Well after much deliberation of what direction I wanted to take with my E30M50, I've decided to build a stroker motor for it. Mostly for the experience since I have machining experience, but have not built any motors. I have plenty of measuring devices at my disposal (dial indicators, bore gauges, v-blocks, etc.) so that will aid me, but I'll still end up taking quite a few parts to an automotive machine shop.
I've had an M52TU Crank and M50TU longblock for about 9 months, but have been indecisive on what specs to build it too. Yesterday, I picked up an S52 bare block and matching pistons w/ about 120K from a local member, as I wanted to run 86.4mm bore pistons instead of the 84mm ones found in an M50TU.
My plan is to build an M5X/S5X variant utlizing BMW pistons, connecting rods and crankshaft.
Crank- M52TU - 84mm stroke
Pistons - S52US - 85.365mm bore
Connecting Rods - 140mm length
With this combination of bottom end parts, I will end up with a slightly oversqaure engine, with a better rod ratio than an M52, S50 or S52, while still having nearly 3 liters of displacement. Haven't calculated the compression ratio, but it is likely going to be around 10.5-11:1 due to the decreased stroke of the M52 crank, but with the wrist pin being moved upwards 5mm due to the 140mm rods.
The block will be hot tanked, magnafluxed and given a clean up hone. The rods will be shot peened and balanced along with the pistons. I will have the crank cleaned, magnafluxed and polished as well, but will not have it knife edged since this will likely just be a street/track car.
I will dulve into the cylinder head details at a later point, but I am thinking it will be a rebuilt M50TU with stiffer valve springs, a mild port/polish, and either S50 or sunbelt sport cams, depending on the $$ I have left.
I'll also have a spare M50TU block and may build spare stroker M50TU short block. That would utilize an M52 crank, 135mm rods and 84mm bore M50TU pistons and give a 11.25:1 compression ratio, but I'll start another thread if I decided to build that.
Pictures will be forthcoming when I have the time and get the M10 block off my stand. Comments, criticisms, and/or feedback is welcome.
-Ben
I've had an M52TU Crank and M50TU longblock for about 9 months, but have been indecisive on what specs to build it too. Yesterday, I picked up an S52 bare block and matching pistons w/ about 120K from a local member, as I wanted to run 86.4mm bore pistons instead of the 84mm ones found in an M50TU.
My plan is to build an M5X/S5X variant utlizing BMW pistons, connecting rods and crankshaft.
Crank- M52TU - 84mm stroke
Pistons - S52US - 85.365mm bore
Connecting Rods - 140mm length
With this combination of bottom end parts, I will end up with a slightly oversqaure engine, with a better rod ratio than an M52, S50 or S52, while still having nearly 3 liters of displacement. Haven't calculated the compression ratio, but it is likely going to be around 10.5-11:1 due to the decreased stroke of the M52 crank, but with the wrist pin being moved upwards 5mm due to the 140mm rods.
The block will be hot tanked, magnafluxed and given a clean up hone. The rods will be shot peened and balanced along with the pistons. I will have the crank cleaned, magnafluxed and polished as well, but will not have it knife edged since this will likely just be a street/track car.
I will dulve into the cylinder head details at a later point, but I am thinking it will be a rebuilt M50TU with stiffer valve springs, a mild port/polish, and either S50 or sunbelt sport cams, depending on the $$ I have left.
I'll also have a spare M50TU block and may build spare stroker M50TU short block. That would utilize an M52 crank, 135mm rods and 84mm bore M50TU pistons and give a 11.25:1 compression ratio, but I'll start another thread if I decided to build that.
Pictures will be forthcoming when I have the time and get the M10 block off my stand. Comments, criticisms, and/or feedback is welcome.
-Ben
Comment