130mph at 6500 rpm in 6th gear

crumpmd · 03-01-2004, 07:18 AM

Actually it was just a hair over 6500, more like 6600. How about it ? Anybody out there willing to say what their current top speed is?
Conditions were 63F, Dry, slight hills no more than 75 feet elevation, going up hill at 130.:p

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cgrx · 03-01-2004, 07:24 AM

That is fast

You got lucky ~ no

or

Don't know whats up with that guy ???

lawrie909 · 03-01-2004, 08:45 AM

154mph
it was good

lilbigman · 03-01-2004, 08:49 AM

Quote:

Don't know whats up with that guy ???

The guys seems to be photochopped in my .02 cents.

Velocity-8 · 03-01-2004, 08:55 AM

I had mine up to 125mph and I was still in 4th gear around 8000rpm.

crumpmd · 03-01-2004, 09:00 AM

Lawrie909,
What was the tach reading at 154mph?

CGRX
No luck. Closed course, professional driver (me), do not attempt this at home. ; )

Overport · 03-01-2004, 09:06 AM

this topic has already been posted a bunch of times.....154

crumpmd · 03-01-2004, 10:32 AM

Thanks Doug
I just joined. My search did not find where RPM and top speed were reported together. I should have asked that because people just give out their max speed, just as you did. I am interested in the conditions at the speed trial as well.
So what rpm did you see at 154?

RobDickinson · 03-01-2004, 10:37 AM

crumpmd - its generaly assumed that 6th gear is bad for top speed, and 5th is where you'll get the highest numbers.

6th is too long for the cars power - 6th will do 190mph at 9.5k, the 8 lacks the power to go that fast (against air resistance).

5th gives you more power because of its shorter gearing - tho what 150+ is on the speedo in rpms I dont know. Speedo will be 10%ish out at those speeds - measure with GPS if you can.

crumpmd · 03-01-2004, 11:35 AM

Interesting Rob. I did not know 6th was not the best for top speed. I'll make a run another time in 5th and see what happens.
Thanks

D MENAC 7 · 03-01-2004, 11:59 AM

If you were truly doing 6600 RPM your actual speed would only have been 118.34 mph. Mazda's precise specs on gearing of the 8's 6S MT is 19.4 mph/1,000 rpm. On our stock equipment there are slight variences in both the speedo and tach and neither are dead exact.

With Mazda's precise formula above, 9500 rpm could yield a maximum speed of 184.3 mph. But, as noted in a thread above, there are other factors that would not allow this such as actual power with wind resistance and there is also wear on tire thread that slightly alters circumference.

lawrie909 · 03-01-2004, 12:23 PM

i was in 6th gear at 154 mph, don`t know tacho

Knerk · 03-01-2004, 01:04 PM

I thought the 8 had a cut off at 148mph, do you have any mods that get you around that?

lawrie909 · 03-01-2004, 01:25 PM

no mods, i have been over 150mph twice, there did seem to be more available tho`.... i am purchasing an amuse titanium exhaust and re amemiya header , which will give me around 15bhp more....

doccable · 03-01-2004, 01:52 PM

145 MPH, about 7200RPM in 6th. Radar detector went off... This was with stock setup, haven't done any engine/driveline mods yet. Waiting for weather to get better.

RX8Bliss · 03-01-2004, 01:55 PM

i hit 140 at around 7500rpm in 6th with 3 other people in the car. on the way to vegas. it took forever to hit 140.

crumpmd · 03-01-2004, 07:07 PM

D Menac
I think your calculations are off(or the Mazda specs are off!). I saw 130mph on the meter at a hair over 6500rpm. There may be some speedo error but I doubt that much. besides, if 9000 rpm gives 180mph why would 6600 only give 118mph. It is not exactly linear as presented, does not make sense. I'll check it with the GPS soon and post it.
Thanks for the input

Jump120MPH · 03-01-2004, 08:16 PM

141mph 5th gear

DemonRX-8 · 03-01-2004, 09:41 PM

Quote:

Originally posted by crumpmd
D Menac
I think your calculations are off(or the Mazda specs are off!). I saw 130mph on the meter at a hair over 6500rpm. There may be some speedo error but I doubt that much. besides, if 9000 rpm gives 180mph why would 6600 only give 118mph. It is not exactly linear as presented, does not make sense. I'll check it with the GPS soon and post it.
Thanks for the input

I think he mistyped the number, I get 19.4*6.5 = 126.1, which sounds about right. Although I always figured the 8 did about 20 mph/1000 rpm, but who am I to argue with Mazda? (sarcasm there, in case you missed it)

D MENAC 7 · 03-01-2004, 10:18 PM

Actually, yes, I did miscalculate because it should have been 19.4 X 6.6 which would have yielded 128.04 which would be why crumpmd would most likely have seen 130 which accounts for the speedo difference. So, I stand corrected, it was early in the morning for me...

project · 03-02-2004, 10:59 AM

Quote:

Originally posted by RX8Bliss
i hit 140 at around 7500rpm in 6th with 3 other people in the car. on the way to vegas. it took forever to hit 140.

damn bliss get out of my head!

i hit 140 on the way to vegas with 2 other people in the car. im not sure what the tach was, but shifting from 5-6 dropped me about 2 mph which took forever to get back. distance 420 miles, total driving time 4.5 hours. luckily every cop i saw on the way down already had someone pulled over.

Rx8Freehk · 03-02-2004, 02:32 PM

261kph (around 160?) on a 6km straitaway on A60 (Thats one of the Autobahn's for you guys in the states!!) thats was with my RE Intake, RP mid-pipe and Greddy Exhaust. Now im forced to live life with a midpipe and stock exhaust (YUCK!!) and havnt tried since then.

I dont frequent those speeds regularly because when I start getting misfires at those high RPM's and with no cat.... I get HUGE clouds of white smoke (fuel smoldering "IN" the exhaust) Hopefully my CZ stage 2 will fix the @#$@#$ misfire crap.

GeorgeH · 03-02-2004, 02:57 PM

Quote:

Originally posted by D MENAC 7
If you were truly doing 6600 RPM your actual speed would only have been 118.34 mph. Mazda's precise specs on gearing of the 8's 6S MT is 19.4 mph/1,000 rpm. On our stock equipment there are slight variences in both the speedo and tach and neither are dead exact.

With Mazda's precise formula above, 9500 rpm could yield a maximum speed of 184.3 mph. But, as noted in a thread above, there are other factors that would not allow this such as actual power with wind resistance and there is also wear on tire thread that slightly alters circumference.

In the other threads, has anyone discussed the effect of centrifugal loading on the rolling radius of the tire? I've heard that tires tend to grow a little at high speeds, which makes sense. This could easily account for a few percent variation from Mazda's gearing specs.

Velocity-8 · 03-02-2004, 06:12 PM

Quote:

Originally posted by GeorgeH
In the other threads, has anyone discussed the effect of centrifugal loading on the rolling radius of the tire? I've heard that tires tend to grow a little at high speeds, which makes sense. This could easily account for a few percent variation from Mazda's gearing specs.

I doubt a low profile tire can swell much but it is an interesting thought.

JimJimElf · 03-03-2004, 06:42 AM

Those are pretty fast speeds. I still haven't taken mine much over 100 mph. But then again that is on the highway and I don't like tickets so I slowed down. If there was a closed course around here I would take it there and play but since there isn't I'm stuck.