posted February 22, 2002 08:03 AM
Do testing on the dyno.....If the power drops off even with tuning it won't pay to raise the piston speed. For some reason, Kawasaki lowered the piston speed on the 12 (4271.3 ft.per min.) vs. the zx 11 (4471.7 ft. per min.) at 11,750 (rev. limiter) for both. Probably because the 12 has larger pistons (83mm vs. 76mm for the 11) even though the 12 has "light" pistons for there size, they may be heavier than the 11's.
Now if you do make power w/o dropping off to let's say 12,000 rpm piston speed would be 4362.1 ft. per min. That could be a significant added load to the rods, especially if you have the 1270 kit w/ even larger pistons!!
I would make shure my bottom end could handle the extra load w/ Carillo rods etc.
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You say PSYCHO like it's a BAD thing!!
posted February 22, 2002 08:52 AM
Note: Even the zx9r w/ the same bore stroke ratio has a piston speed of 4091.3 ft. per min. at 12,250 rpm (rev. limit).
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You say PSYCHO like it's a BAD thing!!
posted February 22, 2002 10:25 AM
Edited By: Y2KZX12R on 22 Feb 2002 10:27
mean piston speed... Phsychos right, 4500 fpm used to be what most race engine builders were told was the limit of ring sealing capability in an automotive type race engine. As in say a small block chevy.
The problem with going above that magical 4500 limit wasnt due to gforce loading of the rods crank etc. But with ring sealing ability. If you cant keep the rings sealing in the pressure then power drops off fast. New ring types come along every few years. Chrom rings came out, then Moly came along, thinner plasma coatings instead of plating, gapless rings ceramic, etc. Once the materials got up to snuff then the application proccess did. Then ring flutter was discovered as a pig power robber. Ring shape kept changing to use the compression available on one side of the ring land to push the rings out to the cylinder wall.
Then the pro-stock guys, like Warren Johnsons team started to use F1 style piston porting for the big 500cc engines with ultra low tension rings.
Then gas porting became popular. Everyone was drilling pistons. Materials and design caught back up and ceramic coatings hit the market.
Right now ultra thin low tension ceramic rings for on ported pistons will seal way way above the 4500 fpm rule of the 60's and 70's.
Ring flutter is alot less of a problem now but at some point it will still come into play.
The F1 engines are running in the stratosphere and seem to have the ring issue under control FOR NOW.
So Swft, the bottom like is, assuming you can feed the air and fuel for the engine at the rpm you want, and the thing mechanically stays in one piece, is ring seal.
JE will drill your pistons. But you will have to do the required math. Actually they may even do that for you.
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Y2KZX12R
CompetitionCNC.com
posted February 22, 2002 07:53 PM
There's definitely more power to be had if you spin an engine tighter assuming you have cam timing that will make power at the extra revs. Everything on the engine seems to be optimized for the factory rev limiter. Raising it considerably might take different header diameters, port sizing, throttle body sizes to really reap the rewards. It's the grenade effect that keeps my tach at relatively low revs.
posted February 23, 2002 01:17 AM
Factory rev limiter... How can you defeat the factory rev limiter? -ZXtra
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Posts: One MEEEEEELLION
posted February 23, 2002 08:49 PM
I've been waiting on the harness, so I don't have to butcher the stock harness. That's going to be released soon, so I'll have more info for you. It does have a *TON* of features that I'll have fun with for drag racing, like launch control. The aux output feature is neat, should I decide to put NOS on the bike. Multistage turbo boost control is pretty fancy stuff too!
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posted February 22, 2002 07:34 AM
posted February 22, 2002 08:03 AM
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