Depends on what track your dealing w/ drags or road courses or even autoX's
Stored energy= drag cars. Lighten rotating mass= road racing Firmer power train mounts does encourage wheel spin= less power being used up. Thats where suspension set up comes in. Yes stored energy is great for DD's, say alloy flywheel vs a stock style flywheel. I was just saying a great upgrade is a poly dogbone vs the oem one, being FWD car's.
Not too many autocrossers or drag racers with 50K track miles lol. That'd be about 10K weekend events which would take about 200 years, assuming no rain cancellations, vacation or sickness.
I make good use of stored energy in my road racing, street driving and even autocross (in most instances) to improve performance and reduce wheelspin. That would definitely apply to my street Focus. I've had good luck with moderate to heavy flywheel on the track, and more importantly, I don't see my friends having measurably better luck with featherweight upgrade parts of that sort. The stopwatch is a valuable tool for quantifying gains. I'm not making an argument for heavy wheels and tires since low unsprung weight is important on most surfaces. I don't want to break traction when launching hard or smacking 2nd gear (due to a stiffer dog bone). I'd rather store the excess torque in a piece of rubber then retransmit it over a second or so, as the motor moves back into position. Tire rubber you grind off against the pavement does not provide any benefit, unless you want to see smoke and buy more tires. I'm really not interested in transmitting greater torque peaks to my transmission teeth either.
Autocross is won by contestants who can maintain max g's thru smooth driving with minimal wheelspin. Abrupt accel or decel is not the key; maintaining higher velocity is. I have dozens of first place trophys running cars with super compliant bushings and lots of mass, rotating and otherwise. My stock, compliant and luxurious Lincoln Mark VII with automatic and air bag suspension served to demoralize hundreds of ponycar drivers, many with 50-75% more HP and 5 or 6 spd trannys with firm bushing, springs and such. Half of them were cheating lol. They were spinning, slipping and losing, and this included
very good regional drivers in the points chase. I was transferring energy to and from rubber mounts to maintain grip, and more often than not, winning.
Poly motor mounts don't belong on a Focus daily driver street car under any circumstances and they won't measurably improve it's autocross, drag or road race performance. Of course, this is just my opinion.
