Light Vs heavy pistons (ie: ACL specs)

[SRacin]

tooooo many numbers....

Anyway

Silvertop Piston Pins = 99 grams
Blacktop Piston Pins = 85 grams

[Hen]

-GT- it accelerates quicker because the car is essentially lighter (ok, the internals have less rotational inertia and weight to be precise). Less weight means more acceleration for a given force.

You are making better use of the available power.

Interesting to note from OCs calcs that the whole "spin up faster story" is fairly negligible. Taking the average velocity and squaring it isn't the best, it should really be the average of the velocity squared. But that'd take some interesting integration. I was bored (on a plane) the other day and tried to work out the energy of crank, rods and pistons. I gave up after an hour.

Sam - From memory the loads on the crank will be related to the square of the speed, and directly to the weight. So if you change pistons and rods to something half the weight, you should be able to rev it to 1.41 times the previous limit (all other things being equal).

Hen

[RT104GT]

Weight, reciprocating weight and strength factors, material from which piston is forged, type or rings, type of pistons design.
Ever thought of offering services to a racing engine guy?

If it was that easy they would have thought about it already.

Early 9RG and 8RG and 18RG pistons used to nick/nip up occasionally and needed replacing.
Usually when you revved the drap out of the engine.

Incidentally the original 88220 heads and 9.7 pistons in the original 18RG Toyota went like the clappers but never lasted the distance.
You could sustain 7000 rpm in most gears.


There are thousands of late model engines with 88235's 250's heads and fitted with lower comp engines but the original high performers are dodo's. now.

So you might design an engine that spins up well but if it has to be stripped down every time you run it what is the point?

Like I said go work for TRD if you think you have the answers.

[Mr Revhead]

does a car with a lighter flywheel have more horsepower?
same theory

[RT104GT]

does a car with a lighter flywheel have more horsepower?
same theory

Accelerates quicker but has less torque?




Thus torque converter (a.k.a. liquid flywheel) in slush box which has only a flex plate.

we also experiment with varous viscosities in autos to get faster spool up.