Different pulley sizes for c30-94 Rotrex... - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Supercharger Discussion For all you misguided souls.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 04-20-2016, 10:55 PM   #1
Mr Broke Pants
Thread Starter
iTrader: (9)
 
thumpetto007's Avatar
 
Join Date: Sep 2010
Posts: 1,539
Total Cats: 48
Default Different pulley sizes for c30-94 Rotrex...

All I'm finding is an old bimmerworld forum thread that mentions wheel2wheel selling 8 rib rotrex pulleys of different diameters.

I'm looking for a few different diameters, 90mm 100mm... maybe larger, idk. The pulley my C30-94 kit comes with is a 80mm, which is like 13psi at 7000rpm (at 675cfm) I'm pretty sure I'd blow something up at that level.
thumpetto007 is offline   Reply With Quote
Old 04-20-2016, 10:59 PM   #2
I'm Miserable!
iTrader: (5)
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,925
Total Cats: 1,437
Default

Run a wastegate on the manifold. Bleed excess boost at higher rpm.
aidandj is offline   Reply With Quote
Old 04-20-2016, 11:16 PM   #3
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 35,756
Total Cats: 2,492
Default

what makes you think 13psi boost will automatically blow your engine
18psi is offline   Reply With Quote
Old 04-20-2016, 11:25 PM   #4
Mr Broke Pants
Thread Starter
iTrader: (9)
 
thumpetto007's Avatar
 
Join Date: Sep 2010
Posts: 1,539
Total Cats: 48
Default

I read about that. I don't think I want to do that. Even if I did use the wastegate to limit boost, I'd still need a larger pulley. I don't see the sense in making the blower rotate close to its max rpm just to bleed it to 6-8psi.
thumpetto007 is offline   Reply With Quote
Old 04-20-2016, 11:26 PM   #5
I'm Miserable!
iTrader: (5)
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,925
Total Cats: 1,437
Default

Quote:
Originally Posted by thumpetto007 View Post
I read about that. I don't think I want to do that. Even if I did use the wastegate to limit boost, I'd still need a larger pulley. I don't see the sense in making the blower rotate close to its max rpm just to bleed it to 6-8psi.
So that you can make more boost lower down?
aidandj is offline   Reply With Quote
Old 04-20-2016, 11:29 PM   #6
Mr Broke Pants
Thread Starter
iTrader: (9)
 
thumpetto007's Avatar
 
Join Date: Sep 2010
Posts: 1,539
Total Cats: 48
Default

Quote:
Originally Posted by 18psi View Post
what makes you think 13psi boost will automatically blow your engine
It's 13psi at 675 cfm... that's literally the max rotrex rpm at 7200 engine rpm? I'd rather try lower boost first. I'm not ready to commit more money for a built engine yet.
thumpetto007 is offline   Reply With Quote
Old 04-20-2016, 11:31 PM   #7
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 35,756
Total Cats: 2,492
Default

Quote:
Originally Posted by thumpetto007 View Post
It's 13psi at 675 cfm... that's literally the max rotrex rpm at 7200 engine rpm? I'd rather try lower boost first. I'm not ready to commit more money for a built engine yet.
ok I'll dumb it down:

why do you think 13psi of boost at redline means blown engine?
18psi is offline   Reply With Quote
Old 04-20-2016, 11:34 PM   #8
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,212
Total Cats: 1,229
Default

Quote:
Originally Posted by thumpetto007 View Post
I don't see the sense in making the blower rotate close to its max rpm just to bleed it to 6-8psi.
Do research on Rotrex systems until you can see the sense in making the blower rotate as fast as possible at all times.
Savington is offline   Reply With Quote
Old 04-20-2016, 11:36 PM   #9
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 35,756
Total Cats: 2,492
Default

it likely won't even make 13psi if you cap it at 7, and if you run low timing and free flowing exhaust it won't be any harder (IMHO) on it than a 10psi turbo setup, aaaand there are many here making 10-13 on turbo setups on 01 unopened engines.

what I'm saying is you're overthinking this and should focus on more important things
18psi is offline   Reply With Quote
Old 04-21-2016, 12:08 AM   #10
Elite Member
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,658
Total Cats: 235
Default

Quote:
Originally Posted by 18psi View Post
it likely won't even make 13psi if you cap it at 7, and if you run low timing and free flowing exhaust it won't be any harder (IMHO) on it than a 10psi turbo setup, aaaand there are many here making 10-13 on turbo setups on 01 unopened engines.

what I'm saying is you're overthinking this and should focus on more important things
THIS THIS THIS.

Run the booost, don't worry about limiting boost, that's not the problem you need to solve. Tune it safe and let the boost flow, I ran 17 pounds on a stock 99 motor for a year with a GT3271 on pump gas, it did it. Just tune it safe. 13 pounds at redline is nothing, you will be fine. In fact I'd run more. Wastegate setup to regulate boost on a SC, I've designed and built one before. I would not recommend it.
patsmx5 is offline   Reply With Quote
Old 04-21-2016, 12:10 AM   #11
Elite Member
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,658
Total Cats: 235
Default

Quote:
Originally Posted by thumpetto007 View Post
I read about that. I don't think I want to do that. Even if I did use the wastegate to limit boost, I'd still need a larger pulley. I don't see the sense in making the blower rotate close to its max rpm just to bleed it to 6-8psi.
You'll work the SC harder ,make more heat, and make more boost at lower RPMs, and need a heavy bypass system in place. I did this, it sucked.
patsmx5 is offline   Reply With Quote
Old 04-21-2016, 12:13 AM   #12
I'm Miserable!
iTrader: (5)
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,925
Total Cats: 1,437
Default

Quote:
Originally Posted by patsmx5 View Post
You'll work the SC harder ,make more heat, and make more boost at lower RPMs, and need a heavy bypass system in place. I did this, it sucked.
Oh god. The horror. Boost at low rpms!?!? That sounds horrible.
aidandj is offline   Reply With Quote
Old 04-21-2016, 12:21 AM   #13
Mr Broke Pants
Thread Starter
iTrader: (9)
 
thumpetto007's Avatar
 
Join Date: Sep 2010
Posts: 1,539
Total Cats: 48
Default

Haha, ok, then I still need to find a place that sells the pulleys, if I'm to make more boost at redline lol.

All the boost, none of the timings...
thumpetto007 is offline   Reply With Quote
Old 04-21-2016, 12:35 AM   #14
Mr Broke Pants
Thread Starter
iTrader: (9)
 
thumpetto007's Avatar
 
Join Date: Sep 2010
Posts: 1,539
Total Cats: 48
Default

Just as an fyi, the C30-94 outflows a EFR 6758 by 70 cfm...
thumpetto007 is offline   Reply With Quote
Old 04-21-2016, 12:39 AM   #15
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 35,756
Total Cats: 2,492
Default

I'm gonna punch you if you interchange pressure and flow again
18psi is offline   Reply With Quote
Old 04-21-2016, 01:35 AM   #16
Mr Broke Pants
Thread Starter
iTrader: (9)
 
thumpetto007's Avatar
 
Join Date: Sep 2010
Posts: 1,539
Total Cats: 48
Default

Look what I found...

Underdog Racing Development

Will these work, even though they are 8 rib?
thumpetto007 is offline   Reply With Quote
Old 04-21-2016, 01:36 AM   #17
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,212
Total Cats: 1,229
Default

Quote:
Originally Posted by thumpetto007 View Post
Just as an fyi, the C30-94 outflows a EFR 6758 by 70 cfm...
And the 7163 outflows the C30-94 by 100+cfm. The comparison is irrelevant to this thread, though.
Savington is offline   Reply With Quote
Old 04-21-2016, 02:03 AM   #18
Mr Broke Pants
Thread Starter
iTrader: (9)
 
thumpetto007's Avatar
 
Join Date: Sep 2010
Posts: 1,539
Total Cats: 48
Default

^does vlad get to punch you? lol

I only brought it up because he asked me why I thought 13psi was a concern to the stock engine. I figured since it flows more than a turbo that has wrecked stock engines at less boost, it might be a safe thing to run less boost?

But idk.
thumpetto007 is offline   Reply With Quote
Old 04-21-2016, 05:15 AM   #19
ʎpunq qoq
 
Join Date: Jan 2014
Location: Western Australia
Posts: 487
Total Cats: 98
Default

The difference is the Rotrex will be making max HP at max RPM so torque is still low, vs the turbo which will be making max HP at less revs = more torque. As long as you don't exceed around 260ft lbs on the stock internals you should be right, which is around 360hp @ 7200. I don't think the C30-94 will get there on a stock engine... might be close.
Madjak is offline   Reply With Quote
Old 04-21-2016, 12:16 PM   #20
Mr Broke Pants
Thread Starter
iTrader: (9)
 
thumpetto007's Avatar
 
Join Date: Sep 2010
Posts: 1,539
Total Cats: 48
Default

Thanks Madjak.

I just got off the phone with Gary at Trackdogracing, he was very surprised I went with the c30-94 blower, on a stock engine. He was adamant about me not going over 7000rpm, even with the 95mm pulley (which I just bought from him) and very retarded timing. He was saying the c30-94 just flows too much for the stock rods at high rpms, and to actually maybe go even lower than 7000rpm for my redline.

I'm at 8000ft elevation, so I don't think I'll have a problem, at least not right away, but that altitude adjustment better be spot on, and have more retarded timing as I go lower in elevation.

So now I'm scared, and sad that I spent 3400 on a rotrex kit that I'm not using most of the parts from, on a rotrex that is too big? :/
thumpetto007 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
2002 Rotrex Track Miata tomiboy Cars for sale/trade 3 07-02-2016 04:24 PM
Begi S4 kit SAVANNAH, GA $2900 zleeperz Miata parts for sale/trade 0 04-16-2016 07:23 PM
Flyin' Miata big brake kit for NA8 & non-Sport NB JTod Miata parts for sale/trade 3 04-14-2016 04:34 PM
Larger diameter idler for shaved head Chameleoki Engine Performance 11 04-13-2016 12:30 AM
New Mazda factory alignment bolt kit 90-05 Miata JTod Miata parts for sale/trade 1 04-09-2016 07:10 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 08:30 AM.