[stylnhog]

I was at my local Mini dealer yesterday and asked them about the smaller pulley option on the supercharger. They told me DO NOT put a smaller pulley on for more horsepower as they have had some in the shop for bent cranks and blown superchargers. Anyone heard of this before

Thanks,

Steve

[MINIAC]

Welcome to MINI2

All dealers sell the John Cooper Works Kit which uses a smaller supercharger pulley, and there's at least one US dealer that installs and warrants a reduction pulley.

I've only read about one supercharger failure related to a smaller pulley, and this was an interference fit pulley which required heating to install, and the supercharger shaft seal was most likely damaged from the heat during the install. This is why taper fit pulleys are now used for most intalls.

[Andy@Ross-Tech.com]

Quote: Originally Posted by stylnhog

... they have had some in the shop for bent cranks and blown superchargers.

Sounds like the dealer is trying to bend your crank. Don't let him.

[stylnhog]

Yup they told me that with the smaller pulley the belt was so tight it bent the crank. I said to them that with a smaller pulley the belt would have been looser and not tighter besides the tensioner keeps proper tension on the belt.

[Amigo]

Quote: Originally Posted by MINIAC

I've only read about one supercharger failure related to a smaller pulley, and this was an interference fit pulley which required heating to install, and the supercharger shaft seal was most likely damaged from the heat during the install. This is why taper fit pulleys are now used for most intalls.

MINIAC,

Is the pulley in the AMD kits classified as an interference fit pulley?

[Andy@Ross-Tech.com]

Quote: Originally Posted by stylnhog

Yup they told me that with the smaller pulley the belt was so tight it bent the crank. I said to them that with a smaller pulley the belt would have been looser and not tighter besides the tensioner keeps proper tension on the belt.

Ha! A belt bending the crank. What will they think of next?

[MINIAC]

Quote: Originally Posted by Amigo

MINIAC,

Is the pulley in the AMD kits classified as an interference fit pulley?

It looks like an interference fit pulley. Taper fit pulleys are two or three pieces held together with bolts:

Alta


Helix (P&D)


Mini Madness



Mini Mania

[phil portlock]

Quote: Originally Posted by Max

What this means is that there is a greater chance of you having an engine failure due to a BMW part failure than you have by fitting an aftermarket 15% reduced diameter SC Pulley wheel correctly to your car

*mind you we have yet to see a modded MCS clock up 100,000 miles yet*

Max

Are they perhaps trying to say the extra power output would bend the crank, (not the pully/belt)-because it is possible?

[msenkbeil]

Quote: Originally Posted by stylnhog

Yup they told me that with the smaller pulley the belt was so tight it bent the crank. I said to them that with a smaller pulley the belt would have been looser and not tighter besides the tensioner keeps proper tension on the belt.

I believe most pulley kits include a new, slightly smaller belt. My Minimania kit did include the belt. You're right... the tensioner is what applies the tightness to the belt... not sure what that dealer is talking about when he says the belt can bend the crank. Sounds like a salesman or non-mechanic talking IMHO.

[roland2003]

Hi Guys,
Yes dealers really do talk nonsense at times.There is no strain anywhere enough to bend a spoon let alone a crank.IMO S/C failures are going to be down to idiots with big levers and hammers and small brains.We are about to launch our own range of interference fit pulley systems as we feel they are preferable to the bolt on multi piece type.They can not slip, can not come off, and can not damage the shaft.Our own tooling removes the Std pulley with zero damage, not even a scratch,so can be easily refitted if selling car.(BMW p/x for example) Our pulleys can be fitted, removed and refitted without any 'leg type' pullers etc.Also does not require removal of S/C or engine to fit.Although in the workshop we heat the pulley to 200-300c (nowhere near enough to damage seals)it can be done cold.Standard interference between pulley and shaft is circa 50microns (.002") our pulleys are the same as this. ps About 10mm of travel remaining on the tensioner is optimum,allows maximum belt contact around circumference of S/C pulley without tensioner hitting the end stop during very fast acceleration of the engine. ie flooring it in neutral or first gear. Regards Roland GT Tuning

[Mugami]

Oh come on.. you havent heard the one about a guy who destroyed his SC by simply putting on an after marked Intake. Which inturned bent the crank of his engine. All of which was covered by his insurance??

This is of course Based on a True Story.

[Andy@Ross-Tech.com]

I heard that happened to my brother's sister's mother's cousin's dog-groomer's friend.

[LordOfTheFlies]

I've had the Helix 15% reduction pulley on for about 1600 miles now (1200 of which were logged during MOT last weekend!) and have not had any issues so far (knock on wood).

I think modding the car was the best thing I could have done - got rid of the stumble, more power, more supercharger whine, better handling.......

Get new tires and wheels - you won't regret it, especially if you're going to add that extra power.

[stylnhog]

Well my mini mania setup arrived today and off to the garage to install it. It will be easy as the motor is out of the vehicle. I picked up a 2003 fully loaded with only 4900 miles on it for under 11 grand. Hood and bumper were wiped out due to collision with no frame damage. When done it will cost about 4,000 for all parts to repair.

[obehave]

Quote: Originally Posted by Max

For the record... fact.. if you fit a 15% reduced dia pulley wheel you are recommended to stay with the original pulley belt.

There are plenty of threads discussing this on here. Just do a search of Performance & Tuning. Do not be phased by ppl who give "advice" who invariably are trying to make a fast buck (out of you, mainly)

I am sure that others will back me up on this (obe, Andy etc)

regards

Max

I'm running the OEM belt with no issues.
Never thought about it but with the smaller diameter pulley the tensioner will set slightly lower and get you another couple of degrees of wrap around the pulley.

Sound good??

[Mugami]

Recently .. well ok couple months ago i went to the 19% pulley from the 15% Which ive had on the car for a year before. In the last month or two before the switch the car seem sluggish and at looking at the belt and pulley after it was removed i could tell it was slipping. This may or maynot be a result of the amount of tension with the smaller pulley. Since then i keep a spare belt in my car just incase with the 19% even though it is the smaller belt on the car.

[MINIAC]

From Mini Madness:

Quote:

By changing to a 19% reduction pulley the boost kicks in 750rpm sooner than the 15% pulley, ideal for street driving condition's ONLY! Not recomended for track use or long high reving situation's typically seen on the racetrack! Sustained 6000-7600rpm generates more heat reducing the 19% pullies effectivness.

No point in raising the rev limiter.

From Randy Webb regarding UNIChip development:

Quote:

One interesting find is that the less heat you introduce on the intake side, the more power you can make with ECU tuning. This again suggests that there is a much better map for the 15% pulley instead of the 19% pulley. By the time you get the maping right on the 19%, you are just about at the same A/F ratio you have in the stock ECU to keep the inlet temps under control (the more fuel you use, the cooler the cylinder temps, and the ECU will dump fuel to cool the cylinder head temps at a preset value).

No point in tuning the ECU.

[TonyB]

If it's been posted somewhere (not even on MINI2), you can bank on MINIAC pulling it all together for us! Thanks.

[Mugami]

But if you have a better incooler you dont mind the extra heat.

1) Cars doing just fine. no reported problems as of yet.
2) Havent done the ECU upgrade as of yet. But have plans to install high flow fuel pump. 400cc injectors and the Apexi SAFC 2 fuel controller. Then have it Dyno tuned.(waiting on Hubie from SPI power excel. to send the wiring diagram on the SAFC 2.
3) Haven't raised the Rev limiter yet. Havent really found the need to yet. Since i am a bit worried about over reving the SC and have never crunched the numbers to see what its reving at now. Its not something i want to do. With the Bracket racing i do in drags. I keep the revs in the 4k-6k range with shifts at 6k. This keeps the car consistant down the strip and leaves me room to make up for mistakes.
4) as for the inlet temps. I'm wait for that intercooler by Grass Roots to be available in the US. Could you tell Grahm to hurry up and finish it. then send me one Max

[obehave]

Quote: Originally Posted by Max

Hi Mugami. How are you getting on with yr 19% pulley? Do you have an ecu upgrade to go with it? Any other mods?

What sorta bhp do u reckon u have now? And have you raised the rev limiter? If so, to what rpm?

Sorry lots of questions but we are keen to hear (in the UK) on 19% pulleys - no-one here is really marketing them yet

Thanks

Max

*sorry obe not sure what you mean by "a coupla degrees wrap" *

That would be the number of degrees the belt is in contact with a pulley. A kind of rule of thumb is that any pulley under load should have at least 180º of belt to pulley contact.
The more technically savvy here could explain it better but in a nutshell, more contact is good.