blower RPM question

[SonicION]

is there a way to figure out your blower rpm? based on engine rpm and pulley size?? i know the s/c is rated to 16,000 continuous rpm, but i have no idea where that limit is. just wondering because i plan to have a pretty small pulley on a high-revving engine by the end of next winter. 2.7" pulley at 7000-7500 rpm... is that gonna blow something up? lol

[The Shaolin]

What is the diamater of the crank pulley?

[SonicION]

idk...gotta llok it up

[The Shaolin]

do it. and then I'll use my maths for you. lololol

[ExHempKnight]

drive pulley diameter divided by driven pulley diameter (crank divided by S/C) gives you drive ratio. engine RPM times drive ratio = supercharger RPM if its a roots blower. centrifugals have an internal drive ratio which you need to take into account.

[SonicION]

ion redline, so it's Roots. spent a couple hours searching das intraweb... couldn't find it. not i gots to go to werk. will try again later

[slowion2]

shit I just did a bunch of these equations for Track Slut and Redline13, let me see if I can find them.

[slowion2]

[slowion2]

ok I'm going to put up the math for 7200rpm engine speed. thats where we have most of the redlines here tuned for since they can hold 3rd gear as it comes through the traps:

3.0" = 15,120
2.9" = 15,641
2.8" = 16,200
2.7" = 16,800
2.6" = 17,446

the Stage 2 pulley is 3.01" roughly

on this generation Eaton, 16,000rpm blower speed continuously, so for short bursts the 2.7 will be alright, such as during a track run.

food for thought: GM made 300whp on an LSJ with the 2.87" pulley, so a 2.8" with a solid tune and proper supporting mods should be fine. consider colder plugs too, they can literally save you a cracked piston.

right now we're running I think a 2.9 or 2.8 on Track Slut's car and just put a new header with catless 3" downpipe, and the rest of the exhaust is on its way in soon (3" mandrel). with a retune it should be close to the 300whp mark, and if it's not the 3" will flow enough for the nitrous we're thinking of putting on it [img]{SMILIES_PATH}/icon_twisted.gif[/img]

[BC. Livewire]

now that is some good info

and taesty too

[SonicION]

that's awesome Vin! now that you posted it, i remember seeing that before. works out perfect too, cause i have a 2.7" pulley just waiting for injectors and a tune!!