Just a thought about the Stroker...

Discuss (and cuss) the Nissan LD-series OHC Six diesel engine, popularly available in the US in 1981-83 Datsun/Nissan Maxima Sedans & Wagons.

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Kolatogari
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Joined: 13 years ago
Location: Iceland

Just a thought about the Stroker...

#1

Post by Kolatogari » 10 years ago

Hy there. I was wondering. I'm seeing alot of people using the LD28 block and crankshaft. Is there any reason why you couldn't make a Diesel stroker? usins the piston rods from the L28 mabye? any thoughts?

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240ZD
Posts: 103
Joined: 13 years ago
Location: Longview, WA

#2

Post by 240ZD » 10 years ago

I'm not sure, but I think in auto shop class a decade ago I heard that what makes an engine a "stroker" is when the piston stroke is longer than the piston diameter. So using a gas crank would de-stroke the diesel engine.

As a reformed gas engine user, these compression-ignition engines are so crazy to me. I'm under the impression that one can't even use a thicker headgasket or some such thing to lower the compression to, say, 18:1. A lot of the turbo people want to lower the compression so they can run higher boost, but apparently diesels like the LD28 will pretty much not run at all, let alone well if you mess with the precision of the compression, where the piston gets SO CLOSE to the head. At least, that seems to be the word on the street: don't screw with it!~

On the other hand, is the LD28 already a "stroker?"
"Man, your engine is knocking really bad..."~

Kolatogari
Posts: 30
Joined: 13 years ago
Location: Iceland

#3

Post by Kolatogari » 10 years ago

hmm ok. But is there good to mess around with the head for greather flow? Where could I get a Camshaft for turbo?

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240ZD
Posts: 103
Joined: 13 years ago
Location: Longview, WA

#4

Post by 240ZD » 10 years ago

I've heard that you can "pocket port" the head, where the machinist expands the area where the exhaust exits the valve, basically giving the hot exhaust discharge a bigger expansion chamber. I don't know if anyone has done this to an LD28 yet, but I bet the results would be good.

My diesel expert friend said that, according to his research and experience, there isn't really a good reason that diesel cam profiles are so crappy. There is of course an extremely tight space between the valves and the pistons at TDC, so you'd have to be very wary of the two clashing. It seems that a lot of the things that limit an IDI diesel's power - like shallow cams - have something to do with mass consumption tastes, and trying to make diesel engines palatable for drivers used to gasoline engines, both in emissions and in temperament.

Anyway, I was told that the cam on the LD28 already has a very high lift compared to similar engines. A regular 280zx cam, maybe even a turbo one, might fit right into my LD28, and that it would be like having a hot cam in a gas car. It might not be uh, very streetable, but maybe it would be insanely badass. This is all assuming that everything lines up perfectly with the lash pads, etc. I looked at the cams of the diesel and the gas L6 engines, and to the naked eye there is not much of a difference in the actual grind, except for one thing: the duration drops off very abruptly (on the exhaust) so that the valve quickly closes as the piston approaches the head, I assume to prevent a catastrophic collision.
"Man, your engine is knocking really bad..."~

Kolatogari
Posts: 30
Joined: 13 years ago
Location: Iceland

#5

Post by Kolatogari » 10 years ago

OK, thanks for the information. I'll mabye give a local workshop a call, and check for the prise to work on the head. I was going to overhaul it anyway..

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