'Right' cylinder volume
Discussion
300bhp/ton said:
That'll be 197bhp DIN and 151 lb ft. Which is pretty much class leading today and only a few production engines have produced better specific outputs.
Seriously, what 2.0 litre n/a engines produce more power, or even match this today?
In fact, what naturally aspirated 2.0 litre has ever produced more torque??
Toyota 3sge? Seriously, what 2.0 litre n/a engines produce more power, or even match this today?
| GT-86 | 197bhp | 151lb ft |
| EP9 Civic Type R | 197bhp | 145 lb ft |
In fact, what naturally aspirated 2.0 litre has ever produced more torque??
Edited by 300bhp/ton on Thursday 27th August 15:47
Apparently 500cc with a longer stroke than bore is the optimum when combined with turbocharging:
http://blog.caranddriver.com/why-0-5-liter-cylinde...
Hence all the modular engines from practically every manufacturer have 500cc cylinders; BMW, JLR, Volvo, VAG etc.
Does make things boring though.
http://blog.caranddriver.com/why-0-5-liter-cylinde...
Hence all the modular engines from practically every manufacturer have 500cc cylinders; BMW, JLR, Volvo, VAG etc.
Does make things boring though.
ikarl said:
300bhp/ton said:
That'll be 197bhp DIN and 151 lb ft. Which is pretty much class leading today and only a few production engines have produced better specific outputs.
Seriously, what 2.0 litre n/a engines produce more power, or even match this today?
In fact, what naturally aspirated 2.0 litre has ever produced more torque??
Toyota 3sge? Seriously, what 2.0 litre n/a engines produce more power, or even match this today?
| GT-86 | 197bhp | 151lb ft |
| EP9 Civic Type R | 197bhp | 145 lb ft |
In fact, what naturally aspirated 2.0 litre has ever produced more torque??
Edited by 300bhp/ton on Thursday 27th August 15:47
Good engine though.
According to wiki:
https://en.wikipedia.org/wiki/Toyota_S_engine
Best in JDM trim was
| Altezza, Caldina GT | 209hp | 162 lb·ft |
And I think this might have been available in the UK:
| Celica (ST202), MR2 (SW20) | 197hp | 155 lb·ft |
In either case pretty darn close to what the GT86 is making. The only mass production 2.0 I know of to significantly make more is the Honda S2000. Although it made about the same torque, just revved a bit higher.
300bhp/ton said:
Luther Blisset said:
Except no 86 makes the numbers on a dyno.
What kind of dyno?EDIT:
Figures seem fine here:
http://www.ddperformanceresearch.com/forum/viewtop...
I've had mine tested at c. 178BHP calculated @ flywheel (North London Dynos) after ECUTEK race rom flash (Fensport) and 2.5" cat-back AVO exhaust (Fensport).
LordGrover said:
Do you know whether those figures are back-calculated to fly or at the wheels?
I've had mine tested at c. 178BHP calculated @ flywheel (North London Dynos) after ECUTEK race rom flash (Fensport) and 2.5" cat-back AVO exhaust (Fensport).
You can't get flywheel figures from a rolling road. It is 100% impossible. Sadly a trend in the UK is to try and "guess" flywheel figures based on the whp. But it is only ever a guess, sometimes educated, but even then it's still not at all reliable.I've had mine tested at c. 178BHP calculated @ flywheel (North London Dynos) after ECUTEK race rom flash (Fensport) and 2.5" cat-back AVO exhaust (Fensport).
Those figures will be RWHP.
And the link I posted seems to show a lot of reasons why you might get lower figures. Do you know exactly how yours was tested?
And there are simply loads of variables when using rolling roads. Some alluded too in the link, such as what standard they are being corrected to or not. This is a very fundamental thing to understand, because it can have such a huge affect on the final numbers.
300bhp/ton said:
That'll be 197bhp DIN and 151 lb ft. Which is pretty much class leading today and only a few production engines have produced better specific outputs.
Seriously, what 2.0 litre n/a engines produce more power, or even match this today?
In fact, what naturally aspirated 2.0 litre has ever produced more torque??
Is the F4R clio 200 not 197bhp and 159 lb.ft?Seriously, what 2.0 litre n/a engines produce more power, or even match this today?
| GT-86 | 197bhp | 151lb ft |
| EP9 Civic Type R | 197bhp | 145 lb ft |
In fact, what naturally aspirated 2.0 litre has ever produced more torque??
Edited by 300bhp/ton on Thursday 27th August 15:47
300bhp/ton said:
ikarl said:
300bhp/ton said:
That'll be 197bhp DIN and 151 lb ft. Which is pretty much class leading today and only a few production engines have produced better specific outputs.
Seriously, what 2.0 litre n/a engines produce more power, or even match this today?
In fact, what naturally aspirated 2.0 litre has ever produced more torque??
Toyota 3sge? Seriously, what 2.0 litre n/a engines produce more power, or even match this today?
| GT-86 | 197bhp | 151lb ft |
| EP9 Civic Type R | 197bhp | 145 lb ft |
In fact, what naturally aspirated 2.0 litre has ever produced more torque??
Edited by 300bhp/ton on Thursday 27th August 15:47
Good engine though.
According to wiki:
https://en.wikipedia.org/wiki/Toyota_S_engine
Best in JDM trim was
| Altezza, Caldina GT | 209hp | 162 lb·ft |
And I think this might have been available in the UK:
| Celica (ST202), MR2 (SW20) | 197hp | 155 lb·ft |
In either case pretty darn close to what the GT86 is making. The only mass production 2.0 I know of to significantly make more is the Honda S2000. Although it made about the same torque, just revved a bit higher.
I think 500 is seen as the optimum when cost, driveability, reliability and efficiency are all major factors, but when you are looking for all out no compromise performance a wide bore but a really short stroke can give you a lot more power.
Throughout the 90s in F1 the only rule on cylinders was up to 12, but you didn't see a competitive engine with less than 10, even when they went down to 3L in 1995 some teams still opted for v12s, although this fairly quickly proved to be the wrong direction.
Throughout the 90s in F1 the only rule on cylinders was up to 12, but you didn't see a competitive engine with less than 10, even when they went down to 3L in 1995 some teams still opted for v12s, although this fairly quickly proved to be the wrong direction.
Makes me wonder how Mazda ever got this one through...1.8 V6!
https://s-media-cache-ak0.pinimg.com/736x/c5/ff/6a...
This isn't the time or the place for a wankel.
https://s-media-cache-ak0.pinimg.com/736x/c5/ff/6a...
This isn't the time or the place for a wankel.
In 1954 BRM fielded an F1 contender with a 1488cc V16 - so cylinders of 93cc each - less than one fifth the 'standard' 500cc size.
Broadly, for power:
1) the valves live in the head, therefore the wider the bore in comparison to the stroke, the quicker you can get air in and out to fill and evacuate the cylinder
2) the flame front takes time to spread out from the spark plug, which means if the bore is too wide, the edges of the mixture may detonate instead of burning in a controlled manner
- therefore, (1) means you want a high bore to stroke (short, fat cylinders), but (2) means you are better off with more smaller cylinders rather than fewer larger ones.
So with a given capacity, the optimum for outright power is many very small, short-stroke cylinders, because this will allow you higher revs, allowing you to combust more air/fuel mixture per minute (capacity x revs = total airflow) and thus make the most power. Hence the BRM V16 was very powerful (600hp from 1.5L supercharged), although bulky and unreliable.
For efficiency you want low revs to extract more mechanical energy from the combustion, and relatively large cylinders to reduce heat losses through the walls (the surface area to volume ratio is lower for larger cylinders). This is probably why we are seeing economy cars with two or three 500cc cylinders, rather than four smaller ones.
I wonder whether these factors couldn't make even larger cylinders a better bet for efficiency, although I guess Mercedes might be wary of introducing their new flagship limo with a four-litre V-twin engine!
Broadly, for power:
1) the valves live in the head, therefore the wider the bore in comparison to the stroke, the quicker you can get air in and out to fill and evacuate the cylinder
2) the flame front takes time to spread out from the spark plug, which means if the bore is too wide, the edges of the mixture may detonate instead of burning in a controlled manner
- therefore, (1) means you want a high bore to stroke (short, fat cylinders), but (2) means you are better off with more smaller cylinders rather than fewer larger ones.
So with a given capacity, the optimum for outright power is many very small, short-stroke cylinders, because this will allow you higher revs, allowing you to combust more air/fuel mixture per minute (capacity x revs = total airflow) and thus make the most power. Hence the BRM V16 was very powerful (600hp from 1.5L supercharged), although bulky and unreliable.
For efficiency you want low revs to extract more mechanical energy from the combustion, and relatively large cylinders to reduce heat losses through the walls (the surface area to volume ratio is lower for larger cylinders). This is probably why we are seeing economy cars with two or three 500cc cylinders, rather than four smaller ones.
I wonder whether these factors couldn't make even larger cylinders a better bet for efficiency, although I guess Mercedes might be wary of introducing their new flagship limo with a four-litre V-twin engine!
I've no particular view on this. I liked my 3.5 litre Rover V8 (and the current 30cc-smaller BMW), the 2.5 litre Daimler, the 6.2 litre Mercedes-AMG M156, and some stupidly huge American V8s - the gurgle of the littler engines being as appealing as the bassy thump of the big'uns. I love V12s too whether they're a 3-litre Ferrari Colombo or a 7.3 litre Jag or Merc unit. Straight sixes, again, whether a 1.6 litre Triumph Vitesse, a 2-litre BMW or a 4.2 litre Jag... not fussed. I just like nice engines that deliver their power in a linear fashion and make a pleasing noise while doing so. Variety is the spice of life.
Cylinder volume is more than just swept capacity; the combustion chamber adds quite a few cc's to a cylinder's displacement and plays if anything a larger role in getting power/torque/economy than bore/stroke ratio.
For instance, the hemispherical head made famous by Dodge's 426 has superb thermal characteristics owing to it's ability to maximise volume, but minimising surface area. This allows for good heat retention, higher cylinder pressures and hence more power and torque. You can also fit in some large ports, making breathing characteristics equally good. However, with this shape you lack ample squish and swirl zones. This makes for poor fuel/air mixing and thus poor fuel economy.
On the other hand, take a wedge shaped combustion chamber and the thin end of the wedge makes for a brilliant squish point, making combustion easier as temperatures rise through pressure, plus as the squished fuel moves into the fat end of the wedge it swirls and mixes well. The outcome is a good burn and good fuel economy. However, the surface area is quite large for the volume, resulting in poorer thermal retention properties and, you guessed it, lower power and torque outputs.
To say 500cc or whatever is the optimal size is arbitrary analysis. One 500cc cylinder can have vastly different characteristics to another based on combustion chamber design, breathing properties (including exhaust scavenging), injection type and spark positioning relative to the combustion chamber (among other things).
The variations in cylinder displacement amongst manufacturers is testament to this.
For instance, the hemispherical head made famous by Dodge's 426 has superb thermal characteristics owing to it's ability to maximise volume, but minimising surface area. This allows for good heat retention, higher cylinder pressures and hence more power and torque. You can also fit in some large ports, making breathing characteristics equally good. However, with this shape you lack ample squish and swirl zones. This makes for poor fuel/air mixing and thus poor fuel economy.
On the other hand, take a wedge shaped combustion chamber and the thin end of the wedge makes for a brilliant squish point, making combustion easier as temperatures rise through pressure, plus as the squished fuel moves into the fat end of the wedge it swirls and mixes well. The outcome is a good burn and good fuel economy. However, the surface area is quite large for the volume, resulting in poorer thermal retention properties and, you guessed it, lower power and torque outputs.
To say 500cc or whatever is the optimal size is arbitrary analysis. One 500cc cylinder can have vastly different characteristics to another based on combustion chamber design, breathing properties (including exhaust scavenging), injection type and spark positioning relative to the combustion chamber (among other things).
The variations in cylinder displacement amongst manufacturers is testament to this.
Edited by Alias218 on Thursday 27th August 23:04
I was thinking about this the other day as it doesn't make sense to me that engineers would say the optimum capacity per cylinder is x when surely overall engine scale negates an absolute number having much relevance. Meaning that 500cc per cylinder is often where most car engines seem to be and I recall Porsche saying 750cc for their 4 pot (944) was as big as you'd want due to heat management but... The cylinders on a supertanker can be around 2000 litres each!
As above isn't as much about, say, coming in at just under 2l total for tax and dividing by 4?
As above isn't as much about, say, coming in at just under 2l total for tax and dividing by 4?
The nerd in me thinks there must be some relation in 500cc per pot in
The balance between optimum power vs weight of components (reciprocating mass
such as piston & rod). ie, careful thought has gone in to the choice of capacity as
a "best balance" of component mass vs bhp generated.
I do however suspect it is all to do with cost.
I'm pretty sure that BMW were one of the first (if not the first) to standardise 500cc
cylinder capacity across it's passenger car engine range.
Although much blurb about it was citing efficiency I do recall an engineer explaining the production cost savings.
It simply allowed them to use one machine to bore all the blocks (1.5 triple, 2.0 four, 3.0 six) thus saving a tidy sum.
After all, it was easier (and cheaper) for engineers to raise or lower the tune of
the staple 3 litre six with an ecu flash to create 125/325/330 power outputs than
To run two engine lines with different pistons etc etc.
The modern 1.5 triple in different states of tune finds it's way into Mini's, 1/2/3 series
and even into the i8.
Now that's a canny engine production line !
The balance between optimum power vs weight of components (reciprocating mass
such as piston & rod). ie, careful thought has gone in to the choice of capacity as
a "best balance" of component mass vs bhp generated.
I do however suspect it is all to do with cost.
I'm pretty sure that BMW were one of the first (if not the first) to standardise 500cc
cylinder capacity across it's passenger car engine range.
Although much blurb about it was citing efficiency I do recall an engineer explaining the production cost savings.
It simply allowed them to use one machine to bore all the blocks (1.5 triple, 2.0 four, 3.0 six) thus saving a tidy sum.
After all, it was easier (and cheaper) for engineers to raise or lower the tune of
the staple 3 litre six with an ecu flash to create 125/325/330 power outputs than
To run two engine lines with different pistons etc etc.
The modern 1.5 triple in different states of tune finds it's way into Mini's, 1/2/3 series
and even into the i8.
Now that's a canny engine production line !
Willy Nilly said:
What application are you talking about OP? 500cc/cylinder is a big lawn mower, but would be s
t it a lorry.
I was thinking road going (and possibly track?) cars and motorcycles as per the list in the first post.t it a lorry. What size cylinders would be appropriate in a lorry and why?
A rather clever chap by the name of A.C Lovesey had this to say when he was developing the RR Merlin;
"The impression still prevails that the static capacity known as the swept volume is the basis of comparison of the possible power output for different types of engine, but this is not the case because the output of the engine depends solely on the mass of air it can be made to consume efficiently"
"The impression still prevails that the static capacity known as the swept volume is the basis of comparison of the possible power output for different types of engine, but this is not the case because the output of the engine depends solely on the mass of air it can be made to consume efficiently"
Alias218 said:
Cylinder volume is more than just swept capacity; the combustion chamber adds quite a few cc's to a cylinder's displacement and plays if anything a larger role in getting power/torque/economy than bore/stroke ratio.
For instance, the hemispherical head made famous by Dodge's 426 has superb thermal characteristics owing to it's ability to maximise volume, but minimising surface area. This allows for good heat retention, higher cylinder pressures and hence more power and torque. You can also fit in some large ports, making breathing characteristics equally good. However, with this shape you lack ample squish and swirl zones. This makes for poor fuel/air mixing and thus poor fuel economy.
On the other hand, take a wedge shaped combustion chamber and the thin end of the wedge makes for a brilliant squish point, making combustion easier as temperatures rise through pressure, plus as the squished fuel moves into the fat end of the wedge it swirls and mixes well. The outcome is a good burn and good fuel economy. However, the surface area is quite large for the volume, resulting in poorer thermal retention properties and, you guessed it, lower power and torque outputs.
To say 500cc or whatever is the optimal size is arbitrary analysis. One 500cc cylinder can have vastly different characteristics to another based on combustion chamber design, breathing properties (including exhaust scavenging), injection type and spark positioning relative to the combustion chamber (among other things).
The variations in cylinder displacement amongst manufacturers is testament to this.
Makes a lot of sense.For instance, the hemispherical head made famous by Dodge's 426 has superb thermal characteristics owing to it's ability to maximise volume, but minimising surface area. This allows for good heat retention, higher cylinder pressures and hence more power and torque. You can also fit in some large ports, making breathing characteristics equally good. However, with this shape you lack ample squish and swirl zones. This makes for poor fuel/air mixing and thus poor fuel economy.
On the other hand, take a wedge shaped combustion chamber and the thin end of the wedge makes for a brilliant squish point, making combustion easier as temperatures rise through pressure, plus as the squished fuel moves into the fat end of the wedge it swirls and mixes well. The outcome is a good burn and good fuel economy. However, the surface area is quite large for the volume, resulting in poorer thermal retention properties and, you guessed it, lower power and torque outputs.
To say 500cc or whatever is the optimal size is arbitrary analysis. One 500cc cylinder can have vastly different characteristics to another based on combustion chamber design, breathing properties (including exhaust scavenging), injection type and spark positioning relative to the combustion chamber (among other things).
The variations in cylinder displacement amongst manufacturers is testament to this.
Edited by Alias218 on Thursday 27th August 23:04
In short, as with almost everything, it's going to result in a compromise.
It seems like your optimal cylinder size and shape will be dictated by your intended application.
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