weird supercharger problem...
Thread Starter
Le Mans Master
Joined: Feb 2002
Posts: 5,970
Likes: 20
From: San Marcos Texas
the new pulley seems to have fixed the problem. I have 7200miles on the car, about 1400 miles on the new motor, and about 2500miles on the blower..
Last edited by chriswtx; Dec 14, 2008 at 06:04 PM.
Drifting
Joined: Aug 2005
Posts: 1,686
Likes: 20
From: Florida, Hell's Doorstep
Happy to hear that the problem was found--you gotta love this place!!!
Last edited by ONE BMF; Dec 14, 2008 at 08:09 PM.
Thread Starter
Le Mans Master
Joined: Feb 2002
Posts: 5,970
Likes: 20
From: San Marcos Texas
so what was the problem
no clue..I cant see the belt slipping while making no boost and just freewheeling the blower. Maybe a weird internal harmonics problem in the blower. Who knows..
Thread Starter
Le Mans Master
Joined: Feb 2002
Posts: 5,970
Likes: 20
From: San Marcos Texas
Premium Supporting Vendor
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From: Providing the most proven supercharger kits for your C5/6/7 609-752-0321
very strange! We have a bunch of cars out there with the 3" pulley and never had any issue like that at all. Hell I have my car set up with the ten rib OD balancer and a 2.75" pulley! At least it's gone though so I'll look forward to some healthy track times.
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Melting Slicks
Joined: Mar 2002
Posts: 3,426
Likes: 0
From: Toronto Ontario
I want to pick some brains.. 
don't know if you saw my other posts, but I have been fighting what I thought was a high rpm miss for a few months. At about 5500-5700rpm the car feels like it has a miss(jerks) hard enough by 5800rpm you need to let off..
I went through everything New: plugs, wires, valve springs, crank sensor, checked crank sensor wires, pulled oil pan and checked reluctor wheel, etc... So the other night I was thinking outside the box..So I reved the motor up slowly in neutral with no load or boost(low cylinder pressures) and it still does it at 5700rpm...So pulled the belt off, reved the motor up slowly in neutral and the motor pulls clean and smooth to 7000rpm. Put the belt back on, pulled off the 2 bypass valves and just let the air free flow(no load on the blower) and reved it up slowly in neutral again with no load or boost and it still does it. Very weird..I'm thinking its an internal problem with the Paxton.. Chris from ECS is sending me a 3.25" pulley to test with and see if slowing the blower speed down moves the problem up in the rpm range indicating if it a head unit problem...
Well sorry for the long message guys..Any input would be helpful.
don't know if you saw my other posts, but I have been fighting what I thought was a high rpm miss for a few months. At about 5500-5700rpm the car feels like it has a miss(jerks) hard enough by 5800rpm you need to let off.. I went through everything New: plugs, wires, valve springs, crank sensor, checked crank sensor wires, pulled oil pan and checked reluctor wheel, etc... So the other night I was thinking outside the box..So I reved the motor up slowly in neutral with no load or boost(low cylinder pressures) and it still does it at 5700rpm...So pulled the belt off, reved the motor up slowly in neutral and the motor pulls clean and smooth to 7000rpm. Put the belt back on, pulled off the 2 bypass valves and just let the air free flow(no load on the blower) and reved it up slowly in neutral again with no load or boost and it still does it. Very weird..I'm thinking its an internal problem with the Paxton.. Chris from ECS is sending me a 3.25" pulley to test with and see if slowing the blower speed down moves the problem up in the rpm range indicating if it a head unit problem...Well sorry for the long message guys..Any input would be helpful.
Melting Slicks
Joined: Apr 2005
Posts: 3,418
Likes: 1
From: Chicagoland Area IL
F--- ME!!!Played with it more this morning. Chris at ESC was kind enough to send me a 3.25" pulley on loan to test, so I swapped pulleys from the 3" to a 3.25" and the FN problem is gone...that only changes the blower speed by 4092rpm at 5700rpm WTF!!!
Maybe I can get it on the dyno this week and see what it does under a load...
Played with it more this morning. Chris at ESC was kind enough to send me a 3.25" pulley on loan to test, so I swapped pulleys from the 3" to a 3.25" and the FN problem is gone...that only changes the blower speed by 4092rpm at 5700rpm WTF!!! Maybe I can get it on the dyno this week and see what it does under a load...I'm sure you checked but is the bypass valve working correctly? The more I think about it, in conjunction with the rough bearings, it sounds like you may have been in surge margin of compressor... By slowing supercharger down you removed air flow and potentially opened up your surge margin. When you hit surge margin, you start with localized stalls, followed usually by full or rotating stall, then followed by flow reversal... This is violent and power input jumps up considerably (input power required is that big and can explain why your engine fell on its face), with turbo because its not mechanically coupled it slows the turbine down which does slip. Also surge causes extreme loads and vibration, which can kill bearings.
Did you hear a strange sound when you hit the wall with 3" pulley.
Maybe retest with and old pulley and just let it vent (disconnect blower discharge)... Also reving an engine with low or no load, is when bypass valve has to relieve or vent the most. What size/type bypass valve did you have.
Good luck,
Mike
Edit - did see you tried it with no BOV, but still thinking with discharge venting would be a valid test... If it still does it, then see what you can do about a replacement. Unit could have tolerance, balance, bad volute... issues, list goes on.
Last edited by Skunkworks; Dec 16, 2008 at 11:10 PM.
Thread Starter
Le Mans Master
Joined: Feb 2002
Posts: 5,970
Likes: 20
From: San Marcos Texas
..Going to put it on the dyno Sat. with the 3.25" pulley and see what happens with a load on it...
Unit could have tolerance, balance, bad volute... issues, list goes on
.I know with the larger pulley I probably won't make the numbers I was shooting for...
Last edited by chriswtx; Dec 17, 2008 at 10:16 AM.
Safety Car
Joined: Mar 1999
Posts: 3,611
Likes: 182
From: Toronto, Canada
Thread Starter
Le Mans Master
Joined: Feb 2002
Posts: 5,970
Likes: 20
From: San Marcos Texas
Just got back from the dyno..Problem is still there, you can see it in the graph starting at 6000rpm. Low boost at 13psi was the 693 and high boost was the 832 at 17-18psi...3.25" pulley and 8" overdrive balancer.. Still having the rough high rpm problem starting at 6000rpm...Changing to the 3.25" pulley just moved it up a few 100 rpm..I'm going to try and fine a shorter belt to see if its belt slip, but I don't think its belt slip..
Melting Slicks
Joined: Mar 2002
Posts: 3,426
Likes: 0
From: Toronto Ontario
Just got back from the dyno..Problem is still there, you can see it in the graph starting at 6000rpm. Low boost at 13psi was the 693 and high boost was the 832 at 17-18psi...3.25" pulley and 8" overdrive balancer.. Still having the rough high rpm problem starting at 6000rpm...Changing to the 3.25" pulley just moved it up a few 100 rpm..I'm going to try and fine a shorter belt to see if its belt slip, but I don't think its belt slip..
Does the car still pop and studder ? The fact you took off the belt and the issue stopped leads me to believe it sounds like a charging issue.
Thread Starter
Le Mans Master
Joined: Feb 2002
Posts: 5,970
Likes: 20
From: San Marcos Texas
Melting Slicks
Joined: Mar 2002
Posts: 3,426
Likes: 0
From: Toronto Ontario
When you see the line on the dyno get wavey like that, its usually belt or clutch slip. When you described studders, and saying it would do it out of gear with no load, I would guess ignition or charge related. The fact you took the belt off and the issue stopped would also point to the charge system. I would switch out the alternator and check for feed back in the system.
But i am sure you "THE MAN " will get to the bottom of this PITA!!!
Race Director
Joined: May 2003
Posts: 12,725
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From: ECS : WTF did you break now and HTF did you break it this time
I think I need a OD balancer and a 2.75 now too.....
Drifting
Joined: Feb 2006
Posts: 1,877
Likes: 1
From: Ok! So you don't believe in conspiracies, but will you acknowledge the possibility of there being coordinated activities in secret places? Texas
I want to pick some brains.. don't know if you saw my other posts, but I have been fighting what I thought was a high rpm miss for a few months. At about 5500-5700rpm the car feels like it has a miss(jerks) hard enough by 5800rpm you need to let off.. I went through everything New: plugs, wires, valve springs, crank sensor, checked crank sensor wires, pulled oil pan and checked reluctor wheel, etc... So the other night I was thinking outside the box..So I reved the motor up slowly in neutral with no load or boost(low cylinder pressures) and it still does it at 5700rpm...So pulled the belt off, reved the motor up slowly in neutral and the motor pulls clean and smooth to 7000rpm. Put the belt back on, pulled off the 2 bypass valves and just let the air free flow(no load on the blower) and reved it up slowly in neutral again with no load or boost and it still does it. Very weird..I'm thinking its an internal problem with the Paxton.. Chris from ECS is sending me a 3.25" pulley to test with and see if slowing the blower speed down moves the problem up in the rpm range indicating if it a head unit problem...
Well sorry for the long message guys..Any input would be helpful.
don't know if you saw my other posts, but I have been fighting what I thought was a high rpm miss for a few months. At about 5500-5700rpm the car feels like it has a miss(jerks) hard enough by 5800rpm you need to let off.. I went through everything New: plugs, wires, valve springs, crank sensor, checked crank sensor wires, pulled oil pan and checked reluctor wheel, etc... So the other night I was thinking outside the box..So I reved the motor up slowly in neutral with no load or boost(low cylinder pressures) and it still does it at 5700rpm...So pulled the belt off, reved the motor up slowly in neutral and the motor pulls clean and smooth to 7000rpm. Put the belt back on, pulled off the 2 bypass valves and just let the air free flow(no load on the blower) and reved it up slowly in neutral again with no load or boost and it still does it. Very weird..I'm thinking its an internal problem with the Paxton.. Chris from ECS is sending me a 3.25" pulley to test with and see if slowing the blower speed down moves the problem up in the rpm range indicating if it a head unit problem...Well sorry for the long message guys..Any input would be helpful.
