Is 78mph at 3k rpm too high with 4.10 gears?

[JaguarS4R]

I feel like my motor is revving too high, but I might be paranoid. I have 4.10 gears and supercharged as well as other bolt-ones and it also has the speedcal, so speedo is calibrated. 3k rpm is about 78mph, does that sound normal? Obviously in 5th gear since I have the stock trans

 

[darkhorse276]

What kind of car are we talking about here?

 

[mnewxcv]

What kind of car are we talking about here?

given the forum, an sn95 cobra

 

[scottg]

My 96 runs around 2850 at 77/78, iirc.

 

[mystical]

Seems high for 4.10's.

 

[JaguarS4R]

sorry, its a 97 Cobra with vortech blower, full exhaust, 4.10s... etc. I have the speedcal so speedo's got to be right, correct? 78mph=3k rpm, 80mph= 3100 rpm, is it too high or just a bit over? Whats that mean, something wrong?

 

[4vRedone]

thats what im at

 

[OH3BLKSVT]

I was about the same with my 97 cobra and 4.10 gears.

 

[AZSN95SNAKE]

AC on? mine runs at 3100 going 80mph with the AC on. with the AC off, it runs at exactly 3000rpm @80mph. 78ish is 3k with my AC on. 4.10s and x pipe. frpp Speedcal.

 

[DVJ38]

With my 4.30's I would be going 75 and be at 3k. So maybe seems a little high.

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[bornatiger]

Stock tach: 3000
Accurate tach: 2850
I tested this, multiple times, with gps at 80 on a flat road.

 

[JaguarS4R]

so it seems like i should be fine then

 

[Helomech74]

What size tire are you running? Your rpm looks correct, there's always a slight variance when it comes to tire size, inflation pressure etc.

 

[JaguarS4R]

295/35/18

 

[Helomech74]

Doing the math using your tire size, the rpm at 78mph would be 2756. Now keep in mind your speedo and tach aren't 100% accurate. There is a 244 rpm difference from what the math tells us to what you are telling us the tach is reading, I wouldn't be concerned with that personally.

 

[DVJ38]

OP, use the info in the thread I posted at the bottom of this reply to check the settings in your speed cal.

http://www.svtperformance.com/forums/showthread.php?t=732245

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[scottg]

seems a bit high to me.

 

[Mustang Matt]

How are you guys stating that it seems high/low if the OP hasn't posted his rear tire size? Or did I miss it?

He also didn't post his speedcal settings so we can't deduce his tire size. We also don't know which speedo gear he's using.

The quickest way to check this is drive a constant speed and cross reference a GPS.

 

[Helomech74]

How are you guys stating that it seems high/low if the OP hasn't posted his rear tire size? Or did I miss it?

He also didn't post his speedcal settings so we can't deduce his tire size. We also don't know which speedo gear he's using.

The quickest way to check this is drive a constant speed and cross reference a GPS.

4 posts above yours he listed the tire size.

 

[Mustang Matt]

There we go! I am blind.

295/35/18 = ~771.84 revs/mile. (MFG can often get you the exact loaded revs/mile)

Using Mark Olson's vss calc:
Ford VSS Calculator

4.10 gears and assuming 7 tooth drive gear and 21 tooth driven gear gives 8438.784 pulses/mile.

Then using the speedcal calc:
Recalibrator & Speedcal Calculator

1000011100 for the non-ER speedcal

0010000111 for the ER speedcal