Is anyone out there converting a petrol engine to diesel?

[lex]

I was just wondering about converting petrol engines to diesel, on this site there are conversions of a norton and an italian conversion too. Surely it would be easier to convert a bike engine as there are no transmission or alternator headaches, and it is already designed to fit a bike frame.
Already on this site there are a lot of engineers having parts specially machined and it seems that the skills are out there so I'm suprised no one is working on such a project. A kick start single cylinder project would make sense, beef up the conrod and crank, add injector pump and inject through the plug hole. You could increase the compression rating by 'skimming the head'. Surely this approach is worth pursuing?



Lex

[oilburner]

One of the more promising efforts is that of the Grey Eagles - a bunch of gray haired enthusiasts including former Harley engineers. They have dieselized and turbocharged a Harley. They are aiming for 100mph and 80 US mpg. The task hasn't been without its challenges. IMHO a rather daunting task for the average shade tree mechanic. Of course there's the original RMCS Enfield proof of concept conversion. IIRC it took them a couple years to get it right.

Google gray eagles harley diesel or similar for lots of articles.

There's a picture of the bike A.E.D. Corp Common Rail Diesel Motorcycle on Stuart's website at:

http://www.dieselbike.net/harleydavidson.htm

[oldbmw]

I have looked at this already and believe it is the way to go. As a starting point, instead of converting (as that means changing nearly everything) it might be better to build a crankcase that will hold a known diesel engines crank, and build the motor up from there, The outside of teh crankcase has to mate with the original bike, and the inside with the diesel motors innards. That at least will give you a crank, con rod and piston. mounted in a custom crankcase. whether you could re use teh original barrel and a modified head or make a new one is a matter of choice. Using a traditional Enfield engine layout means it might be possible to use an auto advancing pump from a modified points drive. Or have the crankcase accept a chain driven one. It would be neat and smoother running (at slow speeds) than a fixed timed pump. The key thing with the crankcase is the studs holding the barrel/head need to be stronger than in a petrol engine. and heavy flywheels will make for a smoother running motor ( although it will slow down gearchanges). I expect larger main bearings would also be needed ( take the size from the donor diesel crank)

a slight digression :
It seems from teh rolling tests from Hitchcocks that the enfield gearboxes absorb power more based on the speed of the input shaft rather than by the amount of power transmitted. So to gain a little (maybe a hp or two) keep the original ( primary ) gearing and step it up as required at the final drive. Do not be tempted as i firt thought to increase the primary drive to reduce the torque loading on teh clutch.

[oilburner]

oldbmw wrote:

As a starting point, instead of converting (as that means changing nearly everything) it might be better to build a crankcase that will hold a known diesel engines crank, and build the motor up from there

I totally agree. In addition to a custom crankcase, a custom cylinder head would allow ideal location of the intake and exhaust ports, and the possibility of lugs for mounting the engine as a stressed member. I'm not sure whether it would be more economical to make a pattern and cast a new crankcase and cylinder head or CNC mill new ones from billet. Personally, I'd prefer to go with the billet. You can do dry runs on nylon, make modications as necessary to the CNC program until satisfied, and then attack the billet. If a new cylinder head was required, the combustion chamber and port design could be borrowed from an existing design, but there would be issues with oil galleys etc., particularly if an OHC setup was used. Pushrods would be simpler, but this would probably compromise maximum rpm.

An injection pump with auto advance would be mandatory - IMHO the fixed timing pumps is the achilles heel of the small industrial engines from all viewpoints. I suspect a toothed belt would provide more accurate timing than a chain or gears (no backlash). However, there probably will never be a suitable mechanical single or twin cylinder pump with auto advance, since economical common rail versions appear to be just around the corner. I wouldn't think the common rail pump is timing critical, it should just require a drive.

Know anybody with *deep* pockets? Or someone to build AVL's inline triple concept:
http://www.dieselbike.net/commercialdevelopment.htm

[lex]

I like the idea of a common rail type set up where the pump provides constant pressure and the injector is 'fired' by solanoid valves, you could build a very simple ECU using the existing coil pickups from a petrol engine set up giving variable injection timing.
Personally I would want to keep as much of the bottom end as possible in order to incorperate the primary drive, gear box and alternator - how about using the diesel crank and bearings as suggested and modify the crankcase to take the bearings, keep the piston and cylinder but beef up the conrod - maybe a race one or one designed for a turbo engine. How about a twin arangement so that the size of the flywheel could be reduced? I suspect the result might end up like the kawasaki based army bike - maybe they should let us raid their spares bin (as they aren't doing a civvy version!)


Lex

[oldbmw]

Oil burner wrote:-

Pushrods would be simpler, but this would probably compromise maximum rpm.

"I doubt you will get a diesel running much over 4500 rpm, as the enfield valvetrain with pushrods is easily good for 5500 I do not see pushrods as a problem. 1970's Triumph 500cc twins with pushrods were running at over 10k rpm ( as were 1958 douglas bikes)"

Olburner wrote:-

An injection pump with auto advance would be mandatory - IMHO the fixed timing pumps is the achilles heel of the small industrial engines from all viewpoints. I suspect a toothed belt would provide more accurate timing than a chain or gears (no backlash). However, there probably will never be a suitable mechanical single or twin cylinder pump with auto advance.

"No problem, use a car one with four cylinders, you dont actually need to use all the outputs for injectors just run the unused ones back to teh return line "

[lex]

Yes simple pushrods - would they be easier to adjust when the cylinder head was skimmed a few millimeters to increase the compression ratio?
I've an idea to get an old seized 500 single to play with. do you think the new conrod and crank would really be necessary?

I'd be tempted to beef up the bearings - swap them for roller bearings as that would mean less machining of the crankcase. Why is no one doing this?
It seems no more effort than rigging up drive systems modifying frames and building electrical systems, and exhausts.
So to recap:

Skim the head to increase compression ratio
Uprate the bearings
Mount car type pump driven from a toothed belt
Use ign sensors as sig gens to drive injector solenoid
Make adaptor to connect injector through spark plug hole
Any thoughts?



Lex

[lex]

oh - nearly forgot, a governor of some description too!!!!!

[oilburner]

It probably wouldn't be too difficult to get it to run, the thing is how well. I've never seen the underside of a direct injection cylinder head but I suspect you would want any petrol head modification to resemble a DI head. If the flame front and propagation isn't efficient, power, torque, and fuel efficiency would probably suffer considerably.

Lex wrote Fri Apr 11, 2008 5:06 pm
oh - nearly forgot, a governor of some description too!!!!!

A governor shouldn't be a problem - all auto style injection pumps (actually all inline and distributor pumps) have a built in governor and the max speed is limited by a sealed limiter screw. The limiter screw would have to be readjusted for the new engine. Also, the fuel delivery would have to be changed as appropriate for the requirements of the engine.

Regarding use of only two ports of a four port injection pump from a 4 cyl car engine. There might be problems if the fuel from the unused ports is dumped into the return. First, the pressure at the unused port could be up to 2000 lbs, not good for a rubber return hose. A separate steel line might be required. Second, after an injector "fires" there is still some residual pressure in the fuel pipe to the injector after the injector closes. If there is no pressure due to dumping an unused injector port into the return, the cam inside the injection pump may be unable to recover sufficient pressure in the 1/4 turn for the next cylinder - the cam is being asked to do something it wasn't designed to do. I think the injection pump might require some extensive reworking. Hope I'm wrong.

[oldbmw]

Yes simple pushrods - would they be easier to adjust when the cylinder head was skimmed a few millimeters to increase the compression ratio?
I've an idea to get an old seized 500 single to play with. do you think the new conrod and crank would really be necessary?

I'd be tempted to beef up the bearings - swap them for roller bearings as that would mean less machining of the crankcase. Why is no one doing this?
It seems no more effort than rigging up drive systems modifying frames and building electrical systems, and exhausts.
So to recap:

Skim the head to increase compression ratio
Uprate the bearings
Mount car type pump driven from a toothed belt
Use ign sensors as sig gens to drive injector solenoid
Make adaptor to connect injector through spark plug hole
Any thoughts?

Lex

There was a guy who beefed up Enfields to install a 750cc big bore kit. He welded extra material in the crancases in order to install bigger roller/ball bearings. Personally I would want to get the specs of teh existing bearings and compare them to a similar sized diesel.

I do not think you can convert a petrol head for diesel use by simply skimming abit. most heads are hemispherical and pistons relatively flat. most diesel engines have flat heads and pistons. I think also a petrol piston, small end, con rod or big end simply wont be strong enough for diesel use. by using a diesel piston, it may be possible to build up the head and relocate the valve seats to work... IE make it look like the original diesel head inside.

I had in mind a simple mechanical pump, without using any electronics to drive it.

[oldbmw]

[/quote]
Regarding use of only two ports of a four port injection pump from a 4 cyl car engine. There might be problems if the fuel from the unused ports is dumped into the return. First, the pressure at the unused port could be up to 2000 lbs, not good for a rubber return hose. A separate steel line might be required. Second, after an injector "fires" there is still some residual pressure in the fuel pipe to the injector after the injector closes. If there is no pressure due to dumping an unused injector port into the return, the cam inside the injection pump may be unable to recover sufficient pressure in the 1/4 turn for the next cylinder - the cam is being asked to do something it wasn't designed to do. I think the injection pump might require some extensive reworking. Hope I'm wrong.[/quote]

Hmm, don't know... this idea came about from a recent experience i had with my car. It was running rich, giving poor mpg and pinking.... It turned out to be an air leak in the pipe that takes vacuum from the carburettor to the distributer to work the vacuum advance. How an air leak to a carb would make it rich or disabling the vacuum advance wwould make it pink I have no idea. Once fixed however the mpg went from 33 back to its usuall 44mpg. And i was half wondering if adding a vacuum advance in the form of a car distributer to a motorcycle would improve mpg. With this mindset i proposed using a car type mechanical pump. Maybe use some kind of spring to control a dump valve bit like the pressure release valve in the oil feed system. yes the stuff needs to be piped separatly back to the tank.
seems with bit of a kludge it could work, no need to use injectors on the unused outputs.

[lex]

Yes, perhaps the skimming idea is a little simplistic

do not think you can convert a petrol head for diesel use by simply skimming abit. most heads are hemispherical and pistons relatively flat. most diesel engines have flat heads and pistons. I think also a petrol piston, small end, con rod or big end simply wont be strong enough for diesel use. by using a diesel piston, it may be possible to build up the head and relocate the valve seats to work... IE make it look like the original diesel head inside.

Has anyone a picture of the underside of their cylinder head showing valves etc?
The diesel piston and conrod is still sounding like the best way forward, as for the crankcase I think building it up and adding roller bearings is best combined with a diesel crankshaft, the problem then is loosing the neat solution to primary drive.

I would love a coincidence like a yanclone head fitting a petrol engine right down to the studs and oilways (bit like japanese engines fitting in Morris minors for all those years including 5 speed box apparantly!) but I can't imagine it somehow!

This leads me to my next idea (after some head scratching) What about diesel head and barrell connected to strengthened motorcycle crankcase but with pump arangements as discussed earlier on in the thread?
In this way we can at least have a better final drive arangement.
Cheers




Alex

[andrewaust]

Hi Guy's



Converting a petrol engine to diesel? Even though I've worked with diesel engines for years I've never done a lot of tinkering, although the old Toyota hilux indirect injected 4cyl seemed very close to a petrol bottom end. I once had a Wisconsin side valve engine that you could start on petrol and then run on kero or diesel, but you couldn't load it up to it's full potential as it would pre-ignite, but would run a genset/compressor combo and be much more fuel efficient then running on petrol. Little hint~! I did shave the head. The old pancake engines would swirl the fuel/air mixture OK too so you could lean off the fuel for a clean burn. I'd also guess you could weld the head where the combustion chamber is, raising compression and then place an injector into the combusion chamber with a glow plug? Where the removable magneto is, you'd replace that with an injection pump = now that's an idea, but not all that useful for our bikes though! Unless you wanted to convert a ChangJiang 750 Motorcycle http://www.vintagesidecar.com/history.htm = anybody interested?

Back to converting most petrol engines: I feel it could be done on some engines! Others wouldn't hold up.

You could use a pushrod type cylinder head = Honda CX500's use a 4 valve pushrod V-twin and revs to around 11,000 rpm. So the pushrod variety could be used. Over head cam engines were designed to make engines more compact, lighter, cheaper to manufacture/assemble and are able to make a little more power, but I still personally like the pushrod engine for reliability = just my personal view though. Changing timing belts and chains on some engines is a major job. Shimming an OHV engine throughout its life is an expensive exercise as well with some engines.

With a conversion - you've got a few things to get right = compression, right injection spray and volume, air swirl, valve timing, ignition timing, strong piston's, etc etc. Some petrol bottom ends and conrods would handle the extra compression as the power stroke of most petrols are much higher then a diesel anyway, especially the turbo ones.

If I was to convert a petrol engine I'd use a 4 valve head and if I thought a swirl chamber couldn't be placed on the piston, I'd go from direct injection to indirect injection placing the swirl/vortex chamber in the head. Only setback = If you go indirect injection you have to use a glow-plug for starting.

This new common rail stuff aside, if I was to use a mechanical injection pump, I'd go with the inline one, not the rotary - they are a P.I.T.A. = Inline pumps are more robust, although you have to supply the cam and bushings etc with a pressured oil supply in most cases.

You can run a twin cylinder diesel with a 4 cylinder injection pump. You just feed the fuel back to the tank = thinking about it you may be alble to pull the delivery valves out "but don't get me wrong" so you don't foam the fuel going back. If one was to do this, use steel/copper lines. Even though rubber lines could be used, for safety (just in case of blockage) steel lines are best.

I could go on and on and on, but if your like me, I have a short attention span, and will leave it here.



Cheers guy's - happy riding and tinkering "if your still building"



Andrew

[sbrumby]

I dont want to poor cold water onto this thread, but it seems the hole idea is comeing from its an easy way to do a diesel motorbike. I am not saying it cant be done either because quite clearly it can be done. But converting a petrol motorbike engine to a diesel is a difficult one to crack. Far more skilled engineering required than to fit a standard diesel engine into a bike.
Take the enfield bullet, if you managed to convert it, its reliability would probably be bad, vibration also bad, but the rpm would be half that of the original so the drive train you would like to keep would not be a grate match. A similar problem is with all shaft drive bikes, the gears and ratios are all done for you but are meant for high rpm. The reason the chinese clones are clones is because its easier to copy than create.
Dont let me stop you though.
Sam.

[lex]

Cheers Andrew and Sam for illustrating the two sides of the coin!
I still think that petrol to diesel conversion is worth pursuing for the benefit of not having to chop up frames and fit comet drives etc.

Although the expertise and equipment required to mill cylinder heads is not at everyones disposal, the abillity to work out what is required and get a quote from the local machine shop definately is. (we are all doing this to some degree trying to wedge stationary diesel engines into various bikes)

The diesel haveing half the RPM is of course true, but then it would have half the power in some cases too and so would need lower ratios anyway. I think careful coice of engine would help here - not necessarily Enfields, a big old jap single or twin might be better, especially something like Suzuki's 1980's 'GS' family with roller bearing engines (except they were 4's), you can always up the front sprocket with is not a daunting task!

I will have a look at the engine pile in the breakers next time and see what he has!

I've also found pictures of a DI cylinder head which was for sale on EBay showing valve position and even decompression 'hole' what I need now is a good look at a piston top! (or a good description)
Cheers



Lex

[Fiddler]

Lex,

Im in Sam's corner that cobbling up some engine mounts will be far easier than the mammoth task you are thinking of in terms of getting the swirl, combustion, timing etc workable.
Having said that Im intrigued to follow your progress and wish you all the best.
My advice before you go to the breakers would be to look for an engine with an electric start. Im assuming it will be strong enough to turn over a diesels compression, anyway it ought to cope with a decompressor/ valve lifter. My thinking is that experimentation with stuff like injectors and timing will be so much easier with a mechanical aid turning it over for you.
Even the guys on here with kick start singles will agree that although simple enough to start, a certain knack is required. I cant imagine when you are going through the developement stage that you will be sure if your adjustments are working or if you just havnt kicked it over correctly when it wont start.
In terms of looking for an engine that may be suitable for a head/barrell transplant with an electric start, may I suggest looking at a Suzuki drz400. I havnt done any measurements or proper thinking, Im just wildly guessing from a mental picture in my head that it may be suitable. There are loads available cheaply.
Anyway just a few thoughts for you, good luck.

Mark

[andrewaust]

Hi Guys


They are really great ideas! I've been thinking of a starting aid if you were to go the full hog and convert a petrol engine finding the electric starter is having a hard time to crank the engine.

If one was to it hard to fit a decompression system on the heads, one way to combat the problem would be to fit butterfly valves on the inlets to fully close off the intake air momentarily to aid initial cranking. Why I say momentarily, as we know compression is needed to raise enough heat for starting.

There are always one way around it.

I was also looking at a new engine concept = the rotary valve diesel engine. Apparently it can be modified to run on any fuel with some minor converting. I'm only to find what they mean by "minor converting". Could this technology be used for a small compact bike engine, even use a petrol bottom end and just modify heads and pistons.

http://www.allbusiness.com/transportati ... 132-1.html

http://www.coatesengine.com/motorcycle.html (Rotary Valve Petrol M/C)



Just thought I'd throw them ideas in.



Cheers


Andrew

[jonnyr48]

hi guys, only just noticed this thread (der). what do you think of using the 2cv engine? built strongly enough already, has pushrods, run common-rail pump off toothed belt on crankshaft. if i were to fit diesel-type pistons and get the head built up, what would be the best design to get fuel and air swirl right?
cheers jonny

[coachgeo]

Somebody's been doing his research and brought a thread up from the vault of the dead. Kudo's to ya man!!!

Many of today's diesels have takent the prechamber (swirl chamber) of the diesel engines of the past and put it into the top of the piston. (deep piston cups etc.) My bet this would be your best route. Maybe search up old engine designs from Elsbett. He designed a veg. oil engine (multi fuel more like) long ago. Due to using less refined fuel he really strongly designed into it very good fuel automization. IMHO many of todays small auto diesels were things stolen from him. (deep piston cups for one)

Sorry I can't answer any more of your questions though

[Stuart]

Y'know, If I had the money I'd sponsor something along the lines of the X prize competition (space race) to get people converting engines. There are plenty of big capacity bikes out there just cryin' to be converted. I see all these talented home mechanics turning out amazing contraptions in the magazines and I figure if we could get a bunch of these guys on this case we'd end up with a worthy bike.
If such a competition should get off the ground (could we all chip in?) then there would have to be a few ground rules. I dunno about you but I'd like to see the end poduct based around an existing bike using said bikes engine. I'd like to see as few (modified) parts as possible to keep the cost down and I'd like to see something that produced good HP figures. And it would have to be common rail using an off the shelf technology there.
So, we need a bike with a big air scoop (that could be fitted with an intercooler up front) and an engine big enough to be sleeved down to half it's capacity (so the bottom end could handle the increased compression).
Rocket 3, Thunderbird, MT01, ....anymore

http://www.youtube.com/watch?v=HKEuzxC4 ... r_embedded

[jonnyr48]

thanks for the kudo's coach! not that i deserve them, i was just rehashing the other guys ideas on this thread. the elsbett idea was good, but i'm wondering about lanova fuel cell heads ....anybody know how the valves work/are arranged?

[Stuart]

Just found these wise words on converting engines. Ooer..

"It would be an "Interesting" challenge. You would first need to raise the compression ratio high enough to ignite diesel fuel. You would then need to add a pre-combustion chamber. In indirect injection engines this is a normally a small chamber cast into the cyclinder head. However some engines use a seperately cast one, so in principle you could modify your cylinder head to take some of those. If you wanted to go for the more modern direct injection approach then the pre-combustion chamber is part of the piston crown. By choosing a suitable length of connecting rod and piston deck height you could get the compression ratio you need. You will probably need a new crankshaft with bigger bearings to cope with the higher piston loads.
You then need to modify your cylinder head to accomodate fuel injectors and glow plugs. Probably easiest to just have a new head made as petrol/gasoline engine port geometry is unlikely to be optimal for diesel.
You then need to find a way to drive the high pressure fuel pump. This needs a lot more power than any of your existing accessories, so a custom gear-drive will be needed. You will need a new engine front cover to accomodate this, and to keep the oil in.
To make current NOx emissions limits you will need a valve to allow some exhaust gas to recirculate back into the intake air. Oh, and a different type of exhaust catlyst too.
While you are at it, a turbo is pretty much de-rigeur nowadays too. Computer controlled, of course.
While I remember, you will need to add a vacuum pump or your brakes won't work any more. (Diesels have no throttle, so produce no vacuum)
After you have modified your camshafts to get suitable cam timing you can then settle down to programming the engine computer, making sure that the fuel pressure is right, that the boost pressure is right, and that the fuel is being injected at the right times. I reckon you can pick up the basics of this in 6 months, and then it normally only takes about 20 man-years to finish the job. That assumes access to several dynamometers, of course.

So, the short answer. You could, but it would be stupid to even try. I am a diesel engine development engineer for one of the world's biggest car makers.
Andy P."

Stuart

[johnfireball]

I reckon a moto morini 350 engine would make a good conversion as it has flat heads with combustion chambers cast into the pistons,so only the pistons need be changed.As for the words of wisdom are there not pictures on this site of old petrol engine conversions that appear to work.
John.

[Stuart]

Yes, there are indeed a few conversions like that. But maybe wise words if trying to create a common rail diesel from a petrol. That looks increasingly like a whole new ball game to my untrained eye. But I can dream

Stuart

[TedV]

Since I know VW’s and VW had a successful diesel engine that was converted from their gas motor. I think the only thing that you can use on either a gas or diesel VW 1.6 is the oil pan, oil filter mount, water pump & housing, water necks, valve cover, maybe the block depending on your main bearing diameters, exhaust and intake manifolds have same bolt pattern, valve shims, motor mounts.

Things that are different:
Crank
Timing belt and pulley’s
Rods and rod bolts
Pistons
Head and most everything in it including
Cam shaft
Head gasket
Head bolts
Intermediate shaft – now rotating the opposite direction and if Timing belt is too tight it will eat the bearings fast
Oil pump
Fuel pump (obviously)
Vacuum pump. Can do without if you don’t need vacuum to run anything, I use manual brakes on my autocross diesel.
Oil in the sump

I’m sure I’ve missed some little details. The motor still had it’s quirks but was not the travesty to diesel motors the General motors converted gas engine was. GM is what I believe ruined the US public on diesels, enough to discuss for a whole other thread/argument.

Not to discourage anyone from machining a diesel motor in their garage, I think it is easier to find a small diesel from some other source and adapt it into a motorcycle to suit your needs, or modify one to work better. There is decent challenge just in that.

[Crazymanneil]

Don't tend to need to vacuum pump for anything on a bike. At least thats what I thought and then proceeded to gut mine to destroy the mechanical bit of it but keep the plate to seal off the hole it came from. Til I got my bike and it had a scottoiler...



n

[bob99bob]

Hi guys as a new member I like the enthusasium but a gasoline engine just will not take the force of a diesel. Just look at this way, (ok I worked for the largest independant design / testing world wide company)
1 diesel plain main bearings are totally different to Gas ones and have a harder face.
2 the cranks are a lot tougher as well.
3 the 16 to 1 minium compression ratio is not possible with a hemi head.
4 if you go down the idi route like my ancient Ford Escort then 22 to 1 compression ratio is used
5 the modern injection pressures are enormous I dread to think what a poor ali thin wall crankcaes will do especially when the engine actually fires.
So if i was starting from scratch why not the Fiat / GM 1400cc engine 4 cyls and quite light as well as some 80hp. if you want more then the 2 litre will go to 200hp but at the expense of a lot heavier engine.
I have hand started an Indian ditch pump dieasel engine it actually had a cranking hanle but oh boy did you have to go at it when cold!
Bob

[Stuart]

Thanks for that info Bob. I guess you are right there. There's much more too it isn't there taking bearing hardness and other stuff into consideration etc.
If you find a picture of that Fiat/GM engine do post a link.

Cheers
Stuart

[IgorVigor]

I would like to add my 2p worth

Old Land Rovers (series landy's) had the options of petrols and diesel engines...

in the case of the series 2a and 3, both the petrol and diesel were 2286cc 4 cylinder 8 valve engines...

The engine blocks were identical, just a different engine code number id...

The differences (apart from compression ratio's) were:
Petrol have pressed crankshafts where as the diesels have cast crankshafts
different heads
diesels have wet cylinder liners for better cooling...

The injection pumps were driven by a skew gear that was driven by the crankshaft (a weakness as it caused unstable pump timing when worn, Land Rover changed it to a toothed belt drive on the 2495cc diesel)

So it is more than possible to convert a petrol to diesel, and the problem of the compression ratios of petrols is more down to the fact that petrol will detonate under higher compression.
It is possible to run petrols at compression ratios of more than 16:1 (direct injection compression ratio) by using a water injection system...

Cranks can be strengthened, so that should sort that problem...

Hope that helps...

[albertaphil]

How can the blocks be identical if one has wet liners and the other dry?

If LR got away with this, then it is because the petrol block was built tough enough for a diesel. That is NOT the standard. Almost without exception, diesel engines that were little more than converted petrol engines were troublesome and unreliable. In small car engines, the diesel parts like cranks, pistons, wrist pins, connecting rods, and main bearings are 50-100% heavier than their petrol counterparts.

My thoughts on the whole converting a gas engine to diesel are that you basically have to start from scratch to come up with anything you could use reliably, so you might as well use an engine that is already available. Designing and building an engine from scratch makes wedging an existing engine into an existing frame seem simple. IMHO.

Phil