Diesels odd, petrols even. Why?
Discussion
following on from torque vs. bhp...
Does anyone know why petrol engines are almost all even numbers in capacity (1.4, 1.6, 1.8, 2.0 etc.) when diesel engines are usually odd (1.5, 1.7, 1.9, 2.1 etc)?
it seems that categorising engine type through capacity would be a rather weak reason for dictating something as important as engine capacity, which is the only reason i can think of..
Does anyone know why petrol engines are almost all even numbers in capacity (1.4, 1.6, 1.8, 2.0 etc.) when diesel engines are usually odd (1.5, 1.7, 1.9, 2.1 etc)?
it seems that categorising engine type through capacity would be a rather weak reason for dictating something as important as engine capacity, which is the only reason i can think of..
Know what you mean, but not necessarily the case any more. The latest generation of Audi and BMW diesels for the masses are 2.0 lumps.
However, it is my understanding that due to the compression ratios that you need on a diesel engine you need to have a pretty solid engine block (which is why they are almost always cast iron blocks. Therefore they need to be pretty 'square' for bore and stroke to even out the power delivery.... this means that a engine tends to be of a unusual shape (also to keep them lighter and squarer or the engine bay).
Also do note that the Audi and Merc engines are derivatives of cylinders. The 2.2 is a 4 while the 2.7 is a 5 (work it out - its a 2.2 with an extra cylinder) - same goes for the Audi 1.9 and 2.5 engines...
However, it is my understanding that due to the compression ratios that you need on a diesel engine you need to have a pretty solid engine block (which is why they are almost always cast iron blocks. Therefore they need to be pretty 'square' for bore and stroke to even out the power delivery.... this means that a engine tends to be of a unusual shape (also to keep them lighter and squarer or the engine bay).
Also do note that the Audi and Merc engines are derivatives of cylinders. The 2.2 is a 4 while the 2.7 is a 5 (work it out - its a 2.2 with an extra cylinder) - same goes for the Audi 1.9 and 2.5 engines...
mikeylad said:
pdv6 said: 3rd time lucky
Having computer problems?
the mother of all computer problems.
thanks for noticing. i'll take it that grin is sympathy...
think i've cracked it now pvd6. i've picked you up and dropped you back in here, and deleted t'other!
ps. where was the third?!
Because you sample size is too small.
If you extend the range you will see that the corellation fails and the distribution between i.c and spark engines is fairly even.
PS. Diesels tend to be designed with a long stroke rather than square as suggested in an earlier post. By their very nature diesels tend to rev slower negating the advantage of a square or over square engine. There are exceptions though and in the auto world nothing is cast in stone.
If you extend the range you will see that the corellation fails and the distribution between i.c and spark engines is fairly even.
PS. Diesels tend to be designed with a long stroke rather than square as suggested in an earlier post. By their very nature diesels tend to rev slower negating the advantage of a square or over square engine. There are exceptions though and in the auto world nothing is cast in stone.
gnomesmith said: Because you sample size is too small.
If you extend the range you will see that the corellation fails and the distribution between i.c and spark engines is fairly even.
PS. Diesels tend to be designed with a long stroke rather than square as suggested in an earlier post. By their very nature diesels tend to rev slower negating the advantage of a square or over square engine. There are exceptions though and in the auto world nothing is cast in stone.
and not much is cast in iron these days either ...
Just being contrite: 
1.0 Daihatsu diesel
1.1 Fiat petrol
1.2 Vauxhall diesel
1.3 *everything* petrol
1.4 Peugeot diesel
1.5 Alfa petrol
1.6 Ford diesel
1.7 Alfa petrol
1.8 Ford diesel
1.9 Peugeot petrol
2.0 BMW Diesel
2.1 Ford petrol
2.2 Mercedes diesel
2.3 Honda petrol
2.4 Isuzu diesel
2.5 BMW petrol
2.6 Rover diesel (remember them? yuk)
2.7 Honda petrol
2.8 Mitsubishi diesel
2.9 Ford petrol
3.0 BMW diesel
1.0 Daihatsu diesel
1.1 Fiat petrol
1.2 Vauxhall diesel
1.3 *everything* petrol
1.4 Peugeot diesel
1.5 Alfa petrol
1.6 Ford diesel
1.7 Alfa petrol
1.8 Ford diesel
1.9 Peugeot petrol
2.0 BMW Diesel
2.1 Ford petrol
2.2 Mercedes diesel
2.3 Honda petrol
2.4 Isuzu diesel
2.5 BMW petrol
2.6 Rover diesel (remember them? yuk)
2.7 Honda petrol
2.8 Mitsubishi diesel
2.9 Ford petrol
3.0 BMW diesel
pdv6 said:
pbrettle said:The 2.2 is a 4 while the 2.7 is a 5 (work it out - its a 2.2 with an extra cylinder)
(2.2/4)*5=2.75
Saying that, the 2.2 is probably more like a 2158cc or something, which would work...
Actually:
2148 - 4 cylinder
2685 - 5 cylinder
Maths works perfectly - just rounded up to keep it simple.
trackdemon said: Just being contrite:
1.0 Daihatsu diesel
1.1 Fiat petrol
1.2 Vauxhall diesel
1.3 *everything* petrol
1.4 Peugeot diesel
1.5 Alfa petrol
1.6 Ford diesel
1.7 Alfa petrol
1.8 Ford diesel
1.9 Peugeot petrol
2.0 BMW Diesel
2.1 Ford petrol
2.2 Mercedes diesel
2.3 Honda petrol
2.4 Isuzu diesel
2.5 BMW petrol
2.6 Rover diesel (remember them? yuk)
2.7 Honda petrol
2.8 Mitsubishi diesel
2.9 Ford petrol
3.0 BMW diesel
You have too much time on your hands..
trackdemon said: Just being contrite:
1.0 Daihatsu diesel
1.1 Fiat petrol
1.2 Vauxhall diesel
1.3 *everything* petrol
1.4 Peugeot diesel
1.5 Alfa petrol
1.6 Ford diesel
1.7 Alfa petrol
1.8 Ford diesel
1.9 Peugeot petrol
2.0 BMW Diesel
2.1 Ford petrol
2.2 Mercedes diesel
2.3 Honda petrol
2.4 Isuzu diesel
2.5 BMW petrol
2.6 Rover diesel (remember them? yuk)
2.7 Honda petrol
2.8 Mitsubishi diesel
2.9 Ford petrol
3.0 BMW diesel
i know there are exceptions... (if i didnt before i certainly do now...) but there is definitely a correlation in 'normal' engines. (below, say, 2.5)
M@H said:
Mr E said: My family have a VW Golf 1.9TDI and a VW Polo 1.4TDI.
Same engine. The Polo is simply missing a cylinder......
Of what size exactly.. ? you've got a .5l difference... now I'm confused...
Matt.
Pretty sure that's a rounding error, as described above....
1.4 is 1422cc
1.9 is 1896cc
Spot on.....
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