The Heart of a Record Breaker: Enter the SR15VET 20V


je pistons, sr20vet, sr15vet

Finally, a promising young engineering tech named Joe Popovits, designed the piston crown as part of a fun, personal development type project. Using my input on piston to valve clearance and then 3D scanning the combustion chambers with a Hexagon Romer Arm, Joe came up with this rather trick piston crown design through a series of design iterations.

romer absolute arm
There is a certain sense of satisfaction that comes from knowing that you helped people grow both as a person and a professional. And this sense of satisfaction cannot be dampened by any amount of Office Space shenanigans. It was my pleasure to work with such talented and passionate team… but please allow me to digress (quickly) from this personal tangent.

K1 technologies connecting rod
Maybe next time, we should use the even longer F20C connecting rod from K1 Technologies?  

Ultimately, the combination of the 5.636″ long K1 Technology connecting rod and decreased 2.500″ stroke would result in an impressive rod ratio of 2.25:1. Perhaps the next time around we'll try out the much longer Honda F20C rod, which would yield a rod ratio of 2.41:1 and a much shorter, modern piston height of 1.040″. I'm honestly not too sure if this high of a rod ratio would be a benefit or a detriment in terms of performance. Is there a point when a rod ratio is too high? I would imagine so, but where is that point for our engine?

To help compensate for the loss of displacement, the MotoIQ H.N.I.C. (head nerd in charge) Mike Kojima offered up a super rare, high flowing SR20VE 20V cylinder head that he had stashed away in storage. The SR20VE 20V was the last iteration of the SR head that Nissan would produce before finally doing away with the SR engine family. The 20V designation had nothing to do with the number of valves in the cylinder head (it still had 16 valves). What “20V” means is irrelevant. What's important is the improvements that the 20V head brings to the game.

The 20V cylinder head was the very last of the SR20 heads designed by Nissan. According to Nick Hunter of 5523 Motorsports, much improved flow came as a result of the 20V's unique intake flange (mouth) profile and the port design itself, which moved the divider walls closer to the valves. The intake flange of the intake manifold also divorced the injector tip from the intake runner unlike previous iterations of SR20 cylinder heads. In doing so, cleaner flow through the intake runners was achieved.

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