180 MPH Run & SC Belt melts

limey

Registered User
I figured you guys know more about the M90 Blowers than any other forum, so hopefully you'll give some input on my dilemma.

I have a twin supercharged Lamborghini running M90's with large ports.

Specs are as follows:

4.5" crank pulley steel
2.5" Supercharger pulley Aluminium
Engine redlines @ 7500 RPM
3.0" alt pulley Aluminium
water pump pulley steel
idler pulley steel x 3

Car has been running great, zero belt slip & 4.5 psi boost, low boost i know, but you should see the port work on the motor, as well as a V12 doesn't help with these small blowers.

So, today i had a nice stretch of open road, flat footed it & took the car to 180 MPH top of 4th, shifted into 5th & coasted down to exit, when i come down to a slower speed of 40 mph, blue smoke was emitting from the engine cover, superchargers were quite, not good. Pulled into a gas station and there is the belt, just melted on the grooves, no signs of rubbing. The supercharger pulleys are reaching nearly 200 degrees F, spit on your finger and dab the pulley and it evaporates!

Are these aluminium pulleys causing this belt to melt and then snap?
 
I'm not one of the experts by any means, but I'm thinking that's too much for one belt, even if its not a lot of boost. Am I correct in thinking you have one belt for all of it?
 
Do you have a bypass for the blower setup? A photo would help. You may not be getting enough belt contact. Sounds like a slipping issue to me
 
SC.jpg


Has bypass pipes, was running an 8 rib on that pass with an auxillary belt to drive the alt. wp. ps, both belts destroyed, it has 80-85% pulley wraparound. Also used a 10 rib, as on this photo, but took that off as i wanted to try the aux. belt, but that meant dropping to an 8 rib on the SC. Before, i had 2.25" SC Pulleys and they smoked constantly, the belt was way too hot and would melt. I took the 2.25" pulleys off, they were a fire hazard.
 
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thats REALLY sweet! Lambos were always my favorite exotic. you might need to switch to a cog setup to eliminate the slippage. i notice that they are backwards xompared to the engine. are they reversed? or is it your belt routing that changes the direction? if so that could be your problem as the belt would be too long and not have sufficient tension on the superchargers. hope you get it fixed! oh and feel free to include as many pics as you like of the car! :cool::D
 
Yes, I think Ben is on to your solution. You appear to be spinning the blowers backwards. If so, you can't do that! :) If you are spinning them backwards, contact Charles at Magnum Powers about a reverse drive nose piece. He developed a reverse drive nose for the Honda guys because they have the same issue.
 
How is he spinning them backwards, The outlet is going into the intake. Just like designed.

But thats SICK my friend. It looks like a wide enough belt. You might need better tension on the belts.
 
wow dave. I'm surprised you said something like that.... those blowers aren't spinning backwards. see the lambo intake manifold? see the top of the m90 where our stock m90 hats are? the blower is spinning in the right direction.

also, low boost isn't a bad thing for these m90's. they are heat pumps and since you're not running meth or an intercooler, 7psi is probably the max you want to go without causing high act's.

85% belt wraparound is a lot. I don't see how belt slip would be an issue unless you're not getting enough tension on the belts, But It seems like belt slip is the only possible way for the belts to melt and break.

And I just read that you also used a 10 rib pulley/belt. I'm not an expert, just an enthusiast, but I still say that you're not getting enough tension. That's all that it can be, right?
 
that's why i said I think lol.

There is has got to be something that Im overlooking that Dave sees, ;)

But It looks like a very professional installation and it would not be overlooked that the blowers are spinning backwards. Plus he would not make boost. Maybe lambo engines rotate the other way. I never really owned one :eek:
I hope to drive one one day though.
 
Usually engines in rear engined cars rotate counter clockwise. I know this from my experiance with Corvairs.
 
You guys don't get it.

The blowers are facing an opposite direction than our cars are, so if you maintain the same clockwise rotation, you would be spinning the blowers counter-clockwise.

It would only be spinning clockwise if the snout is pointed towards the front of the car or if those motors have reverse rotational crankshafts.

**Someone got to it before I did!!***
 
lol...why is this such a big deal. just because the blowers are facing the motor you guys freak out. Of course they are rotating the correct way, not to be an a55, but that seems kind of obvious..right?
 
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