This is The Bomb ... with Turbo!

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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chevy43
Posts: 4
Joined: 7 years ago
Location: Cent. Cal.

#136

Post by chevy43 » 7 years ago

I haven't studied the throttle body very much yet. I've just owned my 720 for a couple of weeks.

But from what I know it isn't much of a restriction. There is a vaccum amplifier that works the fuel pump. I think there is a very slight vaccum from the throttle body that operates the diaphram in the pump via the amplifier. I think the engine see's very little vaccum. That's why there is a vaccum pump on the alternator.

The 720 diesel performs pretty well all considered.

It is too bad the pistons are prone to cracking because I'm sure you could have some fun with turbocharging and intercooling.

I got lots of power out of a SD33T with turbo mods and intercooling - but I don't consider it nearly as reliable as the mighty Cummins 3.9 or 5.9.

I replaced the SD33T in my scout with a 5.9 Cummins and it has more power than is safe.

Now I'm back to driving a slow reliable fuel efficient 30+ year old stock truck.......

The 25mpg I get in my Scout just isn't good enough anymore.
82 720 Diesel

Dale
Posts: 19
Joined: 7 years ago

#137

Post by Dale » 7 years ago

Only 35mpg hwy? I dont know what mine got hwy, but in town I had no problem getting 45mpg, and that was with the (previous owner set up) IP well into the "huge clouds of black smoke" territory and a lead foot.

Compared to a gas engine, it's true the sd22 produces little vacuum, not near enough for power brakes. But the TB is still causing SOME vacuum, and I just feel like a diesel shouldnt have a throttle!

Anyone here volunteer to measure their manifold vacuum under actual load conditions? I'd do it, if my 720 had a working transmission in it... :)

If that throttle blade is even partially closed at part load, it's a restriction, and combustion would proceed more efficiently with more air I would think. Others on this forum have claimed decreases in EGT by removing the TB.

Personally, I find the way the engine responds to the pedal to be annoying. It's almost like driving with a speed governor, if you push the pedal 1/3 of the way down, the engine blasts off at full fuel until it hits roughly 1/3 max rpm, then it slams into a wall. Driving without a smoke screen involves gradually pushing the pedal further as it accelerates, and it's impossible to do at night when you cant look for the smoke screen in the mirror! I just want a torque demand pedal dangit! My 83 chevette diesel doesnt use a throttle or crazy vacuum diaphragm system, and it drives just like a gas car (except VERY frikken slow.... 0-60 over 25 seconds...)

chevy43
Posts: 4
Joined: 7 years ago
Location: Cent. Cal.

#138

Post by chevy43 » 7 years ago

Are you talking imperial gallons?

EPA estimate was 33 town 39 hwy and that would have been at a steady 55mph so I thought I was doing well at over 60 mph and some load getting 35mpg.
82 720 Diesel

Dale
Posts: 19
Joined: 7 years ago

#139

Post by Dale » 7 years ago

I only got a couple tanks in, so i could be wrong. It was easy to coast alot so that may have helped.

Nissan_Ranger
Posts: 264
Joined: 13 years ago
Location: Canada

#140

Post by Nissan_Ranger » 7 years ago

Probably imperial. I get 40 - 45 imperial with mine.

N_R
The old 'six gun' was as popular as the cell phone in its time and just as annoying when it went off in the Theater.

Dale
Posts: 19
Joined: 7 years ago

#141

Post by Dale » 7 years ago

Sorry yes, imperial. To be fair, I was utilizing some mild hypermiling techniques, namely pulse and glide (coasting), to boost my mileage. Speeds were 30-50mph. But i wasnt too kind to it when I was accelerating, other than keeping revs fairly low. Was mostly night driving, couldnt see the smokometer.

elboss
Posts: 59
Joined: 8 years ago
Location: Portugal

#142

Post by elboss » 7 years ago

Sd22 with turbo and Power?! with inline pump? is here :D

See the +2Bar boost!

http://youtu.be/1uT5UFzC1bc

Dale
Posts: 19
Joined: 7 years ago

#143

Post by Dale » 7 years ago

Nice! Went with the TB post-turbo I see?

elboss
Posts: 59
Joined: 8 years ago
Location: Portugal

#144

Post by elboss » 7 years ago

I dont understand what you say, please say with another words :(

specs http://nissandiesel.dyndns.org/viewtopic.php?t=2968

Dale
Posts: 19
Joined: 7 years ago

#145

Post by Dale » 7 years ago

Nevermind, I see what you did there.

How're your pistons holding up? :P

elboss
Posts: 59
Joined: 8 years ago
Location: Portugal

#146

Post by elboss » 7 years ago

Holding well.... until now :lol: :lol:
Let see in this weekend 8)

Dale
Posts: 19
Joined: 7 years ago

#147

Post by Dale » 7 years ago

How'd it hold up? 8)

elboss
Posts: 59
Joined: 8 years ago
Location: Portugal

#148

Post by elboss » 7 years ago

the headgasket blowout again... Image


Now i buy a custom made reforced head gasket, with 2.20mm... :D

Nissan_Ranger
Posts: 264
Joined: 13 years ago
Location: Canada

#149

Post by Nissan_Ranger » 7 years ago

I hate to say it, but the results are consistent with others I've seen when these engines are pushed hard...
The old 'six gun' was as popular as the cell phone in its time and just as annoying when it went off in the Theater.

elboss
Posts: 59
Joined: 8 years ago
Location: Portugal

#150

Post by elboss » 7 years ago

I buy a reforced headgasket, i can show you... have 2.20mm

http://sphotos-e.ak.fbcdn.net/hphotos-a ... 2219_n.jpg

And in this sunday, 4NOV, the truck rooled all day, with no problems, just 3 laps and stop to put some water in radiator's, a go again... the temp, arround 90º/110º, with 2 bar boost...

You can see it in this movies:


http://youtu.be/kfEchaVm704

http://youtu.be/8SfaHaDGB7M

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