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View Full Version : Well, ring me up for a MPX rotor failure



mywhite89
11-04-2008, 02:29 PM
So, last week I was working out some driveability issues with the car. Putt-sing around town, feeling pretty good that I had it fixed, and my blower started making some nasty noises. Luckily I was close to a tractor trailer late night repair facility and borrowed a couple wrenches to get my blower belt off.

Drove it home, and I gotta say, this car is so damned quiet without the blower belt on. It was almost a sigh of relief because the engine purrs along so smooth.

Anyways, I took the blower off last night and the case is ruined, rotors are ruined:mad:. MPX DID NOT FAIL JUST FOR CLARIFICATION. Rear bearings are intact just fine. One of my rotors has way too much side to side movement, whatever bearing holds that rotor is junk. So once again, I have a ruined blower, ruined rotors, and I'm kinda pissed.

Charles is a great guy to do business with and has offered to help me out on buying a new case. Just kinda venting on what to do next. I'm starting to think turbo or whipple. I don't know if I can fathum another M90 with my luck, and I hate to buy the same thing twice like this. The rotors came out of a blower that had been assembled by Magnum powers a while back, so I figured they were rebuilt. Turns out, thats not the case typically according to him. I wish I would have known this before, I thought those things were ready to go.

Chris

ricardoa1
11-04-2008, 02:36 PM
So the failure was on th front bearing plate? OR was it on one of the rear bearings.

rzimmerl
11-04-2008, 03:37 PM
That sucks to hear. Finding a good rotor pack is hard to find. They are NOT rebuilt when MP does their builds, and I think everyone assumes he does. MP should state that information on their site. High Speed Lab is the only company I know of that does a rotor pack rebuild. I have seen 2 rotor packs fail, both in which the shaft moved on the front bearing (1 causing contact with the rear of the case and the other contacted the front bearing plate), not the rear bearings failing. More than likely we are exeeding the bearings rated RPM's, which could be cause of the failures.

mywhite89
11-04-2008, 04:35 PM
Front bearing in the spacer plate is what failed.

Ryan, the bearings not being able to hold up for long is what I am afraid of also. I've already had a rear bearing failure at just over 1,000 miles that trashed a blower earlier this year

frdlvr30
11-04-2008, 04:37 PM
Front bearing in the spacer plate is what failed.

Ryan, the bearings not being able to hold up for long is what I am afraid of also. I've already had a rear bearing failure at just over 1,000 miles that trashed a blower. On the other hand, who knows how many miles those rotors have on them.

That really sucks. Guess there is a lesson for everyone to learn from this...

mywhite89
11-04-2008, 05:38 PM
at least its a quick job to replace if thats what I decide. I didn't screw up the case too bad, maybe i'll just slap rotors in it for the time being since I still have 1 good set left. I just like it to run if I need it for alternate transportation.

ricardoa1
11-04-2008, 06:05 PM
Your title of the post should be changed, no reason to discredit the MPX if it did not fail. Mine on the other hand, is not doing too well in the rear bearing area. Charles said he would warranty it. I have not had the pleasure to take it apart again. But I did have play in the right rear one and now makes lots of rattling noises. The bore walls were scraped by the rotor tips. I ran it at the shootout like this, and was planing sending it to charles for inspection and warranty if needed.

Wade will give you an option of getting higher speed bearings on the bearing plate when you have him rebuild the rotor pack.

rzimmerl
11-04-2008, 06:54 PM
Ya, I agree with changing the title of the post since the MPx case had nothing to really attribute to the failure. Post some pics of the damage if you can. I was able to reuse the 2 NON MPx cases I had when the rotor packs failed.

I think it would be wise for Charles to post something about rotor rebuilding, so that if something like this happens people don't say "those MPx's are failing, I'm never gonna buy one". Think of it this way with the MPx, its a new case, new rear rotor bearings, most likely a rebuilt snout, but the same ole rotor pack thats never been touched.

kenewagner
11-04-2008, 07:06 PM
Your title of the post should be changed, no reason to discredit the MPX if it did not fail. Mine on the other hand, is not doing too well in the rear bearing area. Charles said he would warranty it. I have not had the pleasure to take it apart again. But I did have play in the right rear one and now makes lots of rattling noises. The bore walls were scraped by the rotor tips. I ran it at the shootout like this, and was planing sending it to charles for inspection and warranty if needed.

Wade will give you an option of getting higher speed bearings on the bearing plate when you have him rebuild the rotor pack.

Just a question, Since most MPX owners are overdriving way past what the stock M90 is driven, it would make sense that the bearings are not up to the task of the increased speed. Also would not the extra heat generated by the increased heat, decrease clearances between rotors and case? Add that all up and will there be more failures? I also wonder Ricardo if the longer rotors in your blower flex do to the increase length? Just some thoughts on the subject.

Ken

ricardoa1
11-04-2008, 07:24 PM
Just a question, Since most MPX owners are overdriving way past what the stock M90 is driven, it would make sense that the bearings are not up to the task of the increased speed. Also would not the extra heat generated by the increased heat, decrease clearances between rotors and case? Add that all up and will there be more failures? I also wonder Ricardo if the longer rotors in your blower flex do to the increase length? Just some thoughts on the subject.

Ken

On mine the left side is nice an tight, the right is a little loose. i know you had an exception with the rear bearing on your jag blower but. But most JAg blowers that Wade has rebuilt has similar needle bearings as the M90. I asked him today, it was by chance that he called me up today to ask me how the season went with my set up. I gave him my bad news and didnt say much after that.

XR7 Dave
11-04-2008, 08:37 PM
John Ludorf and I lost an MPX due to worn bearings. Then I installed a brand new set of rotors into a brand new MPX case. That blower was QUIET and made significantly more boost than the other one. Until it seized up also after about 8 dyno pulls. :mad:

I don't want to put any scare into anyone either, but there is a real issue here that people need to be aware of. I've talked with Charles about the root cause and a solution but I'm not sure that there is anything that can be done. If rotor bearing packs are bad on average, does that mean that the cases should be made with extra clearance to anticipate what will happen with worn rotor packs? Seems kind of counter productive to me.

In any case, I had a worn rotor failure and a new rotor failure all in the space of 24 hrs.

Mike8675309
11-04-2008, 08:55 PM
Is it possible to find a way for folks to check their rotor pack? Some way of checking for required go/no go tolerance? While many may not be happy to deal with the added expense of rebuilding the rotor pack, I can't imagine they would prefer the alternative of trashing a case, or simply not installing their MPX.

rzimmerl
11-04-2008, 09:14 PM
Does any one have the front rotor bearing number to do some research on? Intereted to see the bearing RPM capacity, working heat range, load rating, etc...

Here's another question, of the MPx's failed what has been the % OD used?

I've ran with a worn pack (there were marks in the rotors from hitting the early case they came from) and a low mileage set at 15% OD running fine. Also when swapping those packs, I noticed that the rear bearing grease had disspated all over the case. My guess is that the heat range for the grease had been exceeded.

frdlvr30
11-04-2008, 09:50 PM
John Ludorf and I lost an MPX due to worn bearings. Then I installed a brand new set of rotors into a brand new MPX case. That blower was QUIET and made significantly more boost than the other one. Until it seized up also after about 8 dyno pulls. :mad:

I don't want to put any scare into anyone either, but there is a real issue here that people need to be aware of. I've talked with Charles about the root cause and a solution but I'm not sure that there is anything that can be done. If rotor bearing packs are bad on average, does that mean that the cases should be made with extra clearance to anticipate what will happen with worn rotor packs? Seems kind of counter productive to me.

In any case, I had a worn rotor failure and a new rotor failure all in the space of 24 hrs.
Why haven't you mentioned this before?? Seems like a very important issue with all the MPX's hitting the streets lately.....

XR7 Dave
11-04-2008, 10:06 PM
Why haven't you mentioned this before?? Seems like a very important issue with all the MPX's hitting the streets lately.....

Mainly because it only happened just prior to the SC Shootout and we did not have any word back from Charles as to why they failed until a couple days ago. Add to that the fact that I get railed any time I say anything that might be construed as negative towards an M90, I am therefore rather careful what I say and when. :cool:

I don't know why the new rotor pack failed, Charles thought it might have been defective...

kenewagner
11-04-2008, 10:16 PM
John Ludorf and I lost an MPX due to worn bearings. Then I installed a brand new set of rotors into a brand new MPX case. That blower was QUIET and made significantly more boost than the other one. Until it seized up also after about 8 dyno pulls. :mad:

I don't want to put any scare into anyone either, but there is a real issue here that people need to be aware of. I've talked with Charles about the root cause and a solution but I'm not sure that there is anything that can be done. If rotor bearing packs are bad on average, does that mean that the cases should be made with extra clearance to anticipate what will happen with worn rotor packs? Seems kind of counter productive to me.

In any case, I had a worn rotor failure and a new rotor failure all in the space of 24 hrs.

When installing the rotor pack what was the clearance between the rear of the rotor and the rear of the case? Can the extra heat generated by lots of overdrive be causing clearance problems? Seems that clearances from the factory would be engineered for blowers running stock speeds. I thought I read somewhere that the MPX has even tighter clearances, is that correct?

Ken

jludorf
11-04-2008, 11:54 PM
I'm not too sure what I will be doing about rotors for the new MPX case when it comes down to installing them. I made a good 15 passes at the track on used set that failed and drove 500-600miles before they locked up in the case while I was racing in Ohio. What was alarming for me is the failure of the new set 24 hours after the first failure when we were doing our final pull of the night. It is too bad it is not easy to change the rotor bearings to eliminate that from the equation.

The MPX can perform for example we made 367 hp with the MPX and 262hp with a completly stock early blower inlet and throttle body on the SCU engine.

John

mywhite89
11-05-2008, 01:05 PM
I changed the title to keep people happy, either way I state my problem in the description. I think it is good to include MPX in this thread, because this may be a problem with how fast we spin them for their best efficiency.

kws6000
11-05-2008, 05:00 PM
Just a question, Since most MPX owners are overdriving way past what the stock M90 is driven, it would make sense that the bearings are not up to the task of the increased speed. Also would not the extra heat generated by the increased heat, decrease clearances between rotors and case? Add that all up and will there be more failures? I also wonder Ricardo if the longer rotors in your blower flex do to the increase length? Just some thoughts on the subject.

Ken


Of course these factors are at play.Why would anyone expect otherwise? Eaton doesnt just pull jnumbers out of the air to determine safe rotational speeds wrt durability. If the design limits are grossly exceeded,parts failure is virtually inevitable.

David Neibert
11-05-2008, 06:17 PM
I'm not too sure what I will be doing about rotors for the new MPX case when it comes down to installing them. I made a good 15 passes at the track on used set that failed and drove 500-600miles before they locked up in the case while I was racing in Ohio. What was alarming for me is the failure of the new set 24 hours after the first failure when we were doing our final pull of the night. It is too bad it is not easy to change the rotor bearings to eliminate that from the equation.

The MPX can perform for example we made 367 hp with the MPX and 262hp with a completly stock early blower inlet and throttle body on the SCU engine.

John

I made similar HP with an MPII overdriven 23% and beat on for years without a blower problem. Back then it was a pretty rare occurance to hear about someones blower seizing up...now it's almost a weekly deal.

David

Mike Puckett
11-05-2008, 06:31 PM
I'm glad to hear that David. I've come into possession of a new MPII that I was going to use to upgrade over my S-model. I was going to boost 10% but now I've gotten concerned that it could fail. I was going to sell my S-model but maybe I should hang onto it. I've never had trouble with it but it sounds like I can rely on the MPII as well from what you're saying. Do I understand correctly though that even though it's "new" the front rotor bearings and seals in the center plate are the original and could have no telling how many miles on them?

XxSlowpokexX
11-05-2008, 06:59 PM
Or you could get your rotor pack rebuilt...I seized one as well and i was PO'd.

New case..Old bearings...

XR7 Dave
11-05-2008, 07:07 PM
I made similar HP with an MPII overdriven 23% and beat on for years without a blower problem. Back then it was a pretty rare occurance to hear about someones blower seizing up...now it's almost a weekly deal.

David

"Back then" it wasn't appropriate to talk about failures, and very few people ran their blowers over 10%. There are people running 25% OD with no issues today, but with the occurrence of high levels of OD being more common, failures are more common as well. I have Bill McNeils' old MPII sitting here that failed several years ago but no one said anything at the time. You and he are two of very few people who ran over 20% OD back then. Todd Jelle is another one who ran his MPII at 20% and never had an issue, but as you may recall, Richard Spiveri burned up a couple of them before going to a centrifugal blower. I don't think failures are more common, I think more people are running them harder.

Ken, the fore and aft clearances are NOT tighter on the MPX case. The radial clearance is a little tighter but that hasn't been an issue.

I don't think the failures have anything to do with the MPX case, but rather the Eaton blowers reaching the end of their useful life and being over-stressed at the same time.

I think we should start looking into getting new rotors from Magnussen.....

ricardoa1
11-05-2008, 07:18 PM
Or we can get another batch of Autorotors or 2.1l kenne bell made. :D

My rotors are freshly rebuilt and the contact my blower is making in in the rear of the case. So rear bearing failures cannot be disregarded.

kenewagner
11-05-2008, 07:38 PM
Or we can get another batch of Autorotors or 2.1l kenne bell made. :D

My rotors are freshly rebuilt and the contact my blower is making in in the rear of the case. So rear bearing failures cannot be disregarded.

Mine seized up twice and damage was in the rear as well. Ricardo's and mine are diffrent as we are running M112s and there might be other factors like rotor flex. I guess i am tired of the Eaton heat pump and have always wondered how much heat a M90 makes running at high overdrive and how much that contributes to the rash of problems we are seeing.
,

Ken

ricardoa1
11-05-2008, 08:12 PM
Mine seized up twice and damage was in the rear as well. Ricardo's and mine are diffrent as we are running M112s and there might be other factors like rotor flex. I guess i am tired of the Eaton heat pump and have always wondered how much heat a M90 makes running at high overdrive and how much that contributes to the rash of problems we are seeing.
,

Ken

well let me clarify, its the tips of rotors that are making contact with the case bore. When assembled I can move the right rotor up an down putting my hand inside the inlet. The left rotor is solid. I even hear a pop pop when i wiggle it. There is play in the right rear bearing and thats causing my symptoms. the Fore and Aft of the case have been clearenced by Wade. No problems there. Also note that I only overdrive 15%

When I feel motivated to take the system off ill post some pictures.

XR7 Dave
11-05-2008, 08:36 PM
always wondered how much heat a M90 makes running at high overdrive and how much that contributes to the rash of problems we are seeing.
,

Ken

I've posted this information in the past. 450 deg at 18-20psi. As to how much it affects everything - I can't say exactly. You'd have to know the actual temp of the rotors vs. the temp of the case to say with any kind of accuracy.

KMT
11-05-2008, 08:48 PM
>When assembled I can move the right rotor up an down putting my hand inside the inlet. The left rotor is solid. I even hear a pop pop when i wiggle it.

Which one isn't typical?

Sounds a bit like one or more bearing bores/seats aren't parallel at some point...

jludorf
11-05-2008, 08:51 PM
I ran the blower for several months last year also without an issue but I swaped out the rotors so I could put a ported 94 back together for a customer. I then had less boost 16psi if I recall correctly so I then swapped out the rotors again and that was the set that failed it was making better boost than the previous set for sure but most of these blowers have 100k miles so I guess it is time for a new rotor pack for the MPX.
John




I made similar HP with an MPII overdriven 23% and beat on for years without a blower problem. Back then it was a pretty rare occurance to hear about someones blower seizing up...now it's almost a weekly deal.

David

Toms-SC
11-05-2008, 11:41 PM
And if you add up the costs of the 25% OD, MPX Case, + Sourcing new rotors you get a Kenny Bell.

jludorf
11-06-2008, 12:40 AM
Tom,
I do not think that is a fair statment, if it was that easy we'd see alot more whipples out there. mpx case is 635, the rotors won't be that much. I already have the 25% od. and rotors won't be that much if I had to guess $350 so still far cheaper to reuse the MPX at this point for me. If an AR kit comes up I'd definatly be up for one but that is a long shot right now. Plus I have an s port with MP inlet to use in the interm. Not that I am ready for it right now as I still need to fix the engine. Hopefully I'll have it figured out on the weekend.

John

XxSlowpokexX
11-06-2008, 12:41 AM
Are we saying that the rebuilt rotor packs are not a worthwhile investment from the High Speed Lab?

jludorf
11-06-2008, 01:07 AM
I'm not sure on the rebuilding. Since magnuson has new ones it might be better to get new rather than rebuilding as most used rotors that I have seen are scratched up a little bit so the cleaner the rotor you would think the better. Cost will be the determining factor so we'll see. I wonder if magnuson has seen the mpx case and maybe sending them the case and having them install the rotors and check clearance might be a good idea.
John

Greg Coleman
11-06-2008, 08:24 AM
I have run 2 mp11's now at 20% overdrive for years, one with coated rotors and one without and never had a problem knock on wood.Now Ive always been concerned about the grease that comes with the needle bearings so I have put a little dab of synthetic wheel bearing grease in the needle bearings and sayed a little prayer that it doesnt break down and I dont have any problems.After a couple of years of beatting on thease bearings I will replace them for safe measure.Over the coarse of this winter I want to change to 2 mpx's and as I understand the bearings in these blowers are supose to be more heavy duty to withstand more overdrive as i will be running 30% overdrive on both.I have 1 rebuilt nose cone and another really good nose cone from my wifes 94 along with the coated rotors from the 94 and it doesnt look like the coating is to thick so I'm not sure if I should use these rotors or not.Now should I scrap the idea of using the 94 rotors and just have 2 rotor packs that I have rebuilt or what? What to do:confused:

mywhite89
11-06-2008, 08:41 AM
Well, after taking a good look at the case last night and cleaning it up I decided to put my extra set of rotors in the their. The case is actually not near as bad as I thought. I think I was kinda scared to look before. Put the blower back together last night and put it on the car while I was messing around. Drove the car and it it still makes the exact same boost and feels just as strong. one small section of one side of the case is niched up slightly, but i'll see how it does for now. I'm just going to carry my 18mm wrench with me in case I gotta take the belt off I guess:rolleyes:.

Chris

rzimmerl
11-06-2008, 08:44 AM
I understand the bearings in these blowers are supose to be more heavy duty to withstand more overdrive


If I remember correctly the rear bearings in the MPx are the exact same part number as the bearings in any other stock case.

kenewagner
11-06-2008, 09:26 AM
If I remember correctly the rear bearings in the MPx are the exact same part number as the bearings in any other stock case.

I beleive they are bigger. My M112 has a bigger bearing and when I could not find that bearing, Charles came through with the correct size I needed. Said they were MPX bearings. MPX bearing is 27MM OD where a stock M90 is 25MM OD

Ken

mywhite89
11-06-2008, 09:59 AM
So I guess that means it has thicker needle bearings, which would not spin quite as fast at the same rpms. Well, thats at least good. My rear bearings were just fine on mine. I think if everything goes well, I may just take my blower apart once a year and freshen things up. If I gotta spend $100 a year and 4 hours worth of work to make sure I don't ruin my case, that is worth it to me as a preventative maintenance method.

My suggestion to anyone that develops a new noise in the blower, SHUT THE CAR OFF RIGHT THEN. Keep an 18mm wrench in the car an just take the belt off. If you shut it off as soon as the problem starts you wont hurt your case much if at all. I shut mine off within a mile. Next time, I'll shut it off withing seconds.

XR7 Dave
11-06-2008, 10:08 AM
There seems to be some misunderstanding as to what the actual problem is. Near as I can tell from what I've seen and what Charles has told me, the problem is rotor growth due to heat and pressure due to high boost. Everyone needs to slooooowwwww down and listen to what I'm going to say here.

1) Running the blower at high OD ratios isn't causing failure. If you are driving down the highway at 2500rpm at stock ratio vs. 30% OD, the added increase in rpm is no different than changing rear end gears from from 3.27's to 4.10's (or 2.73's to 3.55's for you 5spd guys) . The added rpm during normal driving is not an issue for the blower.

2) RPM alone is not an issue either. The Lightning guys run higher OD ratios than we do and don't have these problems. The MP Lightning case is driven up to 4x crank speed which, at 5000rpm = 20,000rpm. RPM is not the issue. Kevin runs his blowers at higher rpms than that and hasn't had too many issues I'm aware of.

3) The rear bearings are not an issue for the most part. Ricardo's issue is an isolated case. I've not seen any other rear bearing issues. If you have lateral play in a rear bearing it would be very foolish to run the blower at all. All M90's use the same rear bearings including the MPX and most blower failures are not coupled to rear bearing failures.

4) Front rotor bearings are a concern. The front rotor bearings are lubricated by the gearbox, and after 100K miles without changing the oil (most SC's) the oil becomes saturated with metal filings which in turn act like a slurry wearing out the bearings. The bearings will not be shot as in chewed up components, but they get loose allowing the rotors to creep backward under load. The backward motion closes up the OE clearances at the back of the blower. Under normal conditions this is not an issue, but if you generate enough boost coupled with enough heat (rotor growth) you can eat up all the clearance at the rear of the blower. Once there is contact, the game is over. The aluminum galls resulting in an interference fit and the rotors seize in the bore. That's what happens. Why it happens and under what conditions is something that has to be studied to find the right solution.

Let's talk about heat. There are several components to heat with respect to a roots supercharger.

1) Heat is generated by the boost alone. Physics dictates that an increase in pressure generates a fixed increase in heat. So more boost = more heat regardless of blower design or anything else. A stock blower making 21psi on a stock motor will make more heat due to coimpression alone than an MPX running 45% OD on a built motor making 15psi. This is the first component of heat. Most MPX owners are making more net boost than before.

2) Blower efficiency. If the VE of the blower is lower, then more heat will be generated. Loose rotors will generate more heat than tight ones. Air escaping around the rotors will generate heat in the blower. The MPX has a lower efficiency at most rpm levels than a square port blower. A reduction in seal time results in a reduction in efficiency. It's physics, there's nothing you can do to change this. This is probably of minor consequence compared to the other factors, but it should be understood that a reduction in VE results in an increase in heat.

3) RPM. The higher the rpm the less time there is for the rotors to dissipate heat from the air. I have logged the net outlet temps of the stock blower as well as ported blowers and the MPX. In all cases temperatures climb in a direct relationship to blower rpm and acceleration rate. Outlet temps will be higher at 5000rpm in 4th gear than they will be at 5000rpm in 1st gear. The reason for this is two-fold. First, the longer the air is in contact with the rotors and blower case, the more heat will be dissipated, (RPM) and 2nd, the longer the rotors and case are exposed to the hot air (acceleration), the less additional heat they will be able to absorb from the air.

4) Temperature. So what are the temperatures we are talking about? It would be typical to see an outlet temp in the neighborhood of 275 deg on a stock blower at stock OD ratios (12psi). With a correctly ported blower running 15% OD and 15-16psi it would be normal to see 350 deg air temps. I'm not aware of anyone having any issues at either of those boost or temperature levels. The combination of 25% OD and 18psi+ will result in 450 deg outlet temps when pushed hard. Or course under normal conditions the temps are far lower, but they can reach that level. Kevin has told me that on his blower at even higher boost levels the coating has literally melted and blistered off the rotors.

5) Metallurgy. At even 200 deg aluminum expands quite a bit. If the rotors actually come anywhere close to 300 deg the expansion is going to be ridiculous. Not only that, when aluminum gets that hot it becomes very soft. Now since the case and rotors are both aluminum, as long as they are expanding at the same rate, it may not be an issue but I have a feeling that it may be common for rotors to hit 250 deg when the case may be only 150 deg. This is where issues may start to creep in.

Hopefully you are beginning to understand that there are many factors involved that can lead to failure under a variety of circumstances. It most likely takes the right combination of heat, bearing wear, rpm, and boost to precipitate a failure. If you are lucky (or smart) enough to avoid a combination of circumstances that generate a failure, there is no reason why the blower can't run a long time successfully. But it will require an understanding of why failures occur to be able to stand a good chance of avoiding one.

The one thing that is clear and must be understood is that the vast majority of these failures are the result of the rotors colliding with the back of the case. Aluminum will not 'kiss' the back of the case and leave some little marks so that you can say "oh, my blower is running out of clearance." On the contrary, there will be no evidence whatsoever until contact occurs and then there will be instant galling (aluminum tends to stick to itself) and instant failure. How bad the failure ends up being can be a result of a variety of circumstances and luck.

So, on summary there are several things you can choose to pull from this.

1) Play in rotor bearing packs are probably the #1 trigger for a failed blower. Check your end play before assembling. I don't have the specs on hand but Charles has them. When I get them I'll post them. Bearing play is more important consideration than rotor tip condition. Rotor tip condition is a function of miles and quality of air filtration. Bearing condition is a function of supercharger oil maintenance. You can have perfect rotors but shot bearings and vice versa.

2) High boost is going to put you at higher risk than blower boost. 15-16psi is relatively low risk. 18-20psi is much higher risk.

3) Sustained high rpm (and repeated high rpm)will generate much more heat in the rotors than short bursts followed by cool down periods.

4) Do NOT use ice or any other cooling device on the blower case at the race track or dyno. Excessively cooling the case while the rotors remain hot could be fatal. If the case shrinks and the rotors stay hot then the difference in the expansion of the aluminum could result in a collision that would not otherwise have occurred.

5) The design of the MPX case is NOT the cause of the failures. The failures are the result of a combination of the factors discussed above. Where your blower fits in this is a function of your boost level, blower rpm, bearing wear, temperatures encountered, and duration of load experienced by the blower.

Like GI Joe says, "Knowing is half the battle."

ricardoa1
11-06-2008, 10:30 AM
Are we saying that the rebuilt rotor packs are not a worthwhile investment from the High Speed Lab?


The latest rebuild has not been an issue, but the first one that thrashed the MPIII could have been a problem since that failure consisted of the left rotor hitting the back plate. Then we also saw that I had cracks on the rear bearing boss. No one gets a free ride with SCs...:(

mywhite89
11-06-2008, 10:56 AM
Thanks for the information Dave. Here's an e-mail that Charles sent me with some specs.

Chris

I have had a couple failures like this however the causes were defective rotor packs. I am coming up with some inspection procedures to help my customers identify defective rotors before they are installed in the case. I think you will find the rotor that hit the rear of the case has a loose front bearing or it has more clearance in the front then in the back. The rotors should not move forward or rearward when pushing on them. The clearance between the rear of the rotor should be .012" to .017".

Charles

ricardoa1
11-06-2008, 12:10 PM
Also on another note. While we are on the MPX discussion. Remember my post about me needing excessive force to get the mounting holes of the MPX to line up with the manifold?
I spoke to Charles about it and he knew the problem right away. If you are using an early producion inlet or an MPIII inlet to convert to the MPX. He made the bypass hose tube on those units too long and whats not letting the SC assym to line up, is the inner ridge of the factory bypass hose. The remedy is to file down the inlet bypass tube at the end to allow the unit to move more to the right and not be stopped by the rubber hose.
Just in case anyone has problems mounting the MPX like I did that is the fix for that problem. ;)

David Neibert
11-06-2008, 12:19 PM
"Back then" it wasn't appropriate to talk about failures, and very few people ran their blowers over 10%. There are people running 25% OD with no issues today, but with the occurrence of high levels of OD being more common, failures are more common as well. I have Bill McNeils' old MPII sitting here that failed several years ago but no one said anything at the time. You and he are two of very few people who ran over 20% OD back then. Todd Jelle is another one who ran his MPII at 20% and never had an issue, but as you may recall, Richard Spiveri burned up a couple of them before going to a centrifugal blower. I don't think failures are more common, I think more people are running them harder.

Ken, the fore and aft clearances are NOT tighter on the MPX case. The radial clearance is a little tighter but that hasn't been an issue.

I don't think the failures have anything to do with the MPX case, but rather the Eaton blowers reaching the end of their useful life and being over-stressed at the same time.

I think we should start looking into getting new rotors from Magnussen.....

Dave,

Maybe it was my excessive use of Permatex RTV which likely created additional clearance between the rear of the rotors and the case, that kept me from having problems.

http://www.sccoa.com/forums/showpost.php?p=445169&postcount=1


David

Quik95SC
11-06-2008, 02:20 PM
I only know of a few running the methanol injection before the blower, I was wondering if this will help to any degree with the temps folks are seeing at the 20% OD and above. If you can cool the intial inlet/air temps, does it not stand true that the outlet temps will be reduced as well.

Now, to what extent this would help I don't think has been tested, but I think it would be interesting to know how effective this 2 nozzle application is, and if it would benefit those running higher OD and Boost.

Thoughts?

Smitty

MagpoweredSC
11-06-2008, 02:42 PM
I'm not sure on the rebuilding. Since magnuson has new ones it might be better to get new rather than rebuilding as most used rotors that I have seen are scratched up a little bit so the cleaner the rotor you would think the better. Cost will be the determining factor so we'll see. I wonder if magnuson has seen the mpx case and maybe sending them the case and having them install the rotors and check clearance might be a good idea.
John

Just got off the phone with magnuson. They will not touch a Magnum Powers blower, even with just the MPX case. I asked if they sell just the rotor packs, the guy said no. So it appears that magnuson is a no go for new rotor packs.

XR7 Dave
11-06-2008, 02:54 PM
Just got off the phone with magnuson. They will not touch a Magnum Powers blower, even with just the MPX case. I asked if they sell just the rotor packs, the guy said no. So it appears that magnuson is a no go for new rotor packs.

Call and ask what it will cost to rebuild your stock blower. Then swap the case once you get it back. Problem solved.

David, that's pretty funny! But don't discount that, it might have had an effect...

Smitty, I was running two stage meth injection on the brand new rotor pack that failed due to clearance so I don't know that it had any impact on the end result.

MagpoweredSC
11-06-2008, 03:02 PM
Call and ask what it will cost to rebuild your stock blower. Then swap the case once you get it back. Problem solved.


I dont have a stock blower anymore. I bought a used one from bill at scp and hade it sent to charles to use the core for a MPX that was rebuilt and assembled. I checked last night on my mpx and, with the snout facing you, the left rotor has no play back and forth, but the right rotor has some play back and forth. There is not much play but i thought you want none. I dont want to trash this blower if the rotor bearings can be easily replaced. I want to smash my face into the wall. :)

XxSlowpokexX
11-06-2008, 03:03 PM
The High Speed Lab will rebuild an dcoat your rotors. No reason to go to magnusun and get litterally RIPPED with an m90 rebuild. I believe teh high speed lab charged 400 or so. Cant expect a rotor pack with 100,000 plus miles to work better then new

ricardoa1
11-06-2008, 03:12 PM
If we start to add things up its not such great deal after all.
$1150~ for MPX.
$376 for jackshaft and supercharger 20% OD
$235.99 Crank pulley for extra 10% OD
$60.00 for tensioner springs.
Between $500min to $1000or more to rebuild the rotor pack either from Highspeed lab or Magnusen.

Best case scenario $2321.99 to more then $2821.99. For something that requires ideal conditions so it does not malfunction.

Ive support everything that makes up HP. I support Charles, Wade, SCU and all of their efforts. It simply stinks to not have choices.

kenewagner
11-06-2008, 03:26 PM
If we start to add things up its not such great deal after all.
$1150~ for MPX.
$376 for jackshaft and supercharger 20% OD
$235.99 Crank pulley for extra 10% OD
$60.00 for tensioner springs.
Between $500min to $1000or more to rebuild the rotor pack either from Highspeed lab or Magnusen.

Best case scenario $2321.99 to more then $2821.99. For something that requires ideal conditions so it does not malfunction.

Ive support everything that makes up HP. I support Charles, Wade, SCU and all of their efforts. It simply stinks to not have choices.

What would be a solution to that Ricardo in your mind?

Ken

David Neibert
11-06-2008, 03:43 PM
David, that's pretty funny! But don't discount that, it might have had an effect...



Dave,

I was being serious...Charles Warner even mentioned my excessive use of RTV as being a possible reason for why I couldn't make more power with the blower, because of it increasing the rotor end to case clearance.

David

PS: My MPII ingested a couple of stainless steel screws that fell off the throttle body while on the dyno. Even with the case and rotors looking horrible, I ran it for another year without loosing any RWHP...which was around 360 at the time.

ricardoa1
11-06-2008, 03:50 PM
There is no solution, for those that already are invested in this setup well just have to keep hoping that it doesnt fail and keep dumping money into the set up when it fails.
Or for those that have the choice they can jump ship into an screw or turbo.
We dont have alot of choices but for those looking to get into it, should think hard. Since the money youll be spending on a HIPO M90 could be used to fund a turbo or a twinscrew.

Charles has the resources to make a twin screw kit for our cars. He makes inlets for M90s from cast aluminum, and the rest like snout brace is not that hard. The SC head units and snouts could come from KenneBell itself or Autorotor. Or even Whipple if Kenne Bell or Opcom has problems suppling the units. Till then youll have to leave it stock or follow along on the same journey that some of us are in.

rzimmerl
11-06-2008, 03:58 PM
Has anyone contacted PSE Supercharger, for a supply of rotor packs? They also offer a full rebuild service for the Eaton and other manufacturers. Their website posts a complete rebuild of an early model for $449, if thats for a rebuild snout and pack that would be a great deal.

johnrada
11-06-2008, 04:50 PM
what if you got your own rebuild kit with instructions from victor at spinning wheels? its only like 100 dollars that's wayyy cheaper than 500 if you ask me :D

ricardoa1
11-06-2008, 05:12 PM
what if you got your own rebuild kit with instructions from victor at spinning wheels? its only like 100 dollars that's wayyy cheaper than 500 if you ask me :D

That kit is not going to rebuild the rotor pack bearings and seals. It will probably do the snout and rear bearings. Thats the easy part. ;)

kenewagner
11-06-2008, 05:22 PM
what if you got your own rebuild kit with instructions from victor at spinning wheels? its only like 100 dollars that's wayyy cheaper than 500 if you ask me :D

The problem with the front bearings is the gears are pressed on to the rotors and have to be timed. On one of my first blowers I tried it. If the gears are not pressed on perfectly the rotors will contact each other with very bad results. Everyone thinks you can just modify or do the work yourself on a blower. Some things are best left to professionals who know what they are doing. I have done my share of doing it myself and now Im careful on what I chose to attempt. I learned the hard way in most cases. A guy has to know his limitations:D

Ken

fturner
11-06-2008, 05:40 PM
So what is the recommendation then for folks considering the MPX setup. I'm not going to be one of those guys aiming for more than 20% at most (for now ;) ) but initially 15%. I'm running a mildly ported '94 at about 12% OD and I'm happy with it. Would an MPX at 15% be worth it, or am I going to have problems and should stick to what I've got?

Frit

rzimmerl
11-06-2008, 05:58 PM
I switched this year from the MP2 @15% and the Flowmaster exhaust with 2.25" catless downtubes to the MPX @15% and dual 2.5" exhuast and gained almost 30 RWHP without a retune. So I'd say it was worth it.

XR7 Dave
11-06-2008, 07:28 PM
So who is going to call Magnuson and find out how much it costs to have new rotors put into a stock blower?

jludorf
11-06-2008, 10:09 PM
David,
I'll try them in the morning as I need a set anyhow. though knowing the clearance will be good to check other used blowers for future.

John

jludorf
11-07-2008, 08:30 PM
The guy that does the quotes for the rebuilds is at SEMA today so I'll have to try again on Monday.
John

XR7 Dave
11-07-2008, 09:10 PM
I'm curious if they will price the snout rebuild separate from the rotor/case rebuild. In other words if you sent them a blower that didn't need the snout rebuilt but needed a set of rotors installed.....

jludorf
11-07-2008, 10:25 PM
I was reviewing the web site while I was on hold and they actually hone the case, so I wonder if they have different size rotors depending on how much honing they perform? If not wouldn't this affect how the rotor seals with the case? I'll see what they say about the snout aswell

John

Toms-SC
11-07-2008, 10:31 PM
I was reviewing the web site while I was on hold and they actually hone the case, so I wonder if they have different size rotors depending on how much honing they perform? If not wouldn't this affect how the rotor seals with the case? I'll see what they say about the snout aswell

John

I checked last year-about $900usd for rebuild-it sounded like the blower would be virtually new except for the case and snout.Their rebuild process is a lot more extensive than other cheaper places.

superbirdx
12-02-2008, 04:01 PM
I know this thread is a couple weeks old ,but, I was wondering if any new info had become available regarding Magnuson rebuilding an early model blower. I just sold my MPII and Plenum and swapped out my rotors myself.Now I'm a little concerned that maybe it wasn't the best idea to let them go. Not that I can do anything about it now. I'm just curious to find out if there is any hope of new rotor packs.

Toms-SC
12-03-2008, 12:24 AM
I know this thread is a couple weeks old ,but, I was wondering if any new info had become available regarding Magnuson rebuilding an early model blower. I just sold my MPII and Plenum and swapped out my rotors myself.Now I'm a little concerned that maybe it wasn't the best idea to let them go. Not that I can do anything about it now. I'm just curious to find out if there is any hope of new rotor packs.

Why dont you call them?

jludorf
12-03-2008, 03:55 AM
I did speak to them about rebuilding a supercharger but during discussions I was told they hone the supercharger case. though they did not elaborate I would assume they need slightly larger rotors to seal properly. If so I'm not sure this will work with an MPX case. I did not want to let them know about my plan to put them in an MPX case once I got the blower home as it was stated earlier they would not rebuild it with an MPX case.

John

superbirdx
12-03-2008, 06:35 AM
Why dont you call them?
Well I will ,but, others had stated they were planning to and then would get back.I was checking to see if that had been done since if it already had been done they would have an easier time answering the question after having done the leg work to get to where they were.
Maybe I should've been more specific and mentioned them by name in a pm and not made it like I was asking you.:rolleyes:

superbirdx
12-03-2008, 06:38 AM
I did speak to them about rebuilding a supercharger but during discussions I was told they hone the supercharger case. though they did not elaborate I would assume they need slightly larger rotors to seal properly. If so I'm not sure this will work with an MPX case. I did not want to let them know about my plan to put them in an MPX case once I got the blower home as it was stated earlier they would not rebuild it with an MPX case.

John
Thanks for the reply back. I guess I'm just going to run it and see what happens. Probably will get the rotor pack rebuilt and go for it. Thanks again.

jludorf
12-03-2008, 04:35 PM
I called again today and spoke to David about the rebuild process and he cleared up a few things. First they do hone the case but only take off 1 thou and they install new rotors and rotor bearings. The cost is between 850-900 for the rebuild as was mentioned before. The previous fellow had given me David's name but I just kept missing him when I called to talk to him to clarify the rebuild etc.

So Magnuson is a viable option for us to have the supercharger rebuilt. I did ask about purchasing the new rotor section without shipping the case and that was a no go for them they want to fit the blower case to the rotor section themselves.

I forgot to ask about the snout too the guy is out for lunch right now so I'll try again later.

John

jludorf
12-03-2008, 07:01 PM
I spoke with David again and the $850-$900 is including a snout rebuild. If you do not need the snout rebuild then deduct $200. He also did not have a problem installing the rotors into modified cases etc. He said to send the original case and the modified case so they can compare clearances. I explained the problem from My MPX and rotor combination and it contacting the back of the case and ultimatly locking up and he said they will check clearances to ensure they will not have the same clearance issues. Basically you will have new rotors and bearings throughout the supercharger. If we use the aftermarket case there won't be a warranty on the blower but it is kinda hard to get a warranty on performance parts when we will be using them beyond thier original design anyhow.The agreed that worn out rotor pack bearings are an issue for the M90 as they get older and incur higher mileage.

John

superbirdx
12-03-2008, 07:35 PM
I spoke with David again and the $850-$900 is including a snout rebuild. If you do not need the snout rebuild then deduct $200. He also did not have a problem installing the rotors into modified cases etc. He said to send the original case and the modified case so they can compare clearances. I explained the problem from My MPX and rotor combination and it contacting the back of the case and ultimatly locking up and he said they will check clearances to ensure they will not have the same clearance issues. Basically you will have new rotors and bearings throughout the supercharger. If we use the aftermarket case there won't be a warranty on the blower but it is kinda hard to get a warranty on performance parts when we will be using them beyond thier original design anyhow.The agreed that worn out rotor pack bearings are an issue for the M90 as they get older and incur higher mileage.

John
This is good info. I sent them an email today and haven't heard back. I called ,but, believe it was too early as they were closed and I'm in Maine and they're in California. Thanks for getting all this out to us.

pablon2
01-05-2009, 03:44 PM
I just installed a supposedly low mileage uncoated rotor pack into my MPx. 'Rotor-lobe-edge-to-case (V opening)' shows .007". 'Rear-rotor-to-case-rear' clearance measured .012" for both rotors. .012" seems a bit much, perhaps I too used too much Permatex? I tend to overdo it on that stuff. If it does affect performance, I'll glady give up 25rwhp to avoid locking her up. I'm curious to know the clearances others are seeing in their set-ups.

Kevin Leitem
01-05-2009, 05:40 PM
mine was set up for 13 thousandths on the end.

Toms-SC
01-05-2009, 07:05 PM
After all this is said and done has anybody taken a look at what a new generation MP90 would cost? :confused:

XR7 Dave
01-05-2009, 07:11 PM
How about we stop dragging up old threads about blown up M90's and start a new thread where we can talk about these new topics. :)