got a question, for Jake Raby Options

[bd1308]

you said in a previous post that one should not go below 3500RPM in 5th gear, as the airflow is not sufficient enough for proper cooling.

i have some problems with this....

1) in my car, at 70mph, I am around 3200RPM in 5th...sometimes i am even running 3000RPM and occasionally run even 2800RPM for short periods of time. Are you suggesting that I should not shift into 5th gear at all?

2)I have also heard that the type 4 cooling fan efficiency goes down after around 4000RPM....it was mentioned by someone on this board, but the user name escapes me. Is this true?

I tried running 75 in 4th gear and I was running more than 4000RPM.....

I think i am missing something....

[lapuwali]

The stock tires were 165/85-15, which is roughly 661mm tall (26" for the metric challenged). A 195/60 would be 615mm tall (24.2"), so your tire is quite a bit shorter than stock, thus it has a smaller circumference than stock, so the tire spins faster at a given road speed, so your speedo reads high by about 7%. 70mph indicated is 65mph actual, assuming the speedo was accurate to begin with (not bloody likely).

It's actually pretty difficult to find new tires that are as tall as the stockers for 15" wheels these days.