jediknight7

i was thinking, porting has the downside of lowering low end torque, espcially a bridge port. but what if a half bridge was done on a six port, but kept it na, and still used the acutators, and then maybe some mild porting on the primaries. any thoughts on how torque and power would be affected? just post your thoughts, or your experiences if you have done this.

RETed

This is what half BP's with the bridge porting only on the secondaries are supposed to do.


-Ted

rotarygod

iTrader: (1)

If you aren't running a standalone ecu such as a Haltech, Mictrotech, etc, you are wasting your time. the porting can work. Just not with that ecu setup. Go look at all the people who try huge or bridge type ports on an n/a with the stock ecu. Not a single one has ever hit over 200 rwhp. Waste of time. Get a new ecu first or just do a mild streetport.

j9fd3s

iTrader: (3)

the full bridge i drove pulled harder under 2000 than my gsl-se. the only thing the bridge didnt do is cruise at part throttle

Andrew.

iTrader: (4)

On the subject of bridge ported na's, what do people use manifold wise when doing a bp? can a s5 na flow enough? or would they have to use a TII manifold or go carb? Thanks

-Andrew

BklynRX7

I may be wrong but I have always been under the impression that a turbo manifold on a n/a would do more harm than good.

BlaCkPlaGUE

Naw man, it makes perfect sense to me. Using a manifold that was designed for forced induction on an NA engine would probably be shitty.

If you port the NA manifold (ive been told that the s4 is better than s5 for flow) and run a standalone, eliminating the afm, and porting out the TB, your going to probably have a good enoughe intake. Carb or self made intake is always the best tho. Short runners with independant throttle bodies would be the best.

White_FC

Thank you for someone else saying this!
I said it on here once and no one believed me that they had low rpm power..

They may not help emmisions but they DO make power... When properly setup at least.

RETed

You know we've gone through this in COUNTLESS threads.
That so-called "increase in power" does not show up on a dyno graph, period.
Therefore, I still stand on my claim that the high overlap from the BP does not make "more power" than an aggressive street port, period.
The dyno graph does not lie.



-Ted

Maxthe7man

No, but comparing apples to oranges does....
Show me a streetported 13b n/a that makes 342 rwhp..
I've seen a full bridge 13b Bp do that in person, and guess what, it was street driven...
You always seem to know alot about Bp's for person that has never built one, let alone even driven one...
In your last comparison you were taking one motor running a turbo half the size of the other, circling one part of the powerband and claiming victory with the disclaimer the sp car would be faster if the race was over at 4000 rpm, are you going to tell us now, that turbo size has nothing to do with power band?
Yes you can alter turbo characteristics to gain power in parts of the power band, but the trade off is larger at each end of the spectrum with the sp compared to a bp, if turbo A is put a sp motor, and makes 600 rwhp, it may not spool to 5000 rpm, doesn't make for a very fun car, knock the turbine size down to improve the spool, and the 600 rwhp peak dissappears as the motor chokes off on the smaller turbine. Take the original turbo A, put on a bp, not only will you make more peak power, but all of a sudden the turbo spools making power when it never made power before on the sp..
I am probably one of a handful of people on this board that have driven a car with the same turbo and gone from SP to BP, and then moved to larger turbo's and actually have seen the results first hand..
Comparing varying dyno charts from different turbo's dyno's motors, and coming up with a definitive answer based on that is pure speculation... Some people's bp turbo's don't work, some don't work till full potential, the main reason being, improper turbine selection, or not enough compressor...Turbo charger selection and like wise exhaust system selection on a n/a is far more critical than it is on a sp, but the rewards are there for the people that stick with it and tune it.. yes its harder to tune and takes some playing to get it to work, but its the way for maximum power on a side port motor....Max

Aaron Cake

iTrader: (1)

When you have ports that are open all the time (ie. bridge), then things change. The stock NA upper and dynamic chamber is designed to take advantage of pressure waves created when the ports close. With a bridge, they never really close, so those waves are not generated. Thus, all the optimization that Mazda has done to the intake system gets thrown out the window.

This is one of the reasons that I am keeping the NA lower, but making a new upper intake patterned after the RE unit.

If you could somehow fit the TII lower manifold and NA upper, you would have some seriously long runners which would be great for low end, but crap up high (where the bridge shines). Of course, you can't physically do this, because the result would be a manifold taller then the hood.

So long story short is that if you are building a bridgeported NA, you need to switch manifolds to get ideal results.

Rotard4life

Aaron, are you talking about the ports closing due to the Rotation of the Sleeves at low RPM, or the closing of the port due to the Rotation of the Rotor?

Because originally I thought that you were talking about the sleeve, which dosn't make sence cause the original post was about Bridging the 5th/6th ports and using working actuators, so they would be closed at low RPM....but then I occured to me that you may have been talking about when the rotor turns and opens the ports....

And I'm going to stop there before I continue this into a ramble.

Aaron Cake

iTrader: (1)

I've referring to the rotor closing the ports. With a bridge, they never really close.

Now, if you only bridge the 5th and 6th ports, they close for a very slight amount of time. Statement still applies though.

Rotard4life

Ok...how much of an effect would that have? especially when looking at the ability to close the ports to control the low RPM torque loss?

White_FC

1, show me a dyno that starts from below 2krpm?
2, are you talking about turbocharged engines here Ted or N/A ones? theres not too many N/A BP dyno's floating around. Point being alot of turbo'd BP use the stock intake manifolding.

...
May i draw you attention to this quote, as quite rightly you state the dyno doesn't lie.
"At the fly we made 180hp 3500rpm, 260hp 6000rpm & 303hp 10200rpm. The injection and serious ignition curve gives the engine heaps of bottom end also."

Show me a street ported engine that can do 180hp@3.5krpm. Hell most can barely put that down at the wheels at _red line!_


the thread I got that from... http://ausrotary.dntinternet.com/for...ra+bridgeports

RETed

Oh, now you're going to start putting RPM limitation here?
How about taking just 4kRPM+???


The specific example was for turbo, but NA should be similar.
HOW MANY BP NA'S ARE IN HERE?
I'd bet there are more BP turbos running around.
You gonna disagree with that too?
This was gone over in detail on NoPistons.COM - I'd suggest go looking for that thread over there.


-Ted

White_FC

no RPM limits here at all, just never seen a dyno run start at that low of an RPM
but if you wanna just talk 4k+ im fine with that.. show me a street port making 180hp@3.5krpm


Similar?! how is it similar? with a turbo motor you have a dirty big turbine housing restricting air flow though the exhaust. Everyone knows and its not disputed that BP's are _very_ sensitive to intake & exhaust systems.

er yes? at least here where i live theres alot more N/A BP's than turbo'd ones.
In fact I can't think of one single turbo BP in the city where i live.

Why not tell me what it said, and give me your dyno proof.
You seemed dammm sure about the dyno not lieing before, so why not post it in here?
I'm as eager to see the proof as anyone else.

RETed

Most people who street their cars run from 2kRPM.
I don't see it unreasonable to talk about power going from that low.



I'm not disagreeing with you on those points, but a turbo motor is basically a percentage increase over an NA motor IN VERY GENERAL TERMS.
The majority of theories that apply to an NA motor can be applied to a forced induction motor.


It was posted on NP, but I can't find it even after searching over the past 15 minutes over there - it might've gotten eaten after the hack a few months ago.

Check the dyno graphs from Wargasm's site.
The graphs are all there.



-Ted

White_FC

I have no problem talking about power generation that low either? it's what im getting at in fact.
Only unfortunate thing is most dyno graphs posted don't have sub 2krpm information.

You can't compare a turbo BP and an N/A one.
One of them utilises an exhaust system than actually scavenges the left over mixture out of the chamber and the other restricts it trying to push it back?
This is much more pronounced at low rpm opperation such as the type we're talking about here.

What is the address to Wargasm's site and what dyno graphs might a find there?
One of an N/A street port and one of an N/A bridgeport?

jediknight7

im not sure why people care so much about sub 2k rpm operation. i drive my stock ported NA daily and i rarely go below 2k rpm, theres simply no power at all. im curious what would happen if i left my engine NA, bridged the 5th/6th ports, and left the actuators in, and perhaps street ported the other ports. im guessing there would be a small drop in low end power, but would it be worth it to bridge the 6 ports or just street port them? also, in terms of porting i think turbos and non-turbos are different in their response due to overlap being compensated for with forced induction etc.