86-95 Turbo "Street Porting"
Main Engine Page | Mazdatrix Home Page
Port "timing" in a Rotary Engine is equivalent to cam timing in a piston engine.
To change intake port timing
(as in street porting), the upper edge of the intake port is raised (later
intake closing and longer open duration), and the side is moved slightly
out (it can not be moved very much due to the corner seal and
apex end piece needing support).
To change exhaust port timing, the
upper edge of the port is moved up (later closing) and/or the lower edge is
moved down (earlier opening) which also gives more exhaust
duration.
The port runners also are
worked on.
This was a VERY simple explanation of what constitutes "street
porting"
"Street Porting" began its' wide-spread use back in the 70's. On those early 4-port engines there was substantial amounts to be gained in porting. The intakes could be moved up a bunch, and the exhaust ports required a lot of work due to most of them being quite small.
The majority of the port timing that could be added to those early engines is already built into the 86-95 Turbo engines.
The exhaust ports, and the front and rear intake ports require less time to do than the earlier engines. The center two intake ports do not have very much metal behind them, so the amount they can be enlarged is not very much.
The labor cost to do porting is determined by the amount of time required/spent. Since these 86-95 Turbo engines can not / do not need to be modified nearly as much as the earlier engines, the labor cost is less.
By the same token, do not expect substantial gains in power from "street porting" these engines - it's a worthwhile addition IF the engine is going to be apart anyway, but definitely not worth taking a running engine apart just to street port it.
We still adhere to our engine building policy of not wanting to increase the power of the base "A" level engines (using used rotors and used rotor housings). We therefore will only port "C" level and above, engines.
| Part Number (86-95 Turbo) to Add to your engine order: | |
| Part Number/Cost | Description |
| SV-PORT-STB | Porting of four intake ports and both exhaust ports |
| Other (Partial) Options: for housings sent in, or rebuild of previously ported engine - | |
| SV-PORT-SEXH-TB | Street Port two exhaust ports only |
| SV-PORT-SINT-TB | Street Port four intake ports only |
| 86-95 Street Porting Images | |
|
|
|
|
Also, please remember that any porting is not emissions legal, and may result in your vehicle failing emissions testing.