What Is a Cross Port?
 

I was reading in a magazine about two FD racecars out of Japan. One is a champion Time Attack car and the other is a 3 Rotor GT300 Class car. Both cars have cross ported engines. It is supposed to offer more torque and a more flexible powerband. It sounds like a combination of periport and street port.

Anybody know about this type of porting and what is it?

Eric

From getting ahold of Re Amemiya's book on their GT300 car, it's just "plain" peripheral ported. I don't know if they're calling it cross ported since I can't read Japanese, but there's a data point for ya.

Never heard of that term, but it is a peripheral port.

http://www.youtube.com/watch?v=zVyVp9mb9m4

I think I have heard of cross port in reference to the Revolution time attack FD. Is that the one you are talking about? It has a crazy cf widebody and lots of custom tubeframe suspension...used to be all black but now has Hankook livery. Anyways if its that car, their cross port is basically what people on the English boards call semi-peripheral, or basically a small pp. For turbo semi-pp the Revolution guys got it down. For N/A, I believe Mr Judge Ito outta Jersey is da man. Defined Auto off this forum (GtoRx7.) is pretty easily reachable, he has a very cool 20B N/A semi-pp and prices on his website. Your FC is tight, one of the inspirations for me to take the N/A route. Props!

You nailed the cars. In the latest issue of DSport they have articles on both cars. The Time Attack car is a cross ported 13b REW which they describe as a combination of both a Peri Port and a street port to provide more transient response and more power under the curve.

The RE Amemiya Gt300 car has an RE20b NA motor and it has a cross port as well and they attribute this cross porting to adding torque and tractability.

In looking at the RE20b motor it looks like a regular PPort, but with some oddly wide intake runners. I just wonder if it the same concept as guys who are PPorting their motors and leaving the primary ports in place as well?

Pretty interesting stuff.

Eric