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Cylinder size limitation

Cylinder size limitation

Cylinder size limitation

Hi Friends
What are all parameters limit the size of the gasoline engine engine cylinder? Upto what power levels single cylinder engine can be developed?


RE: Cylinder size limitation

There's really no hard limit.  Everything is a compromise.
In favour of fewer cylinders: cost, package size, maintenance, possibly weight, possibly efficiency.  In favour of more cylinders: specific output, smoothness, acoustic quality, drivetrain mass/inertia (due to reduced torque pulsation), more flexibility with turbocharging integration.
The above is a partial list and for every item there are probably exceptions.

RE: Cylinder size limitation

When the cylinder size goes up, the maximum revs go down, and the size of the flywheel necessary to keep it running at an acceptable idle speed goes up exponentially and so do the measures necessary to keep vibration under control. No hard limit as noted, just a varying set of compromises that are different in each application.

In motorcycle applications, single cylinder engines are common up to 600 - 700cc or thereabouts, but rare beyond that.

RE: Cylinder size limitation

They've got single-cylinder engines out there with bore size >280mm, but not gasoline (as far as I know).

I seem to recall a textbook on combustion describing a size limit related to mixing of the charge, propagation of the flame, or quenching at the OD.  Can't remember.  Not a very practical limit if you're talking about car-size engines, but probably worth considering if you're looking at a few hundred mm bore.


RE: Cylinder size limitation

The largest spark ignition I could find being made currently was the Wartsila 50DF. It has a 500mm bore, 580mm stroke, and maximum speed of 514rpm. I wouldn't be surprised if there were larger bores used in some of the early stationary engines though.

I agree with IvyMike that the flame propagation speed is probably the limiting factor, with a direct relation on the maximum engine speed. I though that maybe you could use multiple spark plugs but I wondered if that may cause multiple pressure waves to collide creating a knock?


RE: Cylinder size limitation

Yes, if you want to really delve into the theory, there are a bunch of other factors to consider.

The length of the stroke and the maximum RPM are linked by piston speed and acceleration limitations. It works out that almost regardless of the scale of the engine, the mean piston speed at maximum rated engine revs will be somewhere in the 20 m/s range - perhaps a little more than that for high performance applications (25 - 27 m/s for Formula 1 cars and some high performance motorcycle engines) and a little less than that for applications where durability and longevity are prime importance. So, if you know the RPM range that you desire to operate at, you can pick where in the piston speed spectrum you want to operate and thus find the stroke of the engine. Or vice versa, whatever works out for you.

The other consideration is the bore / stroke ratio because this affects the proportions of the combustion chamber. It takes time for flame to go across the chamber and if it's too close to the cylinder walls it can be quenched. Most production automotive-scale engines fall in a range where the bore is 80% - 150% of the stroke. Formula 1 car engines are in an extreme range where the bore is more than twice the stroke, but it's only like that because the rulebook is dictating some of the constraints and physics (piston speed) is dictating some of the others, and they pay very careful attention to combustion chamber shape and spark plug location. If you go to high performance motorcycle engines, the 1000cc class normally has four cylinders, and some of the big 1000cc V-twins (notably Honda RC51) are thirstier than the four-bangers - possibly in part because the high revs and wide, flat combustion chamber shape aren't as favourable.

If you have a horsepower target you can figure out the plausible range of RPM and engine displacement, and from that (and whether you are looking for durability or outright performance), the plausible range of stroke length can be estimated, and from that you can find a plausible combination of bore / stroke ratio and number of cylinders. There will generally be multiple possibilities that are plausible, but for anything in an automotive/motorcycle scale, a 2 litre 1-cylinder is not going to be in the plausible range, but nor will a 100cc 8-cylinder ...

RE: Cylinder size limitation

regardless of the scale of the engine, the mean piston speed at maximum rated engine revs will be somewhere in the 20 m/s range

That's commonly said (especially in textbooks), and it's reasonable for car engines, but it doesn't seem to hold up if you calculate rated mean piston speed for a wider variety of engines.  Examples:

MPS (m/s)    Engine    stroke (mm)    @    rated rpm    reference
7.1    model aircraft EVOE0360    18    @    12000    link
7.6    EMD 16-645F    254    @    900    link
8.4    EMD 16-710G3B    279.4    @    900    link
8.7    model aircraft Y.S. 170DZ     31    @    8500    link
9.0    Cat C280    300    @    900    link
9.7    wartsila 50DF    580    @    500    link
9.8    Detroit DD15    163    @    1800    link
9.8    Cat C11    140    @    2100    link
10.0    Cummins B3.3    115    @    2600    link
10.0    Deutz F6L413W    130    @    2300    link
10.1    Cummins QSK50    158.75    @    1900    link
10.2    Caterpillar C7    127    @    2400    link
10.9    Cat C9    149    @    2200    link
11.3    Cat c32    162    @    2100    link
11.4    Cat 3512B    190    @    1800    link
11.6    Deere 6135H    165    @    2100    link
11.6    Navistart Maxforce 13    166    @    2100    link
11.8    Cummins ISX    169    @    2100    link
12.0    MTU 4000    190    @    1900    link
17.4    GM LXV I4 gasoline    81.5    @    6400    link
19.2    GM LJ3 I4 diesel    96    @    6000    link
19.8    Honda D16A    90    @    6600    link
23.4    Honda S2000    84    @    8300    link
24    BMW S54B32     91    @    7900    link
25.1    Formula 1    40    @    19000    link

RE: Cylinder size limitation

The larger the cylinder the more difficult it is to control detonation. And why in the days of the recip aircraft engines cylinder size was optimized and to increase power more of them were added.  

RE: Cylinder size limitation

ivymike, your post is very interesting.
I think an additional factors that should be included when comparing mean piston speed across diverse applications is the ratio between nominal operating rpm (e.g. cruising rpm for automotive applications), and peak rpm.
I suspect that passenger cars and motorcycles will exhibit the highest ratio between nominal and peak rpm, with commercial vehicles in the middle, and stationary powergen applications a ratio of 1:1 (i.e. nominal rpm = peak rpm) or at best 1.2:1 (1800 rpm vs 1500 rpm), maybe 1.33:1 (1500 rpm vs 1200 rpm).

RE: Cylinder size limitation

I am really surprised by the Honda D16 as I have one.

The design is well over 20 years old and has cast pistons and has a relativly short rod and mine is pretty second hand, but original and has 400,000 Km on the clock.

I am boreing and stroking it to 1800cc as part of the rebuild. It will get better rods and rod bolts and forged pistons, but I am now seriuosly rethinking raising the redline and rev limiter at all.

I am now more serious about raising the deck and using longer rods if I can buy longer sleeves and get a longer timing belt. I can easily make a head plate to accommodate the longer sleeve.  

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RE: Cylinder size limitation

An IHRA pro stock engine with 5.75" stroke(146mm) and an 8500 rpm redline then dwarfs the F1 engine with 41.4 m/s.

RE: Cylinder size limitation

"An IHRA pro stock engine with 5.75" stroke(146mm) and an 8500 rpm redline then dwarfs the F1 engine with 41.4 m/s."

Of course you need new rods every 4 miles or so. winky smile


RE: Cylinder size limitation

They would have to come down a lot if an engine had to last 2 race weekends like F1.

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