pdq67 wrote: ↑Wed Nov 29, 2017 5:49 pm
Like I said earlier, go over to, "Yellowbullet", and ask Mark O'Neal, the guy with the fat orange and white cat as his avatar.
Mark should/will know!
He owned Probe Pistons.
And if you do, please ask Mark to come over here so I can ask him something. Oh, just tell him that ol' pdq67 sent you asking, he knows me...
amcenthusiast wrote: ↑Sat Dec 02, 2017 1:28 pm
Newton's three laws is where one might start to learn the scientific explanation.
Those laws of Physics have not changed since.
The heavier pistons will require heavier counterbalancing.
The increased inertia will require more fuel to match the former acceleration rate of the lighter components.
Basically the goal is the opposite from the proposed question.
Correct in theory, irrelevant in practice. 14 g. per rod at 50% balance factor plus the requisite CW equals 112 g. (3.95 oz.) increased rotating mass at a radius of less than 2" . Since the moment of inertia varies as the square of the radius of gyration, this would be equivalent to a mass increase of at the periphery of a 12" flywheel of 3.95 x (2/6)² or less that half an ounce.
pdq67 wrote: ↑Wed Nov 29, 2017 5:49 pm
Like I said earlier, go over to, "Yellowbullet", and ask Mark O'Neal, the guy with the fat orange and white cat as his avatar.
Mark should/will know!
He owned Probe Pistons.
And if you do, please ask Mark to come over here so I can ask him something. Oh, just tell him that ol' pdq67 sent you asking, he knows me...
Thanks,
pdq67
He is here too. Or used to be
I is here. The question has been answered so I thought I'd not do my know-it-all routine this time..
Sorry MadBill I was just trying to be polite by making a simple reference to Newton's laws, I'm stuck now not to make any more explanation, not to embarrass anyone in public.
Not at all. Until delving into the details, many people feel slightly lighter parts have a significant effect on engine power, or at the least response. It's not until you run the numbers that it's clear leaving off the ring gear would have a far greater effect..
piston guy wrote: ↑Fri Dec 01, 2017 1:24 pm
RDY4WAR,
The toughest thing to do as a "racer" is not "overbuild" it. If it's only going to 5,000 max there is no need for a 6,000 rpm cam , manifold or heads. I recently built a 521 Ford stroker for my F350 box truck race car hauler. Two goals in mind TORQUE and still pass emissions ( CA required). The original plan was a mild hyd roller, aftermarket aluminum intake and heads. Went with a "tiny" hyd roller , 9.2 compression , Production iron big valve ( PI) heads and big port iron ( SCJ) intake. The results were 515hp @4,800 BUT 628 ft lbs of torque @3050 rpm. The low end torque would have suffered with the "hotter" parts and made power beyond where the engine runs. Emissions would have been a challenge but now pass with flying colors. In fact they are less than the tired original 460!
Properly done , I could see a 392 with 400 hp ( easy) and 500 tq on 87 octane that would work with the stock torque convertor and get better mileage.
I bet it changed the personality of that truck. Nice.
Ahh so relieved MadBill said that; the seemingly small half ounce added to the periphery of the flywheel technically 'weighs' more by centrifugal force. This is even a very basic balance example where we have two equal weighted boys on a see-saw at same distance, but move both boys further away from the fulcrum and they 'get heavier' (at the expense of placing more load on the balance beam -which translates into increased crankshaft flex)
A while back i thought to myself (and i never really give it a complete study)-----How many times a piston goes to TDC at max. RPM, WOW at 9000 rpm it is 150 times per sec. 8000=133.333 7000=116.666 6000=100 . Changing the stroke will not change the just entered numbers "BUT" shortening the stroke WILL slow down piston speed, and lengthening the stroke WILL speed up the piston FPM (Feet Per Minute) speed. The reason an F-1 can stay together at 18k RPM's is because it's stroke is 1.6 " + or - , 18k with a 1.6" stroke=4800 FPM piston speed F-1, 9000k with a 3.25" stroke=4875 FPM piston speed NASCAR Cup engine. When you stop and really think about it, i for one wonder how in the world the con-rods and pistons can take it like they do for 3 hrs. Mark H
A 500 ci NHRA Pro Stocker with a 3.525" stroke (4.75" bore) @ their 10500 set RPM limit is 6169 fpm. Before they put a limit on RPM, some were turning 11500 - 6756 fpm.
When I was last involved a few years ago, piston deck thickness was as thin as .150" on 4 sq. In. deck sections of competitive 4.750" bore 500" pro stock car and 5.125" bore 160" pro stock bike programs.
Saw Stan posted some piston speed calculations.
Was working with a 825" pro stock program, he was turning 8800 rpm with a 5.750" stroke, makes my head hurt lol.
