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Old 06-09-2010, 05:36 PM   #1
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Default What RPM's are you guys running around 70mph?

Just wanted to know. I just picked up my first Miata and noticed I ws running around 3.5K around 70mph. Is that pretty normal? BTW it is a open diff from a 1.8. But that would'nt affect the ratio right?
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Old 06-09-2010, 05:38 PM   #2
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In fif gear maybe 3.8k.
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Old 06-09-2010, 05:44 PM   #3
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I run a little above 4K at 80, but I have an exhaust leak an no turbo.
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Old 06-09-2010, 05:45 PM   #4
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Quote:
Originally Posted by latena View Post
I run a little above 4K at 80, but I have an exhaust leak an no turbo.
...Please explain to me why that would have any effect on cruising RPM.
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Old 06-09-2010, 05:50 PM   #5
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Originally Posted by jeff_ciesielski View Post
...please explain to me why that would have any effect on cruising rpm.
no
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Old 06-09-2010, 05:52 PM   #6
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Quote:
Originally Posted by Jeff_Ciesielski View Post
...Please explain to me why that would have any effect on cruising RPM.
He's right Latena. The exhaust leak and being a non-turbo would certainly not have a effect on your cruising RPM's. This is solely responsible on your gear ratios. But you need to take care of that and get yourslef a turbo om that thing ASAP!
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Old 06-09-2010, 05:53 PM   #7
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http://www.flyinmiata.com/tech/gearing.php

^ That many RPMs. ^

A friend of a friend of mine was convinced that he had to turn an extra couple hundred RPM to maintain speed in a headwind. ******' drivetrains, how do they work?
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Old 06-09-2010, 05:54 PM   #8
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Originally Posted by phatspud View Post
******' drivetrains, how do they work?

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Old 06-09-2010, 05:55 PM   #9
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no
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Old 06-09-2010, 06:00 PM   #10
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???????? Jeff, classic pic man, classsic! I remember my ex-gf had a nephew who was so into ICP that he had a Eclipse that had a mural of there faces on the back window. I would never, and I mean never, let him park in our driveway!
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Old 06-09-2010, 06:02 PM   #11
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Quote:
Originally Posted by phatspud View Post
http://www.flyinmiata.com/tech/gearing.php

^ That many RPMs. ^

A friend of a friend of mine was convinced that he had to turn an extra couple hundred RPM to maintain speed in a headwind. ******' drivetrains, how do they work?

This link misleads me to this conclusion:

Tire size: 275/75/18....Result: 2nd gear top speed: 94.7 mph...

It also says top speed in 5th gear is close to 220mph...

(OP should do this to achieve lamborghini diablo status)
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Old 06-09-2010, 06:03 PM   #12
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Unsubscribed.
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Old 06-09-2010, 06:04 PM   #13
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Quote:
Originally Posted by 92verty View Post
Just wanted to know. I just picked up my first Miata and noticed I ws running around 3.5K around 70mph.
That's pretty screwed up and definitely not normal. I'm turning 85mph at 3500rpm.
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Old 06-09-2010, 06:21 PM   #14
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Originally Posted by hustler View Post
That's pretty screwed up and definitely not normal. I'm turning 85mph at 3500rpm.
Wow man seriously? I mean, I really thought it was a little high myself especially being a 5spd. I mean my wheels are 17's and the tires are 205 35's front and 245 35's in rear. So Now I will assume that my speedo is aboout 10mph off. That would put me in the range of about 3000rpm @7omph maybe?
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Old 06-09-2010, 06:27 PM   #15
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Originally Posted by 92verty View Post
Wow man seriously? I mean, I really thought it was a little high myself especially being a 5spd. I mean my wheels are 17's and the tires are 205 35's front and 245 35's in rear. So Now I will assume that my speedo is aboout 10mph off. That would put me in the range of about 3000rpm @7omph maybe?
Wrong. I get to about 3200-3500 around 70mph too...factory speedo will show about 73-74mph...and my brother's miata does about the same rpm's too...both are 1990 5-sp.

You're fine, if you're worried, get a 6-speed.
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Old 06-09-2010, 06:35 PM   #16
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Only way I know how fast I am going is to take 5th gear indicated rpm and multiply by 2, then add a zero. Meaning 3k is 60mph, 3.5k is 70, 4k is 80, so on and so forth. So yeah, 3.5k at 70 is normal. Stock speedometers are not accurate down to single MPH's usually, so a few off is completely expected. Assuming you have the same rear gearing, my above should stand.
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Old 06-09-2010, 06:43 PM   #17
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Quote:
Originally Posted by NA6C-Guy View Post
Only way I know how fast I am going is to take 5th gear indicated rpm and multiply by 2, then add a zero. Meaning 3k is 60mph, 3.5k is 70, 4k is 80, so on and so forth. So yeah, 3.5k at 70 is normal. Stock speedometers are not accurate down to single MPH's usually, so a few off is completely expected. Assuming you have the same rear gearing, my above should stand.
Okay that makes me feel alot better. Was just used to my 944 cruising [email protected] 2500rpm. Although it's a 2.5 litre i was just curious to know if 3.5rpm's was average around 70mph for this car. I know they rev to keep highway speeds in check. And i do realize that teh average speed was 55 when this car was built. And few highways were still 60-65 at this time.
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Old 06-09-2010, 06:51 PM   #18
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I'm at 75 at 4000 rpm in 5th
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Old 06-09-2010, 07:22 PM   #19
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I'm at 7600 rpm at 74.38 mph.


Sorry, couldn't resist, I have been good all day, really I have.

2nd gear (5 spd), 275/35/15 tires, 3.63 rear end.
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Old 06-09-2010, 07:31 PM   #20
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Quote:
Originally Posted by Chris Swearingen View Post
I'm at 7600 rpm at 74.38 mph.


Sorry, couldn't resist, I have been good all day, really I have.

2nd gear (5 spd), 275/35/15 tires, 3.63 rear end.
Whoa man!!! What the hell? 3.63's are causing this? Whats the factory ratio for a 92? Does anyone know?
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