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Old 07-10-2018, 07:36 PM   #30 (permalink)
Ecky
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Join Date: Dec 2011
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ND Miata - '15 Mazda MX-5 Special Package
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Quote:
Originally Posted by Daox View Post
Do you have a torque/hp graph for both engines? That would help show what kind of loads you'll be at cruising.
Yep.

K24Z7 is ~170ft-lbs torque peak, ~205HP on paper, redline is 7000rpm.

K20Z3 is 139ft-lbs torque peak, ~197HP on paper, redline is 8000rpm.


Sample K24Z7:


Similar K24A2:


Sample K20Z3:


Similar K20A2:



Both motors have basically flat torque curves. The smaller motor would have a slightly shorter top gear (I doubt I'd bother switching that). With the Insight's stock tire size:

Stock engine - 1705rpm @ 50mph, 66 ft-lbs of torque and it cruises at approximately 50% load. So let's say it takes very roughly ~35 ft-lbs to cruise at 50.

K20 - 1680rpm @ 50mph, ~120ft-lbs torque, around 25-33% load
K24 - 1647rpm @ 50mph, ~140ft-lbs torque, around 24-28% load

Taller gearing, longer stroke, but lower load...

Last edited by Ecky; 07-10-2018 at 07:42 PM..
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