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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Zarghareth
Posts: 19
Joined: 8 years ago
Location: Sisters, OR

#166

Post by Zarghareth » 7 years ago

Finally found the thread on posting pics!
Image

If you want to see more, let me know or check out the post I made in user rigs.

waynosworld
Posts: 517
Joined: 7 years ago
Location: Vancouver Washington USA

#167

Post by waynosworld » 7 years ago

Zarghareth wrote:So I was just looking through the later parts of the tread more carefully and I hadn't realized there was so much confusion about the fuel regulation system before my previous post. I believe I can give a good explanation of how the stock governor works and how to set it up to make it work with a turbo.

NOTE: I am referring to the BOSCH KIKI pump.
Basically, the way the joint diaphragm-mechanical governor on the SD22 in the 720 is: if you open the throttle, more air is allowed to bypass the venturi generator located in the throttle body, thus decreasing the vacuum being applied to the diaphragm on the IP and subsequently increasing the amount of fuel delivered to the engine. Because of this, it is essential that the hose from the TB go to the correct side of the diaphragm. The mechanical governor just keeps RPM stable.
The reason why this system is set up using vacuum and diaphragm mechanism is very important. It dampens the movement of the regulating mechanism inside of the pump which is very sensitive and must exist constantly in a dynamic state. This is achieved by the diaphragm's inherent elastic properties and the "loose" actuation of it by the vacuum supplied from the throttle body. "Loose" meaning not capable of overly violent changes or holding 100% static.

With all of this in mind one can see how important it is to set up the throttle body and associated plumbing correctly. The main reason for leaving the TB in its stock position is that it measures the velocity of air moving through the engine and therefore, indirectly, volume not pressure. With the installation of a turbo, the velocity of air moving into the engine is much greater and thereby the vacuum being applied to the regulatory diaphragm is much greater, that is if you install the TB pre-turbo. With the TB post turbo, the pressure of the air in the intake system negates this increase in vacuum while still producing the low vacuum required by the IP control mechanism. In addition, it detracts greatly from turbo spool rates to have such a significant restriction before the turbo.

If you simply leave the throttle body in its stock position with the hose from the throttle body connecting to the rearmost hose barb on the IP and the forward hose barb on the IP open to atmosphere, It should work great. At least it has for me.

If you actually read all of that I really hope that it helps!

So basically you have left the throttle body and lines stock and put a turbo on before the throttle body, where did you connect the IP vent line, that is the line/section closest to the rack that is supposed to have cod liver oil in it, on the IP side of the diaphragm?
This is so simple, seems like someone would have tried this and succeeded already, do you think that everyone is just using the wrong turbo?
I had one running with the throttle body before the turbo, but I was scared it would empty the crank case eventually on the hiway, so I never used it in my truck, only on a test stand.
Your way seems like when you let off the throttle, the turbo would pressurize the venturi line, briefly anyway, and that would pump fuel into the engine, but since the butterfly is closed, the engine cannot get air, so it would seem like it would blow black smoke, but if the vent line is between the throttle body and turbo, it might turn the vent line into a pressure line pushing the diaphragm back to idle position, it's all so confusing.
I bought an engine that had a VE type pump and had it shipped to me, I just need to get motivated on the project, the Sd22 just doesn't have the power to move a Datsun 720 properly, so I don't drive it much anymore, I just drive my Datsun 521 kingcab I made with a SD25 in it, it will go 80mph all day long on level ground, but it is lighter than the 720.
I am very interested in how/where you routed all your lines.
This is my 521KC diesel(SD25)
Image
The 720 in the back ground is my 720 diesel that I will be turbocharging.

Wayno
I know the voices are not real,
but they have some really good ideas.

dn29626
Posts: 249
Joined: 10 years ago
Location: Anderson, SC

#168

Post by dn29626 » 7 years ago

Waynosworld

OT but is that bed original to the 521? I have seen one other like it on a 720.

I also notice different fenders on the 720 in the background. Does it have a dually rear end?
82 King Cab 2wd (nice)
82 Reg Cab (body damage)
Anderson , SC
Since Fall 2009

Zarghareth
Posts: 19
Joined: 8 years ago
Location: Sisters, OR

IP venturi and vent line line routing

#169

Post by Zarghareth » 7 years ago

waynosworld,

To answer your first question; The IP vent line is open to atmosphere with a little in-line sintered fuel filter to keep stuff out of the diaphragm. Second question; No, I don't think that the turbo has anything to do with it. And about the pressurization upon closing the throttle body; when you close the butterfly valve (TB) it is forcing more air to go through the venturi generator in the TB and thereby increasing the vacuum being applied to the IP diaphragm. Because the strength of the venturi generated by the TB is dependent far more on the velocity of the passing air than the surrounding pressure, there is no surge in fuel delivery. In fact, sudden closing of the TB causes a substantial peak in vacuum and momentarily reduces fuel delivery considerably (this prevents over-reving on all but red-line up-shifts during which the turbo is going hard enough to blow the TB open). If you have the vent line go in between the turbo and TB, it will dump in the fuel in extreme excess because the IP control rack works in reverse; when it is moved towards the back of the engine, it increases the fuel delivery and when it is moved towards the front of the engine it reduces fuel delivery. Thereby pressurizing the vented (forward) side of the diaphragm will increase fuel delivery.

I gaurentee that the line routing I previously described will work very well on the vacuum regulated inline pumps. If I were you I would sell that VE pump and get an inline Kiki going. The 521 is sweet for sure, but the 720 looks good too. I would definitely encourage you to do the turbo on it if you have the resources which it sounds like you do.

I'll try to describe the routing I am using as clearly as possible. The rear-most hose barb on the IP is connected to the hose barb on the TB. The front-most hose barb is open to atmosphere with something to keep dust and crud out. And it's as simple as that! I'd be happy to answer any other questions you have!

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

#170

Post by elboss » 7 years ago

Nice project mate! very clean engine! how much Psi/bar boost you can got, with that turbo and fuel delivery?

Zarghareth
Posts: 19
Joined: 8 years ago
Location: Sisters, OR

Boost

#171

Post by Zarghareth » 7 years ago

Hi elboss,

Last night I broke 10psi several times on a hard drive. Because I'm not running an intercooler, the boost I get is very dependent on the ambient air temperature. During the winter, I can get up to 12psi pretty reliably if its not slick out. The thing is a nightmare in the snow and ice, way too much torque!

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

#172

Post by elboss » 7 years ago

thanks for the answer! it's the normal pressure with thant kind of intake. Nice project!

dn29626
Posts: 249
Joined: 10 years ago
Location: Anderson, SC

#173

Post by dn29626 » 7 years ago

I do not see any response from waynosworld. I will guess he does not have notifications turned on.
82 King Cab 2wd (nice)
82 Reg Cab (body damage)
Anderson , SC
Since Fall 2009

larrynsr
Posts: 25
Joined: 9 years ago
Location: portland oregon

#174

Post by larrynsr » 7 years ago

I have just finished turbocharging my sd25 with a turbo from a 1.8l audi quattro. This engine is in a 1981 volvo 240 wagon. I put the turbo pre throttle body and vents the hose from the injection pump diaphram into the atmosphere per what zarghareth suggested. Wow what a difference it makes. Power is very smooth on the bottom end...until you hear the turbo spool up, manifold pressure turns from vacuum to boost, the power comes on really quick. It has a 2.5" down pipe that leads to a 3" straight pipe. I have had it boost up to 5psi but let off the throttle as I did not want to blow up the engine (334k original miles). EGT got up to 1200 degrees. I use to take the same hill to work in 4th gear but now I can take them in 5th with power to spare. I havent driven a tank of fuel yet to know what my mpg is, but i am sure it has stayed the same or even dropped because i like to play.
Image

waynosworld
Posts: 517
Joined: 7 years ago
Location: Vancouver Washington USA

#175

Post by waynosworld » 6 years ago

I seen larrynsr's Volvo wagon a month ago maybe, and took some photos myself, I am not a writer, but here is a link to what I wrote and the photos.
http://www.nwdatsuns.com/viewtopic.php?f=44&t=545

dn29626, that bed is not original to the 521KC I made, it likely came off a chevy luv pickup, I bought it in a wrecking yard
The 720 in the background has a rebuilt SD22 diesel in it with a VE type injection pump, this will be the one I turbocharge first, and I have a SD25 engine in the back that I will rebuild that will eventually end up in this truck with the turbocharge package.
It is a dually truck, but it is a cheat, the true Nissan dually rearend gearing is not appropriate for a diesel engine, the best gearing that can be bought for the dually axle is 411s, they came with 437s and 456s I believe, so I had adapters made to use the stock 720 rearend housing with 370 gears in it, and then I mount the adapters, then mounted the dually rims onto the adapters.
It's for looks, I would never haul a lot of weight in this truck, but I will tow with it, and have without issues.
My notifications are not on, I will have to look into doing that, I am not computer savvy though, so I will try.
Image
Image
Image
Image
I know the voices are not real,
but they have some really good ideas.

waynosworld
Posts: 517
Joined: 7 years ago
Location: Vancouver Washington USA

#176

Post by waynosworld » 6 years ago

I have the "watch this topic" notification turned on, I am hoping this notifies me when someone posts tom this thread via email, then you will get timely responses from me.
My biggest issue is getting someone to make me the pipe from the exhaust manifold to the turbo, I have went to a couple shops and they look at me dubiously.
It is also hard to get motivated when I am the only one around playing with these engines locally, but Larry(larrynsr) has me thinking about it again.
I know the voices are not real,
but they have some really good ideas.

dn29626
Posts: 249
Joined: 10 years ago
Location: Anderson, SC

#177

Post by dn29626 » 6 years ago

My ac compressor is in your turbo location. The turbo has a clean appearance : - ) .
82 King Cab 2wd (nice)
82 Reg Cab (body damage)
Anderson , SC
Since Fall 2009

larrynsr
Posts: 25
Joined: 9 years ago
Location: portland oregon

#178

Post by larrynsr » 6 years ago

I have driven over 5000 miles in the past few months. Its been my daily driver since the installation. The sd25 is holding up very well. No problems... weird noises or oil consumption. Power is great! I am currently running 10psi boost. A front mount intercooler has been installed but I have yet to do the plumbing as it's too cold! I'm hoping to run 12psi or so after the intercooler is hooked up. On thanksgiving I drove 200 miles one way using 4.2 gal of diesel. That's about 47 mpg. I am happy.

https://www.youtube.com/watch?v=laQjoO3 ... ata_player
https://www.youtube.com/watch?v=t37TJeg ... ata_player

waynosworld
Posts: 517
Joined: 7 years ago
Location: Vancouver Washington USA

#179

Post by waynosworld » 6 years ago

larrynsr wrote:I have driven over 5000 miles in the past few months. Its been my daily driver since the installation. The sd25 is holding up very well. No problems... weird noises or oil consumption. Power is great! I am currently running 10psi boost. A front mount intercooler has been installed but I have yet to do the plumbing as it's too cold! I'm hoping to run 12psi or so after the intercooler is hooked up. On thanksgiving I drove 200 miles one way using 4.2 gal of diesel. That's about 47 mpg. I am happy.

https://www.youtube.com/watch?v=laQjoO3 ... ata_player
https://www.youtube.com/watch?v=t37TJeg ... ata_player

That is really good mileage Larry, what EGT are you at while just driving down the freeway?
What is the boost at just going down the freeway?
Did you lean it out making this trip?
Great job on this, I am happy I met you that day, I am happy I responded to the craigslist wanted ad.
I know the voices are not real,
but they have some really good ideas.

larrynsr
Posts: 25
Joined: 9 years ago
Location: portland oregon

#180

Post by larrynsr » 6 years ago

waynosworld wrote:
larrynsr wrote:I have driven over 5000 miles in the past few months. Its been my daily driver since the installation. The sd25 is holding up very well. No problems... weird noises or oil consumption. Power is great! I am currently running 10psi boost. A front mount intercooler has been installed but I have yet to do the plumbing as it's too cold! I'm hoping to run 12psi or so after the intercooler is hooked up. On thanksgiving I drove 200 miles one way using 4.2 gal of diesel. That's about 47 mpg. I am happy.

https://www.youtube.com/watch?v=laQjoO3 ... ata_player
https://www.youtube.com/watch?v=t37TJeg ... ata_player

That is really good mileage Larry, what EGT are you at while just driving down the freeway?
What is the boost at just going down the freeway?
Did you lean it out making this trip?
Great job on this, I am happy I met you that day, I am happy I responded to the craigslist wanted ad.
Thanks. I am running about 4 psi at 55 mph on level ground at speed. Egt at this speed is about 600 degrees. fuel was left alone. I have read that for maximum efficiency and lowest egt, the exhaust manifold pressure to intake manifold pressure should be at a 2:1 ratio. Ideally it should be at 1:1 but I don't think that would be possible with a single turbo like this. I would one day like to swap this turbo for a vgt turbo. This way I can adjust for turbo lag and exhaust back pressure (to control egt). Im still doing my homework now, but i have my eye on a vgt turbo from a late model vw TDI.

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