in first gen b-16's on a stock ecu the car will top out at 115 mph but i got mine up to 125 mph one time and the car felt as if it copuld easily go more but i backed off, but recently i tried to get up there again but now i am limited to 115 mph. what could be the cause of this higher mph and now lower mph. thanks.

 

ttt

 

at the time i was running 14" rims (hx's) when i got up to 125 mph now i am running 15" rims (ls mesh) when i topped out at 115 mph. was told this could be a factor.

 

is there anything you can do to fix this or make up for it? i run 14's on a si speedo made for 15's....would I be going faster or slower that my speedo says?

 

on the hx's i was running 185/60/14 and on the ls mesh i am running 195/50/15. was told that the 15's has more rotational mass so will be gioing faster on them than on the 14's that has less rotation or something like that.

 

ttt

 

rotational what!!! like cronic said run as close to factory diameter as possible for the most acurate readings. whether the rim is 14" or 20" if the diameter from one side of the tire to the other at its widest point is the same then the circumfrence is the same and as a result your speedo will read the same.

by the way I had the same issue with my 88 crx, I have the pr3 ecu and hit 125 but I was on 205/40/16