Port opening RPMs

MikeW · 01-18-2003, 10:12 AM

At what engine rpms do the second and third ports open up at?

Tenatively, we thought at 4000 rpms and 7000 rpms respectively. Does anyone have any hard numbers on this?

Maybe the port opening isn't purely determined on revs alone, but also load (throttle position) either adding or subtracting 500 revs?

This is very important, just like where the VTEC engagement is in the Honda S2000, etc.

Thanks

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Buger · 01-22-2003, 09:50 AM

Hi MikeW,

3750 secondary port valve opens
6250 auxiliary (3rd) port valve opens
7250 variable fresh air duct
7250 variable intake valve opens (shorter path timed for dynamic charging at high rpms)

Brian

ggreen29 · 01-22-2003, 02:32 PM

Thanks for the info Buger! It finally gave me the initiative to look through the press kit downloads.

In the previous rotaries (13Bs) weren't the secondary ports always open?

And the press kit says there are 3 (!) injectors per rotor. Do these phase in and where are they in the air stream? The pix seem to show only one injector.

wakeech · 01-22-2003, 11:53 PM

no, on the S4 and S5 13B's, the 5+6 ports opened with an exhaust-backpressure activation system...

that pic is just a schematic of the "jet stream" injection system... it's probably the same setup for all 3 intake ports per rotor...

ggreen29 · 01-23-2003, 11:14 AM

Maybe I've got the nomenclature wrong, but I thought the secondary ports were ports 3 & 4 and always open. It was the auxiliary ports that I thought were ports 5 & 6, that were opened and closed by actuators.

Is it possible that each port in the Renesis has its own injector? 3 ports per rotor, 3 injectors per rotor=>1 injector per port?

Buger · 01-23-2003, 12:02 PM

Hi Ggreen29,

According to Mazda, the auxiliary intake ports on the previous 2nd gen RX-7 were opened and closed by a cylindrical valve operated by exaust pressure.

The 2nd gen RXX-7 had 2 injectors per rotor chamber. The primary injector was in the intake passage next to the primary intake port. At high rpm and high load conditions, the secondary injector is used to provide additional fuel [edit - to the secondary port].

The renesis has 3 injectors per rotor chamber and it would make sense that each one would be placed by one of the 3 intake ports per chamber. The huge difference in the amount of fuel needed between 700 rpm and 9500 rpm is the reason for multiple injectors. 2 or 3 smaller injectors that work as needed are much more efficient that one very large injector.

Brian