Has anyone seen the Lightweight Crank Pulley being sold by Mini Madness? http://new.minimania.com/web/SUBTYPE..._Inventory.cfm

Has anyone tried this?

 

Beware lightweight crank pulleys. I believe there are other threads here about their less than friendly interaction with the oil pump. I KNOW in the Miata world they are linked to oil pump failures on F/I engines. That harmonic balancer is there for a reason. Use at your own risk.

 

I have one but am afraid to install it due to harmonic balancing problems. Everyone has kind of gotten me scared. If i can trick my insurance to cover the price of install, ill do it and let yall know the difference.

 

There are other treads about this mod and some concern about it.
I emailed Ken Suzuki of Mini mania and got this reply-

Quote:
The Lightweight Crank Pulley retains the same dimensions as the stock
pulley therefore has no negative effects on the belt or any of the
peripheral components driven by the belt. Performance is increased
through the reduction of rotational mass, similar to replacing the flywheel
with a lightweight version. This lightweight crank pulley weighs only 25% of
the stock pulley.

From the manufacturer:

"These lightweight crank pulleys are CNC-machined from lightweight
6061-T6 aluminum billet. Premium U.S. made 6061-T6 aluminum billet ensures the consistency of the material's strength and balance. Tolerances are held to within .001", and numerous machining steps are used to ensure the lightest possible design. In addition to fit, finish is just as important and
each piece is representative of this. Every pulley is inspected multiple
times from machining to anodizing to stocking and finally at shipping time.
If at any point a pulley does not pass inspection it is pulled from
production.

Lightweight crank pulleys on average can provide gains of 5 to 14 HP
and 4 to 12 lbs.-ft. on normally aspirated engines and 8 to 18 HP and 8 to 14
lbs.-ft. on forced induction engines.

Power gains are obtained through weight loss. An average of 2.7 HP is
gained from every pound lost off the crank shaft."
--------------------------
I guess they think it is safe enough to be able to offer it

 

I'm no engineer, but as I understand it the issue with the lightweight crank pulleys is that harmonic balancer absorbs vibrations (dare I say harmonic imbalances?!) and is in close proximity to the oil pump. If the crank pulley isn't there to absorb them, the remaining components have to.
A lightened flywheel takes weight away from crank assembly as well, and further from the center of mass. Flywheels, of course, have their own issues.
Just be sure to do your research, and ask the knowledgeable ones (Randy Webb, Eric @ Helix, etc.) before you jump at 'easy horsepower'.

 

I agree with Eric. I have a turbo Miata I built about 6 years ago, a bunch of us bought underdrive pulleys that were on special and almost immediately guys began losing their engines. I took mine off and sold it for a small loss.

Tom

 

The crank uses balance weights to minimize the need for balancing from the crank pulley. That said, I still wouldn't mess with the crank pulley. It's not worth the risks for the moderate reduction in rotating mass (compared to say, a lightened flywheel).

 

Just so everyone knows... these are NOT underdrive pulleys, they are only lighterweight. Therefore, the only possible way of damaging your engine is due to the harmonic balancing issue.

So all the problems with the miatas you cannot relate to the mini and this lightweight crank pulley

 

On an in-line 4-cylinder motor, the points of highest vibration is at the crank pulley and the flywheel. Vibration is focused at these points. Even if the motor is exceptionally well balanced, you need a good harmonic balancer. Whether the particular lightened pulley on this motor will be a problem or not is up to the engineers. I know that on my ITC Datsun 510, I lost a harmonic balancer at about 7000 RPM when the bolt apparently vibrated loose. Within 50 feet on the track, I also lost the flywheel. All 6 grade 10 bolts (new) holding the flywheel were sheered off cleanly.

I wouldn't go too light at the pully end. I think a lightened flywheel would be a better option for me.

 

It's your motor Dude. The pulley I was using was lightweight as well as being an underdrive pulley.

 

We have some rather brave souls on these boards, but I don't recall any of them wanting to venture down this road bad enough to give it a try. I guess for me that says a lot...

With that said, I would contact Mania and any other vendor out there selling these to the MINI community. Tell them that you want a list of folks that you can contact who have made such a purchase. Ping those folks to get their input to see if they installed them, how many miles ago, impressions, etc...

Express to Mania these concerns, and if they cannot provide such contacts for referrals, I would drop it. They must be running it on some of their cars, I would think. Ask about their testing. If this were just another intake, such questions would be overly ****, but this mod merits such concern.

If you pursue this, please share! Thanks.

 

My point, Dude, is that in your case the problems were caused by the pulley being an underdrive pulley (most likely). Underdrive pulleys are known for opening up a whole can of worms on you engine as far as problems are concerned.

And I have to agree w/ TonyB... anyone wanna go through with it?

 

Like I said, It's your motor Dude.

Tom

 

The only difference is that underdrives spin accessories more slowly - the can of worms should be associated only with the accessories, not those connected to the crank. We can't confirm the causal factor, but the harmonic balancer is the only other missing piece. But as Tom says, "It's your motor, dude."

You've got one. Try it out - what do you have to lose?

 

what you get with a lighter c7pulley is a lighter c7pulley and no balancer........ain't worth it.....unless mah motor man says so and I don't paln on taking mah motor to mah motor man just yet......after the next race....maybe.....