But the reality is that it can't, and that is the point.

There is really only a very narrow range of radii on the flywheel where mass can be removed and your 6kg example will simply have more of it in the same spot where the 5kg unit has removed it.

The flywheel is only 225mm or so in diameter. Almost all of the "r" in the MOI formula sits over the r/.7 area. Even the PP falls in that same part of net "r"

Oh, it was funny alright, just not in the way it was "about" me.
That is why I quoted it. lol

 

I've never actually seen the rx8 flywheel, yet. I was just talking in general about flywheels, but based on the lengths mazda has taken to squeeze every ounce of performance out of the car in other areas (intake, etc.) it makes sense that they would do the same for such an important component as the flywheel.

 

I'm probably wrong but I think I heard that the RX-8 flywheel was one from a previous Mazda model?? The hotter ticket for a lower MOI and lighter assembly would be to reduce the size of the clutch. We have one---a 7.25" (smaller than the stock RX8) single disc clutch mated to a custom flywheel that is both lighter than stock and has a better MOI (at least the clutch pack has a better MOI---no data on the custom flywheel).

I think the RX-8 market could benefit by someone making one of these scooby doobies. It could still easily handle the power loads and should be OK for the street and track crowd. You may have to replace it a little more often but a clutch is a consumable like brake pads, tires, etc.

Here is a link which reveals the standard clutch sizes that people use in racing:

http://www.hrpworld.com/index.cfm?tp...ction=category

 

Handle FI numbers? or are we talking only NA (as I know that's where you specialize)... because even if we have a 230whp FI rx8 vs a 230whp NA rx8 the torque numbers aren't the same...

 

Possibly, but not entirely.

HP is a function of torque. If you have a 230whp NA and a 230whp FI where those peak numbers are at the same RPM, then the torque at that RPM is the same.

Agreed, in general, you will see a different torque curve for each.

If the FI peaks at 230 at a lower RPM, they will have more torque at their peak power RPM than the NA, and vise versa. IF the FI peak torque is higher, then it means that the torque is dropping off faster than the NA to have the same power.

 

Yes I completely understand and didn't want to go into great depths.... moral of the story is with FI there will be more stress/wear and tear on the clutch.... and besides most FI people are hitting more than 230whp anyway.... I guess what I should have asked is up to what HP/Tq would Eric expect this welded assembly to withstand?

 

There are actually several that will "fit".
But now you are ignoring the balance of the whole rotating assembly.

 

I don't think that's where he was going..... he was more just questioning the depth of R&D that went into the Rx8 Flywheel


You guys sound like little school girls with all your bantering


except nowhere near as good looking

 

Compare it to an older one to see the kind of development that part had. Then add the fact that our rotating assembly has a different weight and operates at different rpms.
Most of that research and development went towards streetability anyway, performance assemblies are way different but would make a normal customer hate the car.

 

Your opinion is worthless.

 

^ Isn't most of this thread?

 

I don't know is a smaller single disk clutch assembly is practical on a street driven car. If you reduce the size of the clutch disk, you have to use a different friction material and a higher clamping force on that clutch disk. The lack of clutch slip and higher effort required to press the clutch, in traffic, would make this undesirable. This is the same reason some people prefer an automatic transmission over a manual.

 

Pedal effort is a result of balancing the lever-arm of the PP "fingers". You can actually have a very high clamping force with a low pedal effort. It would be very touchy, though.
The big problem is that the rotary motor rotating assembly has very low MOI on its own (without the flywheel) and very low torque at idle, so keeping the motor moving at low RPMs gets more and more difficult as you reduce the MOI of the flywheel/clutch.
Here's the "tidbit" for you that like Eric's style of delivering such things:

"Why smaller? - Why not larger?"

No, there is a lot of good stuff here, if you read between the lines.

 

Just curious, I've noticed an incredibly wide variation between 8s and the amount of pedal pressure needed on the OEM clutch. Mine being one of the hardest I've felt, and a friend having one of the lowest (felt like what a 100hp economy car would have). And plenty in between. Is the balancing point of the lever-arm so precise that manufacturing tolerances can make so big of a change?

 

Dunno. I've noticed a WIDE variance in pedal feel as well, even amongst totally stock setups.

Could be all kinds of interference and friction in the pedal and release bearings, wear at the contact points on the pressure plate or even worn friction material in the finger springs.

 

Well, that dinky little machined replacement flywheel I showed is currently on a rally car with well over 600bhp and 4wd. Coping fine, even with dropping the clutch on the starts...

You'd be very surprised what those little clutches can take with careful selection and setup, but the problem is not many road/track guys want to spend 3k on a clutch setup that'll only shave tenths off here and there.

 

FWIW I was able to adapt a Tilton 7.25" inch twin disk rally clutch to a stock size lightened flywheel while still retaining the stock throw out bearing, fork etc. Works quite well. The clutch assembly runs about $900 and the flywheel I think was another $300 or $400 or so. I think this is very similar to what Erik Meyer used but the flywheel I used it not as extremely lightened and I retained the stock clutch release mechanisms. I actually do some rally racing with the car so I wanted it somewhat streetable as well - it has a fast engagement but once you get used to that it's quite streetable.

I worked with AASCO Performance in Anaheim, CA to get it built. They have the specs on file now and I'm sure they'd be happy to make one for anyone who asks.

 

Yes, something very much like this is available now from AASCO in Anaheim, CA as I posted above. Total cost should be around $1300 give or take.

 

where is all this going?
i am dizzy.
OD

 

yeah... thread is a bit off topic I suppose... from high dyno sheets to powertrain loss to flywheels and clutches!

 

Ok, trying to sum up the original post to now, if I correctly have followed the key elements:
It's possible to have impressively high (for a NA Renesis) wheel horsepower and torque levels if the rest of the driveline has less parasitic drag than our stock drive line, therefore, in the quest for improvements, we ought not merely look at the engine; but the entire drive line.

Assuming that is the key take-away from the eight pages this discussion has so far amassed, are there any vendors offering more efficient but viable alternatives (clutch, transmission, differential, CV joints, etc)? Obviously, dropping in a Hewland 6 speed sequential transaxle is not a simple matter, although I am curious as to its feasibility, given the layout of the RX-8.

 

There is only 1 item that I am aware of that fits your criteria longpath, the REmedy water pump. though it's marketed as a reliability mod (rightfully so) and not a power mod, it does not struggle to push the water around as much as the OEM one, and it's been shown to have a positive effect on whp dyno charts.

At least from the vendors serving the community as a whole. I'd expect that there is a vendor offering a more efficient part for every single part of the drivetrain if you include price ranges that most of us simply can not pay.

 

coatings and treatments would be the easiest?

 

I knew that the REmedy pump was more efficient in preventing highspeed cavitation; but had not heard that it had any positive effect on whp. Was this with non-stock pulleys?

 

I'm assuming I'd have to tear down my differential and transmission so I could send the parts out for coating. For CV joints, I doubt I could get it back together again if I took it apart. Are there companies that makes CV joints that have the kind of friction fighting coatings and treatments we have discussed?