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Old 06-15-2015, 06:49 PM   #1
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Default my 155mph miata

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Old 06-15-2015, 08:20 PM   #2
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What transmission and rear end?
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Old 06-15-2015, 09:04 PM   #3
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Nice. What's the setup?
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Old 06-15-2015, 10:08 PM   #4
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My money is on 3.9 and a 6 speed.
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Old 06-15-2015, 10:29 PM   #5
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Old 06-15-2015, 11:04 PM   #6
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A 6 speed and 3.9 would need 7,750 RPM to reach 254 kmh, acceleration would be 1.63m/sec2. A 4.1 around 8,250 and a 4.3 around 8,400.

A quick aero calc (1,100 kg and Cd of 0.34) shows about 360 RWHP would be required to get to that speed.
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Old 06-15-2015, 11:21 PM   #7
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Quote:
Originally Posted by Eipgam View Post
A 6 speed and 3.9 would need 7,750 RPM to reach 254 kmh, acceleration would be 1.63m/sec2. A 4.1 around 8,250 and a 4.3 around 8,400.

A quick aero calc (1,100 kg and Cd of 0.34) shows about 360 RWHP would be required to get to that speed.
I didn't check your math, but my bone stock 99' miata with a crystal mod did 140mph, that's with ~110rwhp. I don't think you need 360whp to go 18mph faster.
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Old 06-15-2015, 11:25 PM   #8
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Definitely don't need 360whp to go 155mph. My 320whp car would pull 3.63s hard into the 7400rpm limiter at ~152mph GPS.

Keep in mind that tire diameter fluctuates dramatically at high speed. 7400rpm with 3.909s and a 6-speed calculates to ~154mph, but if you actually try it, the GPS will say ~146mph.
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Old 06-16-2015, 12:13 AM   #9
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Quote:
Originally Posted by Eipgam View Post
A 6 speed and 3.9 would need 7,750 RPM to reach 254 kmh, acceleration would be 1.63m/sec2. A 4.1 around 8,250 and a 4.3 around 8,400.

A quick aero calc (1,100 kg and Cd of 0.34) shows about 360 RWHP would be required to get to that speed.
I can gear out my T25 200whp setup easily in 5th gear with a 4.30 at 7400rpm, at an indicated 142mph (233.36kph) on 195s. While it's a sweet video, it isn't really an indication of mad power.

With 205/50R/15, 6speed, 3.9, and stock 7200rpm rev limiter, you can do 250kph. So, 7538* rpm for 254kph. With a 5speed, it's 7278rpm. So, my new guess with actual maths is 5speed and 3.9.
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Old 06-16-2015, 12:22 AM   #10
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Were you on a NASCAR oval track at the time?
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Old 06-16-2015, 12:38 AM   #11
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Quote:
Originally Posted by Schuyler View Post
I can gear out my T25 200whp setup easily in 5th gear with a 4.30 at 7400rpm, at an indicated 142mph (233.36kph) on 195s. While it's a sweet video, it isn't really an indication of mad power.

With 205/50R/15, 6speed, 3.9, and stock 7200rpm rev limiter, you can do 250kph. So, 7538* rpm for 254kph. With a 5speed, it's 7278rpm. So, my new guess with actual maths is 5speed and 3.9.
He shifts through 6 gears in the video.
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Old 06-16-2015, 01:14 AM   #12
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Quote:
Originally Posted by Savington View Post
Definitely don't need 360whp to go 155mph.
Agreed, I made some rough assumptions on frontal surface area, Cd, weight, Crr, Fuel energy density, Drivetrain efficiency (95%), Engine efficiency.

From Race Technology Knowledge Base | M / Mazda
94 Miata CD 0.38, frontal area 1.71 sq m, CDa 0.65

Gearing is one thing having the power to overcome aero drag and reach the gear speed is another.

For my car last time I did coast down tests I got Drag coefficients for a given Wing Angle (frontal area of 2.1 sq m):

00 Deg: 0.25293
05 Deg: 0.36337
10 Deg: 0.34050

Plugging my setup into the formula I would need 300 RWHP to get to 155 mph (wing at 00).
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Old 06-16-2015, 01:48 AM   #13
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Quote:
Originally Posted by mgeoffriau View Post
Were you on a NASCAR oval track at the time?
Look at the location in first post. Probably on the Autobahn.
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Old 06-16-2015, 02:47 AM   #14
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Hey guys,

some answers:

- transmission is 6speed with 3.6torsen (from a 10th anni edition) (I think this is a great gear ratio step up for the car; gears 1-4 are nearly the same like 5speed with 4.3end)
- setup: 1.6 stock engine, 10psi, GT2560R
- last dyno was 222hp at flywheel, and 190rwhp
- the car was still accelerating, but then a idiot block the left lane, so I had to brake and slow down
- and yes video was filmed on autobahn, so all legal


I meassured 862C after turbo and 970C at the collector in the exhaust manifold before turbo at that high speed . All cool I think, what do you think?

Best regards!
Basti

Last edited by Mazdaspeed_Miata; 06-16-2015 at 07:50 AM.
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Old 06-16-2015, 03:00 AM   #15
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3.63 master gear, do want, want bad.

Did you have that imported from somewhere, or is it not oem? Can you find me one lol
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Old 06-16-2015, 03:50 AM   #16
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Quote:
Originally Posted by deezums View Post
3.63 master gear, do want, want bad.

Did you have that imported from somewhere, or is it not oem? Can you find me one lol
3.6 was delivered on every 6speed in Europe, and Australia, and ... Ebay is your friend
3.9 was used in US/CA and JP (and maybe somwhere else).
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Old 06-16-2015, 11:31 AM   #17
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I've been in a race prepped miata at 156mph, but never in a street car.

How does that feel? That's gotta be scary, my nb's get real floaty past 120
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Old 06-16-2015, 11:58 AM   #18
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Nice video. That's intense to watch, especially once the speedo is burried in 6th.
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Old 06-16-2015, 12:07 PM   #19
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Quote:
Originally Posted by 18psi View Post
I've been in a race prepped miata at 156mph, but never in a street car.

How does that feel? That's gotta be scary, my nb's get real floaty past 120
My feelings exactly. My car doesn't feel like it's in a happy place above 100, to the point that I've only done it a couple of times in 4 years. And I used to hit 120+ on my bikes practically every time I took them out, including the work commute.

OP: Haben Sie aerodynamische Abaenderungen gemacht?
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Old 06-16-2015, 12:56 PM   #20
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Well, I won't say that it feels very comfortable past 120mph, but in my own sensation it is still ok. My biggest fears are that I have to do an emergency braking from high speed (because i have no ABS) or that the engine blows away at that speed. The feeling inside of the car without any problems is ok. Only the wind noice gets pretty loud at that speed

Again my question:
I meassured 862C after turbo and 970C at the collector in the exhaust manifold before turbo at that high speed . All cool I think, what do you think?

And I have no aerodynamic specs, only the factory airdam at the front.

Here 4 pics of my miata:

<a href="http://www.directupload.net" target="_blank"><img src="http://fs2.directupload.net/images/150616/yqwidcl5.jpg" title="Kostenlos Bilder und Fotos hochladen"></a>
<a href="http://www.directupload.net" target="_blank"><img src="http://fs2.directupload.net/images/150616/ehl9luko.jpg" title="Kostenlos Bilder und Fotos hochladen"></a>
<a href="http://www.directupload.net" target="_blank"><img src="http://fs1.directupload.net/images/150616/owka3uam.jpg" title="Kostenlos Bilder und Fotos hochladen"></a>
<a href="http://www.directupload.net" target="_blank"><img src="http://fs1.directupload.net/images/150616/caqr3hcv.jpg" title="Kostenlos Bilder und Fotos hochladen"></a>
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