bobby777

on my 2001 Z--Just had new plugs-wires-fuel filter--complete tune-up on my 12,000 miles Z--car buzzed right up to 6500 red line with chrome wheels and firestone WO--Than I put my original wheels/tires back on and what a difference--now I have the tach lag--fuel cutoff kicks in at 6200-6300--can an extra 7 pounds in the wheel and tire-28 pounds total make this difference? The rate of acceleration? Thx

ZeeOSix

Wheel spin-up inertial definitely affects how much HP is going into moving the car forward. Heavy wheels and tires suck usable HP away that would normally be there to accelerate the car.

bobby777

So im getting the tach lag because of faster acceleration and the tach cant keep up with the real rpm?

skyavonee

Probably... 7 lbs per corner is a lot of rotating mass to shed.

bobby777

I just did the slow 1st gear up to 6500 rpm--no problem- so this confirms tach not keeping up with engine RPM and also how extra weight on wheels/tires does affect performance a lot--

skyavonee

Thanks for sharing; it's always nice to have real-world observations to back up the tried and true laws of physics.

bobby777

Yes it is! Lots of talk also on the tach lag--this is also confirmed--I think maybe the tires being alittle hard-still have 7/32 tread-its spinning all the way in 1st gear--also with the Vararam bringing outside air in-helps in the H/P game--

halp

Good info. Every time I think about getting repo chromes I worry about the weight. Most say you will not feel it during street driving, but it looks like you do.

How were your plugs and wires at 12,000 miles?

I replaced my valve springs at 13,000 miles on my 02 and the plugs and wires looked so good I put them back in.

bobby777

The car has sat for along time--not driven much so I got a complete tune-up--plugs-wires-fuel filter--runs like someone stole it--very pleased--yes I did prove about extra wheel weight and tach lag--