Courtshark

Any other lighter flywheels besides 928 Motorsports? Not opposed to buying Carl's, but I want to be sure I'm not missing anything. I recall Carl posting here about his, but can't recall seeing any posts about results from other users.

blown 87

I love the feeling of power induced oversteer.

mark kibort

I think your probably or could be right about track vs street use, as far as clutch wear and stress. sometimes, i would think street use can be more stressfull, not because you are taxing the clamping power, but the slipping some do when acceleration off the line that doesnt really happen at higher speeds, due to being more accurate shift RPM timing. There is a little technique of shifting at redline that you get drivig at the track a lot, as with the higher speeds of the rotaing mass, comes more wear and abrupt forces when effectively (speed shifting) when looking at the disparate speeds and greatly increased kinetic forces . Burning rubber, contrarily, would be easy on the clutch. BUT, i must say, you might not see it on the video, but im spinning the tires on the exits of turn 11 and 2 at laguna. (my rear cam shows the two black lines on the exits of turn 11 at laguna. )

I think this is the main goal. "blipablity" I did notice going from the heavier S4 clutch, going to the dual disc clutch (older 928 version). no HP gains on the dyno, but bettter for blipping.

Thanks for that! I wonder what really happens with the lighter flywheel on the 928 motor. Did anderson and fan also go with lighter flyweels on their 3 disc set ups? or do they use the stock flywheels. the stock flywheels are not that heavy, but you really have to look at the entire rotating mass, all the way to the tires, because when you have the car in gear and accelerating, its all the mass, all the way to the tires that matters. all that inertia adds up. however, bliping, is the only area where the difference will be felt.

Carl Fausett

Our lightweight flywheels have years of service on them - both racing and street use. Each features a replaceable steel wear plate. This is common in aluminum flywheels.

Here is the link: http://www.928motorsports.com/parts/...umflywheel.php

We have aluminum flywheels for both twin-disk and single-disk applications.

Photos below are of single-disk flywheel.

mark kibort

carl's flywheel sure is pretty.. 5.5lbs saving is pretty cool to if you are racing.

as long as they are strong enough, which they look like they are, it should be a nice little upgrade.

GregBBRD

My carbon carbon clutch will come with its own aluminum flywheel....with carbon in the place of the steel insert.

Very light flywheel....and perhaps just as important....a very light clutch.

It's never made any sense, to me, to buy a lightweight flywheel, when the crankshaft weighs 62 pounds and there is a 30 pound clutch package hanging on the flywheel....kind of like a 500 pound person having liposuction done on their thighs....that's why I have never offered one (except with a Tilton clutch assembly.)

Lightweight flywheel with stock crank and clutch probably a waste of time/money? It is silly to worry about taking 3 pounds off of flywheel, when the pressure plate, alone, weighs 3 times the weight of the flywheel?

That has always been my thought....

That's why I've "started over" on crankshaft design, using more current technology. The "Moldex" design (which is just a copy of the "Scat" crank) is over 25 years old!

Lightweight 5.0, 5.4, and 6.5 crankshafts with lighter Carrillo rods are almost here! (The rods are actually here....cranks about 2 or 3 weeks!)

These cranks/rods will be the first step into turning out an 928 engine which has the potential to spin to 8,500 rpms. This will allow the use of more aggressive camshafts and cylinder heads that already have more airflow than we can use.

The "path" that the 928 engine has followed, over the years of modification, is very close to the path of big block Chevy engines. Gobs of torque...with limited rpm potential....mostly because of the weight of the reciprocating assembly.

I think that I have seen the limits and have built engines at the limits of this technology. I took this "early" technology, which had severe problems with durability (and still does, in some hands) and worked with these engines until I made these engines bulletproof.

Think of my "new path" being more along the lines of a small block Chevy engine. Still have ample torque, but with higher rpm horsepower potential and acceleration. Much easier on our "torque limited" drivetrain.

I've solved the oiling problems with heads "packing" with oil at higher rpms. The oiling problems that the 928 bottom end suffered from at higher rpms have been solved. I've got head designs that have airflow which works very well at higher rpms. Camshafts lifts and durations are no longer an issue.....

Increasing the rpm potential is a natural evolution.

There an entire new chapter of 928 engine development on its way....

Carl Fausett

They have handled 450 BHP, 560 BHP, and now 900 BHP without failure since 2007. I have had no failures myself nor from any of my customers who have installed them. The difference they make in engine acceleration is significant and noticeable.

Mark Anderson

I thought Moldex made a 928 years before Scat ever did.

Carl Fausett

I agree with Greg.

My concentration has been on increasing torque, a natural match to my supercharged applications. So my developments have been for sub-7000 rpm motors. For example, the rods to handle 1000 HP are not lighter than stock, they are heavier (but only barely).

If developing a rev motor, Greg's right, the emphasis will be on lightening every part of the entire rotating assembly, not just the flywheel.

GregBBRD

Did not know that.

So Scat is the copy?

GregBBRD

I'm not giving up on the torque of the 928 engine....that would be a huge mistake, in my mind. I don't think that the weight of the rotating assembly determines the amount of torque the engine can make....so there is very little downside to reducing the weight of the reciprocating pieces, for me. I've always engineered my pieces to be able to spin at 7,500 rpms, even at their current weights. Correctly centered connecting rods, custom oiling in the crankshaft, removal of the two "extra" counterweights that are "completely useless (direct quote from Whitey at Moldex) below 7,500 rpms", current camshaft and valve train technology, all combine to make my engines function fine at 7,500.

However, once I reached over 500 ft lbs of torque at 5,000 rpms (and maintained that torque all the way to 6,000 rpms) the weaknesses of the transmissions became very apparent. Mark Anderson has broken virtually every single gear inside the 5 speeds.....and that is with an "older technology" engine. Making the automatic transmission work, behind all this torque, took me months, all by itself.

And although I am bringing several stronger transmission pieces into the equation, I think that moving the power range up perhaps 800-1,000 rpms will make the life of the drivetrain much better, as well as increasing horsepower, while not killing the great torque these engines make.

mark kibort

Carl, you had me right up until "significant and noticable".

are we talking acceleration of the engine for blipping the throttle? or acceleration of the car. if you are talking and promoting acceleration for the car, stop right there, as that woud be complete BS. saving 5lbs on a flywheel , is like the effect of 10lbs at best, if it was in the car. Ill give you the equation if you want. remember,when in gear the inertia is the entire rotating mass all the way to the tires and THEN ADD the weight of the vehicle!!!
5lbs off the flywheel is almost nothing and not measurble on the dyno, but I certainly can calulate the actual physical effects of what 5lbs off the flywheel would cost or add as far as hp. its a very easy calculation.

so, tout strenght and some slightly better bliping performance. (but as Greg B) ssays, we are talking blipping the throttle weight as crank, pistons, and clutch assembly, so near 100lbs of rotating mass, removing 5lbs. yes, it is near as insignificant as it seams.

Put it this way, i for one, dynoed and went from single 50lb clutch and flywheel vs 25lb clutch and flywheel for the dual disc. no HP gains to be found. again, give me a time to acceleration, i can give you the HP it would save or provide.

for an actual answer to your lighter flywheels effects on HP . in 3rd gear with 400rwhp, its effects would be around 1 hp for a 5 lb flywheel savings. now, if 1hp is significant on acceleration, then yes its significant.
Now, in 1st and second gear , it could be near 10 hp which is significant I guess for drag racing

mark kibort

actually, there are some great benefits for a heavier assembly, heavy being relative. vibration harmonics are a given. those 3rd and 4th harmonics if not surpressd, can rob HP no matter how balanced the assembly is. too light is not good, too heavy will hurt as far as stress on the rotating components like rods ends.

there is a reason for the harmonc balancer, its not there just for the timing marks!

unless you care about quick neutral blibs, the main reason to lighten the rotating assembly for high RPM engines is for rod and crank stress relief.

GregBBRD

Mark:

10.45 - 6.85 = 3.6 lbs. Not 5.5lbs!

Sub 3% Delta?

I'm not sure I'd ever know...unless I had "wrote the check" for it and desperately needed there to be a difference.

GregBBRD

No doubt your thought might be a consideration in some applications, but keep in mind that I'm not building a 22 lb. crankshaft.....

I just don't think it needs to be 63 pounds, for the relatively small stroke of our engines.

The stock harmonic balancer isn't very good technology. It isn't even very good bad technology. Nothing that fits that loose on the crankshaft can properly absorb harmonics....much less a rubber style damper. To say that there is a lot of harmonics that are "lost" between tthe stock crankshaft and the stock damper, is a severe understatement.

And yet, how many broken 928 crankshafts have you seen or even heard about?

I'd say that the lack of broken cranks, even with the terrible stock damper, would pretty much prove that we are no where near the "lower" weight limit of these crankshafts. Keep in mind that the 928 crankshaft isn't even built out of a "high end" piece of steel and the lack of broken cranks becomes even more of a consideration.

As far as what reduced mass does for the engine....reciprocating mass becomes very important as the rpms increase....especially with the terrible problems we have with the strength of the stock block. Turn the current technology at 7,200 rpms for extended periods of time and the block is going to be the weak link...that is a given, for me.

Sure, I've been working on a billet block, but perhaps a slightly lighter crank, rods, flywheel, and flywheel will solve the problem for the guys that are not going to be able to afford a $15,000+ block.