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View Full Version : 180 MPH Run & SC Belt melts



limey
08-24-2009, 02:25 AM
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?

esw0001
08-24-2009, 02:37 AM
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?

XxSlowpokexX
08-24-2009, 02:55 AM
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

limey
08-24-2009, 03:17 AM
http://www.whiteracingproducts.com/images1/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.

ben m
08-24-2009, 07:34 AM
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

XR7 Dave
08-24-2009, 08:56 AM
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.

baer198
08-24-2009, 10:52 AM
That's just nice.

ricardoa1
08-24-2009, 11:02 AM
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.

baer198
08-24-2009, 11:09 AM
I think they are referring to the direction on which the pulley is spinning.

scxr7
08-24-2009, 11:12 AM
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?

scxr7
08-24-2009, 11:14 AM
Hey Limey, who made those shorter SC snouts for you?

ricardoa1
08-24-2009, 11:19 AM
I think they are referring to the direction on which the pulley is spinning.

Isnt there only one way? Clockwise?

baer198
08-24-2009, 11:23 AM
Isnt there only one way? Clockwise?

that's why i said I think lol.

93superchicken
08-24-2009, 11:25 AM
the superchargers are facing the motor, I would agree the rotation of the motor is spinning them backwards!

ricardoa1
08-24-2009, 11:33 AM
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 :o
I hope to drive one one day though.

baer198
08-24-2009, 11:35 AM
counter clockwise spinning engine I think like the Honda's....

gsp393
08-24-2009, 11:37 AM
Usually engines in rear engined cars rotate counter clockwise. I know this from my experiance with Corvairs.

baer198
08-24-2009, 11:39 AM
ah, so it is spinning the SC backwards .....

CMac89
08-24-2009, 11:40 AM
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!!***

scxr7
08-24-2009, 11:43 AM
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?

baer198
08-24-2009, 11:44 AM
wow lmao...

scxr7
08-24-2009, 11:44 AM
crankshafts can be spun either direction, thats no big deal, its the camshaft that has to be changed around for the engine to be spun backwards. along with the water pump, ps pump, alt, etc.

CMac89
08-24-2009, 11:52 AM
Since I brought it up, I understand that, but I don't know if the motor is designed like that, or not.

90blkbrd
08-24-2009, 11:52 AM
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?

How do YOU know they are turning the RIGHT direction. The only obvious thing here is there is a chance he is spinning the rotors in the wrong direction. The rotors are supposed to move the air to the outside of the case and NOT down the middle of the rotors.

baer198
08-24-2009, 11:55 AM
try this take a pin in your hand spin it clockwise , now rotate the pin it would be spinning the wrong direction, but the lam has a counter clockwise engine right . So the blower would be spinning correct?

CMac89
08-24-2009, 11:55 AM
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?

It's a big deal because he's having problems and is asking for our help. Not freaking out, just trying to solve the problem.

Anyways, Lambo guy, can you verify what direction the blower pulleys are spinning whenever standing in behind the bumper?

thunderkid84
08-24-2009, 11:57 AM
Post more pics of that thing !

What model lambo is it ?

baer198
08-24-2009, 12:03 PM
I'm freaking out man ,,,,,,LMFAO

ricardoa1
08-24-2009, 12:07 PM
he makes boost. He is spinning the correct way>>>>>>>>ahhhhhhh im freaking out>>>>>>>>>>>>>>>>>ahhhhhh

rzibilske77
08-24-2009, 12:12 PM
very different here nice to see, what power are you making?

baer198
08-24-2009, 12:14 PM
he makes boost. He is spinning the correct way>>>>>>>>ahhhhhhh im freaking out>>>>>>>>>>>>>>>>>ahhhhhh


True. I cached that late, or read past it, but man i was laughing. That was cool

scxr7
08-24-2009, 12:20 PM
lol. so anyways. Since apparently I'm wrong, and he's spinning the blower the wrong way, and since he's spinning the blower the wrong way and still making boost I'm a fool. ~~~.

Could he be burning belts from the rotors binding on each other from thermal expansion? (serious question). If you're flooring it for an extended period of time, wouldn't this be possible?

BTW I did a youtube search on "limey" to see some videos and didn't come up with anything. Got any vids of this thing in action?

90blkbrd
08-24-2009, 12:40 PM
I would be willing to bet if you spin a M90 backward it would create boost but at some point as rpms rise things would go wrong such as eating the belts.

baer198
08-24-2009, 12:46 PM
i would be willing to bet if you spin a m90 backward it would create boost but at some point as rpms rise things would go wrong such as eating the belts.

sounds like a possibility...

Tony8470
08-24-2009, 12:55 PM
I remember reading a thread from Charles saying the 8 rib setup isn't enough at high rpm for the belt to keep contact. He verified this and said at a certain rpm the belt was guaranteed to slip. I imagine that the lobes being spun are probably the most torque demanding from the serpentine system. Add the resistance of the boost. And times that by 2 blowers. Assuming the blowers are spinning the right direction. I'm gonna put my bet that your gonna need a cog setup.

DrFishbone
08-24-2009, 12:58 PM
I figured you guys know more about the M90 Blowers than any other forum...

You just might've figured wrong. :p

I wonder what types of temperatures are seen in that somewhat enclosed area with two sc's. Perhaps the heat generated + heat from engine + pulley/belt friction raised the belt temperature to a point where it just couldn't take it anymore.

Any pictures of the damaged belt and pullies?

And so everyone can stop freaking out - which direction does the Lambo engine rotate? :p

Sweet setup btw. :cool:

bigpoppa822
08-24-2009, 01:04 PM
I think Tony is right. 7500RPM is much more than any SC motor sees. The blowers are also running tiny 2.5" pullies. I think the amount of force necessary to spin the blowers that fast to make boost is more than the belt can handle and it just melted itself. A cog setup would be the way to go, or reattach the 10 rib pulleys and see if that helps any. Good luck, that is an amazing car.

ben m
08-24-2009, 01:09 PM
You just might've figured wrong. :p
all i can say is wow. i dont come on here very much for this reason. this poor guy , well not POOR lol, came on to our forum for professional knowledgable advice from people who know what they are talking about and might help him with his dilemma. now im not saying I had the right answer or anything, but all this freaking out is pretty childish. come on guys! pull it together!

90blkbrd
08-24-2009, 01:11 PM
I just found the very same picture on ebay.

http://cgi.ebay.com/ebaymotors/Lamborghini-:-Diablo_W0QQitemZ380151039839QQcmdZViewItemQQimsxZ2 0090821?IMSfp=TL090821176003r5067

and it had a youtube link

http://www.youtube.com/watch?v=6VyCac2xu7c

baer198
08-24-2009, 01:13 PM
I think he is in the right place for asking the ? at hand, because solving an after market mod problem will take a few good opinions to eliminate cause , and who better to ask. not myself, but their are guys on here who are experts in this field. they don't mind helping out when you have a problem.

baer198
08-24-2009, 01:18 PM
AS fare as people freaking out, i don't think so. I'm sure he don't mind people asking ? because all these automotive site's are for wrench's to get together, and talk about CAR'S, and solve problems.

ricardoa1
08-24-2009, 01:27 PM
all i can say is wow. i dont come on here very much for this reason. this poor guy , well not POOR lol, came on to our forum for professional knowledgable advice from people who know what they are talking about and might help him with his dilemma. now im not saying I had the right answer or anything, but all this freaking out is pretty childish. come on guys! pull it together!

It was just a joke. Adding two blowers to the belt can be the problem in the set up. They are slipping for whatever reason. Tension or too much resistance by the two blowers. what kind of tensioner system is being used on this car. Is it a fixed bolt style tensioner or a pretensioner with a spring loaded in it? The belt stretches as you start to go up in the rmps. If you dont have a spring loaded pretensioner to compensate you will have belt slip as the belt stretches...

limey
08-24-2009, 02:24 PM
Hi Guys,

Back again.

The engine spins CCW, i make boost :-)

Now, i have tried Dayco belts and Goodyear gold belts, there is no slipping or squealling driving the car "normal", by that i mean, 1st gear mash the throttle, shift into 2nd, boost goes up, 3rd gear and let out, no issues. When though i held on the gas pedal Saturday night upto 160 in 4th, the belt melted & that was the 10 rib Goodyear gatorback, i was able to drive 30 miles home with 4 ribs left on the belt. Changed the belt Sunday to an 8 rib, with an aux. belt driving all other pulleys. Car was runing great again, but this time when i took the car upto 180 & into 5th, let out & smoke bellowing out from under the engine cover. You can see the pulleys have rubber on them from the belt melting, not to mention the belts outer sheath has ripped off, not from jumping grooves, but from shear heat, as well as the fcat the belt is very brittle in places, you can bend it and it snaps.
I'll take some pics tomorrow when i bring the camera to work.

Now, i'm only spinning these blowers to 13500 RPM @ 7500 Crank RPM, 7500 X 4.5 CRANK PULLEY / 2.5" SC Pulley = 13500 RPM, Correct?

I know these M90 can spin higher right?

Tensioner setup is a bolt style, tighten the bolt & it pulls the belt up onto the pulley, i get excellent pulley wraparound & don't see any dust or such on the motor.

Are these gates racing blue belts any good?

My number 1 question is this, the aluminium SC pulleys get to nearly 200 degrees temp, that seems awfully high! Anyone know what a satndard SC pulley gets to after a good spirited run? & would steel pulleys help, as i know aluminium absorbs heat better than steel by a LOT.

Keep the questions coming if you would, as to the HP, on 4 psi boost it makes 765 HP.

Kurt K
08-24-2009, 02:27 PM
I would imagine the the belt slipping would cause the high pulley temperatures.

ricardoa1
08-24-2009, 02:29 PM
Tensioner setup is a bolt style, tighten the bolt & it pulls the belt up onto the pulley, i get excellent pulley wraparound & don't see any dust or such on the motor.



.

Ding Ding
I think this is the issue. :D The belt stretches alot and you are belt slipping under the conditions you are putting it under.
Get a pretensioner set up.

baer198
08-24-2009, 02:51 PM
765 HP man that must be fun to drive. it looks like you don't have a ic that air has got to be hot as he`11 . i wounder what it would do if the air charge after the blower was cooled by a ic.

David Neibert
08-24-2009, 02:59 PM
Ding Ding
I think this is the issue. :D The belt stretches alot and you are belt slipping under the conditions you are putting it under.
Get a pretensioner set up.

I agree...you must use a spring loaded belt tensioner to keep the belt tight when it stretches under a load. The belt stretches a lot more than you think it would (more than a 1/2") and once it starts slipping, the supercharger and crank pulleys will get very hot very fast. I shredded several belts because the tensioner didn't have enough travel or a strong enough spring to keep the belt tight under a load. Keep in mind that one blower turning 14,300 rpms pulls about 65 HP, if you have both on the same belt then it's pulling close to 130 HP off the crank. You may actually be slipping on the crank pully since it's only 4.5" diameter.

You would be much better off with a dedicated blower drive belt (10 rib) and using a larger diameter crank pulley for the blower drive, and a larger diameter blower pulley. The more surface area you can get the less belt tension you will need.

David

Kurt Sunday
08-24-2009, 03:07 PM
765 HP. Wow! Very nice setup.

I wish you could bring that sweet car to the Shootout.

mywhite89
08-24-2009, 03:25 PM
cool setup for sure. You got a picture of the car?

scxr7
08-24-2009, 03:33 PM
I noticed your superchargers are before the throttle body. How do you vent your excess pressure when you let off of the throttle? Unless you have blow off valves hidden underneath the bypass valves.

scxr7
08-24-2009, 03:34 PM
Nevermind, I see the BOV's now.

XR7 Dave
08-24-2009, 09:12 PM
Keep in mind that one blower turning 14,300 rpms pulls about 65 HP, if you have both on the same belt then it's pulling close to 130 HP off the crank. You may actually be slipping on the crank pully since it's only 4.5" diameter.


This is a good point. How much wrap does the belt get on the crank pulley?

Are your tensioners spring loaded?

Do you have a picture of the other blower?

90blkbrd
08-24-2009, 09:35 PM
There is a few pictures on the eBay page and a engine running walk around on the youtube link. It truly is an impressive install.

thunderkid84
08-24-2009, 10:10 PM
i think one of those blowers might be mine :D

is one of those the 94 i sold you Limey ?

Ddubb
08-25-2009, 01:28 AM
Keep the questions coming if you would, as to the HP, on 4 psi boost it makes 765 HP.

Is that a DIABLO ?!??! :eek:

My all time favorite car.

- Dan