Dale's 81 720 na-sd22

SD diesels were widely available in the US in the 1981-86 Datsun/Nissan 720 pickups, and in Canada through '87 in the D21 pickup.

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Dale
Posts: 19
Joined: 11 years ago

Dale's 81 720 na-sd22

#1

Post by Dale »

Pulled the exhaust manifold to replace broken studs and stop that nasty exhaust leak. Intake manifold is full of nasty gunk! Thick burnt greasey coating in all 4 runners that stops short of climbing up to the TB. I'm guessing, since I have no EGR or any other path for it to get there, that it came out of my intake valve seals?


While it's off, getting it tapped for a EGT, and the intake tapped for a REAL *manifold* vacuum line so we can see how much damage the throttle blades do to actual engine air intake (not the vacuum amplified signal coming off the throttle body)

I'm also working on a clamp on injector line 'pressure' sensor to estimate realtime fuel flow and timing, and an amplifier that reads the glowplugs as temp/press sensors to see what's actually going on in the engine in real time. In theory, the clamp sensor should be able to see when the injector fires and shuts down, getting timing and duration, and reading the individual plug resistances should show onset of combustion (roughly) and combustion combined temperature and pressure curves. I'll be using an oscilliscope at first, may adapt through a laptop later to do recordings of multiple sensors simultaneously.

Anyone want to 'loan' me a turbo setup to really play with? ;)
Dale
Posts: 19
Joined: 11 years ago

#2

Post by Dale »

Got some results with the vac and egt...

Vac never goes over 2" even at redline and part load. You have to be nearly off the throttle to build any manifold vacuum at all, and idle is only a bouncing 1-2". The only time it builds vacuum is when engine braking, which is usually around 5", a bit more near redline.

EGT reads around 300-400C cruising around 55-60 on the flats, highest I saw was 650C near the end of a WOT acceleration to redline through 4th gear. No smoke visible in mirrors except maybe a lil white near the top end, hard to see for sure. It is puffing a lil at idle when cold, hoping that's due to the old fuel I'm burning off.
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