Author Topic: M47 crank + custom pistons, rods, etc. (Read 51206 times)

Febi Guibo · « **Reply #45 on:** May 06, 2006, 10:51:08 PM »

I will have final specs on the pistons shortly;

forged, custom from wiseco, and, um, they cost a lot... ugh!

The engine will be installed, hopefully around this time next week... so everybody cross your fingers...

thumper3ld · « **Reply #46 on:** May 07, 2006, 12:35:09 AM »

Quote from: Febi Guibo

On my end, I've been gathering up all the other various parts... stuff that I can deal with when the motor is out... the starter, power steering pump, belts, plug wires, coils, etc. My coolant and vacuum lines are pretty new and I did the alternator in january...

I'll try to post some more pics shortly...

Power steering pump?

Dont be a wuss, eliminate that ishh.

shellback · « **Reply #47 on:** May 07, 2006, 09:32:29 PM »

Quote from: Febi Guibo

I will have final specs on the pistons shortly;

forged, custom from wiseco, and, um, they cost a lot... ugh!

I thought S50 pistons were being used:confused:
Can they be used?

Chris

Febi Guibo · « **Reply #48 on:** May 07, 2006, 10:51:31 PM »

s50 pistons can be used, but the overbore is 'only' around 86mm...

more deets soon!

thumper3ld · « **Reply #49 on:** May 07, 2006, 10:56:25 PM »

Quote from: Febi Guibo

s50 pistons can be used, but the overbore is 'only' around 86mm...

more deets soon!

Off Topic,

I'm assuming since u were able to post this u and dennis got home ok.

dude8383 · « **Reply #50 on:** May 08, 2006, 10:25:28 AM »

lol you doubted our ability?!

thumper3ld · « **Reply #51 on:** May 08, 2006, 10:47:51 AM »

Quote from: dude8383

lol you doubted our ability?!

Lol, nah I doubt jonas' ability to read the correct torque specs from the manual and superman's ability to sheer off shock bolts in a single twist.

Febi Guibo · « **Reply #52 on:** May 08, 2006, 10:54:44 AM »

...hey, I've been working out, what can I say... I tore up the swaybar mount bolt too... I'm a monstrrrrrrrgh!

dude8383 · « **Reply #53 on:** May 10, 2006, 11:28:24 AM »

jay next time you'll be reading the torque specs, and doing the torquing!

thumper3ld · « **Reply #54 on:** May 10, 2006, 12:06:55 PM »

Quote from: dude8383

jay next time you'll be reading the torque specs, and doing the torquing!

Lol, I'll over torque on purpose. Febi is not the only one that can sheer off a nut.

Zoso · « **Reply #55 on:** May 10, 2006, 01:36:54 PM »

Quote from: thumper3ld

Febi is not the only one that can sheer off a nut.

Is that the same as busting a nut? SICK!

dude8383 · « **Reply #56 on:** May 10, 2006, 03:13:39 PM »

Quote from: Zoso

Is that the same as busting a nut? SICK!

haha good call!

mrjezza · « **Reply #57 on:** June 05, 2006, 10:12:40 AM »

Sorry to semi-hijack...

I'm now super eager to do a stroker kit myself, but I think im going to keep stock pistons so I don't have to bore and do a budget stroke.

The m47 crank is 88mm stroke and that with the 84mm bore = 1950cc.

m42 crank is 81mm stroke. I'm guessing that a simple crank swap would push the stock pistons too far up and make compression too high?

Would the answer be to get conrods that are 3.5mm shorter (7mm extra stroke /2)? This would place the piston back in the same place at TDC and 7mm lower at BDC right? Thus the stock compression ratio (10.5:1 or 10:1) is maintained?

What would I need to do to increase compression ratio to by 0.5:1?

sheepdog · « **Reply #58 on:** June 05, 2006, 12:10:14 PM »

Quote from: mrjezza

Sorry to semi-hijack...

I'm now super eager to do a stroker kit myself, but I think im going to keep stock pistons so I don't have to bore and do a budget stroke.

The m47 crank is 88mm stroke and that with the 84mm bore = 1950cc.

m42 crank is 81mm stroke. I'm guessing that a simple crank swap would push the stock pistons too far up and make compression too high?

Would the answer be to get conrods that are 3.5mm shorter (7mm extra stroke /2)? This would place the piston back in the same place at TDC and 7mm lower at BDC right? Thus the stock compression ratio (10.5:1 or 10:1) is maintained?

What would I need to do to increase compression ratio to by 0.5:1?

You are asking for SERIOUS trouble doing this.
You will have to bore and hone the block, the reason is you increased the stroke, at the bottom and top of the cylinder wall will be a ledge that your rings will catch on. You will not be able to stroke it without doing basically a complete rebuild.

tim_s · « **Reply #59 on:** June 05, 2006, 03:34:47 PM »

Quote from: sheepdog

You are asking for SERIOUS trouble doing this.
You will have to bore and hone the block, the reason is you increased the stroke, at the bottom and top of the cylinder wall will be a ledge that your rings will catch on. You will not be able to stroke it without doing basically a complete rebuild.

i agree. however depending on how many miles you've done you might get away with a re-hone and some new rings. my bores were in surprisingly good condition for a 100k+ mile engine, you could still see the honing marks. the engine i used to make the 2.1 however was too far gone for that.
anyway to me its a bit redundant as imo this wouldnt be the best way to get some bigger capacity on a budget. just throw some massively oversized high CR lightweight pistons in there with the standard crank, put in a lightened flywheel, rebuild the rest of the block and you'd be away. would be much more in character with the m42's revvy nature, you dont want to make it that much of a long stroke imo, and buying a crank, modding it, getting new rods etc is more work than just an overbore. just my $0.02