is mpx worth it?

LordBear

Registered User
hello all..i have kinda been going back and fourth on this and have searched the forums a few times..but not really found what im looking for..

i have owned one sc and sadly had to sell it..but plan on getting another one hopefully in the near future.. any how... i plan on getting the motor rebuild and getting the mpx package that has everything pretty much with it.. what i am curious about is a few small things.. reliability, durability, fuel milage, etc.. it is going to be mostly a dayly driver.. doubt i will ever go to a track..but if i do, it wldnt be more than a couple of times at most...

the scs get good fuel milage..so i was wondering if you killed that with the new set up. and then on the over drives for pullys are those really a good idea or not? i have read around and it seems those seem to be hard on the motor..i dont know.. i really luv the sc i just want to get it up to 300 or so hp... 350 wld be cool..but im not pushing for that..

i want it to be able to drive 4-5 hrs if needed...
 
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I would avoid the MPX overdriven in the 25% range if you want a daily driver to be dependable. I'm not saying it can't be done, but more often than not, you end up with problems. Get a good ported late model blower, ported heads, a good cam, 10% -15% overdrive, a good intake system and exhaust and you should be able to get close to 300 hp without the abuse, reliability problems that could come with a full MPX set up...Now heres the disclaimer, I've never had an MPX, but I've read about quite a few problems with them, so others will be more knowledgable in this...
 
Please explain why a 350rwhp sc can't get the gas mileage of a stock sc or better other than being heavy footed. I'm talking just cruising around like normal.

Fraser
 
what i am curious about is a few small things.. reliability, durability, fuel milage, etc.. it is going to be mostly a dayly driver.. doubt i will ever go to a track..but if i do, it wldnt be more than a couple of times at most...

If I do an MPX housing I'll be making sure I have a good rotor pack. I'd get things adjusted so that max boost of 18psi or so (don't race to over 20) arrives at the maximum RPM you are willing to drive. That'll be for your once and a great while road attacks. Driving around, daily stuff on the highway is then going to be around 12-15psi which is nice and reliable boost, should keep heat down.

Fuel economy will be directly related to how often you run under boost vs vacuum. Keep the engine into closed loop and you'll see the best economy. To support the higher boost you'll need bigger injectors, and a different engine tune. Both will use up fuel faster than stock when you have go pedal because you'll be making more power.

If you just want to improve the performance of you car a little, have a little more fun with it, you don't need a MPX housing. There are many things you can do that will have your car feeling faster, and get you close to 300rwhp, that don't require anything other than a good M90 (94/95, s-port).
 
THE MPX is made to spin. Id say an S port(ported 94-95) blower is probably better for everyday driving..For max power perhaps an mpx..But the extra RPM teh MPX needs probably means reduced lifespan over time
 
you want to have a 350 hp car with the fuel mileage of a stock sc??

I have a 350 hp SC and on the open road on a long trip I've had a bunch of 22 mpg, a few 23 and 24 mpg tanks. I've daily driven it and if I can keep my foot out of it, I can get 19-20 mpg.

THE MPX is made to spin. Id say an S port(ported 94-95) blower is probably better for everyday driving..For max power perhaps an mpx..But the extra RPM teh MPX needs probably means reduced lifespan over time

It may be made to spin but you don't have to. I guess I'd like to see a car on the dyno with a s-port and then an MPx with the same OD. I don't think a s-port would out perform a MPx at 15% OD.

It's hard to find a good used s-port or late model supercharger. So if you want to upgrade right away, I don't see why anyone, even if running stock OD can't have a MPx on their car.

Please note that the MPx shouldn't be driven in very cold temperatures, the clearances are to tight.
 
I didnt run my S port at 15%. From the testing or numbers I have seen of people swapping from one to the other(MPII to MPX) at anything but high OD there wasnt a worthwhile improvement if anything at all. Perhaps someone will chime in. I cant off the top of my head remember the people exactly but Dave N seems to ring a bell.
 
I didnt run my S port at 15%. From the testing or numbers I have seen of people swapping from one to the other(MPII to MPX) at anything but high OD there wasnt a worthwhile improvement if anything at all. Perhaps someone will chime in. I cant off the top of my head remember the people exactly but Dave N seems to ring a bell.

Damon,

I never had an MPX...had an MPIII with ESM rebuilt and coated rotor pack, but never resolved my belt slip issues before switching to the AR blower. I made 356 rwhp at roughly 23% OD with slipping belts. Probably could have made another 15-20 rwhp if I installed the MP 10% crank pulley and upgraded tensioner springs.

David
 
Find a used S-Port or even a MPII. Especially if reliability is a concern of yours.

There has been many vocal documented cases of MPX failures. However, there has been many documented cases of success. It comes down to taking your $1xxx dollars and asking yourself 'are you feeling lucky?'.
 
Find a used S-Port or even a MPII. Especially if reliability is a concern of yours.

There has been many vocal documented cases of MPX failures. However, there has been many documented cases of success. It comes down to taking your $1xxx dollars and asking yourself 'are you feeling lucky?'.

Name one MPx that failed that was doing less that 25% OD. I've heard vocally of a few MPII an MPIII failing as well.

I'm going to generalize here. If you are looking for around 300 rwhp and can find a used s-port or a properly ported 94-95, get it by all means. If you can't, a MPx will do the job and be just as reliable. But if you decide to max out the MPx and go 25% OD or more, the cards to look to be not in your favor.

Any of these blowers are only as good as the rotor pack in them. Whether or not it is a 89-93, 94-95, s-port, MPI, MPIII, or MPx.
 
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someone correct me if wrong, but didn't even Kevin L back off the OD and do some better #'s w/ his mpx?
 
Name one MPx that failed that was doing less that 25% OD. I've heard vocally of a few MPII an MPIII failing as well.

I'm going to generalize here. If you are looking for around 300 rwhp and can find a used s-port or a properly ported 94-95, get it by all means. If you can't, a MPx will do the job and be just as reliable. But if you decide to max out the MPx and go 25% OD or more, the cards to look to be not in your favor.

Any of these blowers are only as good as the rotor pack in them. Whether or not it is a 89-93, 94-95, s-port, MPI, MPIII, or MPx.

How would an mpx be just as reliable if you have to spin it a lot faster to make the same boost as a 94-95 blower?...

If you spin it slower to maintain its reliability then you make less power than the 94-95 blower spun at a comparable speed.,and you defeat the purpose of having the mpx since you arent operating it in its zone of efficiency.
 
How would an mpx be just as reliable if you have to spin it a lot faster to make the same boost as a 94-95 blower?...

I never said spin it faster.

If you spin it slower to maintain its reliability then you make less power than the 94-95 blower

I must have missed that information, I don't believe this to be true.

you defeat the purpose of having the mpx since you arent operating it in its zone of efficiency.

I was merely stating if he couldn't get his hands on a good ported 94-95 or a s-port there is NO reason why he couldn't get a MPx to fill his blower needs.

You must have missed that a MPx at 15% od won the "Most HP with a M90" at the 2008 shootout. :D
 
I'm currently running the MPX and have been pleased with the reliability of it. Now on the same hand I've had an MPIII fail. The one thing I've found that really effects the lifespan of these units is the quality of parts you use when assembling. I.E. rotor packs, snouts, etc. If you use parts that are in great shape, you shall be fine. On the other hand if you use parts with 150k miles then your probably going to experience problems.
 
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I've been kinda scared of the MPx. I am in the process of installing mine now actually and about a year ago I was planning on 25% OD but I think we might be on the right track with the front plate bearings not being up for that. Especially if we're spinning our motors past 6,000.

All that being said, I'm just going to see what it does for my car at 15% OD. The rotor pack I'm using supposedly only has around 30k miles on it. I bought the extra m90 from a friend's dad who had it sitting in his garage for many years and he claimed it was pulled off of a car at a shop and replaced without reason (sounds true enough, sadly...) When I assembled the MPx, the rotors and snout had a lot of dust and grime built up on them but they cleaned up very nice, and I have to say it seemed to be in very good condition. I took my current m90 off the car last night and wow, I don't know how much longer it was going to last, there is so much rotational play in the shaft! But it is much easier to spin by hand than the MPx. I'm not sure if that is normal? I have not the tools to check clearances myself either but everything looks good.

On a quick side note, the rotors in the m90 I took off of my car were coated, but the coating was partly flaked off. It was at 10% OD, I thought the teflon coating could generally withstand that?

At any rate, I have faith in the MPx case, and agree it isn't the cause of the failures.
 
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