Is anyone out there converting a petrol engine to diesel?

[Blunt Eversmoke]

Just a thought , two single cylinder diesel top ends ( separatly removable cylinders) matched to a BMW or Russian boxer engine to make a boxer diesel ??

Any one wanna comment on this ?

Meanwhile, on the other side of the Wall...

MT-10 diesel conversion!

What is an MT-10?

Dnepr (engine) We talk, he did it

[tappy]

I'm currently looking into the idea of converting a petrol engine to diesel.
Petrol engine "big end" bearings are typically 45-50% of the bore diameter, whilst diesels typically have "big end" bearings about 60-65% of the bore diameter. This would suggest you should sleeve down the engine by about 25% when doing the conversion.

Petrol engines typically hit about 1200psig peak pressure during combustion, whilst normally aspirated diesel engines hit about 2000psig. To apply the same force to big end bearings would therefore require a piston area reduction of about %40, i.e. a reduction in bore of about 20%.

So, take say, a BMW R80 which has big end bearing diameter of about 48mm. The existing bore is 85mm. By the above estimates the diesel bore should be somewhere between 68 and 74mm. Stroke is 70.6mm, so the new capacity would be between 510 and 610cc.

Using typical power output for a normally aspirated diesel of about 25hp per litre, that would give around 13hp..

SOO, I'd suggest instead grafting on some 2-stroke top ends and using a low pressure super charger.
Twice as many bangs per revolution, plus constant positive charging should bring the power up to about 26hp, without adding any extra load on the crank.
Then you've just got the problem of the final drive gearing, but plenty of people have been trying to solve that for BMW based bikes on here anyway.

Grafting 2-stroke top ends on does have a couple of issues I'm still looking at, along with an idea that uses 2-stroke top-ends without the supercharger.

In the mean time I really should be getting on with the first one

[Stuart]

Interesting Tappy. It's easy to think that double the compression means double the size of everything else but not so if what you say is correct.
We shouldn't forget that this means it is possible to swap certain key components between bikes of a near size/capacity as done by some of the pioneers in our field.
It just means comparing a lot of parts

[Blunt Eversmoke]

I'm currently looking into the idea of converting a petrol engine to diesel.
Petrol engine "big end" bearings are typically 45-50% of the bore diameter, whilst diesels typically have "big end" bearings about 60-65% of the bore diameter. This would suggest you should sleeve down the engine by about 25% when doing the conversion.

Petrol engines typically hit about 1200psig peak pressure during combustion, whilst normally aspirated diesel engines hit about 2000psig. To apply the same force to big end bearings would therefore require a piston area reduction of about %40, i.e. a reduction in bore of about 20%.

So, take say, a BMW R80 which has big end bearing diameter of about 48mm. The existing bore is 85mm. By the above estimates the diesel bore should be somewhere between 68 and 74mm. Stroke is 70.6mm, so the new capacity would be between 510 and 610cc.

Using typical power output for a normally aspirated diesel of about 25hp per litre, that would give around 13hp..

SOO, I'd suggest instead grafting on some 2-stroke top ends and using a low pressure super charger.
Twice as many bangs per revolution, plus constant positive charging should bring the power up to about 26hp, without adding any extra load on the crank.
Then you've just got the problem of the final drive gearing, but plenty of people have been trying to solve that for BMW based bikes on here anyway.

Grafting 2-stroke top ends on does have a couple of issues I'm still looking at, along with an idea that uses 2-stroke top-ends without the supercharger.

In the mean time I really should be getting on with the first one

Two-stroke? Could run into emission problems burning lube oil. Also you need piston heads with skirts the length of the stroke which would make the cylinders longer.
However, you MIGHT avert both of that if you loop-scavenge the cylinders through valves in the heads instead of ports: You'd get to keep the short piston heads and would have no oil come into cylinders. Also, you would have the possibility to tune the gas exchange timing by swapping cam shafts versus having to re-sleeve the cylinders with new ports.

[Stuart]

2 stroke kind'a goes against the good MPG thing don't it :-/

[Tamber]

Two-stroke? Could run into emission problems burning lube oil. Also you need piston heads with skirts the length of the stroke which would make the cylinders longer.

You might be able to avoid burning your lubrication oil if you don't use crankcase compression, but an external scavenge blower, to get the charge in the cylinder. It does require the extra complexity of a blower/supercharger, and all that goes with that, but if you're already considering supercharging to make up for the lack of displacement it does seem almost ideal.

Of course, as you say, that runs into the issue of the piston skirts needing to be long enough to still cover the intake ports when at TDC, which then means your cylinder needs to be long enough that the piston skirt doesn't protrude from the bottom of the cylinder when at BDC; which results in a rather tall engine.

And, RE: Stuart; Didn't they always joke that the green leakers would pass anything except a fuel station?
I don't think 2-stroke necessarily precludes good fuel economy; it's certainly going to use more fuel for a particular RPM than a 4-stroke of the same displacement does, simply because it's firing twice as much. But, on the other hand, it should result in greater power for the displacement than the 4-stroke so you could perhaps manage with a smaller displacement engine to get the same power than you would if you were using a 4-stroke?

Still, though, I'm puttering around in the theoretical world, and I'm none too bright; it'd be nice to see someone at least trying it, and having some actual numbers to show to say whether or not it works out alright.

[tappy]

My designs don't use crank-case compression hence the use of a low pressure, displacement-based supercharger to provide the scavenging.
Piston porting would indeed require longer pistons and thence longer conrods, but both of those will tend to reduce side-thrust, friction and wear.

A slight complication would be preventing sump oil finding its way up the bores and out of the ports, but again, I've got a couple of ideas to look at.

The longer bores would be offset by a very shallow cylinder head, and a long aluminium walled hole is a lot lighter than a cylinder head full of valves, valve seats, rockers, pushrods & cams.

Conventional 2-strokes have poor mpg because much of the time a lot of the incoming air-fuel mixture disappears straight out of the exhaust port, except when the engine is in its power-band and the pressure waves returning up the exhaust coincide with the port timing to prevent the fresh charge leaving.

With a diesel engine it's not a problem - the fuel isn't injected until all the ports are well closed and the piston is near the top of its stroke, so no fuel is lost.
Large ship 2-strokes achieve phenominal efficiency - up to 40%, compared to about 20 to 25% for a 4-stroke car engine.

[Tamber]

I'd be interested to hear how you stop the sump draining out through the ports; I was dinking around with some (bad) plans for a flat twin 2-stroke with piston porting; couldn't think of anything reasonable. (So now I'm dinking around with some more bad plans for an inline triple. :p (I can dream, can't I? Ah, for want of a home machine-shop. )

[Stuart]

Here's that Yamaha two stroke diesel bike engine
http://worldwide.espacenet.com/publicat ... 7591A&KC=A

http://worldwide.espacenet.com/publicat ... 6997A&KC=A

[Blunt Eversmoke]

Two-stroke? Could run into emission problems burning lube oil. Also you need piston heads with skirts the length of the stroke which would make the cylinders longer.

You might be able to avoid burning your lubrication oil if you don't use crankcase compression, but an external scavenge blower, to get the charge in the cylinder. It does require the extra complexity of a blower/supercharger, and all that goes with that, but if you're already considering supercharging to make up for the lack of displacement it does seem almost ideal.

Of course, as you say, that runs into the issue of the piston skirts needing to be long enough to still cover the intake ports when at TDC, which then means your cylinder needs to be long enough that the piston skirt doesn't protrude from the bottom of the cylinder when at BDC; which results in a rather tall engine.

No-no, port scavenging always leads to some oil burning in the case of intake ports (oil enter cylinder) and, worse, oil exhausting (oil exit through exhaust port as piston ring passes). That's why uniflow scavenging uses exhaust valves and intake ports, mostly.

Oil loss through ports: Dry sumping helps. That way, even crankcase-scavenged two-stroke diesels managed to burn not too much oil (less than oil-mixing two-stroke gassers, for sure).

What you say about length: Only the exhaust ports need to be isolated from crankcase by lower piston ring at TDC so no exhaust gas enters there. Still this is long enough, of course. So here comes: Stepped piston for shorter cylinders and uniflow scavenging:
prototype Soviet fold-up scooter/moped/goped with two-stroke engine; sadly, not diesel. Duh. Pic shows piston with the exhaust-timing smaller piston at its end, complete with exhaust ports. The working piston itself is, as can be seen, very short because of this.

The exhaust-controlling piston protrudes through an opening in the cylinder head and into the exhaust pipe when at TDC. Meaning that the exhaust pipe goes straight out of the top of cylinder head and clearly favors square or oversquare B/S ratios because the exhaust pipe needs to be stroke length before it can be bent.
Sealing is provided by bronze rings on the inside of said opening - "inverted" piston rings of sorts - so as to avoid the need to lubricate said exhaust control piston; working piston head has one compression ring and is otherwise also very conventional, except of short skirt.


In a diesel, a toroidal cylinder space could mean one would have to use IDI with two or more ante-/swirl chambers in the head for more uniform loading of piston head and use of cylinder space.

[Stuart]

I'm currently looking into the idea of converting a petrol engine to diesel.
Petrol engine "big end" bearings are typically 45-50% of the bore diameter, whilst diesels typically have "big end" bearings about 60-65% of the bore diameter. This would suggest you should sleeve down the engine by about 25% when doing the conversion.

Petrol engines typically hit about 1200psig peak pressure during combustion, whilst normally aspirated diesel engines hit about 2000psig. To apply the same force to big end bearings would therefore require a piston area reduction of about %40, i.e. a reduction in bore of about 20%.

Tappy, what you looking into doing & explain above is how Gordon Glover converted his Ariel. He swapped parts putting (I believe) a 250cc barrel on a 300cc bike. This must be possible with so many more machines out there to mix & match parts from.
Maybe we need to start building a database listing bore sizes to aid this kind of conversion. But what's the best way to drive an injector pump? I wonder, would a set of Honda 400/4 barrels fit on a 550/4 for instance?
Can anyone suggest a bigger 4 cylinder bike that has barrel studding holes that matched a smaller 'cousin' of an engine that falls within the realms of Tappy's ratios mentioned above?
Manufacturers always up the capacity of models every year so we're looking for a model that grew by these ratios?

http://m.flickr.com/photos/emscherblues ... /lightbox/

[Blunt Eversmoke]

I'm currently looking into the idea of converting a petrol engine to diesel.
Petrol engine "big end" bearings are typically 45-50% of the bore diameter, whilst diesels typically have "big end" bearings about 60-65% of the bore diameter. This would suggest you should sleeve down the engine by about 25% when doing the conversion.

Petrol engines typically hit about 1200psig peak pressure during combustion, whilst normally aspirated diesel engines hit about 2000psig. To apply the same force to big end bearings would therefore require a piston area reduction of about %40, i.e. a reduction in bore of about 20%.

Tappy, what you looking into doing & explain above is how Gordon Glover converted his Ariel. He swapped parts putting (I believe) a 250cc barrel on a 300cc bike. This must be possible with so many more machines out there to mix & match parts from.
Maybe we need to start building a database listing bore sizes to aid this kind of conversion. But what's the best way to drive an injector pump? I wonder, would a set of Honda 400/4 barrels fit on a 550/4 for instance?
Can anyone suggest a bigger 4 cylinder bike that has barrel studding holes that matched a smaller 'cousin' of an engine that falls within the realms of Tappy's ratios mentioned above?
Manufacturers always up the capacity of models every year so we're looking for a model that grew by these ratios?

http://m.flickr.com/photos/emscherblues ... /lightbox/

Of course, there is also always the option of re-sleeving the cylinders to match a particular piston size.
Edit:
Otherwise, in the vein of your post, I only know of Chinese CVT scooters with engine/CVT/swingarm suspension blocks that usually allow up-boreing without big modifications to the crank and crank bearings. However, I only have data on the 50 ccm engine range - the little critters easily support 80 ccm with same head (increased CR) or 90-100 ccm with bigger heads (same 7.5:1 CR); don't know about the more interesting bigger engines.
Also, Russian Ural/Dnepr boxers come in flavors from 500 to 750 ccm and are known to be modded up to 800(rather commonn) or even 1000(rather rare), but the upper displacement range suffers from crank breakage at "high" (over 5000) RPM and thus usually necessitates reinforced cranks and bearings which are both more or less available on the aftermarket. Say, you buy or have made a crank and bearings for 1000 ccm petrol, go down to 600 or so and install heads from Kubota singles - are they not IDI just like their multi-barrel brethren? -, keep compression low at 16:1 and blow it but good with turbo or supercharger.

[Stuart]

of course. If only I were sitting on a heap of old engines to mess with..

[Tamber]

No-no, port scavenging always leads to some oil burning in the case of intake ports (oil enter cylinder) and, worse, oil exhausting (oil exit through exhaust port as piston ring passes). That's why uniflow scavenging uses exhaust valves and intake ports, mostly.

Oil loss through ports: Dry sumping helps. That way, even crankcase-scavenged two-stroke diesels managed to burn not too much oil (less than oil-mixing two-stroke gassers, for sure).

Aha, both of those make a lot of sense, upon further thought.

What you say about length: Only the exhaust ports need to be isolated from crankcase by lower piston ring at TDC so no exhaust gas enters there.

I was thinking more about pressurising the crank-case (blowing the oil out of seals, perhaps?) and possibly contaminating the oil with anything carried in by the charge air (The worst case being where, say, there were higher levels of boost and water injection was in use. (My stupidity isn't restricting itself to bikes, no. )), in the case of intake ports.

Though, if that's mostly mitigated by running a dry-sump -- since there wouldn't be a large bath of oil for the moisture to contaminate (but I still think it'd present a bit of an oil-contamination issue, even then. Perhaps I'm worrying too much. ) -- then being able to run much shorter pistons due to not requiring the extra length and a sealing ring would definitely be a benefit. Shorter pistons mean less weight, potentially shorter rods, and a shorter engine in general; which would be much more conducive to motorcycle use.

Still this is long enough, of course. So here comes: Stepped piston for shorter cylinders and uniflow scavenging:
prototype Soviet fold-up scooter/moped/goped with two-stroke engine; sadly, not diesel. Duh. Pic shows piston with the exhaust-timing smaller piston at its end, complete with exhaust ports. The working piston itself is, as can be seen, very short because of this.

The exhaust-controlling piston protrudes through an opening in the cylinder head and into the exhaust pipe when at TDC. Meaning that the exhaust pipe goes straight out of the top of cylinder head and clearly favors square or oversquare B/S ratios because the exhaust pipe needs to be stroke length before it can be bent.

Now that's neat. Pretty nifty way of handling the exhaust, though I imagine it's a pig to package if the engine doesn't have a pretty short stroke.
Definitely food for thought, though. Thanks!

[tappy]

Very interesting! Not sure I want to combine it into my designs but definitely food for thought. Clearly piston weight is increased, but with diesel combustion limiting useful revs anyway that's not such a problem. I guess the injector spray pattern and flame spread etc would get quite badly mucked up by such a proboscis in a diesel engine?

[coachgeo]

Elsbitt's original patent is available online. His multi oil fuel engine (primary Rapseed) has a lot built into it to increase atomization of the thicker oils. Thus many ideas can be drawn from it to atomize fuel in engines reworking like ya'll are thinking here. For example I believe it was Elsbitt who had the idea to move the IDI's swirl chamber (the indirect chamber) from being part of the head and put it in the piston top.... AKA a deep cup in the top of the piston surface. Piston w/a cup is seen now in most all diesel engines.

Another engine to look at is to find the discussions on the fellow who made a lawnmower engine highly highly efficient (I forget the fuel.. ... think it was a blend of diesel and gas?) he cut spiraling? groves in the head surface to increase the swirl to help atomize the fuel.

[Blunt Eversmoke]

Aha, both of those make a lot of sense, upon further thought.

What you say about length: Only the exhaust ports need to be isolated from crankcase by lower piston ring at TDC so no exhaust gas enters there.

I was thinking more about pressurising the crank-case (blowing the oil out of seals, perhaps?) and possibly contaminating the oil with anything carried in by the charge air (The worst case being where, say, there were higher levels of boost and water injection was in use. (My stupidity isn't restricting itself to bikes, no. )), in the case of intake ports.

Though, if that's mostly mitigated by running a dry-sump -- since there wouldn't be a large bath of oil for the moisture to contaminate (but I still think it'd present a bit of an oil-contamination issue, even then. Perhaps I'm worrying too much. ) -- then being able to run much shorter pistons due to not requiring the extra length and a sealing ring would definitely be a benefit. Shorter pistons mean less weight, potentially shorter rods, and a shorter engine in general; which would be much more conducive to motorcycle use.

Arrrgh. Serves me right for not reading properly, thinking with my ass and posting dead-tired at the same time. Sorry.
Of course, when using external compressor for scavenging, it IS way better to seal crankcase from the intake ports as well, with a lower ring on longer piston skirt. And it's absolutely NECESSARY when boosting. My mind was kinda stuck on crankcase scavenging for some reason. Yes, you WILL need a longer piston skirt. (All that said, dry sumping still is the favorable way of doing things since it probably lessens the amount of oil burned as opposed to splash lubrication AND, most importantly, prevents engine runaway when piston rings are worn and blow-by into the cylinder occurs.)
Although, with exhaust in the head and an exhaust-timing piston it would still be standard FOUR-stroke dimensions, just look WAY different

Very interesting! Not sure I want to combine it into my designs but definitely food for thought. Clearly piston weight is increased, but with diesel combustion limiting useful revs anyway that's not such a problem. I guess the injector spray pattern and flame spread etc would get quite badly mucked up by such a proboscis in a diesel engine?

Actually, the lil' goped (discovered recently in someone's garage and given to a Jawa enthusiast for restauration) revved its two-stroke quite high and could still higher but was limited by throttled exhaust pipe.
As to the protrusion into cylinder, yes, might prove a problem in a diesel. That's why I would propose two or more antechambers/swirl chambers per head for a diesel of such a design.

[tappy]

Update on this:
While looking into various donor engines that I might one day use to graft 2-stroke top ends onto, I discovered that the big end journals on my Hatz 2G40 are only around 40mm diameter. It seems therefore that the Hatz, Ruggerini & Lombardini twins have a very low ratio of big-end diameter to piston diameter - 40/90 = 45%.
This is the ratio typical on car & motorbike petrol engines, and not typical of car diesel engines.
Any thoughts on why this might be? Does the low-rev ceiling of our "donkey" engines allow weaker big-end bearings? Are the bearings instead much wider than usual?

I'd be interested to hear the big-end diameter and bore diameter of other people's industrial engines...

[Blunt Eversmoke]

Update on this:
While looking into various donor engines that I might one day use to graft 2-stroke top ends onto, I discovered that the big end journals on my Hatz 2G40 are only around 40mm diameter. It seems therefore that the Hatz, Ruggerini & Lombardini twins have a very low ratio of big-end diameter to piston diameter - 40/90 = 45%.
This is the ratio typical on car & motorbike petrol engines, and not typical of car diesel engines.
Any thoughts on why this might be? Does the low-rev ceiling of our "donkey" engines allow weaker big-end bearings? Are the bearings instead much wider than usual?

I'd be interested to hear the big-end diameter and bore diameter of other people's industrial engines...

'Tis strange. It would be explicable if the Hatz were an ante- or swirl chamber design which are reported to put less of a strain on the crank and stuff, but direct injection... Strange, indeed.

Looking into my older-than-me (or somesuch) Hatz E673 EHK I see a really thick crank, about 60% of piston diameter.

I have two talking-out-of-my-ass possible explanations of this:

Either Hatz have stumbled upon a sort of steel that permits cranks of lesser thickness

Or they have through long experiments found out the exact limits of minimal crank thickness, and all other DI diesels are simply over-engineered by these 10% of piston diameter.

[tappy]

The Hatz pistons do have a deep recess in the piston head that the injectors spray into, forming a sort of ante-chamber akin to indirect injection, which may cushion things slightly, but I get the impression that most of our low-revving diesels have a similar arrangement?

[tappy]

On another note,it turns out that the idea I'd had for making a 4-stroke bottom End with 2-stroke top end had already been patented & built by one Bernard Hooper of Hooper Engineering on Shropshire. Well worth a look.
Disappointing to know someone got there first but gratifying to know that my idea works, but unless he fancies helping me make one for his own development reasons I shall instead be going down the roots blower scavenged 2-stroke instead. Still some way of yet as I've got a bike to build first!

[Blunt Eversmoke]

The Hatz pistons do have a deep recess in the piston head that the injectors spray into, forming a sort of ante-chamber akin to indirect injection, which may cushion things slightly, but I get the impression that most of our low-revving diesels have a similar arrangement?

Yeah, almost all modern DI diesels have that deep recess, but it is not really an ante- or swirl chamber - the opening connecting it with the main combustion space is far too wide. See quick pic search for comparison: Here, the lilly nilly bear paw-shaped holes below the valves, somewhat offset to exhaust valve, connect the swirl chamber with the main cylinder space. Compare that to the fat hole in your DI Hatz piston.

These are simply combustion chambers - that way they can be made round (i.e., of ideal combustion chamber shape) versus flat as the cylinder main space. Moving them into the piston instead of the cyl head accomplishes better cooling (with engine oil) in an air-cooled engine.

On your quest for a two-stroke top end: You're Kingdom side, there's tons of two-stroke diesel Foden trucks to scavenge cylinders from, innit? I know (seen on eeh-baaah) at least some the Detroit Diesel two-smokes have separate cylinder shells with ports as opposed to cylinder blocks, maybe the Fodens have a similar arrangement?

[tappy]

Ah, OK - thanks for the background on the piston recesses, it sounds like they exist for several reasons other than promoting good combustion...
On the Foden side of things I've only seen a couple of engines on our *favourite* internet auction site and they were pretty pricey, but I've never just looked for barrels etc so I'll take a shooftie.
I was thinking along the lines of SV1000 / TL1000 crank, with reduced bore. The bore and stroke are pretty close to MZ ETZ301 barrels which are still reasonably available. I suspect that the porting arrangements will be badly wrong for something which is blower scavenged rather than crank-case scavenged but I've got a bit of time to think and see if I drop on anything anyway.
At around the 600 to 750cc engine size there are loads of Aisin R300 (very small) superchargers over in Australia which look pretty useful.

[Blunt Eversmoke]

On the contrary, the recesses are very much for combustion related reasons - less heat loss during the constant volume combustion phase(the most intensive phase) because of a lesser area. (Of course, they also lessen the amount of coke from fuel on cylinder wall and piston rings, as most of the fuel entering cylinder main space will already be burning.)[/quote]

Porting will quite probably be wrong, timing-wise, but this is nothing that cannot be taken care of. I would try and seek cylinders that have your intended bore, but some more than your intended stroke - maybe you could cut off the ported portion of the cylinder and make a wholly new porting arrangement, then. Another possibility is to weld some of the port area shut (probably while increasing it somewhere else if necessary), bore out what sticks into the cylinder, then fine-hone it. I've seen gasser two-stroke cyls where badly over-cut ports have been mended this way. Also, if you go the ante-chamber way, maybe it won't be that wrong altogether, as we all know that IDI engines can rev up almost into gasser RPMs.
As to your concern about the different scavenging method - maybe an increased porting time or increased blower pressure will help with that.

[Blunt Eversmoke]

I quoted a vid of an MT12 engine converted to diesel operation some posts above (or some months before). Now I was able to make contact with the author, a Ukrainian guy named Viktor Kutsenko, and here are the details I could get from him.

Modifications to the engine are not as big as one might have thought. He uses standard Dnepr block, crank, conrods and bearings. No down-boreing!
VAZ piston heads are used in order to increase compression ratio.
Fuel pump is from Mercedes-Benz 123, as are injectors and glow plugs (just something he happened to buy cheaply, he considers Fiat Uno an equal or maybe even better donor of these parts).
Ante-chamber cylinder heads he made himself.
As of now, the engine is installed in a Dnepr bike which is ridden from time to time for testing purposes, but is actually meant for a home-brewn 4x4 ATV, which happens to be the center of author's attention - rather than the engine. Thus, no data on power or revs is available. Bike pulls 60 km/h, but he says he needs to tweak the injection pump so engine may be able of more.

Information on compression ratio and how the heads are made may still follow.

[Blunt Eversmoke]

Oops - typo. MT-10, not 12

More info:

Compression ratio is approx. 22:1, Viktor got it up that high by using VAZ(LADA) 2105 piston heads (they aseem to be same bore as MT-10 ones but taller) and by forming the cylinder heads in an appropriate manner.

Heads are home-made, cast from some sort of silumin - an aluminium-silicium alloy. Ante-chambers are separate, in the form of hemispheres made of some thermo-resistant steel alloy.

I repeat, no further modifications were made to crank, con-rods and respective bearings; thus he says he just hopes nothing breaks Especially the cast-iron crank is kinda worrysome since no re-sleeving in order to down-bore the cylinders has taken place.

Revs and power are yet to be measured, but since he only got 60 kph from a 650 ccm ante-chamber IDI at gearing ratios typical for both the original Dnepr engine and for an ante-chamber diesel, there clearly is a need to tune the injection pump (timing) for higher revs and more power (which is what Viktor says himself).



Bottom line: MT-10 engine of Dnepr bikes seems to be capable to operate as ante-chamber engine with a CR of up to 22:1 with heads and injection assembly being the only modifications. Information on durability and power is not yet available since the bike is only used as a testing platform for the engine and has not clocked any significant distance and the engine has yet to be properly tweaked for its maximum power.

If one were to use a reinforced (forged) crank from later Ural models, let alone replaced its roller bearings with something more appropriate for the task at hand, we can assume with a cautiously moderate optimism that the MT-10 engine of a Dnepr (Dnipro) bike would hold under the higher pressure of an (albeit IDI) diesel engine compressing at 22:1.