I just thought I would ask the question, is there any definitive long term reliable information around about motorbike diesel engine performance tuning? Things like turbos, superchargers, blowers, injector and other engine mods that modify engine performance - hopefully for the good! Especially regarding single cylinder engines, since they are quite popular with experimenters and people here.
For some time, I've seen quite a few "Let's see what happens attempts", but with very little long term real world experiences to go on, whether they improve or reduce engine performance over a long period of time, engine running, and how they affect engine life and reliability - do they shorten it at the expense of extra power and increased top speed? plus effects on fuel economy.
Quite often I've seen information/posts about diesel engine mods, that add quite a bit of cost, complexity and some weight to the engine, but sometimes after a couple of years (at least!) there's no more follow up information about them, whether they were successful or not, and sharing their experiences with everyone. In some cases the engine set up/motorbike might not be running or exist any more!
The reason why I ask this, is that new or good condition diesel engines are relatively expensive, and it's quite a risk "To go into the unknown" with a serious engine modification. That' why some 'modders' end up using old spare engines found lying around, or bought very cheap and hope for the best!
Look forward to some interesting comments/information and ideas about it all.
Diesel engine performance mods - definitive info out there?
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old clunker
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Diesel engine performance mods - definitive info out there?
There's nothing like the smell of burnt vegetable oil in the morning!!
1971 Royal Enfield diesel running on diesel/biofuel.
1971 Royal Enfield diesel running on diesel/biofuel.
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HondaJohn
- I luv the smell of Diesel...
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- Location: Upstate New York
Re: Diesel engine performance mods - definitive info out there?
I can't speak for long term reliability, because I only finished the engine mods this past fall and have put a few hundred miles on it since. The build was written up here:
viewtopic.php?f=31&t=1891
and only applies to the L70 Yanmar and its knockoffs, but I added stronger valve springs from here:
http://www.compgoparts.com/Pages/145/Fl ... rings.aspx
p/n GP961-2 with the original tappets and pushrods, and I reset the engine's redline to 4000 rpm. That was one of the earliest mods, and I have 800 measured miles on the engine with no strange noises or bent pushrods, although I haven't checked for wear on the cam or followers yet.
I also added a supercharger made from an air pump, running about 6.5 pounds of boost at peak, and brought it to a dyno shop for testing. The results are near the bottom of page 2 on the topic above, and I saw a 1hp increase across the power band, as well as a 0.5hp peak increase. Since it makes a measured 6.5hp at the wheel, with slightly knobby and under-inflated Dunlop K70's, then I've estimated the new hp rating at 8 hp at the crank, about a 20% increase in usable power.
Also, reducing pumping loss through the intake and exhaust. The castings used were very rough, so it pays to file off any burrs or ridges to cut down on flow restrictions, as well as carefully port matching the intake and exhaust manifolds to the head. I also found that most of the engine sound is actually INTAKE noise, because the bike got significantly quieter when i added the supercharger, so a high flow, unobstructed exhaust with sweeping curves is an excellent addition. The less power an engine uses to overcome its own internal friction and air flow restrictions, the more is available at the crank.
viewtopic.php?f=31&t=1891
and only applies to the L70 Yanmar and its knockoffs, but I added stronger valve springs from here:
http://www.compgoparts.com/Pages/145/Fl ... rings.aspx
p/n GP961-2 with the original tappets and pushrods, and I reset the engine's redline to 4000 rpm. That was one of the earliest mods, and I have 800 measured miles on the engine with no strange noises or bent pushrods, although I haven't checked for wear on the cam or followers yet.
I also added a supercharger made from an air pump, running about 6.5 pounds of boost at peak, and brought it to a dyno shop for testing. The results are near the bottom of page 2 on the topic above, and I saw a 1hp increase across the power band, as well as a 0.5hp peak increase. Since it makes a measured 6.5hp at the wheel, with slightly knobby and under-inflated Dunlop K70's, then I've estimated the new hp rating at 8 hp at the crank, about a 20% increase in usable power.
Also, reducing pumping loss through the intake and exhaust. The castings used were very rough, so it pays to file off any burrs or ridges to cut down on flow restrictions, as well as carefully port matching the intake and exhaust manifolds to the head. I also found that most of the engine sound is actually INTAKE noise, because the bike got significantly quieter when i added the supercharger, so a high flow, unobstructed exhaust with sweeping curves is an excellent addition. The less power an engine uses to overcome its own internal friction and air flow restrictions, the more is available at the crank.