Hi Everyone,

Our Crank Pulley design is finished, installed and signed off. We're going into production - will announce the usual launch special shortly.

Before we do, we are considering materials. The prototype was make from 316 Stainless, adds some weight, but stronger from a fatigue and belt slippage point of view. It is also more expensive.

Making the pulleys in aluminum would drop the cost approximately $90.

So... market research time. What do you guys want? I'm sure it is possible to do both, would prefer just to stock one part.

 

So no gold-plated titanium option?

 

It's the unobtanium ones that are the most sought after...

 

What is the stock pulley made of? That is what it should be. I'm sure the Jaguar engineers choose the correct material for a balance of cost vs. performance.

 

My opinion as a business owner to another is to not compromise on the quality of the item just to lower the price. $90 material cost isn't insignificant but it's more important to uphold the reputation as the premiere aftermarket performance supplier. That means using the best materials. Let some other company offer the cheap crap to the penny wise/pound foolish.

In the end, we all value reliability and durability over a couple hundred bucks. NO sane person would disagree with that.

 

For $90 I would rather have the better grade pulley.

 

One would hope... and I agree that'd be the way to go.

 

Right. But it wouldn't cost us $90 more. That would be his production cost. We would probably get charged $200-250 more by normal markup standards.

Still worth it!

 

Good point.

 

Would the weight savings of the aluminum affect the crank in any way ? i would think the lighter material would be better, but not sure what the compromise might be

 

A couple of points based on my observation of a similar pulley from another source:


1. The original is indeed aluminum, but is a solid hunk of aluminum (with a rubber dampening donut) and is a solid hunk of metal (1" wide x 6.5" dia.) and weighs a few pounds.


2. A properly designed replacement will have a recessed cantilever design and weigh less than 8 ounces in aluminum, and something more if stainless.


3. Especially for the MT, you want the least possible spinning weight on the crankshaft to allow fast spin-up and spin-down of the engine during shifts. The increased weight of a stainless pulley designed to minimize weight might not add a lot of mass, but it could make a difference. (When I need my first post-warranty clutch, I will be installing a lightened flywheel.)
4. Since I am no longer in the market for a new crank pulley, my vote doesn't count.

 

Are we talking V8 or V6 or do both use the same pulley anyway and we're talking both?

 

Unhinged do you think the rubber portion of the pulley mentioned in 1 was there to damp supercharger crank pulley vibration and/or isolate the supercharger or engine from supercharger drive shock loads? If its there for either purpose maybe it is important for any aftermarket oversize pulley to have a similar feature.

 

Both are the same

 

The rubber damper is present on both the OEM FEAD drive pulley and the OEM Supercharger Crank Pulley. Manufacturing cost of such low run parts pretty much rules out aftermarket versions being made with the same.

One critical aspect is that the OEM Supercharger pulley is also neutral balanced (or at least very close - 1 gram at 4" from center.)

The more damping you've got on those pulleys the less NVH (noise, vibration & harshness) you're going to have.

That said there are a lot of OEM applications, including supercharged, that do not use similar dampers.

 

I thought the dampener was on the accessory belt portion of the pulley and thus you could add a over-sized supercharger pulley without removing the dampener?

 

The dampener is there to reduce vibration from the engine being transmitted to the SC. The SC bearing life might be reduced, but the SC snout is not a very expensive component.
Both the harmonic balancer which drives the accessories as well as the OEM SC pulley have the rubber isolating donuts.

 

Considering its not press fit like the upper pulley, T6 Aluminum should be fine.

 

Just a thought, 6061 Aluminum and have it hard Anodized. Easy to machine, very ductile with less risk of cracking and a 60-70 Rockwell (from memory) surface finish, which is very hard.

 

+1.