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Midnitz

Maximum stroke to the L28 block?

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I have the N42 block and was wondering about maxiumum stroke we could use on the existing castings....

 

I may provide dims from the LD28 crank I found and have Crower cut me one out of 4340 alloy....Since I can control the stroke dimension and the rod length as well as piston compression heights....what do you guys think I can get away with in terms of maximum displacement?

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I was going to say somewhere in the 85-86 area if you are bent on using stock rod journal diameter...

 

If you go with smaller diameter journals, then offsetting the pins even more on the 85mm crank can be done. It's really a matter of rod clearance. It's not like you have to cut your cam face lobes and clearance the base diameter of the camshaft to clear the counterweights...

 

I think 87 or 88 may be possible on that same crankshaft from Kameari if you offset the pins 2mm and use a rod diameter correspondingly smaller. Welding on cheeks to existing rods to keep oil throwoff is not a biggie, they do it in Japan all the time.

 

Actually, for $5K that's not too bad a deal!

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You trying to build a tractor?

 

Ugh, where did that uninformed comment burble out from? Yeah, a tractor like the Honda S2000 Engine (take a look at it's specifications before making such ill-informed commentary!)

 

STROKE has an impact on TORQUE and that's about it. If you think it somehow limits an engine's ability to rev you are sadly misinformed! :angry:

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Ugh, where did that uninformed comment burble out from? Yeah, a tractor like the Honda S2000 Engine (take a look at it's specifications before making such ill-informed commentary!)

 

STROKE has an impact on TORQUE and that's about it. If you think it somehow limits an engine's ability to rev you are sadly misinformed! :angry:

 

 

What not implying that it could not rev. It was just my way of expressing my opinion, which is that $ per hp I just dont see the advantage. Just my opinion.

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STROKE has an impact on TORQUE and that's about it. If you think it somehow limits an engine's ability to rev you are sadly misinformed! :angry:

 

Within piston speed limits you're correct. The highest piston speed I'm aware of is 38 m/s for a mid-90s Japanese CART engine that would run for two hours between 9,800 and 10,000 rpm. I'm sure there are higher numbers but that's the only number I'm aware of from direct discussion with the engine builder. Some of the CART privateers were rumored to be in the 48 m/s range (supposed 94mm stroke at 9,800 rpm).

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I'm thinking one can get bigger than the 85mm stroke easily...Look at the LD28 block; see how the webs and the bottoms of the cylinders are clearanced for the rods? I think that a set of first-gen 4GXX rods would work; they are a 45mm bearing diameter and are slightly wider than the L-series, so the big ends would have to be narrowed; rather than widened.

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The closer to 2:1 the better - look at that Honda engine you cited.

 

Seeing as how inertia goes up geometrically/logarithmically with speed, side loads can get out of hand.

 

You might want to make a spacer plate and mill the crank pedestals. Or look at using the Diesel block.

 

Other advantages to longer rods are better detonation resistance.

 

You haven't said if this is to be an NA engine or Turbo.

 

If turbo, just buy better parts and turn the boost up - it'll be cheaper than offset grinding and going for max stroke.

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The car will be turbo charged. I like the idea of leaving the main diamters stock, the current size gives the crank strength and shrinking the size compromises that strength.

 

Money is not an issue....All I have to do is talk to crower with a stroke size.

 

I'll have to mock something up....pics to follow.

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Found this......

OS Giken L-series stroker kit $14,500

 

This complete stroker kit to suit Nissan L26 and L28 engines gives 7mm longer stroke, so if it is used with 89mm pistons, engine displacement becomes 3208.4cc (87mm, 87.5mm, 88mm, 88.5mm, 89mm, 89.3mm, and 89.5mm pistons can be chosen for the same kit price)

 

CRANKSHAFT

Material: Chrome-molybdenum

Full Counter-balanced design suitable for up to 10,000rpm

Stroke OS 86mm (Nissan OEM 79mm)

Pin Width OS 21.7mm (Nissan OEM 27mm)

Pin Diameter OS 48mm (Nissan OEM 50mm) Use RB26 conrod bearings and 1 piece key (key included in kit)

 

PISTONS

Material: Forged Aluminum

Pin Height OS 29.4mm (Nissan OEM 38.1mm)

Pin Diameter OS 20mm (Nissan OEM 21mm)

Pin Length 61mm (Specify piston diameter, valve recess shape, pin height etc when ordering).

 

CONRODS

Chrome-molybdenum and Forged (Main body parts and caps are forged separately.)

PCD OS 135.5mm (Nissan OEM 130.4mm)

Big End Width OS 21.5mm (Nissan OEM 26.8mm)

Big End Diameter OS 48mm (Nissan OEM 50mm)

Small End Diameter OS 20mm (Nissan OEM 21mm)

 

....if money is no issue.......half ya luck mate!

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