Didn't someone make 217 Dynojet WHp using an RE on the 'evil forum'
I was pretty sure that the RE was the best flowing manifold (when stock). Polishing runners decreases the boundary layer thickness in the runner, which effectively increases the cross-sectional area. I have seen visualizations (dust in air, etc.) with a significant boundary layer of 0.25 inches. This decreases the equivalent diameter to 1/2 inch less.
My stock Primaries were 1.1" minimum effective diameter, based on the surface finish they would have a 0.17 - 0.2 " boundary layer, giving a dynamic effective diameter of around 0.75"
My stock Secondaries were 1.375 minimum effective diameter, giving me about 1.0" dynamic effective diameter. This means that I had a dynamic cross-sectional area of about 1.25 in2
With a 400 grit polished surface, I have a 0.03" Boundary layer (using simplifications of eddy generation) This means that my 1.3" effective diameter Primaries have a 1.24" dynamic effective diameter, while my 1.63" Secondaries have a 1.57" effective diameter. This gives a dynamic cross-sectional area of 3.14 in2. Matching these to 2.95 in2 dynamic cross-sectional area (combined) intake ports (80 grit polished) gives a near-optimal combination (slight increase in velocity after fuel mixing).
Ports that are too big are actually worse for NA power than slightly small ones (loss of velocity will cause poor fuel mixture, causing uneven charge distribution, uneven and incomplete combustion.
Some rough on the inside of each bend is good. (Maximizing turbulence on the inside actually improves air distribution in the runner). My LIM is not balanced, nor are the runner lengths any where near optimal (3300 rpm Helmholtz, 18,000 Sonic). Which is why I want to build a 9" runner intake for my engine.
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HA! That's ballsy for an engine that's so pristine I would have to build an entirely new exhaust system and I seem to be getting overloaded with projects this winter. Altough, I think the RE mani would be the best suited for an N/A - least amount of bends.
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Just stick a stock exhaust manifold and 2-feet of slightly bent pipe (to minimize clean air reversion to the wideband) on your engine and run it, that will give you as much power as a full exhaust with headers (Dave might not appreciate the sound). I really want to see what you make, so that I can compare my calculations with some real numbers.
DISCLAIMER:
Actual numbers for my engine have been obtained using careful measurement of the cross-sectional area of the intake runners on my manifold. All other numbers are a result of my interpretations of complex formulas, personal experience with 4 and 2 stroke piston engines, advice/suggestions from competant friends and research into this field (SAE papers, books, etc.).
I am not sure that any of the knowledge applies to rotary engines, which is why I have undergone this process, to determine if it does.
So far these NA piston engine rules of thumb have been validated:
Peak power at 0.9L = 13.3:1
Peak torque at 38 degrees BTDC
Torque is function of VE (up to 6,000 rpm, anyway).
NA piston engine Rules of thumb yet to be validated:
If Torque is not linear function of VE, ignition timing or intensity is suspect
Around 9.0:1 CR, torque increases about 8% per full CR increase (8.5:1 - 9.5:1).
My personal theory about Port overlap being unnecessary on a rotary engine as 270 degrees of duration is possible without it is yet to be validated.
SECOND DISCLAIMER:
Please don't misunderstand my continued abuse on late intake port closing. For a turbo application, it is ideal, as it allows additional boost while maintaining equivalent peak compression pressures.
I don't offer much advise to turbo engine builders, as I have very little experience with turbo cars, Snowmobiles, Small block and big block Chevy, Small block Ford, Small block Chrysler, Type 1 - 4 Volkswagen beetle, etc. is where I have experience.