So I drove a Rotrex on Sunday at Buttonwillow... - Miata Turbo Forum - Boost cars, acquire cats.

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Old 12-23-2009, 06:03 AM   #1
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Default So I drove a Rotrex on Sunday at Buttonwillow...

..and I'm ashamed to say that it wasn't bad at all.

The setup:
'99 chassis, stripped/caged, ~2200lbs w/o driver, 6-speed, 3.909 Torsen
XIDA doubles, 15x9s, 225/45 NT-01s, Goodwin BBK
GTC-200 wing, custom endplates, front splitter

Rotrex blower
RC550s, Walbro 190lph, Adaptronic, E85, 230whp/[email protected] (detuned from ~260 for stock longblock longevity)

This setup turned a 1:57.4, which is the 3rd fastest Miata at Buttonwillow, and the 2nd fastest car on NT-01s (Matt Andrews is 1st, my car is 3rd).

Throttle response was excellent, better than I am used to obviously. The car had a throttle body problem that made it a little sticky right as you cracked it open, but other than that it was really nice. No pre-application to spool a turbo like I do in my car - open the throttle and go.

Power delivery was, in a word, smooth. The best way to describe it is that it felt like the car had a straight 6 in it, very similar to my dad's E46 M3. No peaky rush, no thump of power, it was there right as you opened your foot and built smoothly to redline. I expected it to be a little peakier, a little more top-end oriented, and it didn't feel that way at all - just a nice strong pull from 5000rpm into the rev limiter. I was aware of the torque curve when I was driving it, so I consciously kept the revs as high as I could, but even then when the track required me to stay down a cog in order to avoid a shift in an awkward spot, I never felt like I was off the powerband.

To be honest, this is about as far as you can get from a turbo. There is NO rush of power, no drama, and it's almost hard to get excited about it, but there's something to be said about that. From a driveability standpoint, this is without a doubt more driveable than my car was, even with the T25, and it has the oomph, with 230whp from just 10psi. I got out thinking I had done a 59, and was very surprised to see the pair of mid 57s on the time sheet.

Anyway, thought I'd share my thoughts. It's a neat piece. Not neat enough to switch my track car over (I'm a fan of that big stupid rush of torque), but I could see owning a daily driver with one of these on it very easily.
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Old 12-23-2009, 09:59 AM   #2
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so...after you finish sucking on your pacifier, add an EBC and then set it to make boost increase in a linear function to RPM.

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Old 12-23-2009, 11:16 AM   #3
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Sav,

Do you ever feel like you've come to discuss Martin Luther King at a Klan rally?
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Old 12-23-2009, 12:09 PM   #4
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How much better would this be for an all-out autocross car?
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Old 12-23-2009, 12:50 PM   #5
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How much better would this be for an all-out autocross car?
In my experience, pretty good. Instant throttle is easy to manage.

Although a big roots blower might be a little simpler to drive, as the "full torque everywhere, at any time" curve will eliminate any chance of being stuck between gears. On William's car (and my car) you usually have more torque than you can put down at 4K at autocross speeds, so the loud pedal is used to flatten the Rotrex' rising torque curve.
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Old 12-23-2009, 05:01 PM   #6
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Quote:
Originally Posted by Braineack View Post
so...after you finish sucking on your pacifier, add an EBC and then set it to make boost increase in a linear function to RPM.

<the same dyno plot i've posted over and over and over and ovenroavoeroavoeroavoeroaovoaeovjaksdf>
So your argument is that you can make a turbo mimic a Rotrex, and therefore the turbo is better even though it has worse throttle response...

I'm not arguing that it's better or worse than a turbo - it's not. It's extremely different - the only comparison I can come up with is the 6-cylinder one. It feels like that.


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How much better would this be for an all-out autocross car?
I think it would be pretty good. I've autocrossed my 2871 and it's not fun - even the 2554 was a handfull. I could see it being pretty good for an autocross car - throttle response, instant torque on pedal application, no lump of power to deal with.
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Old 12-23-2009, 05:12 PM   #7
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I've never had this "uncontrollable torque 'lump' terror" from a turbocharger which makes the car burst into flames and crash.

Why is this car so fast with no torque?!?!?! How??? Why????
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Old 12-23-2009, 05:19 PM   #8
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I've never had this "uncontrollable torque 'lump' terror" from a turbocharger which makes the car burst into flames and crash.

Why is this car so fast with no torque?!?!?! How??? Why????
My point is that for equal power, the Rotrex is easier to drive than a Turbo car is, just like a V6 is easier to drive than a turbo 4-cylinder. The turbo might make more torque down low, but the V6 makes the same power up top and is easier to drive. Different strokes for different folks.

I autocrossed my 2871R at ACS in August, and I would spend a lot of time bouncing off the rev limiter in 2nd gear. Someone asked me why I didn't just shift, and I had to explain that it would just spin the tires in 3rd too, and I was using the limiter in 2nd as a traction control device.
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Old 12-23-2009, 05:22 PM   #9
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Originally Posted by Savington View Post
So your argument is that you can make a turbo mimic a Rotrex, and therefore the turbo is better even though it has worse throttle response...

I'd need to feel what the Throttle does, i really dunno what it's like. I just know I drive like that one the street DDing or in the rain, even autoxing, I only run full boost when I have a reason for it, car is much more manageable I agree.
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Old 12-23-2009, 05:34 PM   #10
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Who is exiting the corner faster at "track-out"...the rotrex or the turbo car?
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Old 12-23-2009, 05:35 PM   #11
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In for the answer to hustler's question...
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Old 12-23-2009, 06:33 PM   #12
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Since you can throttle-rotate either car at track-out, they're the same. The Rotrex is just easier to control.
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Old 12-23-2009, 07:08 PM   #13
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That's a solid, un-biased review from a well setup turbo. Thanks.
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Old 12-23-2009, 08:11 PM   #14
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that's my car Andrew drove. when Andrew got out of the car, I could tell he thought he got beat (this was Miata Challenge, and he had to be sub 2 minutes to clinch the title). Car was not setup yet (just threw on the hard top, coilover few days prior, were chasing down some ground issue all day, didn't have time to dial the suspension nor aero), it had turn in understeer, exit oversteer, and high speed understeer. When Andrew found out he did a couple of mid 1:57s, jaw dropped. He didn't think it was any faster than his own car. I think the word he used was "deceptively fast"

if I had more time to dial the suspension in, fixed the aero, replace 2 flat spotted NT01, more seat time (he did 1:57 by 4th lap in black group). I am sure Andrew would of done a 1:55s.
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Old 12-23-2009, 08:40 PM   #15
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Default dyno plotwars

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Originally Posted by TrackDayHookey View Post
Sav,

Do you ever feel like you've come to discuss Martin Luther King at a Klan rally?
lol. So true

Forget that the cars are stinking fast, stone reliable, fun and easy to drive. That's not the issue at hand. The issue is that they are not turbo's and don't produce a dyno plot like Braineacks.

Jeezuz, how many times have I seen that particular dyno plot? Like it proves once and for all that, um, actually I'm not sure what it proves because it seems he doesn't actually compete with his car. It also seems he has never driven a Rotrex powered car.

One might conclude that his often stated opinion must therefore be based entirely on what he has read in this and other forums. Not, as it might be assumed, on any empirical first hand knowledge. My dyno plots kicks your dyno plots ***!

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Old 12-23-2009, 08:48 PM   #16
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I just melted down my 6ULs in protest. I kept the FM lugs though, lol.
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Old 12-23-2009, 08:56 PM   #17
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I just melted down my 6ULs in protest. I kept the FM lugs though, lol.
Please recycle!
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Old 12-23-2009, 09:01 PM   #18
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We need a special forum for members running under X-time on Y-track. Oh wait, thats track HQ. lulz
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Old 12-23-2009, 09:20 PM   #19
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When do the TR 15x9s come out?
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Old 12-23-2009, 09:22 PM   #20
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^Oh noes...
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