58mm pulley

[Justin14100]

now you need to find specs of bearing  for differences in rpm, if there is one!

After googling(< holy shit that doesn't set off spell check) for hours I can't seem to find anything, maybe i'll have to buy the Bar-Tek ones to see. I'll probe contact them as 2.18*6500 is 14170rpm in the charger which is a huge amount so if its substantially above that I'd be quite tempted to rebuild the charger, make a stand alone supply and run the smaller pulley.

[PeteG40]

i'll ask my bearing supplier if they can supply.. Expect they'll be quite a bit dearer as they arent as comon

[Richg40]

Got loads in the shed.

[Justin14100]

Got loads in the shed.

of the Bar-Tek bearings?

[PeteG40]

Got loads in the shed.

of the Bar-Tek bearings?

he means the zz bearings - they are the same price as rubber sheilded and dead easy to get..  We meant the viton rubber shielded bearings.

pete

[Justin14100]

Ok, I contacted Bar-Tek and they say those Viton high RPM bearings are rated to 18,000 rpm. Pete do you know the next RPM limited bearing after this top one? I presume the Viton seals you sell are better at dealing with the heat from the friction on the main shaft than the black ones I got from jabba last time I rebuilt it?

[PeteG40]

from previous posts and searching..

normal top bearings have a limit of 12,600rpm

the charger spins 1.6x crank speed on a 76mm normal pulley.

therefore at 6500rpm= charger spins at 10,400 rpm

76/65 = 17% smaller (ish)

therefore a 65mm pulley is 12,160rpm

a 60mm pulley is 13,173 rpm

a 58mm puley is 13,628 rpm

so the bartek ones be fine.

I've asked my supplier, who's gettin back to me with prices.


And yeah - viton seals i supply deal with heat better (and actually cost 10x price to have supplied rather than nitrile - black - ones)

[Justin14100]

Well my bottom pulley has 48 teeth and my charger pulley has 24 teeth, so thats 2:1 drive, so at 6500 rpm its 13,000 rpm already - PSD's toothed systems where also 2:1 so should put out 13,000 rpm too - unless there is another measurement I haven't calculated about pulley sizes?

[Richg40]

I don't see how how any of this makes any difference, everyone knows that 58mm pulleys destroy chargers so why bother? The bearing arent all you need to worry about, what about shitty apex seals sitting in waffer thin aluminium guides and tiny little teeth on tiny little belts? Yeah it be great fun for a while, and then a pretty big paper weight not long after that.

[Justin14100]

They seem to get away with it in portugal though, 58mm seems to be a standard upgrade there. I've almost done 40k with the charger spinning up to 13k rpm, with different bearings and other oil supply modifications why not another 1k rpm? I understand what you are saying - but sometimes its good to do something different.

[PeteG40]

you very rarely go up to the full speed anyway, 6500 probably past peak torque

[Justin14100]

Maybe I should make some of these too....

[scotsjohn]

Is that the 20mm internals Justin? If so you need a bit of milling to fit them.

[PeteG40]

i'd not bother.. seeing as i've never seen one fail (wider ones anyway) without top bearings failing.

Plus the fact that the bracket is also weak, the last 8 i've seen have hairline cracks in them at the top bolt hole where the oil feed P clip is.  Routing it out to take these will only weaken it more i would've thought.

[scotsjohn]

IIRC Bar-tek took material out of the casing; don't know how much would be available, but pretty dicey I'd imagine.