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Radix Mp112 Swap To Mp122


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OLD thread here, but have the same question as the OP. Didnt wanna start a new thread. Ive got the MP112 and i see there are several upgrades available for this blower. Ive heard that magnuson has discontinued their MP122 upgrade? Any idea on the Jackshaft upgrade? An extra 2psi would be nice. I know some others have also went with the Radix intake spacer and have seen pretty good gains. Any ideas? I dont wanna spin the radix too fast, raising IATs and sacrifice performance by any means. I have the upgraded 90mm J-tube and throttle body, with a 2.8in pulley. Currently around 8psi, i believe. Havent gone WOT with the new motor yet. Also seen some oversized crank pulleys being used. Any gains to expect there? Any input is greatly appreciated.

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Going to an Over Driven balancer will not require you to pulley down any further on the SC, Most OD balancers are a 20% OD. West Coast Innovaters makes them, so does Powerbond. But the Issue I have ran into, is when you want to use one of the OD balancers you have to convert all of your pulleys to 8 rib. For the most part there isnt a cheap alternative. But if your still looking for an OD balancer, I have found the Powewrbond balancer for $209 + shipping. and the West coast innovaters kit typically runs around $1200-$1400 for the whole kit. Good luck finding the right belt and the SC pulley would have to come from the maker of your SC, if they even make one...................

 

Another thing to take into consideration is everything that is belt driven will be turning 20% faster.

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Yeah. So the gains of a 20% oversized harmonic balancer is just to spin the blower faster (and everything else). Just not quite sure why you wouldn't just decrease the size of the blower pulley? Maybe to prevent slip? Once you get a tiny pulley on the blower, its smart to oversize the crank rather than decreasing the blower pulley even more and risking belt slip? An 8 rib woul be sweet, just not sure if its necessary. A mp112 isn't really that rowdy of a supercharger. That's why I was looking into upgrades for this unit, rather than seeking a TVS style blower (which would be nice to have, but its more money spent and I'm just looking for a few extra psi. Nothing too crazy.)

Edited by MID12sSSS (see edit history)
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Bad thing is like you said, if you pulley down too far one the SC it will be prone to slipping becaust the surface area of the pulley/belt is overcome by the load of the SC.

 

I ended up calling procharger and asked them their reccomendations about pulley sizes for my application. They explained to me that the 3.2" is the smallest size pulley they reccomend without running into slippage issues. But there are other tricks and things you can do to prevent slippage to.

 

The best thing to do, is to do the 8 rib conversion, while it can be expensive, the belt life is outstanding and the tendancy for slippage is almost eliminated. That is like I said before, if you can find all of the pulleys your going to need and the belt..............

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  • 1 month later...

In case anyone is still following this. My truck came with the built 408 (AFR 225's), and MP122. Has the 8 rib setup but I see the belt walk one rib regularily on the tensioner. Curious as to what tensioner you guys are running? May need to upgrade mine further.

 

BTW, no belt slip with 8 rib setup, approx 9psi, overdrive crank, and smaller super pulley (need to measure - will post once I have the diameter).

 

Truck pulls strong past 6K rpms!

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^^ Yep! Bigger idlers, hd tensioner.. John just started a group buy for a bigger coolant tank. They're pretty sweet! And you could run a dual heat exchanger set up like the one I've got and you'll be golden. So do you have an mp122, or were you just looking into how to upgrade your 112? What all does the 122 have that the 112 doesn't? Is it a port job and that's about it? I ordered a lower intake spacer for the radix and I have a 90mm Jtube and throttle body. I also plan on upgrading my fuel system and going with the 100mm idlers, HD tensioner, gates green belt, and a 16% OD crank pulley. Should be able to get 10psi out of it. For obvious reasons though, I don't wanna work it too much harder than I already am. It's already being pushed to the limit. If i can find a TVS2300, I'm gonna go that route. You're probably running a 2.75-2.8in pulley if you're seeing 9psi. I just changed the oil in mine. You don't have to do it often, but it'd be a good thing to do if you never have.

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^^ Yep! Bigger idlers, hd tensioner.. John just started a group buy for a bigger coolant tank. They're pretty sweet! And you could run a dual heat exchanger set up like the one I've got and you'll be golden. So do you have an mp122, or were you just looking into how to upgrade your 112? What all does the 122 have that the 112 doesn't? Is it a port job and that's about it? I ordered a lower intake spacer for the radix and I have a 90mm Jtube and throttle body. I also plan on upgrading my fuel system and going with the 100mm idlers, HD tensioner, gates green belt, and a 16% OD crank pulley. Should be able to get 10psi out of it. For obvious reasons though, I don't wanna work it too much harder than I already am. It's already being pushed to the limit. If i can find a TVS2300, I'm gonna go that route. You're probably running a 2.75-2.8in pulley if you're seeing 9psi. I just changed the oil in mine. You don't have to do it often, but it'd be a good thing to do if you never have.

 

Where do I find an HD tensioner? I imagine I just swap the 8 rib pulley I have onto it. I bought the truck already built with the MP122. Not 100% on all differences, but a little research brought up slightly larger displacement (1.9 vs 1.8) and larger in size. I callipered the face of my pulley was 3.0". Also have the Innovators West overdrive crank.

 

Hopefully the group buy also ships to Canada so I can go to a bigger coolant tank. TVS would make more power judging by the other forums. Will be changing the oil in my MP122 this coming weekend.

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Where do I find an HD tensioner? I imagine I just swap the 8 rib pulley I have onto it. I bought the truck already built with the MP122. Not 100% on all differences, but a little research brought up slightly larger displacement (1.9 vs 1.8) and larger in size. I callipered the face of my pulley was 3.0". Also have the Innovators West overdrive crank.

 

Hopefully the group buy also ships to Canada so I can go to a bigger coolant tank. TVS would make more power judging by the other forums. Will be changing the oil in my MP122 this coming weekend.

Sounds like you got yourself a hell of a truck man. Good find. Ill do some shopping around for the HD tensioner. You'd think the 8rib tensioner would be pretty damn stout unless the previous owner just installed the 8rib pulley on the stock tensioner. Anyway, im sure you could install it on the HD tensioner with no issues.

Yeah. Hopefully you can get in on the coolant tank group buy. Might have to throw in a little extra cash. They're shipping me one up to middle of nowhere AK. Haha.

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Mid12s, truck is a beast. Think I got a pretty good deal. There are some pics in the Member Introduction section : http://www.silveradoss.com/forums/topic/81496-new-member-fort-kent-ab-canada/

 

It's no show truck, definitely could use a new paint job and has been driven year-round in Canada, so frame and suspension are rusty. Body is in good shape though, only one small pea size dent on driver door I am getting fixed in May.

 

Sounds like our trucks would be a good race :cheers:

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