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Engine speed at 55 MPH by josef644
Started on: 01-13-2008 07:43 PM
Replies: 11
Last post by: josef644 on 01-14-2008 07:37 PM
josef644
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Report this Post01-13-2008 07:43 PM Click Here to See the Profile for josef644Click Here to Email josef644Send a Private Message to josef644Direct Link to This Post
I was wondering if this is about correct rpm's for a 5 spd 2.5. I am turning about 1600 rpm for an indicated 55 MPH. When I bought the car there was a 120 MPH speedometer in it, and I read some where that was a GT only speedometer. If it is reading incorrect, how do I get it to read correct? It feels about right for 55 mph. Or could the tach be reading incorrect thinking it was still a 6 cyl engine?
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linuxpowered88
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Report this Post01-13-2008 08:59 PM Click Here to See the Profile for linuxpowered88Click Here to Email linuxpowered88Send a Private Message to linuxpowered88Direct Link to This Post
The tach could be off but It sounds about right im not sure how much difference the 6 and 4 cyl tachs are in calibration. Also are you sure the speedo only wasn't switched? If you have an oil pressure guage in with the tach you have the dukes tach.
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josef644
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Report this Post01-13-2008 09:42 PM Click Here to See the Profile for josef644Click Here to Email josef644Send a Private Message to josef644Direct Link to This Post
No, my oil pressure is in the auxilery gauge set along with a volt meter. I thought some one with a 4 cyl might know where their rpms are at 55 mph
Joe

[This message has been edited by josef644 (edited 01-13-2008).]

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Graham
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Report this Post01-13-2008 09:48 PM Click Here to See the Profile for GrahamClick Here to visit Graham's HomePageSend a Private Message to GrahamDirect Link to This Post
At 55 I am about 2500 my duke is a 87 auto and I might have some engine problems so that could be off.
I was about to post the same question
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88White3.4GT
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Report this Post01-14-2008 12:54 AM Click Here to See the Profile for 88White3.4GTSend a Private Message to 88White3.4GTDirect Link to This Post
 
quote
Originally posted by Graham:

At 55 I am about 2500 my duke is a 87 auto and I might have some engine problems so that could be off.
I was about to post the same question


is it about 3000-3100 at 65 mph? that sounds about right for a 3speed ..
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Graham
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Report this Post01-14-2008 01:52 AM Click Here to See the Profile for GrahamClick Here to visit Graham's HomePageSend a Private Message to GrahamDirect Link to This Post
 
quote
Originally posted by 88White3.4GT:


is it about 3000-3100 at 65 mph? that sounds about right for a 3speed ..


yes about that, so it is good?
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niemann99
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Report this Post01-14-2008 11:23 AM Click Here to See the Profile for niemann99Send a Private Message to niemann99Direct Link to This Post
 
quote
Originally posted by josef644:

I was wondering if this is about correct rpm's for a 5 spd 2.5. I am turning about 1600 rpm for an indicated 55 MPH. When I bought the car there was a 120 MPH speedometer in it, and I read some where that was a GT only speedometer. If it is reading incorrect, how do I get it to read correct? It feels about right for 55 mph. Or could the tach be reading incorrect thinking it was still a 6 cyl engine?


That is about right. I have an 88 duke/5 speed and turn 2000 RPM at 60 MPH. Never took a reading at 55, but if you divide it out, it's 33.333MPH/1000 RPM. At 1600 RPM = 53.3328.
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Pyrthian
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Report this Post01-14-2008 11:35 AM Click Here to See the Profile for PyrthianClick Here to Email PyrthianSend a Private Message to PyrthianDirect Link to This Post
 
quote
Originally posted by josef644:

I was wondering if this is about correct rpm's for a 5 spd 2.5. I am turning about 1600 rpm for an indicated 55 MPH. When I bought the car there was a 120 MPH speedometer in it, and I read some where that was a GT only speedometer. If it is reading incorrect, how do I get it to read correct? It feels about right for 55 mph. Or could the tach be reading incorrect thinking it was still a 6 cyl engine?


depends on the transmission.
but - that does sound way low in RPM.
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niemann99
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Report this Post01-14-2008 11:42 AM Click Here to See the Profile for niemann99Send a Private Message to niemann99Direct Link to This Post
 
quote
Originally posted by Pyrthian:


depends on the transmission.
but - that does sound way low in RPM.



Duke 4 cyl, if manual, normally has Isuzu 5 speed behind it, for economy. Final drive ratio on Isuzu is 3.35:1 Final drive on Getrag is 3.61:1.
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Pyrthian
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Report this Post01-14-2008 11:50 AM Click Here to See the Profile for PyrthianClick Here to Email PyrthianSend a Private Message to PyrthianDirect Link to This Post
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slinger
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Report this Post01-14-2008 03:16 PM Click Here to See the Profile for slingerSend a Private Message to slingerDirect Link to This Post
i run about 1500 to 2000rpm at 55mph at about 70 im a little over 3000rpm.

i got a 86 duke with the 5 speed
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josef644
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Report this Post01-14-2008 07:37 PM Click Here to See the Profile for josef644Click Here to Email josef644Send a Private Message to josef644Direct Link to This Post
I haven't had mine to 70 yet, I just made 500 miles on a whole engine rebuild today. I'm turning about 1750 rpms at 60mph by my tach.
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