x hp- wheels off the ground in neutral/brakes off/ engine off spin the tires by hand. calculate the effort needed to turn them,thats how much the loss starts at.

But as rpm increases the friction and heat increases and the loss increases. different gears also change the loss. this change from base loss to total/final loss is where the percentage comes in.

so standing still you can say "drivetrain losses are 40 hp" but once its moving "about 15%" works too because its difficult to pin it down to an exact number.

the only real way ( and this pertains to the original assertion of the op about the calculated flywheel power) to find out is to measure the engine hp on an engine dyno. then put it in a car and strap that to a chassis dyno and find the difference. and even then it only matters for that time on that chassis dyno.

thats why calculating flywheel numbers from chassis dynos is pure BS and shouldnt be done. EVER. its just candy for the rubes.

Brettus

iTrader: (2)

Think you have that wrong Charles . You don't majically reduce the drivetrain losses by fitting a light flywheel .

Charles R. Hill

iTrader: (7)

I knew the nosepickers/navel contemplators would appear after my comment. The drivetrain begins with the bolts connecting the flywheel to the engine. So Brettus, yes, reducing drivetrain losses can happen when we install lightweight flywheels.

It isn't a fixed number when installing lighter flywheels, but I have a pretty good record of indicating to people what their likely flywheel h.p. numbers are going to be as compared to the RWHP numbers they have gleaned and those are the two values I use. This is called "bench racing" and it will never go away.

The use of percentages to calculate drivetrain losses is flawed, and not for reasons most might think, but people never seem to ask me to explain THAT notion. Probably because there is no debating it, it is not embracing some magical math that we can all speculate about, and nobody can feel smarter for learning it.

The rest of you are free to follow or eschew this info as you see fit.

zoom44

did you just call me names?

Brettus

iTrader: (2)

A light weight flywheel reduces the hp needed to accelerate the flywheel so you have more hp available to accelerate the car but it does NOT reduce the drivetrain losses . So you cant measure the effect of a lightweight flywheel on a dyno .

paulmasoner

iTrader: (1)

then pray tell, how do you define drivetrain loss?

this is pretty commonly accepted across the entire automotive community

Mawnee

I fill my flywheel with nitrogen. It makes mo betta powa! Only newbs use steel.

Brettus

iTrader: (2)

what is commonly accepted ?
Lumping the flywheel in with frictional losses is more or less the the same as lumping in the weight of the car as a 'drivetrain loss' .

paulmasoner

iTrader: (1)

who said anything about fricional loss... we are talking drivetrain loss. that includes anything involving moment of inertia and angular momentum. any rotational weight is a parasitic loss. look it up, the math is calculus based, but the principles are easy to understand

Brettus

iTrader: (2)

let me ask you this - how much power does it take to keep a flywheel rotating at 9000 rpm that is already rotating at 9000rpm assuming zero friction ?

Work that out and you will see what i'm getting at .

Mawnee

42? o.0

laythor

i like this new universe where mass and friction do not exist

paulmasoner

iTrader: (1)

well in never never land, zero friction means zero power required to maintain rotation. when you live in that world where your drivetrain never changes its rotational speed, then i'll listen to you.
moment of inertia is an objects resistance to CHANGE in rotation.

http://en.wikipedia.org/wiki/List_of_moments_of_inertia

4rth graphic down should get you started, learn the math, figure it out, then come back and see where you're thinking is flawed

Brettus

iTrader: (2)

heh good guess .
The answer is zero - it takes virtually no hp to keep it going except for a tiny bit to overcome air resistance .

laythor

i wish i could keep the RPM of my flywheel completely constant.. i fail at driving

Brettus

iTrader: (2)

Where your thinking is flawed Paul is that you have not defined 'drivetrain losses' correctly .

paulmasoner

iTrader: (1)

actually i did define it, you never bothered to answer how YOU define it... but it seems from your posts you think the only losses in a drivetrain are from friction alone. thats ONLY true if you never change the rotational velocity of the parts. if you dont get that, i give up, and its disappointing

paulmasoner

iTrader: (1)

tell ya what, go attach 50 pounds of lead weights to your driveshaft. dyno your car, pull the weights off, dyno again. jeez