TBIThrottle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.
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My tach claims 2,400 RPMs at 75...is that true? Seems kinda high to me for 3.08 gears...I highly doubt my rear end has different gears in it. I have a 3/90 Motor Trend road test of a '91 RS, that showed 60 MPH at 1600 in the spec chart...mine shows 2k at 60.
Any help is appreciated...I assume my tach is off?
__________________ '86 Trans Am -Bright Blue, Black/Grey cloth, LB9, AT, hardtop, 34k miles - Stock - Norwood Gathering 2011 TGO Entry '88 IROC-Z - Medium Grey/Grey cloth, L98, t-tops, 22k miles - Stock '88 Trans Am - Bright Red, Grey cloth, LB9, M5, t-tops, 27k miles - Stock '97 30th Anniversary Z28 - White/Orange Stripes, White leather, M6, t-tops, 71k miles - 13.96 @ 100.8
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Your tach is off. So is mine, so I made a spreadsheet of my rpm vs speed. Here is yours and I guessed on your tire size. I can email the spreadsheet if you want it.
My tach says 2750 at 75. That's how I judged my speed on the interstate, cause my speedo dosen't work.
I don't know how accurate my tach is though either. That's also with my GPS at 75 MPH.
Your tach is off. So is mine, so I made a spreadsheet of my rpm vs speed. Here is yours and I guessed on your tire size. I can email the spreadsheet if you want it.
I'm using 245/45/17 BFGs at the moment...could that have something to do with it? Based on having other cars clock me on the highway, I know the speedo is accurate. I figured the tach was off...it seems like it gets to 3k in first gear a little on the quick side Is there any way to re-calibrate a stock tach? Thanks...
can you upload this spreadsheet as a picture by changing its extension to jpg?
could be helpful for a couple of us. thanks
Here ya go. It's saved as a .doc file extension, so after you save it to your harddrive, change the extension back to .xls and it will open as an excel file.
After that you can modify the tire size, rear gear, and transmission parameters to match your current combo. It's also helpful to see how a different tire size or rear gears will effect speed.
if you are changing tires, you will need this site to determine how much off your speedo will be compared to the stock tires http://www.miata.net/garage/tirecalc.html
based on this, you could change the speedo gears in your trans to correct it
OR
you can use another link to check for tire alternatives and find out which ones you can use without having to correct your speedo: http://www.dsm.org/tools/tiresize.htm
If People Drove Any Slower They’d Be Going Backwards
Is there any way to re-calibrate a stock tach? Thanks... 
