Big bore VS Small bore

Well guys, it's been awhile since we had a meaningful chat. We often relate engines, with being air compressors, because of there ability to pump air.

So here is my story problem:

Can a small bore engine (example 1015cc) pump as much air, as a big bore engine (example 1200cc), in the same amount of time? If so, then how? If not, then why?

Are we talking about both engines operating at the same RPM? Ed

in order for the small motor to do it its gonna to have to spin a lot more rpms with same cylinder head and cams.lots of guys like the smaller engines ,i prefer the 1170-1197 motors since they dont have to be wound to 9000 rpms to get em rolling,just crack the throttle at 5000 in any gear and just roll on smooth power! :laugh:

now if the 1075 was built by Larry C,all bets are off! :laugh:

PLUMMEN wrote:

now if the 1075 was built by Larry C,all bets are off! :laugh:

If the head was built by Byron Hines or Jerry Branch or Rob Muzzy, is the bet on? Haha!

I'm thinking all things equal, except bore size.

650ed wrote:

Are we talking about both engines operating at the same RPM? Ed

We are only talking about bore size and time.........

well youre basically comparing an ice cream bucket and a 5 gallon bucket,hope you like ice cream cuz youre gonna have to eat fast! :laugh:

Turbo

Well I don't hear any how's or why's......Turbo doesn't count!

"We are only talking about bore size and time.."

In that case, a smaller displacement engine may pump more air than a larger one. Example, let's say a high tech modern engine like a ZX10R is 1000 cc's (actually 998cc)and redlines at 13,000 RPM (no joke). An unscientific measurement says 13,000 RPM X 1000cc = 13 million cc per minute. If I have a 1200 cc KZ that redlines at 10,000 RPM the same equation 10,000 RPM X 1200cc = 12 million cc per minute or 1 million cc per minute less. Of course, if both bikes achieve the same redline the larger displacement machine will suck in the most air. Or, as Thomas Ed points out, if one has a turbo it wins.


2009 ZX10R

Some quick number crunching:

3 motors - 1166cc, 1075cc, 1015 all w/ 10.5:1 compression

Peak HP RPM of 8200 for the 1166
Piston demand at 75* ATDC 140.2 CFM
@113% Ve - Cylinderhead CFM requirements 123.4 - 129.4 CFM
Average Crankshaft HP@600RPM Accel Rate 135.3


Peak HP RPM of 8800 for 1075
Piston demand at 75* ATDC 140.2 CFM
@113% Ve - Cylinderhead CFM requirements 123.4 - 129.5 CFM
Average Crankshaft HP@ 600RPM Accel Rate 136.8

Peak HP RPM of 9300 for the 1015 motor
Piston demaind at 75* ATDC 140.2 CFM
@113% Ve - Cylinderhead CFM requirement 123.4 - 129.4 CFM
Average Crankshaft HP @600RPM Accel Rate 137.8

This assumes all are cammed and carbureted properly for their intended peak hp rpm

Making peak horsepower is one thing. Making broad, street friendly power is another.

ok so a tz250 and a harley .....ah......or a zxr600rr and 84 kz1100 shaft.......lets see...how about if superman was having a bad day could batman beat him up if they both had the same thing for breakfast....???????.';l][





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