Well, seeing how I have lost most knowledge of rotaryness, why not ask some simple questions. I'm going to start a P-Port project and want to know some basics of port timing. When looking at a rotor housing with spark plugs facing left, where is TDC of that housing? I've been tooling around with a housing and trying to figure it out. The figures I have say that on the Mazda Factory Peripheral Port the Intake opens at 86 degrees BTDC, and closes at 75 degrees ABDC, where the exhaust opens at 73 degrees BBDC, and closes at 65 degrees ATDC. What is a simple way to figure all this out, my head is spinning I've used search but came up with a lot of random things that pointed me no where. Any suggestions?

 

Can't answer your question, but where in Michigan are you located?




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Easiest way to find TDC on the front rotor: position the eccentric shaft with the keyway facing the exhaust ports.

 

Kentetsu- I am about 30 miles north of Grand Rapids, 10 miles south of Lakeview, and about the same west from Stanton.

I want to know the position of the rotor in the housing at TDC. I now know that but I am trying to figure out where to place the tube for the P-Port relative to when the intake opens and closes. I am using the Mazda Factory Peripheral Port specs. I just need to visually see where the port will go. The specs are

:intake opens at 86 degrees BTDC
:intake closes at 75 degrees ABDC
:exhaust opens at 73 degrees BBDC
:exhaust closes at 65 degrees ATDC

Also, reading the thread by Scalliwag, the OD of the tube he is using is 2 1/4"
Is this the best way to figure where the port should be for timing or am I making it way to complicated??

 

^ he's not lying.
at the plugs, the rotor face will be as close to the housing as it's going to get - chamber volume is smallest.

 

For the extremely technical type question you are asking, you might want to try posting at www.nopistons.com They have a very good engine building section, and some very qualified people to assist (Judge Ito, and a couple others).

Good luck.


P.S. Web address of local car club is www.furrin.org

 

That's what I thought. I'm just trying to figure placement for my port from the Mazda factory P-Port specs.