How fast was I Going?

[MrSony]

On a non-descript day in the distant or near present past, I may or may not have exceeded the reccomended speed limit coming back from selling a pair of slicks to a fine fellow with a bracket nova. Anyway, I was in third (drive), engine screaming at 4700 rpm with 195/75r/14 tires and 2.41 gears. Speedo was waaaayy buried. I let off the gas, didn't touch the brakes, and it took a solid 10 seconds at least for the needle to pop back to 85mph. Road was flat as a sheet of glass. Anyone who's good at car math can ya figure out how totally not fast I was going?

 

[Texas82GP]

148 mph which doesn't seem like a smart thing to do in that car on those tires.
http://www.csgnetwork.com/multirpmcalc.html
http://www.wallaceracing.com/tire-aspect-calc.php

 

[pontiacgp]

get a garmin and that will tell you what speed your are travelling. I don't trust those online calculators, my GP would be doing a little more than 180 mph at 4700 rpm based on that calculator...

 

[lilbowtie]

My racing spread sheet has you @ 127 w/ a 92% converter

 

[drogg1]

It's simple math really.

Your tire has a circumference of around 80 inches. Multiply that by RPM (4700 RPM) and divide by gearing (1 * 2.41) which gives you about 156,000 inches per minute. Multiply that by 60 to get inches per hour (9.361 million inches per hour) and then divide by 12 to get feet per hour (780k feet per hour) and then 5280 to get miles per hour (148 mph).

 

[pontiacgp]

It's simple math really.

Your tire has a circumference of around 80 inches. Multiply that by RPM (4700 RPM) and divide by gearing (1 * 2.41) which gives you about 156,000 inches per minute. Multiply that by 60 to get inches per hour (9.361 million inches per hour) and then divide by 12 to get feet per hour (780k feet per hour) and then 5280 to get miles per hour (148 mph).

but that does not take into account slippage in the drive train or wind impedance or friction...

 

[drogg1]

but that does not take into account slippage in the drive train or wind impedance or friction...

Right I meant to mention that. That is the ideal number with no drivetrain slippage and constant tire contact. At 4700 rpm I would think the converter would surely be 90-100% locked. Perhaps something like 120 mph is more likely.

 

[MrSony]

Yeah, I'm more inclined to believe it's at the 120-130 mark. sh*t, I had 1300 more rpm to go. But that car is in NO way set up to go that fast. I had the chance to do it, and I took it. Who wouldn't? Flat stretch of decent highway, no cars in either direction for miles, new engine, new transmission (at the time), new tires, even though they aren't rated for anything over what... 80? Curiosity got the better of me.

 

[gbodytoys]

perfect time to have 2.41 gears. I was doing 100 or so for 10 seconds...and a I found a nice little hole in my oil pan.

 

[MrSony]

perfect time to have 2.41 gears. I was doing 100 or so for 10 seconds...and a I found a nice little hole in my oil pan.

😛