1980 Datsun 720 turbodiesel

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handcannon
Posts: 58
Joined: 8 years ago

Re: 1980 Datsun 720 turbodiesel

#46

Post by handcannon »

Hi Wayno, I have an Albany address, but I'm just south of the I-5 and Santiam River bridge, about 75 miles south of where I-5 crosses the Columbia.

I did figure that putting the SD-22 into the 620 engine bay would be reasonably easy. I haven't measured, but I'm hoping the 620 transmission and the SD-22 transmission are the same length. If so then my only concern would be what I may need to do with the motor mounts. I'm hoping that the mounts are close enough to the same that all I will need to do is maybe make a plate to adapt the motor mounts to the frame mounts.

My biggest concern right now is finances. I'm on disability, and my wife just lost her job. So we are at the moment in limbo as far as finances go. Being able to get it running this summer would possibly be a big help to us financially (cheaper to operate than my big pickup). Getting it into the 620 and running, without having to worry about drive shaft modifications/expenses would be very helpful to us.

I do have an idea for a possible way to put a turbo on the SD-22, hopefully without the problems that others have had to deal with. I'll try to explain what my idea is, and if someone else likes it and is able to make it work, that would be my reward.

From what I understood about the past attempts to add a turbo, the lack of some kind of mechanically connected control of the rack has allowed for a vague, indecisive movement of the rack.
I spent a lot of time mulling this over in my mind before I had this harebrained idea. Since then I've continued to mull it over, and refine the idea.

To start with, the vacuum diaphragm system that operates the IP rack seems to be the fly in the ointment with all prior attempts. If the diaphragm is able to withstand being constantly in contact with either vacuum pump oil, or clear power steering pump oil, then I think everything will work. What needs to be done is to replace the vacuum on one side of the diaphragm, and the outside air pressure on the other side, with a suitable light oil.

A couple of small master cylinders, side by side, connected to the fuel pedal would operate the diaphragm. The two masters would be connected together by way of a rocker arm and a pivot. This rocker would have the pivot in the exact center between the two masters so that each master cylinder would have equal, but opposite, movement. When the fuel pedal is pressed, the first master would be pressed, and send oil pressure to one side of the diaphragm, thus moving the rack, while the other side of the diaphragm would send the same pressure back to the second master. When the fuel pedal is allowed to come back towards the resting position, by way of a spring return system like on a carbed system, the fluid from the masters would reverse direction and move the rack back towards the resting position.

This would have to be a sealed system, like a brake system, so that no air is allowed to enter. A reservoir, like on a brake system, might need to be incorporated to help keep the system full of fluid.

Initially it sounds like a complicated system, but after spending a lot of time thinking about it the complications seem, to me, to become simpler. I may be way off base, but I invite others to give me feedback about this.

Don
handcannon
Posts: 58
Joined: 8 years ago

Re: 1980 Datsun 720 turbodiesel

#47

Post by handcannon »

plenzen wrote:Welcome Don.

There is someone on here that did a 620/SD swap as well.

Keep up posted as to your progress
Thank you.

Do he do a build thread, and if so do you have information/link to it?

Don
waynosworld
Posts: 571
Joined: 11 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#48

Post by waynosworld »

The diesel mounts are an inch or two farther forward than the other engines put in the 720, an adapter plate will likely work, but I have never went that way myself, I always use the 720 diesel kingcab frames and wiring harnesses in my builds.
The total movement of the rack is nine sixteenths of an inch which includes the fuel cutoff position and the engine start position, that doesn't leave a lot of movement to control the engine RPMs, and a very small amount of movement is all that is needed to make a big difference as far as the rack is concerned, the way I look at it is that the engine is controlled more by the amount of air it gets rather than how much fuel it gets with this basic inline injection pump.
There is a guy in Australia that modified his inline injection pump to a mechanical throttle, he basically said that either it was floored or it wasn't, he raced/drifted his engine so it didn't matter, but in the end he converted over to a VE type injection pump.
I actually tried to do what he did to his inline injection pump, but it didn't really work all that well, and I could not figure out how to make it work off the key(off/on using key), so I gave up.
I also tried an inline type injection pump for a stationary engine or marine application, but I could not get it to run properly, so I gave up.
The way it was with the throttle body in between the intake and turbo, it ran alright but was always running way to hot(EGTs), I could not even go 70mph without the EGTs going over 1400 degrees, in my opinion the reason it ran so hot was that the rack was always floored, and it really didn't any more power than a stock SD25 engine without a turbocharger, but it did get up to hiway speed a little faster, now the guy on here with the turbocharged engine(the bomb) figured out how to do it the way above(throttle body in the stock position) by adding boost to the injection pump vent vacuum hose using a valve, he said it worked, but I didn't really have the option to ask him any questions about this.
My only issue is the vacuum issue I have posted about, I have way more power than my other lighter SD25 powered Datsun 521 kingcab, and this 720 weighs a lot more than a stock 720 as it has been lengthened to except a longbox on a kingcab frame, and it has adapters and dually wheels on the rear, I believe it will go faster and get better mileage, but in the end I drive both of them by the EGTs which do get high if I have my foot deep into the pedal, it just takes longer for the non-turbo engine to get there.
I hope you can figure out how to control the IP rack the way your thinking, but I think it will take a very sensitive master as the rack movement is going to be less than three eights of an inch total, as I mentioned, I believe that these engines are controlled more by how much air they get than how much fuel they get, and all that boost did was make the IP think it was floored all the time in the stock position, but engine rpm was still controlled by how much air it would get.
I was having a lean fuel situation at first, but once I found out how "the bomb" turbo guy did it, I added boost to the vacuum injection pump rack line, what that did was at an idle there is vacuum in that line to pull the rack to the idle position, but when I give it pedal and get boost, it helps the rack move to a richer position, the more boost the richer it gets.
But again I have the vacuum issue when I let off the pedal, I have not been able to completely fix this issue, and I know it is an issue, as when ever I take the system apart, or when the intake tubes blow apart from so much boost, oil gets sprayed every where in the engine compartment on that side.
Right now I would just get the engine in the truck and get it moving down the road without a turbo, you may be happy with it the way it is, not a lot of power, but they get good mileage if the drive train is set up right, you need a 1980+ 5 speed transmission, and a 390/370 gear ratio in the rear, I have SD25 engines, I run 330 gears in the 720 turbodiesel, and 350 gears in the 521 kingcab diesel without the turbo, I have the torque to turn them kind of gears.
handcannon wrote:Hi Wayno, I have an Albany address, but I'm just south of the I-5 and Santiam River bridge, about 75 miles south of where I-5 crosses the Columbia.

I did figure that putting the SD-22 into the 620 engine bay would be reasonably easy. I haven't measured, but I'm hoping the 620 transmission and the SD-22 transmission are the same length. If so then my only concern would be what I may need to do with the motor mounts. I'm hoping that the mounts are close enough to the same that all I will need to do is maybe make a plate to adapt the motor mounts to the frame mounts.

My biggest concern right now is finances. I'm on disability, and my wife just lost her job. So we are at the moment in limbo as far as finances go. Being able to get it running this summer would possibly be a big help to us financially (cheaper to operate than my big pickup). Getting it into the 620 and running, without having to worry about drive shaft modifications/expenses would be very helpful to us.

I do have an idea for a possible way to put a turbo on the SD-22, hopefully without the problems that others have had to deal with. I'll try to explain what my idea is, and if someone else likes it and is able to make it work, that would be my reward.

From what I understood about the past attempts to add a turbo, the lack of some kind of mechanically connected control of the rack has allowed for a vague, indecisive movement of the rack.
I spent a lot of time mulling this over in my mind before I had this harebrained idea. Since then I've continued to mull it over, and refine the idea.

To start with, the vacuum diaphragm system that operates the IP rack seems to be the fly in the ointment with all prior attempts. If the diaphragm is able to withstand being constantly in contact with either vacuum pump oil, or clear power steering pump oil, then I think everything will work. What needs to be done is to replace the vacuum on one side of the diaphragm, and the outside air pressure on the other side, with a suitable light oil.

A couple of small master cylinders, side by side, connected to the fuel pedal would operate the diaphragm. The two masters would be connected together by way of a rocker arm and a pivot. This rocker would have the pivot in the exact center between the two masters so that each master cylinder would have equal, but opposite, movement. When the fuel pedal is pressed, the first master would be pressed, and send oil pressure to one side of the diaphragm, thus moving the rack, while the other side of the diaphragm would send the same pressure back to the second master. When the fuel pedal is allowed to come back towards the resting position, by way of a spring return system like on a carbed system, the fluid from the masters would reverse direction and move the rack back towards the resting position.

This would have to be a sealed system, like a brake system, so that no air is allowed to enter. A reservoir, like on a brake system, might need to be incorporated to help keep the system full of fluid.

Initially it sounds like a complicated system, but after spending a lot of time thinking about it the complications seem, to me, to become simpler. I may be way off base, but I invite others to give me feedback about this.

Don
I know the voices are not real,
but they have some really good ideas.
handcannon
Posts: 58
Joined: 8 years ago

Re: 1980 Datsun 720 turbodiesel

#49

Post by handcannon »

I apologize for being so slow to reply. Been a very busy week for me between graduations, weddings, birthdays, and helping the women's group at church with a rummage sale, and more to come in the next week.

You posted some very good, and important information, Thank you!!

Anyway, I am planning to get the SD-22 into the 620, and running properly, before doing any experimenting with the IP diaphragm control system. In addition to the motor, I have the transmission that was mated to the motor, the IP control/shut off motor (but not the electronic control), all the fuel and oil filters, and the stock air filter.

I do not have the diesel rear end gears. What I do have is the rear end that was stock to the 620, which apparently has 4.38 gears. Your information about needed gearing for the diesel answers one of my big questions about what gearing is needed. So, I need to eventually find a different set of gears, or a complete rear end, or maybe an overdrive like the older Volvo's had.

The information about how short the rack travel is was very good, and definitely surprised me. So, consequently, if I do eventually experiment with a turbo I'm definitely going to have to, at minimum, make some big changes to current ideas. Also, if you make any changes to your current control system I'm very much interested in how it works, good or bad.

I do have some questions that hopefully someone on this forum can help me with.

The first deals with the injection pump control system (can't remember what the correct name is). I was able to get it to operate, but it only occasionally stops at the three positions like it is supposed to. Does the electronic control system reduce the voltage to the electric motor? Instead of reliably stopping at each of the three locations, it seems that the electric motor may be turning too fast. The crank on the outside of the gearbox appears to start to slow down, but the coasting of the electric motor carries the gearbox beyond the stop position that is called for from the switch I'm using. The switch I'm using is a six position rotary, but I'm only using three positions. Once beyond the stop position of the gearbox, the contact for the next position is apparently engaged and the motor continues on and the same scenario happens for that stop position. The best thing I can think of is that the electronic control sends a lower voltage to turn the motor at a slower RPM, which allows the gearbox to properly stop at each position.

My next question is about the exhaust system. Since I might eventually end up with a turbo I want to size the exhaust tubing so that what I start with on the non-turbo motor will work for a turbo system. What diameter tubing should I use?

If preferred, I can start a new thread to deal with my questions as I don't want to get this thread choked up with non-turbo information.

Don
waynosworld
Posts: 571
Joined: 11 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#50

Post by waynosworld »

It's easier to just buy the gearing you need and switch out the pumpkins than to change out a whole rearend, and keep in mind that as the years have gone by, the rear axles have got wider and wider, an 85 720 axle is likely 4 inches wider than a 620 axle, it's really not that hard to change/drop out the pumpkin, couple hours, but I have done it dozens of times.

I am not sure what you are talking about when you talk about the 6 position switch to control the IP controller, the 720 harness has the DPC module and the IP controller, it is all done automatically, when the key is turned on if the wire going to the oil light is removed from the sensor it will move to the start position, once it starts it will move to the run position, and when the key is turned off it will move to the fuel cut off position.
If the wire to the oil light is left on the sensor, then it needs oil pressure to build up before it will move to the start position, but once running it will move to the run position, now if you look at the arm that the IP control arm goes to you will see that it has an oval slot, this slot as far as I know is there to let the rack have room to move around to richer or leaner positions, it is not a lot of movement, but it doesn't need to be a lot of movement as the rack doesn't move that much, very little movement is a big difference, that is why that guy in Australia said either it was floored or it wasn't with his mechanical throttle setup, but he was drifting, that was all he needed.
If you don't have a 720 wiring harness to use, it's just easier to use a choke cable to start and shut down the engine, if done right the IP will still have the slot to let the IP move around a little.

The exhaust is kinda hard to address, you see my 720 turbodiesel has no muffler, the turbo is the muffler, but you will likely need a muffler with the engine in stock configuration, although the kid down the street just used the front flatbed 4X4 inch metal tube as his muffler with 2 uprights like a semi truck, and his isn't really all that loud, I just have about an 8 foot long 4 inch round exhaust tube that dumps out the side just in front of my rear dually wheels on the driver side.
handcannon wrote:I apologize for being so slow to reply. Been a very busy week for me between graduations, weddings, birthdays, and helping the women's group at church with a rummage sale, and more to come in the next week.

You posted some very good, and important information, Thank you!!

Anyway, I am planning to get the SD-22 into the 620, and running properly, before doing any experimenting with the IP diaphragm control system. In addition to the motor, I have the transmission that was mated to the motor, the IP control/shut off motor (but not the electronic control), all the fuel and oil filters, and the stock air filter.

I do not have the diesel rear end gears. What I do have is the rear end that was stock to the 620, which apparently has 4.38 gears. Your information about needed gearing for the diesel answers one of my big questions about what gearing is needed. So, I need to eventually find a different set of gears, or a complete rear end, or maybe an overdrive like the older Volvo's had.

The information about how short the rack travel is was very good, and definitely surprised me. So, consequently, if I do eventually experiment with a turbo I'm definitely going to have to, at minimum, make some big changes to current ideas. Also, if you make any changes to your current control system I'm very much interested in how it works, good or bad.

I do have some questions that hopefully someone on this forum can help me with.

The first deals with the injection pump control system (can't remember what the correct name is). I was able to get it to operate, but it only occasionally stops at the three positions like it is supposed to. Does the electronic control system reduce the voltage to the electric motor? Instead of reliably stopping at each of the three locations, it seems that the electric motor may be turning too fast. The crank on the outside of the gearbox appears to start to slow down, but the coasting of the electric motor carries the gearbox beyond the stop position that is called for from the switch I'm using. The switch I'm using is a six position rotary, but I'm only using three positions. Once beyond the stop position of the gearbox, the contact for the next position is apparently engaged and the motor continues on and the same scenario happens for that stop position. The best thing I can think of is that the electronic control sends a lower voltage to turn the motor at a slower RPM, which allows the gearbox to properly stop at each position.

My next question is about the exhaust system. Since I might eventually end up with a turbo I want to size the exhaust tubing so that what I start with on the non-turbo motor will work for a turbo system. What diameter tubing should I use?

If preferred, I can start a new thread to deal with my questions as I don't want to get this thread choked up with non-turbo information.

Don
I know the voices are not real,
but they have some really good ideas.
handcannon
Posts: 58
Joined: 8 years ago

Re: 1980 Datsun 720 turbodiesel

#51

Post by handcannon »

I haven't looked at the rear end yet. So the rear end gears are in a carrier, like the Toyota Landcruiser/pickup? That does make things a lot easier. All I need then is to find a carrier that has the correct gearing.

The six position switch I was talking about is one I got from the local Radio Shack, before they closed up. I wasn't as clear about that as I should have been, my bad.

I have a three inch notebook full of stuff pertaining to the SD-22, and a little bit of the 620 and 720 pickups. In one of my searches I found information about diagnosing the injection pump control motor. With that information I was able to get the control motor wired and working, sort of. I don't have the DPC part of the IP control mechanism. Even though I don't have the DPC I was hoping to be able to figure things out so I could use the ignition key to not only operate the starter, but also maybe run and stop the motor. But I ran into problems with the injection pump control motor not wanting to reliably stop at each of the three positions. This is why I was wondering about the DPC module reducing the voltage to the IP control motor.

For the low oil pressure shut down part of the electronics control, I have a parts list from other vehicles that will help. It won't shut the motor down, but it will turn on a buzzer for low oil pressure.

Don
waynosworld
Posts: 571
Joined: 11 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#52

Post by waynosworld »

I don't know how the DPC module works, it just does, at least most the time, it is tied into a lot of things, so it is kinda hard to make something that replaces it in its entirety.
Fact is that I have had to pull the oil light sensor wire as mine will not start when that wire is connected, and I have tried other DPC modules with no improvement/positive results, I even replaced the IP controller and the glow plug timer just in case the issue was one of them.
There is a guy around here that used a solenoid to move the IP pump arm to the run/off positions using the key, he said he got that idea from the VW diesels, so he doesn't have the start position and it still starts, a lot of guys out there running veggie oil that don't have a functioning DPC/IP controller that use a 2 position choke cable because they possibly don't know about the 3rd start position or they are driving their truck in the start position all the time.
The guy I bought my engine from currently in the 720 used a choke cable, when on the hiway he would pull on it till it was the leanest he could get it and still be able to drive it down the road, he said one trip he got 48mpg, but he drives 50mph, I cannot drive 50/55mph as I want to get where I am going ASAP.
Below is a photo of a Nissan drop out pumpkin.
handcannon wrote:I haven't looked at the rear end yet. So the rear end gears are in a carrier, like the Toyota Landcruiser/pickup? That does make things a lot easier. All I need then is to find a carrier that has the correct gearing.

The six position switch I was talking about is one I got from the local Radio Shack, before they closed up. I wasn't as clear about that as I should have been, my bad.

I have a three inch notebook full of stuff pertaining to the SD-22, and a little bit of the 620 and 720 pickups. In one of my searches I found information about diagnosing the injection pump control motor. With that information I was able to get the control motor wired and working, sort of. I don't have the DPC part of the IP control mechanism. Even though I don't have the DPC I was hoping to be able to figure things out so I could use the ignition key to not only operate the starter, but also maybe run and stop the motor. But I ran into problems with the injection pump control motor not wanting to reliably stop at each of the three positions. This is why I was wondering about the DPC module reducing the voltage to the IP control motor.

For the low oil pressure shut down part of the electronics control, I have a parts list from other vehicles that will help. It won't shut the motor down, but it will turn on a buzzer for low oil pressure.

Don
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I know the voices are not real,
but they have some really good ideas.
handcannon
Posts: 58
Joined: 8 years ago

Re: 1980 Datsun 720 turbodiesel

#53

Post by handcannon »

At this time I am unable to get the IP control to work reliably. So, do you have a link, or know any information about setting up a solenoid for start/run/stop as this person you know of? I guess I'm a bit OCD in that respect. I would really like to be able to do the start/run/stop strictly with the ignition key, and not have to add in a cable. If I have to I will use a cable, but I'd prefer to be able to use the ignition key.

Lets see if this might sound like what the guy you know of did. Run an excite wire from the power on side of the ignition switch to a solenoid hooked to the control arm of the IP. Key turns on ignition switch, solenoid is turned on by power from ignition switch and moves IP control arm to run position, key turned to start position and operates starter, motor begins to run and solenoid continues to hold IP in run position. Might have to run a second wire from starter solenoid excite circuit to keep power to IP solenoid unbroken during starter running time (run wire from ignition switch might lose power during start function?). Ignition key turned off breaks the excite circuit to the solenoid and solenoid retracts which moves IP to off position. I will have to do some out of the box type of searching as I have no experience with this type of solenoid that moves something, except for a starter solenoid.

Thanks for that picture of the Nissan/Datsun pumpkin. That is exactly the same idea as the pumpkin that Toyota used in the Landcruiser/pickup. That makes switching gear ratios very easy.

Don
waynosworld
Posts: 571
Joined: 11 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#54

Post by waynosworld »

If there is a 3 position solenoid I have never heard of one.
The 720 diesel inline injection pump wiring harness is a pain when one starts to change things, there is no reliable power source that works when the key is in the run position and the start position, I ended up using the window washer motor hot wire for key on/run position, and I put in a relay wired to the battery to supply power to the VE type injection pump using the starter activation wire, that way I had power to the VE type injection pump fuel cut off solenoid starting/running, the VE type injection pump is not like the inline pump and has a fuel cut off solenoid, the reason I mentioned this is because of the relay option.
I have not seen the guy lately that did the solenoid thing, he borrowed an inline injection pump from me to set it up and has never returned it to me, I know where he lives, but it is way out there, I expect I will get the IP back some day.
Here are a few push/pull type solenoids on ebay, I don't know if it has the correct throw as I have never looked into this way of starting/stopping an engine.
http://www.ebay.com/itm/10mm-3-1Kg-6-8l ... Sw-vlVidw1
Here is another
http://www.ebay.com/itm/DC-12V-Push-Pul ... SwSHZWdUlp
and another one.
http://www.ebay.com/itm/250g-Force-10mm ... Swu4BVlc5V
It seems like these could be purchased at the local auto parts stores, you just need a push/pull type that has a long enough throw, that pulls when power is cut and make some kind of mount above the smog screw.
I have no idea how these type of solenoids mount, I would have to have one in my hands to figure that out, or see one mounted on something.
The only way I can think of to make a 3 position solenoid would be to have two solenoids connected to each other, and that sounds like a pain.

handcannon wrote:At this time I am unable to get the IP control to work reliably. So, do you have a link, or know any information about setting up a solenoid for start/run/stop as this person you know of? I guess I'm a bit OCD in that respect. I would really like to be able to do the start/run/stop strictly with the ignition key, and not have to add in a cable. If I have to I will use a cable, but I'd prefer to be able to use the ignition key.

Lets see if this might sound like what the guy you know of did. Run an excite wire from the power on side of the ignition switch to a solenoid hooked to the control arm of the IP. Key turns on ignition switch, solenoid is turned on by power from ignition switch and moves IP control arm to run position, key turned to start position and operates starter, motor begins to run and solenoid continues to hold IP in run position. Might have to run a second wire from starter solenoid excite circuit to keep power to IP solenoid unbroken during starter running time (run wire from ignition switch might lose power during start function?). Ignition key turned off breaks the excite circuit to the solenoid and solenoid retracts which moves IP to off position. I will have to do some out of the box type of searching as I have no experience with this type of solenoid that moves something, except for a starter solenoid.

Thanks for that picture of the Nissan/Datsun pumpkin. That is exactly the same idea as the pumpkin that Toyota used in the Landcruiser/pickup. That makes switching gear ratios very easy.

Don
I know the voices are not real,
but they have some really good ideas.
waynosworld
Posts: 571
Joined: 11 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#55

Post by waynosworld »

Ok, so as many of you know I figured out how to turbocharge my 521 that has an inline pump and it runs great as a blow thru, this truck I tried and tried and I could not get it to run properly the way that Larry had it set up as a blow thru, I tried a different type of pump at one point, in the end I made it into a draw thru and fought it till I got it to run decently, but I never felt it was good for a long trip with the vacuum pulling oil thru the seal issue, but I did finally get the power I was looking for.
Well yesterday I looked at this truck and thought I didn't need the lower turbo manifold to see if I could get this truck figured out, so this morning after breakfast I went to work on this one, and it actually didn't take that long.
It is now a blow thru, I didn't need to even use a valve anywhere on it this time as it has an adjustable waste gate, so I put the throttle body back in the stock position, piped everything like the 521 and started it, adjusted the idle a couple times till I had it below 900rpms and I took it for a test drive.
The EGTs run a little warmer than the 521(couple hundred) and I did seen slightly over a 1000 degrees, but otherwise it ran as expected, actually better than expected, Larry had the pump turned up so it is getting more fuel all the way around, I said this before, this engine has grunt/torque, it puts me firmly in the seat when accelerating, it's a good thing I put all the tools I was using in the truck before I left as I needed them, I seen 20psi boost more than once on the hiway when I put my foot in it, the second time it blew the intake piping apart at one of the connections, so I pulled over and put it all back together, I then adjusted the waste gate to 15psi and continued on.
This truck has way more power at lower RPMs and it will kick the 521s ass everywhere except maybe at fast hiway speeds, when I try to drive 75/80mph in this 720 I keep maxing out the boost at 15psi and I really don't like it, at the same speed the 521 is at 5/6psi boost and it will go faster which I am comfortable with, but 15psi plus boost just cruising down the freeway on level ground bugs me, it likely has something to do with the intake vane being larger.
Now I like having the 15psi boost when getting on the freeway, but it's not there all the time when accelerating, I let off and shift gears and such.
In the end/big picture, it was a complete success, it acted like the 521 and didn't have super hot EGTs, I am happy with the results, it did exactly what I was hoping for, it drove normally like the 521 and doesn't have vacuum issues anymore, so this is a repeatable setup and it doesn't need control valves to adjust to get it to run properly except for the waste gate which would have to be tinkered with on any turbo conversion.
My 720 is so much heavier than the 521, yet this 720 will leave my 521 behind off the line, but on the freeway is yet to be determined, turning that pump up does make a difference, although I don't know exactly how it was done other than a diesel injection shop did the modification.
I could hardly believe I seen 20psi boost, I thought I had it adjusted lower than that, as a matter of fact I am sure I had it adjusted lower than that, everything I do to this engine lately makes it run better and better.
I know the voices are not real,
but they have some really good ideas.
handcannon
Posts: 58
Joined: 8 years ago

Re: 1980 Datsun 720 turbodiesel

#56

Post by handcannon »

This is good news Wayne. Now to see how it does long term, and fuel mileage for your normal way of driving.

Don
waynosworld
Posts: 571
Joined: 11 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#57

Post by waynosworld »

I don't drive the 720 that much, at least I did drive it when the 521 kingcab was not turbocharged, but now that the 521 kingcab is turbocharged I would rather drive that one, even though the 720 has more power around town, but I don't like looking at 15psi boost on the hiway all the time, I can adjust that so it never sees more than 10psi, I will think about it for a while.
The big thing here is that it is repeatable, that is why I did it today, to see if things improved from the last time it was setup as a blow thru.
What I don't get is why Galen(knucklehead) didn't show a happy ending to that thread "This is The Bomb ... with Turbo", he is the one I chatted with via email that gave me the idea to do it this way, although he used a valve in the vent line while I used nothing.
What interests me now is if I get better MPG with it set up this way as when it was a draw thru I was just getting above 20mpg, that is terrible mileage for me considering Larry said he got 48mpg on a trip up north, but he does drive real slow, at least that is what it sounded like when he told me I drove it wrong on the test drive.
I was just going thru the thread I referred to and found out what turbocharger Larry used on the SD25 engine I bought from him, it is a 1.8l audi quattro turbocharger on this engine.
This is the thread I am referring to that has no happy ending, he says in that thread to have the vent line vented to atmosphere, but that is not what he said to me in our emails.
http://nissandiesel.dyndns.org/viewtopi ... &start=150
I know the voices are not real,
but they have some really good ideas.
waynosworld
Posts: 571
Joined: 11 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#58

Post by waynosworld »

Well I am turning this into my work truck for a while, as soon as I deem it reliable I will be doing a major conversion on my 521 work truck which has a gas hybrid engine.
I pulled the dually box off and put a Knapheide flatbed on it, I have all the lights/marker lights working on the flatbed that count, they are LED lights, I am thinking I might like these lights, might convert over to them on the 521 work truck also as the regular lights rust and quit working every few years, these LED lights all work after sitting in a field for years.
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I replaced the power brake booster oil line as the one in the truck had kinked, I am hoping it didn't ruin the vacuum pump, the brakes were not working all that great.
I also figured out a couple other things, one was my glow plug light had quit working properly, well it turned out to be that the plug in the alternator had fallen out, that was the reason the volt meter only showed 12 volts all the time, that is now fixed.
I made a new bracket to hold the intake housing onto the throttle body, I was using zip ties and one had broken, since I plan on using this as my work truck for a while I want it to be dependable.
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This flatbed also has a Tommy Gate that works great so far, that will make it easier for me to get the debris in my wheel barrow into the truck, as normally I throw it in the bed a shovel full at a time, but I have started using a wheel barrow recently as I am getting old and walking a shovel full of debris around a house 20/30 times is tiring.
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I am planning on making my 521 work truck a dump bed, I have everything I need, I just have to do it, it will take a while as I also will be using a 1980 Datsun 720 wiring harness in it.
I know the voices are not real,
but they have some really good ideas.
waynosworld
Posts: 571
Joined: 11 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#59

Post by waynosworld »

This is what it looks like today, I have used it once for work so far as the 521 work truck would not start, I ruined a starter trying to get it to start, but after replacing the starter it started right away. (insert shake my head here).
The rear suspension is too soft, I don't like it, but this is temporary till I get the 521 work truck cab/bed over onto the new frame that has a dump bed assembly.
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It has a working Tommy Gate but until I have the trailer light wiring set up to this truck I likely will not have a reason to use it, as I need my pressure washers hauled around in the trailer to make a big enough mess to warrant the need to use a wheel barrow which would warrant the use of the Tommy Gate.
With these wheels on it the truck is not near as smooth, but I didn't trust the adapters I was using to mount the dually rims with that much weight, so aftermarket wheels is the way I went, the engine runs awesome right now and starts easily even when cold outside, not cold like some of you guys talk about, but cold enough that the 521 turbodiesel doesn't want to start without warming up the block before trying to start it.
I know the voices are not real,
but they have some really good ideas.
waynosworld
Posts: 571
Joined: 11 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#60

Post by waynosworld »

Ok, so I got ripped off by the guy that was supposed to make the turbo exhaust manifolds, 4 manifolds are gone.
I decided I wanted the good hood back on this truck, so that means I will have to lower the turbocharger, I was having an issue with this turbo, since LarryR modified it, and I have been good enough to make the system airtight, either the turbo is on bypass 100 percent of the time to keep it under 10psi, or I am decelerating, I decided to use another unmodified turbo and make my own setup to get the whole thing under the hood.
So far I have drove it once without a functioning EGT gauge, it runs and drives now, and today I took the exhaust pipe going from the stock exhaust manifold exit to the turbo out and put the bung in the pipe I made last night and I now have a functioning EGT gauge, but I didn't drive it today.
I am just going to post photos without text, I will try to keep them in the order I took them.
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I added a brace to the top of the turbo to the second headbolt/stud.
You can see that I mounted the turbo on a 90 degree piece of angle iron bolted to the to top bolts and the front bottom bolt on the exhaust manifold that originally held the heat shield, that all the weight is on the exhaust manifold is the reason for the top brace.
Its late so I will answer any questions tomorrow after I drive it and see how things have worked out.
I know the voices are not real,
but they have some really good ideas.
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