+2

I had a C30-74, no restrictor, 70 mm pulley, pumped 13 psi at 6000, 224 hp

BUT


belt tensioner fractured, next idler started wobbling, then starting eating belts, got so bad could not get more than 100 miles on a belt

jerked that junk off, took car out to Spring Branch for a GT2860RS

Sounds like what my car has been doing since day 1. I just replaced the tensioner, idler and Gates Blue belt on Sunday (12/19) to the tune of over $150 and guess what? Ate the belt on my no-boost test drive. :vash:

Implosion happened a while ago.

Bought my C30-74 base kit from 949, probably the last one they sold before the KW split. 949 does not offer support, Kraftwerks does not offer support, Skunk2 will sell you parts but I've not seen much support. I'm in contact with them currently but its not going well. I'm still having problems and they have no solutions. I don't bitch about it around here because its a turbo forum (I should start a thread here so the turbo guys can laugh at me :loser: ) Go to Miata.net and look in the supercharger section. Do seperate searches for "Rotrex" and "Kraftwerks" and see what you are in for. When I spoke to Emillio back in April about my purchase, I believe he said there were about 200 KW Rotrex miata kits on the road spread over the US. That makes for very little concentration of knowledge, other than on the internet. No one has any real experience troubleshooting these things except the Jacksons and Kraftwerks, and they pretty much said "fuck-all" to their customers and walked.

I'm not trying to shit on a vendor here, I'm just trying to let you know what's up from a current owner. I've been quietly suffering with this mess since April. This is possibly the worst upgrade I've done to date. The kits have some issues that need to be worked out and no one seems to want to stand up and "make it right" for the customers. I had an engine build planned for 2011 to match the smaller pulley, larger injectors, MegaSquirtII and intercooler that are sitting in my garage, but I'm thinking of selling it all in disgust. If the stock kit has these issues, no way I'm going to bother to upgrade it, or do the upgrades to support it. My rotrex may literally come off the car this week so I can drive the 800 mile round trip to my folks house for the Holidays.

:2cents:

My car seems to be holding together just fine. At more power and more RPM. I still can't figure out all these belt issues people seem to be having. I've done road trips in my car, a shit load of track days, hill climbs... what have you.


At the end of the day the Rotrex is not for everyone. I like it.

I knew you would pop in here eventually. You should come fix mine and show me how its done :makeout: :giggle:

Actually, when mine was running, it was a fucking blast to drive. Everything as advertised and more. What killed it for me was lack of any kind of support or assistance when things went sideways.

You should have PM'd. What exactly is your issue? I'm not doubting that people have had pulley problems.. I've seen the photos. I just haven't so I don't really get it.

I may have to eat my hat and edit my earlier post. After making the post yesterday I got fired up and angry again and emailed Skunk2. I got a reply this morning from a tech named Brian who is helping me out at the moment. He's the guy I ordered parts from a week or so ago. The Skunk2 guys want me to pull the mounting plate and idler setup and send it in after sending them pics. It's a bitch but its at least something.

My setup is eating belts like its going out of style. I consistently loose the first rib (furthest from the engine, closest to the front of the car) within the first 10 minutes of running on-road so its not rubbing on anything. At idle it will go all day and track straight. It's the '00 in my sig with AC and PS. I've seriously considered starting a thread here in the SC section... the signal:noise ratio is far better here than over on m.net.

Been thinking about eliminating the AC and PS this winter, I've got a '03 rack sitting in the garage waiting for me to get up the nerve to make it happen. Everyone that's had belt or pully issues has AC and PS, but I'd like what I bought to work as advertised.

What really grinds my gears is the fella on the local forum with a LSx & T56 for sale for $3800... that's only $500 less than my C30-74 and just as emissions complaint :vash:

Do you have the kraftwerks machined pulley? I'm starting to think the reason I have not had problems is because I run the actual rotrex pulley. it's 8 ribs but it works. Perhaps the design was off on the pulley.

Started my own thread... with blackjack, and hookers!

https://www.miataturbo.net/supercharger-discussion-38/eo2k-contemplates-universe-his-rotrex-why-they-both-fail-62346/

I think the belt issues boil down to either everything lines up properly, or it doesn't. Also some have gotten bad autotensioners. I've put 6k on mine now, and noticed some scuffing of the back of the belt. I took the belt off and examined things; my autotensioner was slightly misaligned. I have shimmed the lower mounting pin and it looks ok now. The tensioner itself seemed to be fine, no wobble or play in the pulley, spun freely, etc. I will replace the belt and see how the new one wears.

Good to hear some of both sides guys, thanks for the input.

-Sam

Was really interrested, ordered BEGI turbo stuff after the summer because of prices. Still think that the rotrex is nice due to driveability (as in sloppy mid corner throttle) and "not eating fivespeeds-wise".

Probably less exhausting to drive in anger than a turbo car, my choice for long stints or endurance (based on former turbo track car, no miata turbo track experience yet).

Slower cars are generally less exhausting to drive in anger, yes. :)

(Given the same peak power, a turbo car will be significantly faster than a Rotrex-powered car)

I was pretty sure that you would say that ;)
Sure they are, seing that it takes less fiddling with the right pedal :)
Btw, I would love a clip with The black car going up against the 949 rotrex, just for kicks.

The only thing slower then a kraftwerks miata is a stock miata. Twin screw or don't bother supercharging.

The closest thing to Theseus is Trackdayhookey's ~400whp Rotrex, and even he will freely admit that my car pulls much harder in a straight line than his does. We compared power curves on m.net and I make more power from idle to 6800rpm.

The Rotrex does lots of things well, but torque is not one of them.

Haha... yes.

Now sav, in a tight track how does it compare to TDH's car? All things considered...

I'm pretty confident in saying my Rotrex'd car will walk on your "superior" twin screw car. :makeout:

^^ In for results!

Sav: Got a launch date for your TSE turbo goodies yet? ;)

Tight track, long track, doesn't matter - I have the power advantage. On an autocross course he might have an applied power advantage, but that's really nitpicking.

No release date on the TSE turbo kits. Right now our goal is Spring 2012. You'll see photos of pre-production parts on a race car before we confirm a release date.