87 na porting options?
10-08-10, 02:09 AM
#1
Rotor>Piston
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87 na porting options?
I have a 87 na pretty much stock daily driver, lowered 2" has k&n air filter, 3" straight pipe all the way from the stock headers. I am planning on taking the motor out and rebuilding sometime soon due to bad oil rings, while its out I want to have it ported, but which is more reliable, bridge, street, j ported? I love the sound of the bridge ported, but my friend said that is the most unreliable. Any info is greatly appreciated!
10-10-10, 10:02 AM
#2
Out of those options, the J port is the leas reliable. Its a race port only, stay away.
The bridgeport will move your power band into the 7k - 10k range and you will need to use an aftermarket intake manifold and engine controller to do it effectively.
The streetport is going to be the most reliable, and probably what you should go with.
The bridgeport will move your power band into the 7k - 10k range and you will need to use an aftermarket intake manifold and engine controller to do it effectively.
The streetport is going to be the most reliable, and probably what you should go with.
10-10-10, 10:09 AM
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Engine, Not Motor
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Honestly, for 6 port engines, one of the worst things people can do is aggressively porting them (this includes big street ports) without considering the consequences.
Forget j-ports. Not an option for so many reasons (engine life measured in hours, for one).
If you bridgeport a 6 port engine, all that port area makes an engine that is into it's powerband at 9-10K but will be gutless below 5K. This is maybe fine on a race car, but not on the street. Plus you will need a new intake manifold and standalone to make it run properly.
Now, stick to small street ports. Even large street ports will result in way too much port area and the gains will be well out of the area that the stock manifold can support. Suitable street porting templates can be found at Mazdatrix, and you'll see that they only move the secondaries and aux closer to the rotor housings by about 2MM at the most. The primaries are where most of the work is done, simply making them taller but not altering opening timing.
Forget j-ports. Not an option for so many reasons (engine life measured in hours, for one).
If you bridgeport a 6 port engine, all that port area makes an engine that is into it's powerband at 9-10K but will be gutless below 5K. This is maybe fine on a race car, but not on the street. Plus you will need a new intake manifold and standalone to make it run properly.
Now, stick to small street ports. Even large street ports will result in way too much port area and the gains will be well out of the area that the stock manifold can support. Suitable street porting templates can be found at Mazdatrix, and you'll see that they only move the secondaries and aux closer to the rotor housings by about 2MM at the most. The primaries are where most of the work is done, simply making them taller but not altering opening timing.
10-10-10, 01:18 PM
#4
Rotor>Piston
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Thank you for the help, I didn't realize it moved the powerband that high, which would have made it pretty much useless to me as im just looking for a clean daily with some umph... and maybe some sideways stuff ha ha.
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