Rub20B

By the looks of it, it would be easy doable using 2 setscrews at the 10 and 2 o'clock position to hold them in place, or as an extra insurance

RotorMotor

iTrader: (5)

One last question... do those coolant passeges get filled with epoxy or no? All the other semi-pp's I've seen (if I remember correctly) had those passages filled. Thanks

GtoRx7.

iTrader: (12)

Hmmm indeed....

After a triple step machined sleeve is pressed in, its completely impossible for it to move. Setscrews would be redundant for sure. But you are free to add them if you wish!

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.

j9fd3s

iTrader: (3)

after thinking about it, the combination port (what mazda called it), actually should be letting you have the port timing of a street port with the port area of a full PP.

which means you should be able to get big power, like the PP, but at lower peak rpm...

peejay

Every time I look at a diagram of a "combination port", it just looks like a bridge port to me. Odd.

ultimatejay

iTrader: (1)

Alot of top drag racers are using a full bridge with the semi p turbo setup. I would like to see how that would work out with a N/A car.

bhop

iTrader: (1)

^ This is true... As for N/A, I have little experience as there is so much more detail that goes into an N/A setup...

j9fd3s

iTrader: (3)

more port area with less overlap!

rotarygod

iTrader: (1)

A peripheral port has less overlap than a bridge. Look at a housing with a rotor in it and you'll see what I mean. Pay attention to when each is fully open. I know you have at least one lying around!

ultimatejay

iTrader: (1)

Now that sir depends on how big your pports are.

Not in this case.

Rub20B

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..

rotarygod

iTrader: (1)

How do you figure p-port size has anything to do with it?

GtoRx7.

iTrader: (12)

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

peejay

There's a big fat "well....." in that.

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.

rotarygod

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.

peejay

...this is the exact opposite of what you wrote above, and more or less what I was saying. Just FYI.

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.

Oh yes it does! Or maybe, semantically, bridge "depth" has everything to do with it.

- Pete (Lay it on the ground? We don't want to measure length, we want to measure height!)

ultimatejay

iTrader: (1)

Really?

Well, peejay explained it in his post. It depends on how big the bridge eyebrow is
and port timing. If you have a huge diameter pport then the overlap is going to be higher, especially if it has an earlier opening.

Narfle

iTrader: (16)

There's more than one way to skin a cat, gentlemen.

dj55b

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

GtoRx7.

iTrader: (12)

Cool, at that length you are very similar to the shortened 13b-re intake I run. Let me know when you are ready, header production is going to be starting in the next 1-2 weeks.

dj55b

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.

GtoRx7.

iTrader: (12)

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

dj55b

iTrader: (2)

Is there anyway you can PM me a phone number to contact you through?

rotarygod

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.

ultimatejay

iTrader: (1)

You said in the first quote above that pport has less overlap than a bridge and in your second quote youre saying the opposite. That is what me and peejay are debating with you. Did you make a typo????