Changement Poulie dans le sud ???

[DeK]

"arrache roulement" un peut-être un nom grossier, à mon boulot ils ont exactement l'outil qu'il faut pour déplacer la poulie de son axe...

</font><blockquote>citation:</font><hr />Débat lancé par DeK:
oui 15% c'est déjà amplement suffisant, j'ai même déjà vu 21% !!! mais là ça devient carrement critique pour la mécanique.

voir dans cette galerie perso: il y a des photos de compresseur, avec poulie démontée, et poulie remplaçée, ça a l'air pas compliqué, c'est que de la mécanique
photos de poulies

si il n'y a pas besoin de reprog. changer la poulie est quelquechose de "vite fait", il faut juste un arrache roulement, pour pouvoir enlever la poulie d'origine de son axe.
de plus généralement une nouvelle courroie est livré avec une poulie. </font>[/QUOTE]Tu parles d'un arrache roulement !!!!! Sur miniMania ils parlent d'un "SuperCharge pulley removal tool" que tu peux louer pour 1£ ..
Cet outils ressemble pas trop à un arrache roulement ...

Pour revenir à ma question d'origine, où puis je faire cela dans le sud ???
En fait pourquoi ne pas faire une rencontre MINI special POULIE ...... celui qui sait montre aux autres .....

[DeK]

oui 15% c'est déjà amplement suffisant, j'ai même déjà vu 21% !!! mais là ça devient carrement critique pour la mécanique.

voir dans cette galerie perso: il y a des photos de compresseur, avec poulie démontée, et poulie remplaçée, ça a l'air pas compliqué, c'est que de la mécanique
photos de poulies

si il n'y a pas besoin de reprog. changer la poulie est quelquechose de "vite fait", il faut juste un arrache roulement, pour pouvoir enlever la poulie d'origine de son axe.
de plus généralement une nouvelle courroie est livré avec une poulie.

[size="1"][ 07.03.2005, 10:51: Message édité par : DeK ][/size]

[JNS513]

Avec une poulie de -15%, il n'y a pas besoin de reprogrammer la bestiole. La poulie de 19, perso je n'y toucherais pas, car elle va vraiment faire tourner le compresseur à la limite. C'est plutôt pour des prépas circuit.

Il me semble que le kit JCW est en -15%, mais je peux me tromper.

Sur http://www.mini-motorsport.com/faq.php
"Why do you only recommend the 15% reduction supercharger pulley? [img]graemlins/thumb.gif[/img]

My thoughts on appropriate pulley reduction are based on a lot of time spent on the subject - including track testing with real-time data gathering of manifold inlet, supercharger outlet and water temps, long engineering discussions with Eaton (the manufacturer of our supercharger), and plenty of dyno testing.

We started developing the supercharger pulleys in the US before most all of the aftermarket, including the "factory" aftermarket - John Cooper Works. I started with a 10%, 12%, 15% and 18% reduction from stock. What we came up with after all that testing was that the 15% is the optimum reduction based on several factors. Remember that the goal of all of this is to have the highest DENSITY air parcel at the inlet port to the combustion chamber. Density is directly proportional to pressure and indirectly proportional to temperature, or D=p/t .

That makes the most significant performance factor the adiabatic efficiency rate of the Eaton supercharger at increased RPM. In short, it isn't great. The forte of the Roots type supercharger (which includes the Eaton) is high efficiency at low boost - giving rapid response without "lag". The faster you spin the rotors, the more you compress the air going through it - however, you are also increasing the heat (remember that from physics - anytime you compress you also heat). Some rotor designs minimize the effect of this, but the Roots does not. All of that means that while you are increasing pressure, at some point the heat you generate with additional compression will outweigh the pressure increase, and that point is with a 15% at about 5400RPM and higher. You also need to outweigh the fact that you are causing additional drag on the crank pulley by spinning at a higher resistance when you are forcing a higher parcel compression.

The other factors are more reliability based. The most significant of these is belt life. No matter which belt we try to use, they all fail with anything greater than a 15% reduction pulley on the track. I have three cars we have used on the street and track with higher reductions than 15% for data gathering, and even on the street it is a 50/50 on the belt failing. We have tried literally every belt on the market, and the issue is not corrected.

Also related to reliability, but much less of an issue, is the water pump speed. We didn't think this was an issue at first, until we started monitoring oil temp as well as coolant temp. On the track, we noticed elevated oil temps that we didn't see with 15% pulleys . It took a bit to figure this one out, but if the pump is cavitating, it will show first on oil temp. The reason behind it has to do with the volume of water and its movement through the entire head versus through the oil cooler. On the MINI, the oil is cooled with a water-oil exchanger. The water volume is great enough in the entire system that a small flow change does not effect coolant temp at the coolant temp sensor, but with the small volume in the oil cooler, the oil is not cooled as efficiently if the flow is decreased even a small amount, resulting in higher oil temps. This seems only to be an issue with the 19% reduction pulley at sustained high RPM.

I have personally installed over 400 15% reduction pulleys, and have not had a single issue with any of them. I have installed 4 pulleys greater than 15% reductions, and have had issues with all of them . Based on this, the preliminary testing we did, manufacturer discussions, and the fact that a few months after we came out with a 15% reduction recommendation John Cooper Works came out with a pulley on their supercharger that was within .03" of a 15% reduction, I can confidently say that the 15% reduction pulley is the best choice for not only performance, but reliability as well."

[size="1"][ 07.03.2005, 10:50: Message édité par : JNS513 ][/size]

[DeK]

j'ai des photos de la poulie démontée, et de quelques détails concernant le montage d'une autre, enf ait c'est pas le prix de la poulie (dérisoire), mais la reprogramation qui pose problème, non ?
on ne peux pas le faire soi-même... oubien ?

C'est bientot l'anniversaire de ma MINI Cooper S ....
Elle rêve d'une belle Poulie -15% ou -19% + Reprog ....

Mais où aller dans le sud (Près de Nimes) pour faire cela :
Pour l'achat du Matos ???
Pour le Montage ????

Certe, je peux commander sur Internenette, mais j'aurai voulu connaitre quelqu'un qui l'a déjà fait pour avoir son expérience ...

Merci.