Bruhman

Why dosen't a 6 port N/A engine build as much HP as a 4 port N/A when modified, such as street porting?
It seems that the 6 port configuation is allready some type of bridgeport from the factory and should flow air/fuel better than a 4 port?
What is the highest horsepower possible out of a 6 port without going with a peripheral port ?

Brett

KiyoKix

IN MY OPINION...you have to tune a 6 port motor differently to get the best results from it. You can't just tune it the same way as the 4 port and expect it to do the samethings. I still believe that it's the better motor all around if it's tuned right (especially the manifold design), but both are great.

KiyoKix

The 6 port actually reminds me quite a bit of a Ferrari engine, the ports are larger than normal (more area), but the manifold design make up for all of that when tuned correctly. It'll provide the best power over a full spectrum instead of just peak power. Very similar to the Ferrari F355 (S4) and Ferrari 360 Modena (S5) intake manifold designs.

SoRRoW

This should be stickied

4 port

silverrotor

iTrader: (1)

Because a 6 port doesn't have a evil snail attached on the side of It.

White_FC

Or maybe because there hardly anymore casting behind the ports so you can't port them out as far as the 4 port blocks.

Bruhman

silverrotor, If you are going to quote me, be sure to do it right. My question was " Why dosen't a 6 port N/A engine build as much HP as a 4 port N/A when modified, such as street porting? " We are talking non turbos here.

skyypilot

6 ports are better than 4

silverrotor

iTrader: (1)

Ya, I know. Just trying to add humor to a question I'm not sure on.

SlimJim

the reason 6 port motors don't make the same power with street porting is the lack of area in the primary ports to really inlarge them,plus the bad flow (shape)of the 5 and 6 ports,plus diffusers in exhaust.All that said I think 200+ should be posible with mild porting and new(pineapple) inserts in 5 and 6 sleaves....Jim

jcina7

HERES A PIC OF ME PORTING THE 6 PORT VERSION OF THE LOWER INTAKE MANIFOLD. more pics will be up later, and i even enlarged the 6 port valves themeslves, and lowered the side of the sleeve opening to sort of advance the timing on it so as it starts to turn over, it'll release air ealier then stock.. ill let everyone know how it works out. also, all other manifolds have been ported and gaskets enlarged to match openings. engine has been ported, so i just figured that doing the manifolds would enhance the overall output.

http://geocities.com/jcinarx7/page20.html?1049648181920

von

I went alot further than that. The secondaries look oval like an egg. Pluss I grinded away that bridge in the lower manifolds to go with my streetport

I also grinded the bridge in the housingings as well to make one large port thats bigger in volume than a 4port bridge so your ansewer is beyond popular believe I think the 6port engine is better for top horspower if you make those two aux ports into one large port. In fact I just got my engine fired up today but cannot drive it until its broken in. Then I will be dynoing it so Ill let everyone know.

rotarygod

iTrader: (1)

This is long and technical.

Both engines are capable of very good horsepower numbers. The 4 port engines can be ported very nicely with good large ports. The single runner per port has good area for good airflow numbers. When you port these engines you design them around a particular rpm powerband and design accordingly as with any other engine. The larger the port the higher the max rpm but the narrower the powerband becomes. The lack of turbulence in the ports themselves are a big contributing factor to its good power.

The 6 port engines are somewhat of an bastard child of rotaries when stock. They have terrible flow through really small ports but there are 6 of them. The rotating auxillary ports have airflow restricting rods running through the airstream. Add this to the terrible brick wall turn at the end of the sleeves and you have lousy flow through those ports. Pineapple sleeves when measured on a flowbench over stock sleeves only show a 1% increase in airflow. This is not saying that they don't work. What is happening is that there is such a big restriction from the intrusive actuator rods and also so much turbulence that the sleeves don't have much of a chance to really be used to their potential. By removing the actuator rods completely (and leaving the Pineapple sleeves glued open) there is a huge increase in flow through these ports. It is a very nice increase above 4000 rpm with a sacrifice below. This rotating sleeve is what makes the 6 port engine so streetable though. The reason they can still be made to have good horsepower numbers despite the flow restrictions is due to the way that air flows through the individual ports. On the outer housings there are 2 ports per plate with 2 individual intake runners. One runner per splits off to two just before the engine block. When the rotor passes over the bottom port and completely closes off this port leaving only the upper port open, all of the remaining air in the intake runner is forced to into the top runner. When this happens the air speeds up as it enters the engine due to the fact that this little runner is only half the area of the inertially moving air that is moving towards it from the intake manifold. This gives the engine an inertial ramcharging effect that the 4 port engines don't have on the top end. Also the 6 port engines have much later timing than the 4 port engine allowing air a longer amount of time to enter the engine. If you can free up this auxillary port and allow more air to enter the gains become more impressive than merely just altering the timing alone.

The real key to good power is in the tuning. We can't forget proper intake manifold design and exhaust length either. Both have their advantages and disadvantages in relation to each other. I have one of each, both streetported. The 4 port is a turbo and the 6 port is about to be a turbo. Its going to be interesting to see which one makes more power in the end. I hope I helped you out without confusing you.

nitroracer

iTrader: (5)

dam sounds like you name says it all... good info man. ill be following vons foot steps so ill take some advice from you and use it.
nick

rotarygod

iTrader: (1)

Its just a nickname

I also port my intake manifolds like some have mentioned above however I do NOT do the egg shape thing. It does take care of a couple of problems but creates some others along the way. I tried the egg shape thing before and while it does give a power increase on the high end it sacrifices in the midrange a little. I completely fill in the secondary injector locations by welding them shut. Then the inside of the intake runner gets ground smooth. New injector bungs are welded on above the stock location to get them out of the airstream but keep them in the relatively same location. I have also put them on the lower manifold where the 6 port actuator rods originally were. The middle manifold has a couple of spots that are then filled in with epoxy instead of being ground out. Its hard to imagine exactly what I'm describing without showing you a picture but I can't get a picture up inside the manifold. Basically this gives all of the advantages of the ported manifold but with retained mdrange power. Average power is what counts not peak power.

I can show you how to mod the manifold much farther if you don't rely on the car for gas mileage or its not a daily driver but too many people always cry about how it can't work. I guess they'll never know!

von

Well I did some of those things but the porting of th emanifold was only for top end power. I only race in the high rpms anyways so midrange is not an issue...Everything I do is for top end like this new porting idea...In fact it idles at 2500 and almost stalz everytime I leave from a stoplight.

Nitro !!! Take whos advice ? Ill tell you what your going to do with your rebuild port job...Your not going to cut the bridge like me. Instead you will just port one aux-port and leave the low end one alone...Then on that ported aux ask Jeff to drill holes on the top of it like a bridge without the bridge. That way you will have the power of a J-Bridge but with low end and good idle and gas mileage. The top end should kick in like boost.

You still wont beat me though. I will have more top end SUCKAAAAA

nillahcaz

iTrader: (2)

your "NEW PORT IDEA" was know as the Godzilla port from one place till they where sued by another that had that name for there D-Port's, and is at lest 5 years old. And what they found out was you make more HP with a ported 4 port motor and its easier to drive. just thought you may want to know be for you make an *** out of your self...

Jimmy325i

Drilling holes rather than making a real bridge causes hella turbulence and probably reduces power over the stock porting.