So, I bought a few books and downloaded some software to sharpen up on engine performance; Performance Automotive Engine Math - John Baechtel and Engine Analyzer v3.4 by Performance Trends. Pretty cool stuff if you're a nerd like I am.
Anyways ... I think I've developed a pretty solid plan for this engine build. In short:
- BC Stroker Kit
- 83mm 11.1 Pistons
- Rather than boring the block, I'll just get 83mm Darton sleeves.
- Toda 264/256 (10.3/9mm lift) cams
- BC Valve Springs
- Headwork (obviously)
After talking with oldskewltoy I think I'm going to pass on using the oversized valves. Besides the massive cost increase to be able to use them, I'm after torque and mid-range power and based on all my little experiments, the benefit of using the oversized valves would be marginal. The biggest thing I had to determine was what cams to use. That's where my little research/experiment started.
I tried my best to simulate (key word:
simulate. This whole thing is only a
simulation) a stock 16v bigport 4AGE motor on this engine analyzer software. They have 4age block data already, but not the heads so I had to manually input that data. This is the best
ESTIMATE I could get:
According to wikipedia lol, stock jdm 4age is 126hp @ 6600 rpm, so this is close enough I guess.
Here's the simulation settings:
(The software measures everything in standard only. So f*cking annoying)
Head Specs:
- Intake valve diameter: 30.5mm
- Exhaust valve diameter: 25.5mm
- Avg Port Diameter and Volume was calculated using the software (65mm width, 30mm height, Rounded Rectangle Shape)
- Port Length: ~95mm (this is a
rough estimate. I just eye-balled it using a little scale, measuring from the intake port to the chamber)
- Flow Efficiency. The 1999 Honda B18 example head they have loaded measured an intake efficiency of 79% and exhaust efficiency of 76%. I arbitrarily picked 75%. Both heads have 16 valves.
Cam specs: I stole this from the Bill Sherwood page,
http://www.billzilla.org/4agstock.htm.
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Now that I had a reference point, I plugged in my stroker kit and camshaft values:
I arbitrarily increased the efficiency from 75% - 85%.
After inputing my cam specs, I let the software choose the "optimized" centerlines to yield Max Average Torque.
Which led to the following:
I'll be spending most my time between 4k and 8k, so this figure looks pretty good. With a peak at 211hp, this would put me in the 160whp range which is perfect for me.
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While you're here .... (you're still reading this?)
Its really easy to spend hours trying out different combinations of specs and seeing how it affects your power output, especially camshafts. For example, Duration vs Angle vs Timing.
Here is a comparison between the Toda Cams I've picked vs Tomei Poncams; Set TA301-TY01C (306/290 angle and 11/10 mm lift). Both sets of Centerlines are "optimized" for Max Average Torque; Toda = Retarded 2 degrees, Tomei =
Advanced 9.5 degrees.
Here is a comparison with the Tomei Poncams Advanced 9.5 degrees and 0 degrees straight up:
Obviously the Poncams would give me more "power". Nearly 240hp at the crank sounds good on paper, but it peaks at 9k. This car isn't some N2 spec time-attack monster, so i'll never even see that 240hp. If anything, it will drive like absolute ass around town!
Here's a comparison of the 1.8L motor with the fat poncams versus the bone stock 16v:
Below 4500 rpm, the stock 16v makes more power Lol.
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A little comparison between stock valves and oversized valves. This plot is using the camshafts I picked above, Toda 264/256 with 10.3/9mm lift.
Run 1 = 2.0 Retard (max avg torque) - Yellow/Purple
Run 2 = 6.5 Retard (max peak HP) - Light Blue/Red
Run 3 = 7.5 Retard (max peak HP) - Blue/Green
So ... yeah, this turned out to be longer than I expected! What do you guys think?
(If I'm wrong about anything or missing key details, please let me know!!)