That's really fun, thanks! That's what it feels like too. It "ramps up" torque faster than my 22r and pulls harder, longer.
Must be the "square" bore and stroke design. I can't wait to see the numbers when you throw some cams at it.
Hey H8PVMNT,
If you are interested, here's a glimpse of some of what has taken me 100's of hours of reading, research, self-educating to better understand these little engines..... I'm still a very long ways from an engine builder, but learning new "stuff" every day.
I was playing with the 20R last night. I ran into a different issue while looking at the results when changing from the stock cam to several of the cams I've tried in the past for the 22s. I also changed to a larger cfm intake and exhaust.
What's was initially puzzling to me is the torque numbers drop? Since the internal combustion engine is really a big air pump, typically, when we improve flow (bigger cam, larger exhaust, more fuel and intake cfm) we improve the numbers - torque and HP.
Because this software is very sophisticated I've had to spend more time in the analyze and reporting feature to see what is causing the drop.
Here's and example of one section out of multiple pages of the Analysis Report on a stock 20R engine with 261C cam, DT header, 2" exhaust with free-flow muffler, Weber 32/36 carb:
"Maximum Exhaust System Backpressure 'Exh Pres' is .5 PSI.
This is low for a street vehicle with a full exhaust
system. This is simulating either an extremely free flowing exhaust
system or open headers or open exhaust manifolds. This may be
illegally loud for street operation."
"Minimum A/F Mixture Quality 'A/F Mxtr Qlty' is 63.3 %.
This is Very low and represents a real power loss in your
desired operating range. This can be improved by reducing intake
runner sizes, carb size, going to fuel injection, heating the intake,
increasing compression ratio, going to a lower octane fuel (the
program assumes high octane fuel has lower Reid Vapor Pressure and
therefore does not atomize or mix as well), smaller plenum, etc."
"The Inertia tuning of this intake is tuned to 5475 RPM,
which is close to your 'Desired HP Peak RPM' of 5000 RPM.
Since this RPM is about where the HP peak should occur, peak HP
should be good. If you specify longer and/or smaller diameter intake
runners, you will likely gain Peak Torque and lose some Peak HP."
Although this program may not produce the exact numbers for a given set of factory engine specs, it is very accurate at analyzing and then reporting on "changes" from a baseline. In other words, if Toyota's factory publishes the brake torque and HP for my 1986 22RE at 116 HP at 4800 RPM, and 140 lbs of torque at 2800, the program may not necessarily indicate the same numbers. Why? Well, how do we know under what conditions Toyota tested that engine? But, if change the intake and exhaust valves from factory stock to engbldr's over-sized valve option in the RV head, the program will accurately analyze that change... laws of physics and history data.
I'l do some more research. It may be that a stock 20R, as designed by the Japanese auto engineers, is limited to modifications to improve power by the smaller valves and flow??
So..... this leads me to understand why, as reported by guys, that the 20R head on a 22R block improves the performance over a 22R head on a 22R block?? I'm probably just missing something real obvious.
Gnarls.
