Rotrex anyone?
 

Oscar Jackson, who started Jackson racing, then sold it to Moss Motors, is now selling the Rotrex SC. Has anyone put one of these SC's in their car ?
http://www.papdoc.gr/photos/rotrex/rotrex1600_2.jpg

I just dont see the point in putting any supercharger on our cars when turbo's are so cheap

Miata Rotrex You Tube Dyno Video
 

The point is to make less power for more money! Don't you get it?!?

183hp at 10psi? I made 241 on a Mustang dyno at 10.5 psi with my BEGI S4 system.

I got a ride in the Rotrex car @ Miatas@MRLS and it pulls VERY nicely - WAY stronger than the JRSC and more than the FFSC. Of course it was intercooled, but it was still very impressive (and quiet if that matters to you). It would be my first choice for supercharging a 99-05 and I might end up going that route after I swap out my LE's 1.6 for the '99 I have sitting in my backyard :)

Talk to Emilio.


here's my rotrex:

Attachment 207074




ps. not really :giggle:


But here's the reason that for most intents and purposes superchargers are FTL:

Attachment 207075

Impressive, yes, quiet, no. It was just about the only car breaking the LS sound rules. Very fast though, I rode with Savington for a few laps chasing that thing.

I meant the blower sound and the reason his exhaust was so loud was just that - his exhaust.

Ahh, gotcha.

The graphs show the exact reason why I have been working with Oscar to change the way SC boost is managed. We have come up with a simple way to improve "spool up" dramatically while still limiting top end boost to a reasonable number. I will post some graphs soon.
I put 600 miles on the test car at California Speedway over three days, with the only problem occuring under high lateral G load all the fuel went to the right side of the stock tank (only 1/8th on the gauge when level), and we fueled starved under full boost!! Detonated the spark plug electrode and insulator into a bizzilion pieces.
Will drop a fresh crate motor in and be back at Buttonwillow for a three hour endurance race at the end of this month for further testing, but this time with a fuel pressure safety kill loop in the ECU.

Rotrex
 

Yes, I have recently fitted A Rotrex 74,crank pulley 150mm SC pulley 95mm
intercooled,xede ecu.180rwhp
Cheers
OD

need pics ^^ :)

Read the 949racing site: super reliable, upgrades for >200whp available, no overheating. If it is all true and I would start over it'd be a serious candidate.

One of the local shops here in Huntsville does modified BRP MP62 kits on S2000s and Miatas, and they flat haul ass. In kill mode, the shop manager's Miata makes ~240 wheel and more torque, and it makes that torque from idle to redline. I've autocrossed it some, and the thing is simply disgusting. It'll blow 225/60-14 Hoosiers off at will at essentially any reasonable autocross speed.

That said, big power centrifugals are... a pain in the ass at best. My buddy's 97 Cobra makes 600+ through a C4 and a 9", and it was nigh un-drivable. It made so much power on the top end that you couldn't shift it fast enough with the 5 speed to stay out of the limiter, and every time you hit the limiter it would toss/ shred the belt (10 rib aftermarket setup, aftermarket tensioners, etc). For a medium power setup, I could see it being fun, but I can't ever see it being economical...

Begin threadjack

You've got to give me a ride in your miata. Joined the army haven't seen mine in almost 7 months, and now I'm stationed at Redstone in Huntsville.

/threadjack.

did you get the photo
 

Rotrex[

Photo
 

Sorry about the poor photo if you go to Bullet Cars: Supercharger Kits & Installation, Performance Parts, and manufacturers of the Bullet V8 Supercar, while it is not my car, mine has 3 more KW's and more torque,you will find a better photo and dyno sheet.
OD

Are you talking about 2 different transmission setups in your buddys Cobra? A C4 is a 3 speed automatic...

Sorry I was unclear. He had a TKO600RR and a Spec twin plate, but swapped to the C4 so that he could get the thing down the street. When I say it was undriveable, I mean you could barely get it to the store without tossing the belt unless you absolutely babied it... It was a blast if it didn't belong to you, though, lol.

BTW, we used a Rotrex on an FSAE engine project in ~2005, and while the engine package sucked, the blower sounded siiiiiick.

Coming from the turbo camp but trying to be very un-biased when looking at new boost packages of any kind, I really don't think the dyno number is the biggest factor for guys searching for a blower for track applications.. turbos are reliable for a DD, but there are a TON of things that can go wrong with them under sustained abuse at the track. Sure with deep enough pockets, who cares, and some people have not had problems with their turbos at the track, mostly a product of meticulous maintenance, and luck. Something like this Rotrex, if it was puting down a clean 200+ whp, would probably be a better choice for a track miata than a turbo in terms of how many parts there are that might break... trust me, I know the turbos can outperform them, but that's not the point really. Yes, a turbo can also be done pretty reliably, but I guess what I'm saying is the SC has a higher chance of being reliable and not having issues.

Nobody will argue that a turbo system with the same peak CFM as a Rotrex won't make torque sooner. Given the same CFM output, the Rotrex will run cooler IAT's, underhood temps and EGT's though, guaranteed. So everything else being equal, you'll see more peak power with the Rotrex at the same boost. Peak torque remains about the same with the Rotrex but more area under the curve with a turbo having the same peak CFM.

Everyone wants maximum torque so we have experimenting with reducing top end CFM and spinning a larger Rotrex unit faster, to get more CFM down low. The boost number is low but CFM very high. While in theory, reducing the top end CFM might increase IAT's, in practice we see only mild increases.

The characteristic that tells the story is that the production 165whp non-intercooled Kraftwerks kit running stock injectors and an inlet restrictor requires no timing retard. You can't do that without low IAT's. That same basic C30-74, belt tensioner and intake side piping make up the core components for the base intercooled and big boost intercooled kits to come later. On a strong enough 1.8 motor with a good flowing head, I think 300whp on race gas will be possible from the exact same C30-74. That, is an upgrade path :)

ITA's and SC speed
 

Excuse my ignorance, ? what is a ITA

Maximum safe SC speed is 120000 rpm
With my 95mm pulley it is spinning at a lazy 104900 rpm at 7000rpm
with a 90mm, 110600 rpm @ 7000rpm
With a 85mm, 117250 rpm @ 7000rpm, ? can I pull enough timing out to stop detonation and what power increase would I expect.
ps It is a DD no track work and I am looking for more torque in the lower rev range.
Cheers OD

Intake Air Temperature

What has BulletCars suggested?

I don't know anything and I'm just adding an observation. At the track days I do I've seen a lot more BMWs, S2000s and other cars people spend significant upgrade money on running Rotrex units than any other single FI system. It's very popular among the big buck crowd. Don't know what that means, just an observation.

Rotrex
 

Hi Do you have any more info ie size of SC @ diameter of restrictor or how do I contact these guys
Thanks
Steve

Rotrex
 

Hi do you have any more info ie size of SC and restrictor or a contact for these guys
Cheers
Steve

I think it's throttle response.

This is a super old post but I'd like to see how you guys have progressed.

Restricted Rotrex Dyno Sheet
 

Here is a dyno sheet from the Black Super Spec Miata. The Rotrex unit has been fitted with an inlet restrictor, much like the early Indy Car restrictors. The end result is a shift to the left for the torque and HP curves, and a significant drop in the curves post max value ( this is when the inlet restrictor does its job).

The black lines are prior to tuning the Omnitek ECU, the red lines represent final values. The peak Boost is 10PSI @5900rpm, nominal (average) boost 2k-6k of 7PSI

Also attached is dyno sheet from a Greddy kit at 7 PSI for comparison. This is the kit that is also being considered.

Below that is a dyno sheet from the Rotrex without the restrictor, and with a slightly different pulley size (less max boost).

The guys running centri's on the LS V-8's have been using restrictors for a while to get better low/mid range for a while. People are also starting to run a wastegate on cetri blowers without the restrictor to limit peak boost also.

This looks really nice! I want a supercharger now. hehe.... :)

If you work at it, you can get serious power from a Rotrex :D

[NA] DIY Rotrex Miata Challenge Build - MX-5 Miata Forum

still, area under curve fail.

Seems a little bitter, don't you think?

On a street car, if you don't like to shift and want peak torque at 4K, sure. But for a track car with a 6 speed it makes a lot of torque over a bigger rev range than the gear shift covers, so no downside.

bitter, not at all...

but this is what I mean by area under curve fail. All other things being equal, I'm sure one of these cars will accelerate out of corners faster...

http://www.boostedmiata.com/gallery2...serialNumber=2

Agreed, particularly if you don't shift. Not much difference if you do.

Don't hate because your setup cost less Scott.

Oh and I run almost Ambient IATs... and I'm turbocharged. ie: within 5F of ambient.

Good luck keeping your Miata between 6krpm and 7krpm. 6spd 4.3 anyone?

I do like the IM....

Mine was fairly cheap:

Rotrex $1500 (craigslist)
TDR IC $1100
Intake manifold parts $350
Tubing & Hoses $150
Ebay BOV $32

Total $3132

This ignores the built motor, etc. since you'd have to do those things for any high power setup.

5 deg F above ambient is amazing. And completely impossible except at low boost and only one pull. If you had a 100% efficient compressor (no such thing) and a 90% efficient intercooler (not likely), you could have at most 5.5 psi of boost and still run only 5F above ambient. That calculation applies to sustained power, not one squirt.

Thanks. It turned out pretty well. It's all Ross Machine Racing stuff, plus composite horns inside to fix the bonehead short runners I put on the first time. The IM helps a lot to mitigate the peaky nature that centrifugal blowers (without any inlet restrictor) tend to produce.

Try 20+ minute track sessions. Datalogs show a max of 88degrees on track, max temp of the day was 85. 10.5psi with a GT28RS making ~230whp on a stock 1.6l. Just for reference. Hottest I saw all day was sitting in grid... once moving... temps just go to their happy place.

I'm assuming you have something beyond stock header? That counts in a way, only because we are comparing to turbo systems which use custom manifolds. May as well compare apples to oranges as close as we can.

Over 3k... with a used 'heart' of your system costing 1.5k. When a turbo can do the same power, with earlier torque (in typical setups) and be replaced if any failure for at least half that price. Over 1k on an IC... you are insane :p Sorry, not saying that in a mean way... but over 1k on an IC is just nuts :p. No qualm with the ebay bov, lubed up they work fine by me. Not sure I see the reason for the Intake Manifold parts in that list, header I could... IM though? We really should include custom work, since the Rotrex mounting was not a production piece (at least I read it that way?).... so a custom exhaust manifold would be a legit expense on the turbo side.

The High end cost of the system just doesn't make sense. Sorry. Of course its just my opinion... I just prefer to make less of a parasitic system. I prefer symbiotic relationships.

I won't dispute your measured temps, but the physics (the same ones used to design the components that your system uses) say no way.

The Rotrex was brand new, and I was lucky to find it that cheap. They are $2200 new.

The IM was on there because it was a big part of the power, and people chasing power frequently do put on aftermarket IMs but usually not that cheaply.

The header is a Racing Beat, $400. I forgot that part.

If I was going for cheap (I wasn't really but it worked out that way), I'd change to an Ebay intercooler and knock another $600 off the cost. The TDR stuff was really nice, though - all the parts fit and didn't look ugly. I figured I had my hands full with building my own intake manifold, plumbing and SC brackets.

Despite what your physics are telling you... my datalogs disagree with you. I have the open cage quicker responding GM sensor. Properly calibrated. I also see nice quick heatsoak while sitting... the highest temps the car ever sees are sitting. Oh and I didn't do any physics work designing my system... we just built it. Its all DIY.

Trust me... the cooling works.... the trick is oversized IC and proper ducting....

Let me know when I should post a picture for a big clue :p

That's some IC. You get exactly that temperature rise with an 80% efficient compressor and a 97% efficient IC.

That it is. Super high quality ebay XSpower unit :p. Heh.

Splitime,

Do you have a datalog in 3rd or 4th gear from say 3500rpm from steady state closed throttle (30~50 kpa) to say 5.5psi indicating how long it takes your system to generate that area under the curve after going to WOT?

I'm assuming a slope, perhaps even a steep one.

I'll only have logs in 10.5 psi. Never saw need to run a smaller spring in the WG.

I'll have to look for the logs, been computer hoping.

IATs drop over the length of pulls though.

Here is the dyno with the damaged turbine wheel though. Also of note is that its just a fuel tune, I'm running someone elses base/safe timing map. Never saw the need to wring it out.
http://i295.photobucket.com/albums/m...otta-dyno1.jpg

Here is a log I have online atm, its a full 1/4 mile run. If it was when I think it was, I believe it was mid to high 70s for that meet.
http://i295.photobucket.com/albums/m...miotta-log.gif

Splitime,

I was looking for more of a roll on. Steady state cruising on near closed throttle to WOT at 3500 rpm in 3rd gear. Something to see how fast it makes boost with the turbo not already spooled.

BTW, where is your IAT located precisely?

Right in the intake manifold. Welded bung sticking out the bottom.

I don't think I have any roll on logs. I'll see if I can find any though. I'm actually done for the season and car is up on jackstands for prep for next season already. So no fresh datalogs anytime soon. I bet Braineack could do some though, he won't have my IATs though. I can assume you are looking to see if the Large IC is affecting spool... thus data from my specific setup. If that is the case, also realize that my IC piping is about 2 feet total.

To me, the giant fat torque plots from some larger turbo installs are dyno queen numbers. Chop the throttle mid corner for half a second, then pick up say 50% throttle and you may or may not instantly get 100% of the torque the system is capable of making at that RPM/TP. Too much like driving an automatic for my taste. Yes its capable of making torque but when? FWIW, I've driven maybe 50 turbo and S/C cars over the last 19 years of playing with Miatas, including two of my own. So there is some relevant experience.

The 2554R, I/C, standalone, 2.5" exhaust set up I ran for about a year was great, particularly for autocross. Perfectly sized for the 99 engine. Instant torque and linear throttle response but weak top end. Every larger turbo I've driven trades off that instant response for top end power. The only systems that matched the response, had less torque, including cold and hotside MP62's. The solution is an LSx!

Anyway yeah, centrifugal SC's lose the .jpg torque curve contest against turbos but win the (never-mentioned) boost response one. Like boost response is taboo on a turbo forum. Perish the thought.

The negative comments on the Rotrex based systems are funny, particularly from guys who never even seen one let alone driven one on the track. The OP, myself and TDH are just sharing our solutions and development. The stuff works, is fast, very simple to tune, reliable and most importantly, super fun to drive.

Drag racing/dyno pulls ≠ driving around corners at the limit of traction.

You asked for data... I provided what I had.

The car is built and used on track. Visits to anything else are to fill boredom between events. Don't try and use that to "put" down the turbo setup.

I find the turbo quite easy to peddle during turns, that is the fun of a BB turbo... just that bit extra response it offers. Partial throttle boost works as i would want.

I know I've not driven as many Miatas as you... and I NEVER will... I don't drive other peoples cars... just the ones I build, it is never worth the risk of an unknown failure and having to replace a car. (if all those setups you drove were yours... I withdraw the somewhat annoyed format I posted that run on sentence up with, I'm not a fan of people driving other people's cars on track... thats a realm for paid drivers only imo)

Mainly I just don't ever see myself being sold on a parasitic system. It doesn't make sense, especially considering the cost (at least in my book). Using the mechanical energy the engine is already putting out... just does.

Don't believe that for a minute.
Show us some dyno plots.

Chill dude..

Turbos are exhaust gas driven and will always have some measurable non-linearity between TP and torque response. I like linearity. That is a preference, not a "put down". You prefer low end torque and are OK with a little lag in some realms of the cars performance envelope.

The whole "torque fail" thing is sophomoric.

You provided torque response when already spooled = dyno queen/drag race.
I have been reading that crap for 30 years. I won't argue that point as there is no argument. Tip in from steady state closed throttle, non-loaded from your "area under the curve" in 3rd gear and lets see how many tenths of a second it take for the system to deliver the same torque @rpm as it did in the loaded dyno plot. I will guarantee you a beer the next time I see you, if it is exactly the same in both logs. That, my friend is the difference between your turbo system and Rotrex based system making the same peak power.

Does it matter to you? Clearly not but that's OK. There is nothing to defend, no one has claimed superiority by either system. Just one guy sharing his data and enthusiasm for his successful DIY build in a thread about the Rotrex systems.

Emilio,

Curious now that you've had some time and experience with and around the Rotrex. How would you compare or contrast the Rotrex unit to the Vortech supercharger? The obvious is the Rotrex is fully self contained for oiling. Other than that?

I don't have any experience with the Vortech other than looking at their data. They have lower gearing with less step-up, so they run a big compressor at low speed (50K rpm) rather than a smaller compressor at higher speed (100K+ rpm) like the Rotrex. The maps look like they are more oriented toward high flow at low boost, not what a Miata wants (unless you have an LS1 in there).

Maybe a compressor guru can chime in with the trade-offs on big/slow vs. small/fast?

The Vortech, running at about a 2:1 drive ratio, needs a much larger compressor to move as much CFM as a turbo or Rotrex moving the same amount. More mass means more load, it runs much hotter and needs more cooling. Because the larger Vortech is not efficient at low compressor speeds, it tends to be even more top end focused in its output than the Rotrex.

For a given CFM output, the Rotrex is about half the size.

The Rotrex, due to the turbo like compressor speeds, uses a much more efficient compressor wheel design that the much slower spinning Vortech.

As far as I cam see, the Rotrex is more efficient in every way you can measure the performance a belt driven centrifugal supercharger.

That boost curve looks a lot like a turbo boost profile.

so im new to boost, and still learning
i want about 190-210whp and ill be more than content
weekend driver
all of my friends with turbochargers constantly have issues/problems/tuning,etc...
the way the kraftwerks site advertises this thing it looks pretty simple (in it's Base kit form) but i need more hp

however exactly what do i need to make these numbers, as i see they don't have any high boost kit/upgrades for the miata, but apparently other people already have achieved said numbers with the rotrex.
sorry for the noob comment, but this is all so new to me.
hence ill do the buying and let someone else install, im not really car savvy

I'll try to answer your question in our main thread here
https://www.miataturbo.net/forum/t35489/