yea, you can still take out a bit more from the looks of it.. stick you finger in the water jacket and pinch that area between you finger and thumb and you can sort of guage how much material is left to dig in to..

 

Nice port by Roger Mandiville. back then it was common to eliminate the coolant seal in the bridgeport area. I feel now a day with new style of side housings it's not necessary to eliminate the coolant seal in that area. This 13B-rew engines have huge ports and allow an engine builder to make some serious power with little effort.

 

Ito - I would be curious to hear more on why the new housings eliminate the need to remove the coolant seal when bridgeporting. I was thinking the opposite - that because the groove extends down into the side housing you have less material that you can remove there and still hold the O ring.



The 12a parts I would need would be things like 6mm apex seals. I don't know if any of the other stuff is different - I can't remember...



Jason

 

So Ito, what's the max hp you've seen out of a side ported 13B at around 20psi? I'm looking for a goal to shoot for...

 

Ok, here's the dummy move I made busting through the water passage...circled in red. It's pretty small. thought about welding it and possibly epoxy, but Judge gave me a deal on a plate he had.

 

here's the primary runners...

 

Here's the primary port face

 

...

 

last one...secondary port face. I've decided agains polishing everything to a mirror finish. Just keeping it smooth transitionally with a semi-rough surface finish. Advice from a friend who sold me the replacement front plate :-) I did manage to nick the plate face twice with really small marks...I should just hit those with 400 grit?

 

I am about to do a street port on a six port FC NA engine. It will be my first time and I will use a TII intermediate housing, but no templates. This is what I have learned so far:



1. Gradual port openings / closings allow broader power band and slightly more low-end torque.

2. Abrupt (square) port openings / closings make a more "peaky" power band.

3. The objective of any port job is to allow more airflow through the engine.

4. Overlap causes lower gas mileage, rougher idle and loss of low-end torque.

5. Short duration primary ports (for NA engines) increase low end torque and MPG.

6. Port velocity increases torque (by virtue of inertial supercharging and the tournament effect).

7. Street port shapes must remain within the oil seal, corner seal, and side seal tracks.

8. Port bowl shape is very important and should be shaped like a skateboard ramp.

9. Fuel atomization is very important for HP and MPG reasons (combustion efficiency).



My strategy with my six port NA engine / TII center housing will be:



1. Primary port will remain within a few degrees of stock timing (open a little earlier and close slightly later) but the tail and nose of the port will be extended as far as the water jacket will allow. Port shape will be fairly curved to allow gradual opening / closing, and the bowl and runners will be reshaped.

2. Secondary port will open slightly earlier, limited by the corner seal track, inside will be ground in slightly limited by the oil seal track and the bowl will be reshaped. Port shape will be slightly curved on the opening edge for gradual opening.

3. 5th/6th ports will be kept fairly square in shape, nose will be extended as far as possible, barrier between secondary ports will be kept, inside edge and opening side will be extended as far as possible and finally, pineapple sleeve inserts will be used.

4. Exhaust port will be ground down about 2mm and kept fairly round in shape.





Experienced NA porters, give me your critique if you have the time, I would appreciate any input. The objective of this port job is to have a low 14 sec. NA FC (@ 2400 lbs) that is also a daily driver.



Thanks, this is the best thread I have ever read!