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Just watching this on BBC4 about the dominance of the diesel engine and it's made me wonder why diesel bikes haven't taken off. Is it a weight issue?
SV650rules
23-01-17, 09:11 PM
Just watching this on BBC4 about the dominance of the diesel engine and it's made me wonder why diesel bikes haven't taken off. Is it a weight issue?
It's weight and engine size and complication - same reason diesel aircraft literally did not take off. Petrol engines produce more power than diesels as well (just look at F1) . Diesels do have a limited rev ranges as well, mainly due to the long stroke that is required to achieve 25:1 and greater compression ratio needed to have compression ignition. personally I am glad dirty diesels never made it into bikes, one of the reasons is that you could find yourself sliding off the road on one of your own fuel spills. Diesels are for tractors and HGV.
Diesels also produce horrible pulses that will destroy the gearbox and transmission, the answer was to have dual mass flywheel, a collection of sliding plates and springs held together with fairy dust that fail on a regular basis and cost lots of money to fix.
Ah yes good points, I've been looking at vans and I'm really put off the idea because of all the horrible stories of expensive failures of modern diesels. Seems to me what made diesels great was their reliabilty/simplicity but that has turned on its head with modern efficiency advances
SV650rules
23-01-17, 09:50 PM
Ah yes good points, I've been looking at vans and I'm really put off the idea because of all the horrible stories of expensive failures of modern diesels. Seems to me what made diesels great was their reliabilty/simplicity but that has turned on its head with modern efficiency advances
It is actually mainly the controls and stuff that have been fitted to Diesels to try to control (unsuccessfully) their filthy exhaust that have made them unreliable and expensive to fix.
I think of power as torque x revs (or the size of the bang x the number of bangs per minute) diesels have long stroke (big diameter heavy crank) and limited rev range (not much over 4K for most of them) - petrol has a smaller torque but much higher rev range (most petrol cars will rev to 7K or more now, and as for bikes well we know that they go well over 10K). People get used to the low down torque of a diesel and mistake it for power.
Diesels are gonna find themselves banned from more and more city centres in coming years because of NOX (oxides of nitrogen) and particulates which cause smog and also kill people, buy a diesel today and in a year or twos time you may have a hard time selling it, also diesel fuel prices and VED will go up as governments try to drive them off the road.
Just watching this on BBC4 about the dominance of the diesel engine and it's made me wonder why diesel bikes haven't taken off. Is it a weight issue?
Weight of engine required.
Diesel's primary advantage is that it contains more energy per unit volume. You can go further on a litre of diesel than a litre of petrol.
However bikes rely on being lightweight, so the added weight of a diesel engine reduces this efficiency advantage to pretty much nothing, and would also negatively affect handling and performance.
Then there's cost. A diesel bike would cost a lot more to produce. More metal and more complexity. Then there's marketing. Would you buy a big heavy slow poor handling bike for a lot of money or a GSXR for a lot less?
I think the only diesel bikes that have any practical use are the ones for the American army, and that's because every other vehicle they use runs on diesel, so they had to have special supplies of petrol just for the bikes.
Ernie Dorset used to put Robin Diesel engines into Matchless and I think AJS bikes not so long ago !!
http://www.pricepartmotorcycles.co.uk/
you can get a speed daemon staggering 13hp 456cc. wonder how far you would get on a tank full :-)
i have know about the Indians doing it for years on their enfields.
andrewsmith
24-01-17, 09:30 PM
http://www.pricepartmotorcycles.co.uk/
you can get a speed daemon staggering 13hp 456cc. wonder how far you would get on a tank full :-)
i have know about the Indians doing it for years on their enfields.
Knowing you, lands end to John o groates
Sent from my MotoG3 using Tapatalk
Dave-the-rave
26-01-17, 01:51 PM
http://www.dieselbike.net/BritishRally14/Britishrally14.htm
BanannaMan
27-01-17, 03:38 AM
Then there's marketing. Would you buy a big heavy slow poor handling bike for a lot of money or a GSXR for a lot less?
Ever heard of Harley Davidson motorcycles?
Put some chrome on it and a Harley emblem and there will be Americans on a waiting list to buy one.
Ever heard of Harley Davidson motorcycles?
Put some chrome on it and a Harley emblem and there will be Americans on a waiting list to buy one.
Diesel engines are really ugly though.
Blapper
27-01-17, 04:02 PM
I'm not too sure that a lot of the comments above apply to modern diesels? They are smaller lighter and quieter than ever. The old tech normally aspirated diesels were huge, massively heavy and noisy as hell, but not now. My diesel is the quietest car (even with the windows down) that I've had. The acceleration is far more useful than petrol engined cars of similar displacement and style. I'm a massive fan of over 60mpg from an MPV too. OK, emissions are a problem with diesels, but that's all that bothers me so unfortunately this diesel will be my last.
punyXpress
27-01-17, 05:31 PM
. . and those original diesels ran on peanut oil!
SV650rules
27-01-17, 06:34 PM
If diesel engines are light and powerful why aren't they used in aircraft. Petrol engines produce more power per kg than diesels, the low down diesel acceleration is torque not power, just like sv650 will stay with most i4 or i3 engines up to 60 but after that its goodbye Charlie.
Take the turbo off a diesel and it is pants, put a turbo on a petrol engine and hang onto your hat.
punyXpress
27-01-17, 09:03 PM
'cos on the M4 you can do 67070 mph if you go the right way?
SV650rules
27-01-17, 10:21 PM
'cos on the M4 you can do 67070 mph if you go the right way?
If you travel west to east on M4 your can do 68,070 mph because earth orbits Sun CCW and earth spins on axis CCW (looking down on north pole). No wonder I get wind noise in my helmet.
Talking Heads
28-01-17, 12:59 AM
Aye, diesels are really slow, heavy and cumbersome which is why diesel power has won at LeMans every year since 2004.
Diesels have been used in aircraft, the Germans used them before and during WW2.
SV650rules
28-01-17, 10:39 AM
Diesels have been used in aircraft, the Germans used them before and during WW2.
Probably helped them lose the war - was not too successful or others would have done it - I guess the Germans knew they may become short of oil and wanted to make the most of what was / would be available.
Germans have always pushed Diesel - even though the Japs told them over 10 years ago it was a 'dead end' technology' and for their pains the Japs were not invited to the European emissions panel any more (we are going to take our ball and play down our own end boo hoo) - now Germans have got to get used to using petrol like everyone else, Germans not keen on electric either (can't say I blame them) - A pitiful amount of EV sold in Germany so far - Daimler just closed down its German battery factory and concentrating on ICE.
Le Mans - It is all down to fuel consumption, meaning diesels make less refueling stops - less stops mean a higher average speed - Diesel fuel is denser than petrol and has more energy per litre - an average 'barrel' of crude yields only about 9 gallons of diesel, but 20 gallons of petrol.
There are some companies today fitting diesel engines in small aircraft. but mainly to use in areas where Avgas is expensive or not readily available.
Blapper
29-01-17, 03:31 PM
The torque Vs power thing? Give me instant acceleration torque over screaming power anyday. That's why it's easier to go very fast in normal traffic overtaking situations on a V-twin than it is on a 600 i4. I'm gone before the i4 has finished changing down.
The torque Vs power thing? Give me instant acceleration torque over screaming power anyday. That's why it's easier to go very fast in normal traffic overtaking situations on a V-twin than it is on a 600 i4. I'm gone before the i4 has finished changing down.
That's only cos his powerband is the wrong colour.
Sir Trev
31-01-17, 10:42 AM
Take the turbo off a diesel and it is pants, put a turbo on a petrol engine and hang onto your hat.
I've said this on the Org before - I have a Ford Ecoboost engine and although it does not provide as much mgp as a diseasal it has most of the torque and everyday usable power (don't care about top end). I'll stick with my petrol turbo for now.
Personally I'd prefer to see diseasal limited to commercial and freight use but in reality the push to clean up the emissions by government and the green lobby/public opinion will inevitably result in much better efficiency and improvements in burn and exhaust technology. 50 years ago we all used leaded petrol until someone realised it was poisoning us all and the resulting improvements in compression, engineering precision, anti-knock, etc. have been measurable. Diseasal is a bit behind that curve as it was not common in passenger car use until much more recent times but it is certainly on that curve and is likely to improve very quickly. The tricky bit will be getting the older tech stuff off the streets quicker.
SV650rules
31-01-17, 12:43 PM
The Japs have said publicly that as far as emissions are concerned Diesel is a dead end technology - I have a lot of trust and faith in Japanese engineers, arguably after all If it was not for them we would still be riding BSA Bantams and driving side valve engined cars LOL
My Brother (a dyed in the wool Diesel man of many decades standing) has just ditched his Diesel and has a petrol Skoda direct injection petrol - loves it, said he didn't have any idea that petrol engines had improved so much - biggest problem hs is gonna have is not putting diesel fuel into it - I told him to paint his filler cap green.
Love turbos in petrol cars. My first turbo injected car was in 1987 and all my cars since have been turbo petrols. 120hp, 200hp (approx), 169hp and 208hp. Tha approx is because, unbeknown to me when I bought it, the previous owner had raised the pressure on the boost wastegate, increasing available boost from the turbo.
My 2.0 182 Clio produces near the same mpg (39 best) as our 1.5dci grand scenic with only 106bhp (44) Figure that one out.
My 2.0 182 Clio produces near the same mpg (39 best) as our 1.5dci grand scenic with only 106bhp (44) Figure that one out.
Size. Weight. Shape (wind resistance).
That's assuming all else equal - eg driving style, traffic conditions, efficiency technology of engine.
Size. Weight. Shape (wind resistance).
That's assuming all else equal - eg driving style, traffic conditions, efficiency technology of engine.
So true. My Nissan Silvia had 135hp and looked sleek but it was a heavy car and the most I got out of it was 115mph. On a long run up on an empty motorway.
So true. My Nissan Silvia had 135hp and looked sleek but it was a heavy car and the most I got out of it was 115mph. On a long run up on an empty private motorway in a foreign non-EU country.
Fixed for ya
:smt043
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