[DirtyDan]

Eric, no apologies needed or accepted. I have read most of your posts and respect your knowledge. I am groping around in the dark, myself. This thread is a "grope".

If you are lean in a turbo diesel you are inefficient, not getting bang for the buck, for the air compression the turbo gives you. If you run rich, too rich, you are throwing more wood on the ole campfire and its going to get hotter. All this in turn is still affected by the temp of the input air per intercooler, if there is one. More than just the lean/rich variable going on here. And we are at the edge of my knowledge....I think I'll just be quiet now .

[anjuna mark]

diesel engines don't care about fuel / air ratio. that's why there's no throttle; you give it all the air you can, then control the fuel [the injection pump does that].
Most any engine can be turbocharged for a 20% power increase. I upped my Swaraj-Mazda about 40%
Just put a thermocouple in the exhaust manifold and keep an eye on the temperature there. 800C is the absolute maximum.
A successful turbo conversion needs a lot of motor specific research to match the turbo, painstaking fabrication, and a lot of math.
Very few mechanics are capable of doing the job right without a prefabricated kit; I can say I'm one of them.
I brought the parts from Europe and did the job under a coconut tree.
That was in '98 or thereabouts.

My advice; if you can get a kit that's known to work, go for it. Otherwise, forget it [unless you're VERY good].

[Sutripta]

Originally Posted by ringoism

Oops.
...
I think I'll just be quiet now .
My apologies...

-Eric

Why? That would be a loss for the community.

If you do some searching in the forum for 'diesel', 'stoichometric', 'AFR' etc, you should get tons of hits. From all kinds of members.
Now there is no point in asking the keyboard warriors to do some homework, and some thinking. (They only know how to fight!)
The know it alls (at least the cleverer ones) realise they were wrong, cover it up, and will not revisit the topic, for fear that their past blooper will not remain buried. (I remember one who was talking about diesels running hot because diesels run lean!)
And the list goes on.

I was confident that you on the other hand would stop, think, do some homework, realise that you had made an error, and now know enough to enlighten others. Which is why I posed the question to you. And you have proven me right on all but the last part.

You shouldn't let down the forum, you have to continue posting! Your posts are reasoned and insightful, and greatly add to the forum. I enjoy reading them.

Regards
Sutripta

[DirtyDan]

Originally Posted by anjuna mark

diesel engines don't care about fuel / air ratio. that's why there's no throttle;

I don't think you meant to say it quite like that. I think you mean that you can make adjustments via instruments and planning. Controlling fuel input has got me scratching my head.

Originally Posted by anjuna mark

I brought the parts from Europe and did the job under a coconut tree.

My advice; if you can get a kit that's known to work, go for it. Otherwise, forget it [unless you're VERY good].

What brand kit do you trust? What instruments would you use? Pyro, anything else? Boost gage? What species of coconut tree do you recommend?

[anjuna mark]

I didn't use a kit, and I only did the one conversion job years ago, so I can't recommend any company's products.

With a diesel engine, you just give it all the air you can, you don't try to control air flow. The more the merrier. The only barrier is heat, and there is a lot of that when air is compressed, first by the turbo and then by the engine itself. You would expect the compression to be a problem, but it isn't unless you go for really high boost.
The fuel injection pump adds fuel as required for the power need. Only the fuel is controlled, not the air. it's normal to have at least 10% excess air to prevent smoke. Extra air cools a diesel engine [opposite to a petrol engine, which would run hot from a lean mixture].

I had a compression gage and a heat gage [pyrometer]. After fitting the turbo I had about 0.25 bar of boost [I have it written down somewhere] at 500C max exhaust temp. Then I took the fuel pump from the engine and took it to the local Mico shop for recalibration and higher fuel output. this is no problem with Bosch type diesel injection pumps.

After refitting the pump, I had max 0.6 bar boost at 650C. this was climbing a long steep hill that I used for testing. Before adding the turbo I had to use 2nd gear, but with the turbo it went right up in 3rd. This thing weighed 7 tons by the way. It was far more drivable with the turbo too, low end performance was transformed.

I got most of the information from a book called "turbochargers" by Hugh mcleans. It would be pretty old by now... He lays out the principles and the calculations you need to do. In feet and pounds unfortunately.

The plumbing in a van is a nightmare, but in a jeep or something with more space it would be a lot easier.

I don't know what species of coconut tree it was; the kind with coconuts on it. The important aspect of the tree for vehicle modification is the degree of shade below it.

I did a lot of research on the motor before I started. the Mazda motor has 18/1 compression, so I let it be. if it had been higher, like 22/1, I would have taken the rods out and had them shortened slightly. This is easily done by a machine shop by [precision] grinding away a little of the bottom, then refitting the bearing cap and regrinding it round.

I also checked that my pump could be recalibrated before I started.

I used a second hand intercooler from a Mercedes truck. It had to have new intake and outlet tubes to fit my application. That meant welding aluminum, which was tricky.

Hoses are a big problem; they look like radiator hoses, but there is always a little oil present after the turbo. this will kill most radiator hoses after a time. I found some silicone radiator hose from a performance catalog.
There was also a lot of steel pipe with multiple elbows to twist around to the intercooler and then back to the intake manifold. And of course modifications to the exhaust system, and the oil supply line to the turbo, and the oil return back to the sump is hot, foamy, has to run only down, and must enter the engine above the oil in there.

[DirtyDan]

Thanks for the specifics. This is sort of how I envisioned doing it, actually. I figure a moderate sized turbo, be real careful with the install, especially the pyro, and then err on the side of safety. E.G. I would be happy with a set up that gave me 18% more power and ran lean and cool from the same set up that could be pushed to 33% more power but threaten to detonate. Maybe toss in an oil cooler for good measure, 'ay?

[anjuna mark]

I would wait to see how it runs before adding yet another lot of tubes and parts.
Off road, an oil cooler is another liability, because if it gets pierced by a stone you're going to need towing to get home.

My engine ran cooler with the turbo than without it, at stock HP; only when I ran it at high output did it get hotter, and even then the stock water cooling system had no trouble keeping up. this is explained in the turbo book; the extra air from the turbo cools the motor. running it through an intercooler cools it even more. After the turbo install but before the pump recalibration, it ran 50C cooler than stock [I tested it before doing anything, so I'd have a baseline measurement].
I used a cheapo hand held pyrometer, it cost 10 euros or something. I installed it in the dash, but had some trouble with its power supply; the probe in the exhaust manifold being grounded interfered with the sensitive electronics in the thing. I'd simply drilled a hole and slid it in there.
I solved the problem with a "dc/dc galvanic isolating inverter" chip in the power supply circuit. The chip cost another 10 Euros. The problem could have been solved by insulating the probe with some sort of ceramic insulating tube I suppose. or run it on the original 9V internal battery instead of trying to use the vehicle electrics.

My truck would run at high power for 10 minutes or more at a stretch when climbing hills, but a jeep would probably never need full power for more than 10 seconds for acceleration.

So I wouldn't worry too much about the heat.

[ringoism]

Originally Posted by Sutripta

I was confident that you on the other hand would stop, think, do some homework, realise that you had made an error, and now know enough to enlighten others. Which is why I posed the question to you. And you have proven me right on all but the last part.

You shouldn't let down the forum, you have to continue posting! Your posts are reasoned and insightful, and greatly add to the forum. I enjoy reading them.

Sutripta, I've had this growing conviction that a very significant part of your value to the forum is in keeping us all honest... making sure whether we know what we're talking about (or not). But you may overestimate me ... and I've been a bit busy lately besides (was just out in Spiti on the bike, and heading to Shimla next week).

However, in light of anjuna mark's comments below, I might have personal cause to approach some serious study of the topic (I KNOW the Marshal would run better with some boost, if it would also hold together...)

Originally Posted by anjuna mark

With a diesel engine, you just give it all the air you can, you don't try to control air flow. The more the merrier. The only barrier is heat, and there is a lot of that when air is compressed, first by the turbo and then by the engine itself. You would expect the compression to be a problem, but it isn't unless you go for really high boost.

The fuel injection pump adds fuel as required for the power need.

I also checked that my pump could be recalibrated before I started.

Great info, thanks so much for posting. Just wanted to clarify: Was your van equipped with a simple mechanical injection pump? If so, there's no way it can "know" to compensate (add extra fuel) for the added air, since ther's no boost sensor, no mass airflow sensor, etc. With electronic cars, changes seem to be a little easier, because you can have sensors that tell the ECU whether it's running rich or lean (O2) or how much air mass is incoming (MAF/MAP) or whatever and can thus automatically compensate.

The full-mechanical Bosch VE as found on the MDI(NA) adjusts fuel delivery via two things: 1) RPM and 2) how far you put the pedal down. Re: calibration, it has a single external screw with a locknut (just above where the injector pipes exit) that according to the service books changes (via restricting/unrestricting input pressure to the high-pressure side of the pump) the fuel delivery ACROSS THE ENTIRE RPM/LOAD RANGE. That means, regardless of air intake (i.e., boost level), which it has no way of knowing. I've played with the screw and the changes are easily observable via smoke levels. I suppose it'd be an easy enough thing to generally richen the pump to compensate for the added boost (that would mean turning it clockwise, incidentally). But wonder whether:

1. At very low boost levels (off-idle/part-throttle) and at idle might it be running over-rich and producing a lot of black smoke?

2. Is it actually possible in a non-boost-compensated pump to get both the power you want AND economy approaching the original NA setup (which, ideally, is what a well-designed turbo setup is supposed to do)?

3. Do you know what specifically was involved in your own pump's re-calibration, and how (if at all) your fuel economy was affected?

-Eric

[ringoism]

(admin: sorry, missed this bit)

Originally Posted by anjuna mark

a jeep would probably never need full power for more than 10 seconds for acceleration. So I wouldn't worry too much about the heat.

We Himachalis (thread-starter Ken & myself) could definitely be running on heavy boost for a lot more than 10 seconds (I mentioned two hours in my earlier post, which is not unrealistic when one has the higher passes in mind (or even Rohtang, a 6,000ft continuous climb from the valley floor!). For me, this is where the reliability concerns come in. I could see the severest service in the most remote of places - a potentially risky mix.

[anjuna mark]

Originally Posted by ringoism

Great info, thanks so much for posting. Just wanted to clarify: Was your van equipped with a simple mechanical injection pump?

Yes.

If so, there's no way it can "know" to compensate (add extra fuel) for the added air, since ther's no boost sensor, no mass airflow sensor, etc. With electronic cars, changes seem to be a little easier, because you can have sensors that tell the ECU whether it's running rich or lean (O2) or how much air mass is incoming (MAF/MAP) or whatever and can thus automatically compensate.

The full-mechanical Bosch VE as found on the MDI(NA) adjusts fuel delivery via two things: 1) RPM and 2) how far you put the pedal down. Re: calibration, it has a single external screw with a locknut (just above where the injector pipes exit) that according to the service books changes (via restricting/unrestricting input pressure to the high-pressure side of the pump) the fuel delivery ACROSS THE ENTIRE RPM/LOAD RANGE. That means, regardless of air intake (i.e., boost level), which it has no way of knowing. I've played with the screw and the changes are easily observable via smoke levels. I suppose it'd be an easy enough thing to generally richen the pump to compensate for the added boost (that would mean turning it clockwise, incidentally).


That's true, but [according to the man from Mico] The screw makes fine adjustments and there are also internal changes that can be made for larger steps.

But wonder whether:

1. At very low boost levels (off-idle/part-throttle) and at idle might it be running over-rich and producing a lot of black smoke?

I observed NO SMOKE at any speed after the mods [and I had a big imported rear view mirror and I did look for it], except if it was floored from low RPM; then there would be some smoke for a couple of seconds before the boost built up. All of those electronic gizmos and microprocessors are to prevent that 2 seconds. You can do the same thing by just not stepping on it all at once from idle. There's always more air than it needs to burn all the fuel; as more fuel is added and the rpm increases, the manifold pressure rises more. I had 0.2 bar just over idle.

2. Is it actually possible in a non-boost-compensated pump to get both the power you want AND economy approaching the original NA setup (which, ideally, is what a well-designed turbo setup is supposed to do)?

No; there is a very slight performance increase due to better efficiency. But to get more power you really just need more fuel.

3. Do you know what specifically was involved in your own pump's re-calibration, and how (if at all) your fuel economy was affected?
-Eric

I don't know exactly; As I recall I told them to increase the fuel 25% [on a per stroke basis], and to increase the max rpm settings on the governor to match the Japanese specs, I think that was an extra 500 rpm. It was an early Swaraj Mazda with a Japanese motor and a Mico fuel pump.

After refitting the pump I was disappointed with the results. I went back to the shop and accused the engineer of not giving it all the increase I'd asked for. He admitted it was true [he didn't believe in my turbo even though he'd seen it with his own eyes], and told me to turn the fuel screw an extra 1/4 turn.

That bus didn't have fuel economy! But according to the book [which I never found an error in] you will get a slight economy increase except when you use the extra power; in other words, 80kph with turbo, slightly better than 80kph without turbo. If you stick your foot into it and have fun, it'll cost you.

I routed around and dug up my old notebook where I noted down the test results. These were all made on the same 3km steep hill road in Goa.

1; stock condition, naturally aspirated [only pyrometer added for temperature reading]; GVW aprox 6 tons, 2nd gear, full throttle, 3000rpm
exhaust manifold temperature 550-580C

2; with turbo installed. 460-480C, I think there's more midrange

3; [0.58 bar] fuel increased to 38cc per 500 strokes test inconclusive due to fuel supply problems

4; fuel pump recalibrated; 0.64 bar, climbs easily in 3rd gear, 500- 520C

5; increase fuel screw 1/4 turn aprox 41cc per 500 strokes, 0.68 bar at 3200 rpm added 1/2 ton load, climbs at 2500 rpm 520C 3rd gear 6.2 bar


OK, not perfectly scientific, but those are my real life results.

Remember that boost is just air pressure in the manifold; it does not increase the load on your engine, in fact it just runs cooler. I know this is counterintuitive, but that's what the book said and that was my real life result.

Only when you add extra fuel and the engine starts producing extra power does the engine come under more physical strain and will also produce more heat.

I don't think you'll be keeping your foot on the floor for two hours! But if you can, please let me express my deepest respect for your skills, and please also let me know where and when this takes place so I can be sure not to be in the area.

High altitude compensation is another thing; I did look into that because I wanted to be able to go over the Rotang pass [I never did though].
A lot of different things happen; the air is [usually] cooler, which is good. but less dense of course.
In the end, the turbo spins faster than down on the plains, but your engine runs with normal sea level power if you've done your matching right.

My installation was a 'free running' turbo, with no waste gate or other control. I also had a big intercooler; the turbo had to be sized differently because of that. Imagine a lot of air entering at .6 bar and 100c, exiting at the same pressure but 60C; it's considerably denser. So more air has to be fed in than if there was no intercooler, since the engine is a fixed displacement device.

When the "pollution test" requirement came along, I put the truck on the emissions tester and they said it ran very clean, well within legal limits.

Most any diesel engine can have a power increase of 25% [according to the book] without a significant loss in reliability.
Just watch that exhaust temperature; a factory installation is tested in all sorts of ways before production, and they don't fit a pyrometer. But if you do a one-off turbo conversion, especially if you intend to run at high altitude, watching your exhaust temperature is really important.
Temperatures over 800c will burn your exhaust valves and the turbo.

[Sutripta]

Originally Posted by ringoism

If so, there's no way it can "know" to compensate (add extra fuel) for the added air, since ther's no boost sensor, no mass airflow sensor, etc. With electronic cars, changes seem to be a little easier, because you can have sensors that tell the ECU whether it's running rich or lean (O2) or how much air mass is incoming (MAF/MAP) or whatever and can thus automatically compensate.

Just a question: Suppose you had bored and stroked your (old world purely mechanical diesel) engine, what changes would you make to your FIP?

Related- what exactly is meant by 'calibrating fueling' in a Bosch jerk injection pump? How is it done?

Regards
Sutripta

[ringoism]

Originally Posted by Sutripta

Just a question: Suppose you had bored and stroked your (old world purely mechanical diesel) engine, what changes would you make to your FIP? Related- what exactly is meant by 'calibrating fueling' in a Bosch jerk injection pump? How is it done?

Guessing more displacement means more air drawn in which would require a proportionate increase in fueling? (???)A "jerk" pump(???)

Perused the VW diesel forums a bit, as there are quite a few who modified them, some (like the guy I knew in college) who have done turbo conversions on N/A diesels, etc, and also because they, too, use Bosch VE rotary pumps (as our Marshal - fitted on a couple model years of the old DI, and all the newer MDI-T's). Lots of good info out there. Seems most calibrating comes down to the internal pressure adjustment screw (a.k.a. "smoke screw") and a certain pin (length, taper) in the diaphragm-operated boost-enriched units. Also some governor mods, which I think A.M. made reference to. BTW, there's something refered to as an "Adenoid" pump for VW's that has the boost-enrichment feature; but it seems a lot of people have added turbos without the special pump, too, and had them run fine.

Originally Posted by anjuna mark

I don't think you'll be keeping your foot on the floor for two hours! But if you can, please let me express my deepest respect for your skills, and please also let me know where and when this takes place so I can be sure not to be in the area.

High altitude compensation is another thing

Most any diesel engine can have a power increase of 25% [according to the book] without a significant loss in reliability.

Sounds like a great book, but can't find any references to it online (I will assume this is NOT the same Hugh McLean who is presently a doctor specializing in transgender surgeries?). Is your copy for sale?

BTW, high-altitude compensating Bosch VE pumps were also made, which utilized a very similar diaphragm-actuated system atop the pump to adjust fuel at varying atmospheric pressures.

I'll propose a compromise on expected full-power duty cycle, and put it somewhere in the middle between ten seconds and two hours... You're right, of course, that I wouldn't have it on the floor non-stop for two hours. But with a smaller turbo that spools quickly and is boost (and therefore power) limited, it probably could be at or near full boost for at least an hour cumulatively of those two (without endangering anyone's life). Remember that the MDI3200T only makes 62bhp. Drove one up over Kunzum-La (15,000ft) in Spiti last week (Bolero Camper) and truly, unless you're well into the boost, it's just not going to be moving along very well; and you've got to try and keep that boost up entering the hairpins, or the lag kills you (and it pumps out billows of black smoke) when you're trying to accelerate out of them again, sub-boost rpm levels.

Maybe reliability shouldn't be a concern, though, if we're only talking 25% or less increase. Probably most Indian diesels have been built with at least that much additional stress/abuse factored in. I had an old Datsun 280ZX turbo that I hung a modded turbo, intercooler, and adjustable wastegate on - I figure that took it from 180bhp stock to somewhere around 250bhp (based on quarter-mile times), and there were no reliability issues there. Depends a lot on the original design - they say the stock 280ZX bottom end was actually good for 650bhp!! Early VW 1.5/1.6 diesels, on the other hand, were bad enough about cracking blocks in N/A form, and turbo'ing them would be a big mistake; whereas they say the later VW 1.6's solved that issue and people often hung turbos even on very well used engines with no issues at all.

Unfortunately, so little info exists in the Indian context re: which engines are robust enough and which ones aren't. Guessing the MDI's/Tata 3.0DI's might handle it - and it seems the Swaraj Mazdas, too - but who knows for sure???

Thanks,
Eric

[anjuna mark]

Originally Posted by ringoism

Sounds like a great book, but can't find any references to it online Is your copy for sale?


Unfortunately, so little info exists in the Indian context re: which engines are robust enough and which ones aren't. Guessing the MDI's/Tata 3.0DI's might handle it - and it seems the Swaraj Mazdas, too - but who knows for sure???

Thanks,
Eric

My copy is lost in India somewhere.

Note that this book is really old now, and the section dedicated to diesels is only a few pages long. Also, it uses imperial units [cubic feet, pounds].
None the less, he actually tells you how to do it, which is a rare and wonderful thing.

http://www.amazon.com/Turbochargers-.../dp/0895861356

http://my.mmosite.com/5316742/blog/i...innes_pdf.html

I found this download link but I didn't try it.

Which engines are reliable; just ask the engine mechanics you know which ones break down less. You know the questions to ask.

The Swaraj Mazda 3.5 liter was probably built to be turbocharged, and a few European versions were shipped with turbo before the Japanese discontinued the model.

[ringoism]

Originally Posted by anjuna mark

Note that this book is really old now, and the section dedicated to diesels is only a few pages long. Also, it uses imperial units [cubic feet, pounds]. None the less, he actually tells you how to do it, which is a rare and wonderful thing.

Which engines are reliable; just ask the engine mechanics you know which ones break down less. You know the questions to ask.

Yeah, 1984 was near the beginning of the turbo craze in the U.S., with a few production models having generated a lot of interest (280zx [inline six] and Pontiac TransAm [V8] in '81, the Buick V6's in '83, and the 300SD Mercedes (my first turbodiesel experience) and Peugeots around that time as well, as notable examples). Things have changed a lot, but on the good side, engines like the MDI are based on designs much older than 1984!

Mechanics still rave about the old MDI (N/A) as being one of the best engines out there. But still feeling pretty tentative about this. "Reliable" at a weak 58bhp (and a LOT less torque) is easy (even then, I'm having some internal leakage problem, whether from a crack in the liner/head or some other issue - and my cylinder head was bowed a bit in the middle, before re-facing). The factory MDI-T's did have beefier blocks and other changes. I got thinking of camshafts, too, since most factory turbos had zero-overlap types. Long story short, if I've got to buy a good second-hand turbo, the manifolds, a cam (w/lifters, which have to either be new or else matched to the wear patterns of the lobes), new steel-shim head gasket, associated plumbing/mods for the oil drain, etc, etc, and get it all put together, I'm guessing I'm going to have to spend not less than Rs25,000 (add several thousand more for the turbo IP), and there are still going to be questions about the basic integrity of components under high / long strain, the fuel economy, and real-world performance gains. At that point, just getting a good, guaranteed junkyard MDI-T for around 40,000 and selling off the MDI for scrap for several thousand is sounding like the better deal.

-Eric

[shashanka]

Originally Posted by Sutripta

Just a question: Suppose you had bored and stroked your (old world purely mechanical diesel) engine, what changes would you make to your FIP?
Related- what exactly is meant by 'calibrating fueling' in a Bosch jerk injection pump? How is it done?
Regards
Sutripta

The only real "calibration" that can be done on the Bosch helical groove plunger type pump is for the injection "cut-off" point. The injection cut-in point is fixed - in most plunger/barrel type Bosch pumps - since the top of the plunger covers the fuel inlet ports (nominal inlet pr. is usually 5-8 bar at booster p/p discharge) at a particular angle of the fuel cam travel (nominal value : 5 deg + - ~ BTDC).
The injection cut-off point is governed by the position of the helical groove which uncovers the same inlet ports, thus connecting the high pr. discharge side (250-350 bar in the pre-CRD engines) of the pump to the low pr (5-8 bar) fuel inlet side, thus theoretically cutting of injection instantly (again nominal value 7-10 deg + - ~ ATDC)
The position of the helical groove on the plunger vis-a-vis the inlet port is controlled by the rotary motion of the plunger which in turn is controlled by a rack & pinion arrangement. The rack position is effectively the throttle position. This relative position of the helical groove can be "calibrated", if you like, by dismantling the plunger/barrel and changing the relative meshing position of the teeth of the rack/pinion arrangement.
There was a later - though short-lived - modification to the Bosh pump by adding another helical groove to the top of the plunger, thus effectively controlling the fuel "cut-in" point also.
As can be visualized this is not a job for most DIY enthusiasts.

The advent of the common-rail diesel of course put an end to any further development of the Bosch type pump.