Wondering something about how fast I'm going. I've read in here that I should be doing around 88mph at 3000rpm in 5th gear. I have the isuzu tranny. But I thought that when your doing 80mph that it should take u 40 seconds for each mile. I have 215-45-17 tires which is basicly the same tire size as the original 185's so is my previous thinking that I should have a 40 second mile wrong? Thanks for your help

anyone?

I think you're right about being at 80 MPH that you'll do 1 mile in 40 seconds. It's easier to figure 1 mile in 60 seconds at 60 MPH. Speedo accuracy and actual RPM at a certain speed depends on rear tire height. Even from the factory the speedo wasn't 100% accurate. Rather than timing miles with a stopwatch, because it's tough to do a perfectly constant speed, it's better to check the odometer reading over a 10 mile stretch of highway, preferable a road with milemarkers, so you can keep track of how you're doing. You can then calculate your percentage of error.

thanks for the reply didn't know if i was going to get one or not. It doesn't matter much right now anyway though because my car isn't even running right now, because my select cable is broke. So I had decided to just keep it parked and fix it up how I want it before I start driving it again :P which really sucks, cuz I don't make much money at all since I work for a fast food place.