Stroke ratio
Oversquare engine examples: WP:UNITS says to use a space between the value and the symbol. Needs references, as per WP:RS. Trimmed A-Series stuff - readers can go to the A-Series article for details. Correct link to A-Series article.
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Oversquare engines (a.k.a. "short stroke engines") are very common, as they allow higher [[Revolutions per minute|rpm]] (and thus more power), without excessive piston speed. |
Oversquare engines (a.k.a. "short stroke engines") are very common, as they allow higher [[Revolutions per minute|rpm]] (and thus more power), without excessive piston speed. |
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Examples include both Chevrolet and Ford small-block V8s; the [[GMC V6 engine#478|GMC 478]] V6 has a bore/stroke ratio of 1.33. The 1.6 litre version of the [[BMW N45]] gasoline engine has a bore/stroke ratio of 1.167. |
Examples include both Chevrolet and Ford small-block V8s; the [[GMC V6 engine#478|GMC 478]] V6 has a bore/stroke ratio of 1.33. The 1.6 litre version of the [[BMW N45]] gasoline engine has a bore/stroke ratio of 1.167.{{cn|date=April 2026}} |
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[[Flat engine|Horizontally opposed, also known as "Boxer" or "flat", engines]] typically feature oversquare designs since any increase in stroke length would result in twice the increase in overall engine width. This is particularly so in [[Subaru]]’s front-engine layout, where the steering angle of the front wheels is constrained by the width of the engine. The [[Subaru EJ engine|Subaru EJ181 engine]] develops peak torque at speeds as low as 3200 rpm. |
[[Flat engine|Horizontally opposed, also known as "Boxer" or "flat", engines]] typically feature oversquare designs since any increase in stroke length would result in twice the increase in overall engine width. This is particularly so in [[Subaru]]’s front-engine layout, where the steering angle of the front wheels is constrained by the width of the engine. The [[Subaru EJ engine|Subaru EJ181 engine]] develops peak torque at speeds as low as 3200 rpm.{{cn|date=April 2026}} |
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BMC produced the |
BMC produced the the 1071 cc and the 970 cc [[BMC_A-series_engine|A-series engines]] in the early 1960's, both being oversquare with shorter stroke crankshafts than the 1275 cc versions. The 970 S being the rarest of all A series engines was produced to win the 1000 cc touring car championship of the time, which it duly did.{{cn|date=April 2026}} |
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Nissan's RB, VQ, VK, VH and VR38DETT engines are all oversquare. Additionally, [[Nissan SR engine#SR16VE|SR16VE]] engine found in [[Nissan Pulsar]] VZ-R and VZ-R N1 is an oversquare engine with {{convert|86|mm|in|2}} bore and {{convert|68.7|mm|in|2}} stroke, giving it {{convert|175|-|200|hp|kW|-1}} but relatively small torque of {{convert|119|-|134|lbft|Nm kgm}} |
Nissan's RB, VQ, VK, VH and VR38DETT engines are all oversquare. Additionally, [[Nissan SR engine#SR16VE|SR16VE]] engine found in [[Nissan Pulsar]] VZ-R and VZ-R N1 is an oversquare engine with {{convert|86|mm|in|2}} bore and {{convert|68.7|mm|in|2}} stroke, giving it {{convert|175|-|200|hp|kW|-1}} but relatively small torque of {{convert|119|-|134|lbft|Nm kgm}}.{{cn|date=April 2026}} |
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Extreme oversquare engines are found in [[Formula One]] racing cars, where strict rules limit displacement, thereby necessitating that power be achieved through high engine speeds. Stroke ratios approaching 2.5:1 are allowed,{{efn|There is no actual restriction on bore:stroke ratio, but cylinder bores are limited to {{convert|98|mm|in|2|disp=or}} and capacity to {{convert|2400|cm3|cuin}}.}} enabling engine speeds of 18,000 rpm while remaining reliable for multiple races.{{cite web|title=2011F1 Technical Regulations|url=http://argent.fia.com/web/fia-public.nsf/2B2B158DE64879C7C12578C0004B1DF6/$FILE/2011_F1__TECHNICAL_REGULATIONS_30-06-2011.pdf|publisher=FIA|access-date=21 July 2011}} |
Extreme oversquare engines are found in [[Formula One]] racing cars, where strict rules limit displacement, thereby necessitating that power be achieved through high engine speeds. Stroke ratios approaching 2.5:1 are allowed,{{efn|There is no actual restriction on bore:stroke ratio, but cylinder bores are limited to {{convert|98|mm|in|2|disp=or}} and capacity to {{convert|2400|cm3|cuin}}.}} enabling engine speeds of 18,000 rpm while remaining reliable for multiple races.{{cite web|title=2011F1 Technical Regulations|url=http://argent.fia.com/web/fia-public.nsf/2B2B158DE64879C7C12578C0004B1DF6/$FILE/2011_F1__TECHNICAL_REGULATIONS_30-06-2011.pdf|publisher=FIA|access-date=21 July 2011}} |
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