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Lightened crank


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Had a go at reducing the weight of the crank along with knife edging it.

Didn't go wild. Started with 40.5lb and finished with 37.5lb

 

45deg chamfer on the outer edge of the counterweights.

http://users.tpg.com.au/blackmas/SG/CRANK/Knife-edge-01.jpg

 

Rounded the leading edge and chamfered the trailing edge of the counterweights.

http://users.tpg.com.au/blackmas/SG/CRANK/Knife-edge-02.jpg

 

 

Evened up all the counterweights so they are now all the same size and shape and thinned down the side of the web between the mains and bigends.

http://users.tpg.com.au/blackmas/SG/CRANK/Knife-edge-03.jpg

 

 

Evened up the thickness on the outer web of the of the bigends.

http://users.tpg.com.au/blackmas/SG/CRANK/Knife-edge-04.jpg

 

It will be interesting to see how it balances up.

 

Cheers.

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I feel like balancing that might be an issue.
I don't expect it to be a problem. I've tried not to remove too much weight, more like getting everything even.

Some of the counterweights were up to 0.710" longer than the others. The thin webbing on the bigend varied by 0.157".

I have also started to lightened the conrods (from 29.3ounces to 27.2ounces) and still have a bit more I can take off.

The majority of that weight was from the balance pads on the bigend cap and pin end.

Again, not trying to make a super light rod, just trimming the fat.

Hoping all this work should make balancing it a bit easier.

 

Same as getting the crank knife edge
Close, a knife edged crank typically don't have a 45deg chamfer on the bottom of the counterweights, just a rounded leading edge and a chamfered trailing edge.

 

Nice, keep us posted on the progress
Thanks, I will.

 

Cheers.

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  • 2 weeks later...

The crank balanced up fine. Could have gone a bit lighter on the bigends but I'll leave that for the next one.

 

Also had a go at porting and generally cleaning up the M7 magna head.

 

BEFORE

http://users.tpg.com.au/blackmas/SG/Head/chamber-00.jpg

 

 

AFTER

http://users.tpg.com.au/blackmas/SG/Head/chamber-01.jpg

 

 

 

Removed all sharp edges, de-shrouded and blended around the valve seats and sparkplug, this should help reduce detonation due to hot-spots.

 

Putting in 2mm oversize titanium valves with 7mm stems on the exhaust and 6mm on the inlets.

 

Copper-Beryllium valve seats on the exhaust (to be put in) and just a larger standard inlet valve seat.

 

The chambers also have to be cc'd but that will be done after the valves are installed.

 

Blended/smoothed the port castings as well as reduce the webbing around the valve guides.

 

New bronze valve guides to be installed after the inlets are nickel-Teflon coated and the exhaust guides are nickel-boron coated.

 

Good heat transfer (you need it when using titanium valves) and great wearing properties.

 

This is for a high compression normally aspirated engine, somewhere between 12.5:1 and 16:1, depending on how much chamfering the Wiseco pistons will handle.

 

 

Cheers.

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  • 2 weeks later...

Just doing some more research and it seems that the diesel 4D56 crank may be a good compromise rather than chamfering the pistons too much.

 

The 4D56 crank has the same size big ends and mains, they run the same size pistons 3.587" (91.1mm)but have a 3.740"(95mm) stroke.

 

Grabbing one on Monday to make sure every thing else lines up.

 

If it fits, it would be a good option instead of using a 0.060" (1.5mm) de-compression plate or double head gaskets, especially on a turbo engine.

 

 

Cheers.

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  • 2 weeks later...
The 4D56 crank has the same size big ends and mains...
Well I was wrong on this count. The big ends are the same but the mains are 2.598" (66mm), so I had them ground down to the standard 2.362" (60mm).

 

http://users.tpg.com.au/blackmas/SG/Hi-Comp_Engine/4D56.jpg

I'll have to knife edge and lighten it a bit before it is balanced but it shouldn't take me too long now.

Expect a few more pics.

 

Apart from the mains being larger, the keyway for the timing chain cog is also a bit further away from the first mains but not enough to worry about.

 

 

Also got hold of a Trochoid style oil pump off a 4G54 forklift.

http://users.tpg.com.au/blackmas/SG/Hi-Comp_Engine/OIL_PUMP.jpg

These spin at 71% of the engine speed (instead of double the engine speed) and have a much higher flow compared to the standard style oil pumps.

You have to remove the silent shafts and buy the proper cog set to use this pump.

 

 

Cheers.

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Also got hold of a Trochoid style oil pump off a 4G54 forklift.

http://users.tpg.com.au/blackmas/SG/Hi-Comp_Engine/OIL_PUMP.jpg

These spin at 71% of the engine speed (instead of double the engine speed) and have a much higher flow compared to the standard style oil pumps.

You have to remove the silent shafts and buy the proper cog set to use this pump.

 

 

Cheers.

is compared to an N/A oil pump? because our pumps flow more than the N/A ones.

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is compared to an N/A oil pump? because our pumps flow more than the N/A ones.

We actually have 2 different standard oil pumps for the N/A 2.6L engines.

http://users.tpg.com.au/backman/SG/OPG.jpg

The one on the right was in the earlier (pre-1992) engines. The one on the left was used in the TS Magna engines.

They flow 30% more than the earlier ones.

The Trochoid style oil pump are supposed to flow even more than the TS Magna oil pumps.

I'll trying to get exact specs on all the pumps.

 

Cheers.

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  • 4 months later...

I am interested in what the driving impression is with the lightweight crank

 

 

When I got mine, it was a clear difference of how the engine revved up. It was a pain to find a clutch that would hold the torque. Had to change it twice. Even now, if I nail it anywhere below 2500 rpm, it feels like the car is ready to take flight.

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  • 3 weeks later...
  • 8 months later...

It has been a while but I decided to remove a bit more weight from my knife edged crank.

 

Just as a comparison..

 

STANDARD CRANK

http://users.tpg.com.au/ntome44/SG/Hi-Comp_Engine/STD_crank_01.jpg

 

 

MK-1

http://users.tpg.com.au/ntome44/SG/Hi-Comp_Engine/Knife_crank_01.jpg

 

 

MK-2 (Work in progress)

http://users.tpg.com.au/blackmas/SG/CRANK/Crank-on-mill.jpg

Had to cut a V-Block into 3 pieces to better support the crank. I also used old bearing shells so I didn't damage the crank.

 

http://users.tpg.com.au/blackmas/SG/CRANK/Crank-mod-002.JPG

 

 

The finished product, just before leaving to be balanced.

 

http://users.tpg.com.au/blackmas/SG/CRANK/Crank-Almost.JPG

 

Work done so far..

1. Reduced the diameter of the counterweights so they are the same diameter as the bigend.

2. All the counterweights are now the same thickness.

3. Machined the edges to make the shape uniform.

4. Knife edged.

 

Work to do.

1. Nickel plate the journals

2. Shot peen.

3. Install and have some fun

 

Cheers.

Edited by superscan811
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Why the nickel plating of the journals? Must have machined off the hardening I'm guessing?
I'm nickel plating the journals for 3 reasons.

 

1. To build them back up as they are on the bottom end of standard.

2. The nickel coat can be harder than hard-chrome, if heat treated correctly.

3. Nickel is less prone to galling (ie: it's slipprier) than the standard cranks, and even nitrided cranks.

 

Looking great Superscan!
Thanks, a lot of time has been put into getting this crank to the stage it is currently.

 

 

Cheers.

Edited by superscan811
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So how'd it balance out? That's a lot of metal to take off the CW's. Are you running aluminum rods? I'm surprised you didn't try to lighten the rod throws much, I would think it would need help to even out all the metal taken off the CW's.
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