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Who has run m46 on 300 plus?

F

fastcomet

Member
Joined
Oct 5, 2016
kinda what heading says. Who has ran somewhere in ball part of 300 hp on a M46 trans? I know all about the M47s being a weak but M46s I find all seem to be intact and runnable. I know I can search and I have, but no solid answers. Next questions are they rebuildable or anyone offer that service? THanks
 
I don't think I was close to 300hp in my old GT and I stripped 3rd gear clean of any teeth on two different boxes.

Jordan
 
If Volvo had the parts to make the M46 strong enough for 250HP plus, I think they would have done that on the group A cars. That is probably why they went with the Getrag transmission.
 
Keep your torque below 250 lbs-ft and they will handle that power. It will require a decent cylinder head.
 
Stock clutch and skinny tires might make it last minimally. Brett/DNAsequence had the Pen15 Hood on m46 for a while. It's a fool's errand to even try. Save the m46s for na replacement, they ain't making any more of em y'know.
 
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Sure, I have access to a 240 wagon, the clutch is gone but the trans feel pretty decent. Another one in local salvage yard. I was curious, if it was worth a giving it a shot. But believe everyone is right, I just need to just save up for a T5 swap.
 
I am running an m46 behind a b230f+t, td0dhl-15g with modified compressor and turbine wheels, 90+ mani, 531 head on a penta 230a engine, ipd turbo cam, gfb boost control set at 12-15 psi, and a sts flat flywheel with a southbend stage two daily clutch. The transmission is original to the car and has 280,000 miles on it, I don't think I have 300hp more like 250 at the crank. Just be nice to the m46 and you should be fine, I daily drive my car 100 miles or more every day.
 
fastcomet said:
Sure, I have access to a 240 wagon, the clutch is gone but the trans feel pretty decent. Another one in local salvage yard. I was curious, if it was worth a giving it a shot.
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Well I would want to road test them well before deciding to rely on it. And check the condition and level of the oil, and take the mileage into account.
 
Torque and abuse will kill it. Actually, I've stripped third gear in an M47 on my non-turbo car, too, so even without torque it can die. I may or may not have missed a 2-3 shift drag racing it a time or two over the years, I can't remember for sure.

If you put a more aggressive camshaft in the car it will help keep torque lower and HP up if that's what you want.
DurableSwedish said:
I have 320hp and 360tq and an m46. I drive the car nicely though. OEM volvo clutch from the mid 90s gave out around 200whp.
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*** Correction: you don't drive your car! It's a project that doesn't get driven. Don't lie! :lol:
 
I have run both M47's and M46's in the 300 ball park without any issues. Always with a stronger clutch as we tow a lot. Main thing is feathering in the clutch and power. Hard launches and banging through the gears will kill one even with NA power if you try hard enough
 
Granted, it was an M47, but it wasn't a hard shift or popping the clutch or anything that, just a nice easy shift into third and then some full throttle WOT on a crisp fall day when the boost hits a bit harder. Spooled, 18 PSI, and a huge metallic grinding sound and I had a 4 speed. Turned around, drove it home, pulled it and swapped a T5 into it.

There's some sentiment floating around that an M47 isn't as strong as an M46, but not a lot of real world evidence to back that up. They're pretty much the same thing in gears 1-4, just has a 5th gear hanging out in a little doghouse on the tail instead of an OD unit. Same design with third gear being in the middle of the output shaft, furthest from the bearings on either end, getting pushed apart from the layshaft by engine torque.
 
I think the most important factors are how worn out it is (deflection of the main shaft or whatever, particularly for third) and how gentle you are. I've ran as much as 26psi through my current m46, which I'd wager is at least close to 300 crank. I just put a new sachs turbo clutch in it since I smoked the last one after about 20k miles.
 
Most M46s have a steel case, right? That would be stronger against deflection maybe than the aluminum cased M47?
 
Even if the iron case one is stronger, I imagine it would be by a negligible amount. I have an alu m46 waiting for when my current one lets go. If that one blows up too I'll probably automatic swap or something.
 
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