DIY Rotrex stage 2 on stock internals? - 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 01-02-2012, 04:12 PM   #1
Junior Member
Thread Starter
 
Join Date: Sep 2010
Location: Denmark
Posts: 79
Total Cats: 1
Default DIY Rotrex stage 2 on stock internals?

While I wait for CCR Racing to get approval for road legal installations of Rotrex SC's on '99 - '00 1.8's here in Denmark, I'm already thinking about what to do with the setup when I can buy one.

I expect it to be very similar to CCR's kit for the '01+ in terms of pulley size and restrictor. The '01+ kit, which is a modified version of the KW kit with water/meth injection, puts out around 191 hp and 236 Nm (both crank) at 5 psi with an aftermarket muffler. Here's a dyno plot: http://www.five-speed.dk/Forum3/view...=asc&start=285

I plan on sticking with stock internals and add an intercooler as odds are that the '99 - '00 kit will not come with water/meth injections. If need be, I'm also prepared to add injectors and a fuel pump. The question is what I should do to make moar powah and stay relatively safe for DD and an odd track day here and there:
- Spin the Rotrex faster
- Pull the restrictor

I understand that keeping the restrictor in place and spinning the Rotrex faster will produce a more desirable power band but wouldn't it be possible to reach higher top-end power with the same load on engine components by pulling the restrictor and not spin it as fast?

Cheers,
- Tom
one-niner is offline   Reply With Quote
Old 01-03-2012, 04:05 PM   #2
Destroyer of Inconel
iTrader: (37)
 
EO2K's Avatar
 
Join Date: Apr 2010
Location: In ur driveway, abusin' ur WPA
Posts: 9,642
Total Cats: 954
Default

There should be plenty of info on this forum regarding the durability of stock components. The "weak points" as it were are the rods and the 5 speed. It's torque that kills BP rods and Miata transmissions and the rotrex is not exactly famous for its low end torque output. Meth/water injection can fail or run out of liquid, my vote would be for an intercooler simply for reliability. Its passive and pretty hard to screw up, virtually no parts to fail.

I believe there are a couple of guys that have pulled the restrictor AND run a smaller pulley on stock engines. IIRC someone on miata.net was running a C30-74 on a 1.8 matching blower redline and engine redline, unrestricted, and was making something like 225-ish hp? Not sure if it was backed up with a dyno plot, but its out there somewhere.

I believe Falcon had a post on here about matching blower & engine RPM, should be somewhere here in the supercharger section. Unless you have a mechanical engineering or fluid dynamics background, I'm not sure where you would get information about the restrictors and there effects on top end output. There are a few guys that have screwed with them (look for the rotrex on a spec miata video on youtube) including KraftWerks/Jackson Racing, but they are keeping these cards pretty close to the chest at this point. If anyone else has done it, with a dyno, they have not shared either (as far as I've seen.) If you DO move ahead with this, please document your findings
EO2K is offline   Reply With Quote
Old 01-03-2012, 04:19 PM   #3
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,851
Total Cats: 1,788
Default

The rotrex makes like negative 100 torque...your internals are fine
Braineack is offline   Reply With Quote
Old 01-03-2012, 05:15 PM   #4
Newb
 
Join Date: Jan 2009
Location: France
Posts: 39
Total Cats: 0
Default

Quote:
Originally Posted by EO2K View Post
I believe there are a couple of guys that have pulled the restrictor AND run a smaller pulley on stock engines. IIRC someone on miata.net was running a C30-74 on a 1.8 matching blower redline and engine redline, unrestricted, and was making something like 225-ish hp? Not sure if it was backed up with a dyno plot, but its out there somewhere.
I have bought his rotrex setup (C30-74 rotrex, 75mm pulley, intercooler, no restrictor) and add a MS and Rx8 injectors. We will see what that will give.
Arny is offline   Reply With Quote
Old 01-03-2012, 05:17 PM   #5
Junior Member
Thread Starter
 
Join Date: Sep 2010
Location: Denmark
Posts: 79
Total Cats: 1
Default

Well, I kind of assumed that both uncorking the C30-74 and spinning it to 120,000 rpm would put the engine internals in the danger zone. If that is not the case, that's what I'll be aiming for.

Arny, I'll be very interested in hearing about your experiences.

- Tom
one-niner is offline   Reply With Quote
Old 01-03-2012, 05:49 PM   #6
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,851
Total Cats: 1,788
Default

once you get close to 200rwtq at 7250RPM (engine speed) you can start to worry.
Braineack is offline   Reply With Quote
Old 01-03-2012, 07:21 PM   #7
Newb
 
Join Date: Jan 2009
Location: France
Posts: 39
Total Cats: 0
Default

Quote:
Originally Posted by one-niner View Post
Well, I kind of assumed that both uncorking the C30-74 and spinning it to 120,000 rpm would put the engine internals in the danger zone. If that is not the case, that's what I'll be aiming for.

Arny, I'll be very interested in hearing about your experiences.

- Tom
Rotrex impeller speed for 75 mm Rotrex pulley would be 7000 (engine) * 135/75 * 9.49 => 119,574 rpm
Previous owner recorded 224 whp at 10 psi with this rotrex but with larger injectors and forged pistons and rods.

We will see what will be the pressure on my stock engine and when it will be properly tuned, I will go back to the dyno to see the changes.
Arny is offline   Reply With Quote
Old 01-03-2012, 09:28 PM   #8
Junior Member
iTrader: (1)
 
Join Date: Dec 2010
Location: Knoxville, TN
Posts: 279
Total Cats: 2
Default

I would post the dyno graph [if I wasn't in Ohio and wasn't so computer illiterate]
mx594m is offline   Reply With Quote
Old 01-04-2012, 05:05 AM   #9
Junior Member
Thread Starter
 
Join Date: Sep 2010
Location: Denmark
Posts: 79
Total Cats: 1
Default

Thanks guys.

Arny, I found your project thread over at m.net - I see we are having pretty much the same thoughts on upgrades and durability. I also see that you have a face-lifted NB, which means .5 higher compression ratio than me and 1 higher than mx594m. Out of curiosity - what are your plans for controlling VVT? I think that you could perhaps see more than 224 whp.

Something else I came across: The '99 - '00 fuel pump may be close to it's limit at max rpm under stock conditions. Does anyone know if this holds up - and if so, what should I be looking for, aiming at no more than 220 whp with perhaps 550 cc EV14's?
one-niner is offline   Reply With Quote
Old 01-04-2012, 12:40 PM   #10
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,175
Total Cats: 2,578
Default

Walbro 190hp should do the trick.
18psi is offline   Reply With Quote
Old 01-04-2012, 12:57 PM   #11
Newb
 
Join Date: Jan 2009
Location: France
Posts: 39
Total Cats: 0
Default

Quote:
Originally Posted by one-niner View Post
Arny, I found your project thread over at m.net - I see we are having pretty much the same thoughts on upgrades and durability. I also see that you have a face-lifted NB, which means .5 higher compression ratio than me and 1 higher than mx594m. Out of curiosity - what are your plans for controlling VVT? I think that you could perhaps see more than 224 whp.
I don't know if I have a higher compression ratio than mx594m because he had a 99 head on a MSN block bored to 84 mm with 9.0:1 pistons and M-tuned H-rods whereas I have stock internals. And if I have a higher compression ratio, I don't know if it will change the power a lot.
Arny is offline   Reply With Quote
Old 01-04-2012, 01:37 PM   #12
Junior Member
Thread Starter
 
Join Date: Sep 2010
Location: Denmark
Posts: 79
Total Cats: 1
Default

Quote:
Originally Posted by Arny View Post
I don't know if I have a higher compression ratio than mx594m because he had a 99 head on a MSN block bored to 84 mm with 9.0:1 pistons and M-tuned H-rods whereas I have stock internals. And if I have a higher compression ratio, I don't know if it will change the power a lot.
As you write, he has 9:1 pistons. The stock '01+ 1.8 NB has 10:1 and the '99 - '00 9.5:1.
one-niner is offline   Reply With Quote
Old 01-04-2012, 01:45 PM   #13
Destroyer of Inconel
iTrader: (37)
 
EO2K's Avatar
 
Join Date: Apr 2010
Location: In ur driveway, abusin' ur WPA
Posts: 9,642
Total Cats: 954
Default

I think what one-niner is trying to say is that from the factory, your 01-05 should have a .5 additional compression in the stock engine. My owners manual for my 2000 claims 9.5:1, so based on one-niner's numbers, I would assume the 01-05 is 10:1 and the 93-97 1.8's were 9:1? It's been a while since I looked this stuff up.

Someone will correct me if I'm wrong, I'm sure

Also: Arny is in France, I have no idea if the EUDM spec 1.8 followed the same compression numbers as the USDM spec cars.

When naturally aspirated, higher compression ration = more powah. Under forced induction, higher compression engines tend to be more prone to pinging than low compression engines. Yes it will make more power but IAT's and timing will be critical at higher boost/load levels.
EO2K is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 57 07-19-2017 05:11 PM
LucaCarMods's Boosted Dutch Miata Build! LucaCarMods Build Threads 11 02-14-2016 07:13 AM
WTB MP62 (Hotside) (NB2) Rick02R WTB 3 01-03-2016 08:18 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 12:04 PM
Going back to stock. Need some 1.6 parts. Trent WTB 2 10-01-2015 01:15 PM


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 11:30 AM.