von

Ok im opting for a 6port bridge port so I can have same low end and emmisions as stock yet having semi bridge horsepower up top. My idea is as follows

After looking at the ports for awhile I found out that the secondary ports allow the faster velocity flow of air for low end power. Stock engines have the Auxilaries open at 35-3800 rpms for top end power.

Now suppose I only bridge the Auxilary Port and not touch the Secondary port. Then I match the 6port sleeve with the bridge by cutting a hole in the sleeve. so when the sleeve opens it reveals the bridge hole in the housing. Then I can decide to open the auxilaries allitle later. Im sure my emissions testing will pass no problem since they only rev to a max of 2500 rpms...

Something you may ask is that to make power you have to have other mods to benifit the semi bridge port. I can put on a stock exaust in like 20 minutes so that wouldnt be a problem to pass emissions. Small intake modifications shouldnt be a prob either.

Now my personal beef on this would be the reduced diameter of the port because of the sleeve my reduce the volume of air coming into the engine on the ported side therefore not taking advantage of th eport size. But I would not know exactly.

I think I would have to take the area of both holes on the sleeve(output side) and add them together and see if it comes out to the same area of the intake side of the sleeve
but I think im missing something here because the intake sides volume would be half the output side of the sleeve. (the end part) but thats my guess just from looking at it. What im saying is no matter how big the output side is with the extra bridge hole I would not see any benifit because the input side is so damn small.

? anyone?

Alex-7

Anybody done this? I've been wanting to for years.

Lets hear some testimonials or opinions.............................




--Alex

SirCygnus

iTrader: (1)

nope wont work

Alex-7

Why not?

totallimmortal

von whats your car run now, the one described in your sig that is

rotarygod

iTrader: (1)

The biggest problem with this type of porting is that both of these outer ports share the same intake runner. The length of this intake runner is set to provide a horsepower peak with both ports open at around 6500 rpm or so. This length is not based solely on rpm as some suggest but is also determined by port timing. When you alter the port timing, you also alter the length necessary for the intake runners to tune the engine to the same rpm. With an auxillary only bridgeport, when the port opens up at higher rpms, your intake tuing will be all out of whack with the primary port tuning rpm. This will be counterproductive at this point to power. If you were to bridge all of the ports the same, you'd roughly keep the tuning between all the runners the same and their effects wouldn't fight each other.

If you were to use a new intake manifold that gave all of the ports their own runners as in the Renesis, you could theoretically make this setup work as each runner length would be tuned to it's particular port.

You also run into the problem with the fact that the auxillary ports don't flow very good. On a flowbench even the Pineapple sleeves have only been shown to increae flow by about a cfm. That's because although the end lack of radius on the stock sleeve is terrible for flow, it isn't the biggest hinderance in this port. The rod that rotates the sleeves runs right through the middle of the airstream. This creates a ton of turbulence and really hurts flow. Regardless of this the 6 port engines can still make some good power. This is because as the rotors rotate and start to close the intake ports, they will completely close the bottom port first. Remember that all of the air in the intake manifold has inertia and has a tendency to keep moving in the same direction. Since this column of air can no longer flow into the bottom port, it speeds up and forces itself to all flow through the top port and in essence ramcharge more air into the engine. This offsets the poor flow in terms of power but it is done based on intake velocity.

When the ports are opening however, we don't have this column of air with it's inertia trying to force it's way into the engine. The very small bridge in the auxillary port will be trying to pull in air past this turbulent actuator rod without any aid. It won't do it very well on it's own.

All of this adds up to why the people that have tried it really haven't had very good luck. The stock ecu doesn't help either. It can theoretically be made to work. It just isn't as easy as it seems.

Alex-7

DAMMIT.....................And thank you very much^^^

von

Well with the mods in the sig on a stock port/stock ecu I got a 9.8 1/8 on a glazed clutch. I had to let off the gas twice to grab when shifting into second. It was capable of low 9's or aprx low 14's. It was my first run and didnt burn out using the 555r's so it was pretty cold.

I made 160rwp stock ports and ecu. After that I put on a light flywheel, ported tb and more SAFC tuning. I never knew where the timing was which was probably why the engine poped This thread might be a couple years old. That car is long gone. I will be starting the same project again someday when I get back to the states but mabye with a 2nd gen renisis.

von

Alex-7,

I have seen my mechanic do bridge ports by drilling holes across the top port instead of the normal bridge. I asked if this would create turbulence because of the smaller area the air has to push through but he mentioned since it was turboed that it would not do that ? I didnt get back to him on the results but if it worked I would assume half bridge power with street port reliability??

My originally posted idea regardless of what rotorygod says would make more power up top but might ? require a stand alone ecu to work because of the port timing and also. I personally think its a good idea and poeple on this forum have done it. I mean your not going to get like 500hp but you would get a kick up top I'm sure.

rotarygod

iTrader: (1)

You'll definitely require a standalone ecu. Show me one person who has done it on the forum who has gotten higher numbers than any other type of conservative street porting. There isn't anyone. I'm not trying to be an ***. It's just the truth that this style of porting doesn't work like people think it would. Neither does hogging out the outer ports into one large port. As with anything, both systems CAN be made to work. They just can't do it with the stock ecu OR the stock intake manifold.

Alex-7

Von,

I've heared of the holes driled thing refered to as the cheese port in the first gen section, with good results I might add. I've had na FCs before and always loved the idea of doing something with the secondairy ports to keep things driveable yet absolutley manic at the top end. I'm with you, I think this could be made to work (at least as an improvement over a pure street port) so I hope Somebody looks into it, and lays the way for us.



Thanks for starting the thread I was about to start,

--Alex


PS. anyone elses input is welcome.

jhammons01

RotoryGod, good job explaining, I learned allot. I had the sam thoughts about those 5/6 ports.

rotarygod

iTrader: (1)

FWIW: Several years ago I built an engine like this. I didn't know much back then other than the very incorrect "bigger must always be better". I didn't have a custom intake manifold and I still had the stock ecu. Mine didn't work either. I was baffled until a few years later when I learned how air flows through this engine. Now I own a flowbench and can actually test these things. I've learned that there are many things that don't necessarily behave like you think they "should". It's strange and humbling sometimes.