mike_rudy

Well i was searching for pics on google on day and searched up lightening rotor parts, or somthing like that. And i found pics of Mr. Yaw's engines, pics of lightened eccentric shafts and rotors,ect. Well what i am wondering is with what i hear about eccentric shaft flex, wouldn't lightening it make it worse?? Also on clearancing rotors how much is taking of the sides of the rotors? thanks mike ( i have included some pics

mazdaspeed7

Those are 12A ecc shafts. All the 84-up 13B ecc shafts are already lightened in such a way. Lightening in that area wont affect the rigidity. As for the rotors, you are limited by the casting thickness, and the balance of the rotor. But I dont know an exact number for the minimum thickness.



Attached is a GSL-SE 13B ecc shaft.

mike_rudy

Thats good because i am working with 12a engines so i will be doing some lightening, will this actually affect anything in power or power respons

Rub20B

Engine will rev quicker and more power on higher rpm's but less torque in the low rpm's...

heretic

Wholly untrue.



The weight of the rotating mass doesn't affect engine power.



What it does affect is how well the engine accelerates. A lighter rotating mass means that the engine spends less energy accelerating itself, and more on accelerating the car.



It may feel like it makes more power at high RPM, but that's an illusion. What is actually happening is the engine requires less power to accelerate itself. This effect is more pronounced at high engine speeds, because rotational inertia goes up as the square of RPM. On a stationary dyno, the engine's power output will not have been affected.



Likewise, the percieved lack of low RPM power is just that, a perception. That is a driver error. A lot of people rely on the engine's inertia to pull the car from a stop when releasing the clutch, instead of smoothly feeding in power as the clutch is released. When you reduce the engine's inertia, you can't rely on it as much to get the car moving. The actual engine output will not have changed.



There is a good reason why top racing teams do not concentrate on power, but instead concentrate (on very expensive computer controlled dynos) on how well the engine can accelerate its load, and how well the engine recovers after being pulled down after a shift. This is why you will see teams with engines that measure out significantly less power on a stationary dyno, but can drive circles around the "more powerful" cars on track.



All of this said, removing weight that close to the axis of rotation, to me, would be the last place to look for a weight reduction. But, combined with the necessary counterweight lightening, and it could do some good.

CypherNinja

You'll see a bit more power to the wheels in the lower gears primarily, because in the lower gears the engine accelerates through the RPM range faster thus making low rotational inertia all that much more important.

Lynn E. Hanover

Everyone has covered this pretty well. The rotors are cut down at a slight angle starting at the end of the apex seal groove and ending just short of the oil scraper grooves. The amount varies by builder, and the thinking is that if you like to run way more bearing clearance, you will loose some control of the rotor staying square on the shaft and you will want more clearanceat the corner seal area to keep from touching the irons. So maybe .020" off at the corner. If you run less clearance and more oil pressure, then maybe .012" to .015" or, even .010" would be fine.



I have only draged the corners once on a 12A and it had turned up close to 15,000 RPM. So, a stock 12A rotor turning 9,600 RPM or less does not need this mod.



The 13B rotor is heavier and the crank is longer, so it needs this done to go very far over 9,000 RPM. This lightens the rotor a tiny amount, but if you can run a lath with any skill at all, and take about the same amount off each corner, you need not rebalance the rotor.



Lightening the rotors is a different thing. Material is removed from the sides of the rotor but no cutting of seal grooves is involved as in clearancing. A great deal of weight can be removed from each rotor and that allows additional material to be removed from the counter weights on rebalance.



Like everything else on the car, reducing mass anywhere allows for more rapid acceleration. The advantage of lightening engine and trans parts is the those are recurrent in nature. They must be done again after each gear change.



This is a tilton clutch for a Chevy. We use it on the rotary. Just cut off that flywheel.



Lynn E. Hanover

jspecracer7

What kind of transmission are you putting together/taking apart in the background Lynn? Straight cut gears :WHOA:

Lynn E. Hanover

Those are parts of a Saenz dog ring transmission. Clutchless shifting up or down.



A steep learning curve, and big shock loads to the drive line. But if you are serious you have to have one. We (the driver) are still learning. At the run offs this year we broke off an attach point for the upper link on the three link rear because of clutchless downshifts.



We had just gotten that repaired and found that all of the bolts that secure the axel tubes to the side bells had come loose and the press fit of the tubes to side bells had vanished. So we took the rear apart one side at a time and repaired that and got it back together in time to go to the false grid. We were literaly poping dzuses back in as he backed out of the padock space. We had not charged the battery since we found the problem, but it has an alternator driven off of the front of the pinion shaft. We went to the false grid with no problem. When it came time to start the engine for the race, nothing. It wouldn't do anything.



We push started it (twice) (drivers are imune to learning bump starting) and away he went. Running fine. If he can get it over 40 MPH the alternator will latch up with 60 amps and we will be OK even if the battery falls out.



The pace car came by going about 30 MPH. It was the slowest pace lap I have seen in 33 years of racing. He couldn't keep it going fast enough, and the engine died at the end of the pit lane. He pulled into the pits going the wrong direction but nobody had to push it, so there was no problem rules wise.



Were I the driver, I would have turned both pumps off and just blipped one pump on when the engine lean stumbled. I know I could have made the start, and once up above 40 MPH??? Well, woulda, coulda, shoulda. And I am not the driver.



Got the damn thing back to the trailer and plugged in the jump cart and wham all the way to the rev limiter at 9,800. Nothing wrong but a dead battery. It was not a good ending to a busy year.



When I get a chance I will change the fastening system on the Speedway quick change. The nuts are inside the axle tube??? I will use longer bolts with the bolt heads inside the tubes and the nuts on the outside. A flat on each side of the end of the bolt will allow me to hold the bolt and tighten the crap out of the nuts.



Just one of 500 ideas I have to look at.



Lynn E. Hanover

89 Rag

With this in mind, it could also be said that this concept should be carried all the way to the differential to maxamize performance; flywheel, clutch disc(s), pressure plate (thier respective sizes and weights), transmission and components of, driveshaft and differential. The "illusion" from these modifications fades quickly with some pedal time in a controlled enviornment.