Machining / Finding Bigger Crank Pulley...

[madspikes 41 1 Cars]

Toying with the idea of spinning the old charger a little faster, and yes I can change the charger pulley, but thats total ball-ake, and its really a one way street. So was think about if there was a bigger crank pulley that could used, or machining new crank pulley. Current I'm running an old pulley from a Mi16, so does anyone has any suggestions on one that might be larger? Or if a larger pulley would fit, and how much a larger pulley would cost to machine?

 

 

Thanks,

 

 

Mad.

 

 

 

 

 

 

 

[Tom Fenton 1,542]

Speak to Carl at Force Racing, he would be able to make a larger pulley to your design, you would need to check how much clearance there is on things but I can't see a problem personally.

 

http://www.force-racing.co.uk/non-mini-components/

[stef205 92 1 Cars]

Don't you run the risk over spinning the others like alternator etc?

 

(null)

[engine killer 6]

beside larger in diameter, will an aluminium (7075?) pulley be able to cope with the torsional force? these will probably reduce the inertia by a fair amount if it works i guess.

[wicked 103 3 Cars]

Why would you like to spin the alternator faster? If you need more current, it might be easier to fit another alternator with more output.

[unariciflocos 49 1 Cars]

He wants to spin the supercharger faster, spinning the alternator faster would be an undesired aftereffect.

[chipstick 382 1 Cars]

Why would you like to spin the alternator faster? If you need more current, it might be easier to fit another alternator with more output.

 

It's the supercharger he wants to spin faster.

[wicked 103 3 Cars]

That makes more sense... the post about the alternator did confuse me...

[Tom Fenton 1,542]

I don't think the alternator will really be a problem. Assuming an 8v is revving to say 6500rpm. A 10% overdrive on the pulley is only the same as the same alternator being used on an Mi16 revving to 7200rpm.

[Miles 331 1 Cars]

I have the pattern's for the 8v pulley's, can even make them wider to stop slip too,

[madspikes 41 1 Cars]

All interesting ideas.

 

I hadn't thought about the alternator spinning faster, but as I don't drive everywhere at 7000rpm I don't see it as an issue - good point through.

 

As to weight, I'd expect a new pulley to made for some sort alloy, so would be lighter than the lump that is the OE MI16 one, well I think its an MI16 one. I'm looking for the pulley to be around 20% larger than standard and will need to be 6 ribbed.

 

I need to get out and check dimensions and clearances before, I start getting proper quotes - I was hoping for a ball park figure from someone!

 

Mad.

[welshpug 1,661]

Worth checking, but an MI alternator might have a larger pulley to slow it down, I do remember noticing variations in the diameters when sorting half a dozen random alternators I have here.

 

Maybe use a std size alloy crank pulley and a smaller charger pulley?

[allanallen 528 2 Cars]

I would think you'll have an s16 6 rib/4 bolt pulley fitted mad, they measure 127mm/5"

 

Al

[calvinhorse 870]

Worth checking, but an MI alternator might have a larger pulley to slow it down, I do remember noticing variations in the diameters when sorting half a dozen random alternators I have here.

 

Maybe use a std size alloy crank pulley and a smaller charger pulley?

 

He's already given a reason for not changing the sc pulley

[madspikes 41 1 Cars]

Just to remind people of my setup..... The alternator is from a 306, no idea which one!

 

 

[welshpug 1,661]

that'll be a gti6 crank pulley with what looks to be an S16 alternator.

[Tom Fenton 1,542]

So the crank pulley is keyed onto the end of the crank as per the 8v pulley? In that case I am pretty sure Carl would make you one to your preferred diameter for more or less the same price as the 8v alloy replacements. Only difference I can see in cost would be for a slightly larger lump of alloy to start with, but the work involved is just the same really. As it is a one off you could even choose what colour anodise you wanted.

Have you got an idea of diameter you would want, I will ask him for a price if you like.

[madspikes 41 1 Cars]

So the crank pulley is keyed onto the end of the crank as per the 8v pulley? In that case I am pretty sure Carl would make you one to your preferred diameter for more or less the same price as the 8v alloy replacements. Only difference I can see in cost would be for a slightly larger lump of alloy to start with, but the work involved is just the same really. As it is a one off you could even choose what colour anodise you wanted.

Have you got an idea of diameter you would want, I will ask him for a price if you like.

 

That would be fantastic - Ball park price really. I need to measure the one I've got then work out how much bigger I want and can go. Yes its keyed, and it a standard 1.9 crank. - Colour dont care - could be pink not fused.

 

How much boost should I got for 10 psi? Its a standard 1.9 engine.

 

I use the car every day, so if I changed the pulley on the charger for say a -19% jobbie and it made the car too noisy or a bit of a mare to drive I'd be stuck with it. However, if I change the crank pulley I can alway swap back to the original one, and just use the other one for track days and like. Also its such a ballake to change the pulley, and to get the charger off.

 

 

Not concerned about the alternator.... I may regret that in the future... but currently going with - It will be fine!

 

Mad

[madspikes 41 1 Cars]

Currently pulley is around 127mm, I think +20% Would give around 152mm diameter for new pulley and estimated 10psi of boost.

 

Just an idea...

[clen666 2]

I may be interested if someone is able to make custom size lightweight pulleys, depending on prices