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Mercedes Benz M104 engine for the 240Z


MAG58

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What's the stroke on the 3.2 crank? Is it as heavily built as the diesel?

 

 

Yes, it's equally overbuilt, also equally forged, induction hardened at the journals and micro polished. I believe it's about an 84mm stroke. So about 8mm less.

 

Edit: With the 320 crank, the 280 rods, and 90mm K24 pistons, I will have a calculated CR of 8.8:1 (give or take .2), a 1.78 Rod/stroke ratio, and 3206cc's of displacement. I could spin the motor 8928rpms without hitting the 25m/s mean piston speed.

 

May just stash the crank away for a heavier car that needs some stroke to motivate it ;)

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Yes, it's equally overbuilt, also equally forged, induction hardened at the journals and micro polished. I believe it's about an 84mm stroke. So about 8mm less.

 

Edit: With the 320 crank, the 280 rods, and 90mm K24 pistons, I will have a calculated CR of 8.8:1 (give or take .2), a 1.78 Rod/stroke ratio, and 3206cc's of displacement. I could spin the motor 8928rpms without hitting the 25m/s mean piston speed.

 

May just stash the crank away for a heavier car that needs some stroke to motivate it ;)

You say "280 rod.." is that 280Z or MB 280??

 

Going on a rough swag here.. the stroke difference is about 8 mm, if you mean to say that the short stroke, L28 rod, KA24 piston combo will do you OK for piston height, then maybe the stroker crank, an L24 rod (133mm) and a VG30 piston (pin height about 31.75mm) put you near the same height for the reciprocating assemblies.

 

According to this utility http://www.ozdat.com/ozdatonline/enginedesign/ there is a "JUN VG30DETT" piston that checks in at 89mm diameter.

 

 

 

Stro-Ker! Stro-Ker! Stro-Ker!

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Mag58;

 

I noticed the "hammer in hand". Is that a Mercedes tool of some sort?

 

Heh, if it was a Mercedes Special Tool, it wouldn't be carried in hand, it would be placed in a highly guarded padded vault with temperature and humidity control as it MOST LIKELY cost more than the house it calls home.

 

That's my father with his favorite ball-joint extraction tool.

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No. The Mercedes Benz 280 Rods. They're 150mm (5.906in) long and a Honda K24 90mm overbore pistons with a compression height of 1.14in.

 

I may still stroke it, it all depends on the cost of each motor.

 

okay, sooo... block height? rod big end bore/wrist pin bore/crank journal thickness? We can only Help Hybridize if you give us specs :)

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Deck Height: 219.675mm

 

Origional CR (280CE) 33.275mm

Wrist Pin Dia: 22mm

Crank Journal Diameter: 48mm (same as 4G63, a bunch of hawn-ders, etc.)

Crank Journal Width (320&280): 24mm

Crank Journal Width (350SDL): 28mm

* Rod Width at wrist pin same as crank journal width

 

Connecting Rod Length:

280 M104: 149mm

320 M104: 144mm

 

Strokes:

280: 73.4mm

320: 84mm

350SDL: 92.4mm

 

I think that's all right...

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SR20, VG30 and VQ series apparently share the 22mm wrist pin, but nissan motors apparently seem to use crank diameters of 51 or 53 mm. I'm basing these conclusions TOTALLY on the info provided at the ozdat calculator I linked to earlier in this thread.

 

Incidentally, I missed the 22mm wrist pin on the VG earlier when I had suggested it be paired with an L24 rod; L-series use 21mm wrist pins.

 

There seems to be a VG30DETT piston at 31.75mm pin height and 89mm bore. If you can find a rod that is just a hair under 141mm long you get to zero deck height with the 94mm stroke crank. (assuming this head has a ~42cc combustion chamber and flat-top piston, this produces 3.5 liters at THIRTEEN TO ONE COMPRESSION!!!! HOOOOHOOOOO!!!)

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  • 1 month later...

That would make for a R/S ratio substantially less than 1.5 which is already too short. Would make piston selection easy though piston accelerations would be through the roof and dwell at TDC and BDC would be nonexistent.

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Yep. Mercedes CLK series 6 speed manual, 16v flywheel and spec clutch.

 

The 6 speed is a nice, tight Getrag unit that, iirc, is used in many a bimmer as well.

 

Though I'm quite sure I'm going back to the 3.2 displacement. Stock motor at 18psi netted 499rwhp @6500. That's without major computer tuning, basically a 'rough' tune which is plenty of go to hospitalize me sufficiently quickly.

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  • 2 weeks later...
NEED UPDATES! haha this thread is like crack, you just keep coming back! Love the swap and now i am thinking about maybe going down this route in the future.

I don't think he has any updates. Last word I got was he's (and I, for that matter) were looking for someone that'll do wild enough cams.

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