Semi p-port n/a 20b results and discussion. 421rwhp
#78
Yes they get filled with epoxy. The sleeves I am sure would hold the seal on their own, but a little extra sealant never hurts.
#79
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 31,130
Received 2,792 Likes
on
1,977 Posts
We have built a full p-port engine for a customer, but never did a entire setup. Or a full p-port engine for myself. Not to step on toes or sound even remotely arrogant, but there are two types of full p-ports. Ones that are street focused, idle/drive more smoothly, and are not so loud. These are the same engines that do not produce "outstanding" power. Many are below, or maybe a touch higher than what we have done with street ports. Then there are the loud, rougher idling, un-friendly light throttle full p-port engines. These are ones that have the tune correct (exhaust/intake), and produce excellent power. And I know exactly why. Full p-port cant have both. They are incredibly sensitive to all regards of tuning. Pick one or the other. This is why I am focused on semi p-ports. We can get 96% of the power from the best track only full p-ports, but still have the drivability and quiet exhaust of a streetport. Win/win
which means you should be able to get big power, like the PP, but at lower peak rpm...
#83
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 31,130
Received 2,792 Likes
on
1,977 Posts
#86
Exhaust Manifold Leak
Overlap shouldn't be a bad thing if you are only focussed on a certain rpmrange where you're exaust length is tuned well, to minimize the internal egr ratio..
#88
Only thing that is hard to correct in the semi p vs. full p is the frictional area. Two side ports, and one p-port has alot more surface area in the runners that causes friction for air. Thus increasing pumping losses. For this reason i am not sure a semi p-port can FULLY get the torque of a P-port. But I sure as hell am going to try Now onto the power peak. Either a full p-port or semi p-port can have a power peak at 6k if you want. Its all about the intake length and exhaust length. 13b and 20b aviation engines are full p-port (for power and gas mileage) and have their peak power at 6.5K
Last edited by GtoRx7.; 12-16-10 at 11:19 AM.
#89
Old [Sch|F]ool
Bridge ports and peripheral ports technically are opened by the apex seal, but the bridge port is influenced by the side of the rotor, moreso the less housing relief you do.
At any rate... the bridges that I've done do not open super early like a lot of people seem to do. On the T2 I did, the port window was maybe 2/3rds the height of the port runner.
#90
Rotors still spinning
iTrader: (1)
I know good and well when each port opens. All peripheral ports open when the apex seal crosses their lower edge. No part of any bridge port that doesn't cut very severely into the rotor housing is open at this point and if you find one that somehow is the total amount of port area open at that point is always greater on the peripheral port. The exhaust hasn't even started to close yet when a peripheral port starts to open.
Bridge height has very little to do with when the port opens.
Bridge height has very little to do with when the port opens.
#91
Old [Sch|F]ool
I know good and well when each port opens. All peripheral ports open when the apex seal crosses their lower edge. No part of any bridge port that doesn't cut very severely into the rotor housing is open at this point and if you find one that somehow is the total amount of port area open at that point is always greater on the peripheral port. The exhaust hasn't even started to close yet when a peripheral port starts to open.
On my peripheral port, there was a period of 20 or 30 degrees when both ports were completely and exclusively open to the same chamber.
On the other hand, the ports were both facing a wall of rotor face with VERY minimal actual airflow possible (and here we get back into the theories/arguments for best port angle) so really it is moot.
Bridge height has very little to do with when the port opens.
- Pete (Lay it on the ground? We don't want to measure length, we want to measure height!)
#94
Banned. I got OWNED!!!
iTrader: (2)
Just going back to where I was ... I measured it to 7.5" that including the 1/4" spacer, between the throttle body, and the manifold, along with the throttle bodies, and the velocity stacks.
So adding in the about 10.5" that I was told from racing beat for the secondaries (remembering that primaries are about 0.5" shorter), plus another 1/2" spacer that I added between the upper and lower manifold, in total I'm at:
18" for Primaries
18.5" for Secondaries
I guess my original measurement of 18" was pretty much dead on
So adding in the about 10.5" that I was told from racing beat for the secondaries (remembering that primaries are about 0.5" shorter), plus another 1/2" spacer that I added between the upper and lower manifold, in total I'm at:
18" for Primaries
18.5" for Secondaries
I guess my original measurement of 18" was pretty much dead on
#95
Just going back to where I was ... I measured it to 7.5" that including the 1/4" spacer, between the throttle body, and the manifold, along with the throttle bodies, and the velocity stacks.
So adding in the about 10.5" that I was told from racing beat for the secondaries (remembering that primaries are about 0.5" shorter), plus another 1/2" spacer that I added between the upper and lower manifold, in total I'm at:
18" for Primaries
18.5" for Secondaries
I guess my original measurement of 18" was pretty much dead on
So adding in the about 10.5" that I was told from racing beat for the secondaries (remembering that primaries are about 0.5" shorter), plus another 1/2" spacer that I added between the upper and lower manifold, in total I'm at:
18" for Primaries
18.5" for Secondaries
I guess my original measurement of 18" was pretty much dead on
#96
Banned. I got OWNED!!!
iTrader: (2)
How close is that length to the effective tuning length of the SDJ header out of curiosity? Also do you know if your headers extend further than the SDJ headers? The reason that I ask is because that would mean having to relocated quite a few things ... which wouldn't be easily feasible.
#97
How close is that length to the effective tuning length of the SDJ header out of curiosity? Also do you know if your headers extend further than the SDJ headers? The reason that I ask is because that would mean having to relocated quite a few things ... which wouldn't be easily feasible.
#98
Banned. I got OWNED!!!
iTrader: (2)
Not very close. I was guessing your intake was shorter. But that is really good news however, it means a bigger gain in power has a greater possibility. Our header would have runners 14" longer than the SDJ you are running now. So yes it would extend further under the car. However, I can make the header wrap up more in the engine bay so the resulting collector will end up where the old one did. It would be more expensive to accomplish though because it will be using mostly all bends. So that is your call
#99
Rotors still spinning
iTrader: (1)
Trust me on this one. A bridge can not have an equal amount of open area as early as a comparable p-port unless it cuts so far into the rotor housing that it essentially becomes a p-port.
#100
Eats, Sleeps, Dreams Rotary
iTrader: (1)
If you have even a large bridge, and lets say that a quarter of a square inch is open at a certain port overlap period while a peripheral port at that same rotor location has about half of it's area open, which one technically opened first is completely moot as the open area is totally different. The peripheral port will always have more area open than any bridgeport at the same given timing unless the p-port location is very high up and is very small. You never see that though. In piston engine terms each one could technically begin to open at the exact same point but the ramp speed of the p-port is far more aggressive. Imagine a camshaft with a profile that has a very sharp ramp up and is then flat on top and then ramps back off at an extreme rate. Then compare that to another cam that technically opens and closes and the exact same point but the ramps of the cam lobe are gradual on the rise and downward sides. Cam timing is the same but they are not equal. The more gradual one could even have a longer duration and still not be equal.
Trust me on this one. A bridge can not have an equal amount of open area as early as a comparable p-port unless it cuts so far into the rotor housing that it essentially becomes a p-port.
Trust me on this one. A bridge can not have an equal amount of open area as early as a comparable p-port unless it cuts so far into the rotor housing that it essentially becomes a p-port.
Thread
Thread Starter
Forum
Replies
Last Post
Turblown
Vendor Classifieds
12
10-17-20 03:25 PM