4port v.s. 6 port
07-19-04, 10:06 PM
#1
The thing
Thread Starter
4port v.s. 6 port
Ok, I just baught an 84 gls se with a 13b 6 port. Whats the differance in performance and capability of 6 v.s. a 4 port. As far as hp up grades i have a stock TT to put on it for now. Is it harder to port a 6 port or doesn't it matter.
07-19-04, 11:02 PM
#5
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For real!!!!
A six port is modded is it not?!!!
What is the method to that Mayham!! if a four port is better why make additional ports!!!!!!
Yapa is intitled to his opinion, Curious t o s ee what others may think!!!!
I like this thread, Hope we get more opinions
A six port is modded is it not?!!!
What is the method to that Mayham!! if a four port is better why make additional ports!!!!!!
Yapa is intitled to his opinion, Curious t o s ee what others may think!!!!
I like this thread, Hope we get more opinions
07-19-04, 11:34 PM
#6
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The six port is better stock, and for daily driving. It serves a similar function to VVTi type systems, adding more air at the top of the rev band. However, this leads to limitations in porting, due to interference between ports and issues with coolant passages and the like. A four port lacks the kick of power at the top end, but can be ported massively. Notice that you almost never hear of a PP six port, but they are common with four. However, since you are putting a turbocharger on you won't need much more than a heavy streetport, so a six port would work just fine.
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07-20-04, 06:27 PM
#9
Lean Mean Speed Thingie
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im curious of the effectiveness of an auxilary bridge port....wouldn't you still mantain the streetability at low rpms, and some substantial performance gains at high rmps??
and how about joining the 5th and 6th ports into the main ports for one large port, and obviously removing all the sleeves and such how would that work???
and how about joining the 5th and 6th ports into the main ports for one large port, and obviously removing all the sleeves and such how would that work???
07-20-04, 06:44 PM
#10
there's a thread that discussed the 4-port vs. 6-port issue, i just ttried to find it but could not. maybe try looking for it, or perhaps someone else may find it and link it. it was pretty good, that's all i remember.
anyway, to answer your questions: no, it is not harder to port a 6-port engine; also, the performance differences will not start to show themselves until we're talking about SERIOUS power levels. generally speaking 6-ports will make slightly (very slightly) less power than similarly prepared 4-ports. the issue of street manners is moot because i don't advise using the 5/6 port actuators with larger streetports anyway.
you mentioned twin turbos and your SE - what are you hoping to accomplish, if you don't mind my asking?
anyway, to answer your questions: no, it is not harder to port a 6-port engine; also, the performance differences will not start to show themselves until we're talking about SERIOUS power levels. generally speaking 6-ports will make slightly (very slightly) less power than similarly prepared 4-ports. the issue of street manners is moot because i don't advise using the 5/6 port actuators with larger streetports anyway.
you mentioned twin turbos and your SE - what are you hoping to accomplish, if you don't mind my asking?
Last edited by diabolical1; 07-20-04 at 06:53 PM.
07-20-04, 06:53 PM
#11
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Originally Posted by diabolical1
yeah ... just want to give him the benefit of the doubt on an explanation for what he meant or where he got that from.
07-20-04, 08:35 PM
#13
84SE-EGI helpy-helperton
In discussion of 'which is better' on this topic, you first need to look at the lineage of the rotary engine in America (and overseas before that) to decide why Mazda came up with this engine design in the first place.
Recall that Mazda had made a really good name for itself in Japan for marketing cars that used a revolutionary new engine design (no pun intended). This engine was the powerplant designed by Wankel and licensed through NSU to just about everyone around the world including Porsche, Mercedes, Ford and Chrysler. Mazda was the first manufacturer to make it work, and in doing so spent a lot of money on research and design to improve the engines fuel emissions, economy, and power output. Nobody else put the time and effort into the rotary engine like Mazda. In this right, Mazda is the king of the rotary engine when it comes to implementing an experimental design and getting it out to the users.
In the early days, all they had was the 4-port engine. Aftermarket tuners and circuit racers found that opening up the ports (intake and exhaust) would dramatically increase power output of these engines which lead to Mazda rotary cars being entered into everything from SCCA to IMSA GTU, all the way to Rod Millen's 4WD Rally contender. This modification of opening up the ports to shove more air/fuel in and get more exhaust out is the simple explanation of what a 'port job' entails.
When Mazda looked at the 1st Gen RX-7's (SA's and FB's), they found that the user base had a very common complaint that the car needed more horsepower. Racing Beat, Rotary Reliability and Racing, and many others came to the needs of these drivers by building exotic intake systems, exhaust systems, etc. to meet this challenge and make the RX-7 driving experience more fun. At the far end of this engine modification was internal porting which required complete disassembly of the engine to perform - this is not a 'bolt-on' modification like the others.
When Mazda heard this call, they introduced the '6'-port engines to help with low RPM torque, broaden the torque band, and also increase high end power output. All these things were features that drivers wanted out of their favorite cars, the RX-7's. Keep in mind that Mazda was doing a lot with 13b development in Japan as well, such as the non-intercooled RX-7's and the Cosmo and RX2/3/4 platforms.
The '6'-port is essentially a Mazda Factory 'ported' engine which offers increased intake duration through the use of variable intake plenum lengths and volumes, thereby altering the port velocity and air column velocity to aide in low RPM torque and high RPM power. In trying to accomplish this goal, Mazda compromised between a big 'street' ported '4'-port engine vs. the driveability, poor fuel economy, and poor emissions output that this would bring. Essentially, they created a street-ported engine that only 'turned-on' when you put the pedal down and that's why they made the SE 13b '6'-port engines tuned to the exhaust backpressure wave. High load equates to opened up porting, thereby increasing fuel/air velocity and volume to further increase power output.
The '6'-port engine is an already-ported '4'-port engine.
To turbo this engine, Mazda chose to go back to the '4'-port design because it doesn't suffer from vacuum based intake systems - being forced induction, the turbo is less dependent on port velocity and air column velocity to attain good power since you're cramming the air/fuel mixture in with a pressurizer, anyway. Lightened rotors with less compression round out this combination of turbocharged design.
To say that a '6'-port motor can't be ported is untrue - you can open the ports up on any engine until you either hit the water jacket or cause a gaping hole that the corner or side seals drop into. Either way, you're going after the same thing - larger intake and exhaust openings.
It's saying something to look at the NA designs that Mazda used in the 86+ cars and the fact that they are all based on the '6'-port 13b design. Aside from the TII and FD's, Mazda knew that the '6'-port offered the best driveability and performance and they had everything at their disposal.
Just something to think about,
Recall that Mazda had made a really good name for itself in Japan for marketing cars that used a revolutionary new engine design (no pun intended). This engine was the powerplant designed by Wankel and licensed through NSU to just about everyone around the world including Porsche, Mercedes, Ford and Chrysler. Mazda was the first manufacturer to make it work, and in doing so spent a lot of money on research and design to improve the engines fuel emissions, economy, and power output. Nobody else put the time and effort into the rotary engine like Mazda. In this right, Mazda is the king of the rotary engine when it comes to implementing an experimental design and getting it out to the users.
In the early days, all they had was the 4-port engine. Aftermarket tuners and circuit racers found that opening up the ports (intake and exhaust) would dramatically increase power output of these engines which lead to Mazda rotary cars being entered into everything from SCCA to IMSA GTU, all the way to Rod Millen's 4WD Rally contender. This modification of opening up the ports to shove more air/fuel in and get more exhaust out is the simple explanation of what a 'port job' entails.
When Mazda looked at the 1st Gen RX-7's (SA's and FB's), they found that the user base had a very common complaint that the car needed more horsepower. Racing Beat, Rotary Reliability and Racing, and many others came to the needs of these drivers by building exotic intake systems, exhaust systems, etc. to meet this challenge and make the RX-7 driving experience more fun. At the far end of this engine modification was internal porting which required complete disassembly of the engine to perform - this is not a 'bolt-on' modification like the others.
When Mazda heard this call, they introduced the '6'-port engines to help with low RPM torque, broaden the torque band, and also increase high end power output. All these things were features that drivers wanted out of their favorite cars, the RX-7's. Keep in mind that Mazda was doing a lot with 13b development in Japan as well, such as the non-intercooled RX-7's and the Cosmo and RX2/3/4 platforms.
The '6'-port is essentially a Mazda Factory 'ported' engine which offers increased intake duration through the use of variable intake plenum lengths and volumes, thereby altering the port velocity and air column velocity to aide in low RPM torque and high RPM power. In trying to accomplish this goal, Mazda compromised between a big 'street' ported '4'-port engine vs. the driveability, poor fuel economy, and poor emissions output that this would bring. Essentially, they created a street-ported engine that only 'turned-on' when you put the pedal down and that's why they made the SE 13b '6'-port engines tuned to the exhaust backpressure wave. High load equates to opened up porting, thereby increasing fuel/air velocity and volume to further increase power output.
The '6'-port engine is an already-ported '4'-port engine.
To turbo this engine, Mazda chose to go back to the '4'-port design because it doesn't suffer from vacuum based intake systems - being forced induction, the turbo is less dependent on port velocity and air column velocity to attain good power since you're cramming the air/fuel mixture in with a pressurizer, anyway. Lightened rotors with less compression round out this combination of turbocharged design.
To say that a '6'-port motor can't be ported is untrue - you can open the ports up on any engine until you either hit the water jacket or cause a gaping hole that the corner or side seals drop into. Either way, you're going after the same thing - larger intake and exhaust openings.
It's saying something to look at the NA designs that Mazda used in the 86+ cars and the fact that they are all based on the '6'-port 13b design. Aside from the TII and FD's, Mazda knew that the '6'-port offered the best driveability and performance and they had everything at their disposal.
Just something to think about,
07-20-04, 08:42 PM
#14
Old [Sch|F]ool
Originally Posted by capri93
TT= twin turbo sorry about that just figured tt would surfice.
Additionally, there's no way in hell that it'd clear the stock intake manifold, at least as-is.
Seems like a lot of work for crappy turbos.
07-20-04, 09:05 PM
#15
The thing
Thread Starter
wow that was an explination and a half that helps a great deal but also brings up more q's ok now i plan on turboing the engine dumb question is there a way to mechanicaly open the 5/6 port to use with the turbo. I don't have to pass emisions here so i can do almost anything to my car and still pass.
To answer another question from above I want this car to fly till im done. I would like to get 400 rwhp eventualy maybe more. I would like to be able to smoke 5.0s and vetts on the road just a good solid but still "street legal" race car. I plan on a cp style wide body kit. intercooler new exhaust no cats 8.8 ford rear, eventualy a large single turbo. and along way off a 20b maybe.
To answer another question from above I want this car to fly till im done. I would like to get 400 rwhp eventualy maybe more. I would like to be able to smoke 5.0s and vetts on the road just a good solid but still "street legal" race car. I plan on a cp style wide body kit. intercooler new exhaust no cats 8.8 ford rear, eventualy a large single turbo. and along way off a 20b maybe.
07-20-04, 09:22 PM
#16
Old [Sch|F]ool
Cheapest way to 500hp involves eight or so aluminum things thunking up and down on forearm-shaped steel things attatched to a kind of cranky shaft thing that the flywheel bolts to.
That said, 500hp is a *lot* of power for a car this size. You won't be able to use it below 80-100 or so MPH. Even 200 is big huge grins.
That said, 500hp is a *lot* of power for a car this size. You won't be able to use it below 80-100 or so MPH. Even 200 is big huge grins.
07-20-04, 09:35 PM
#17
The thing
Thread Starter
Yeah I know that its alot of power and all im really looking to do is be able to crush these damn civics, vw and other noisy 4 bangers. but i'd love to be able to smoke a vett on the highway.
07-20-04, 10:01 PM
#18
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My comment about PP 4 ports was in regards to housing strength. Four port housings have less holes, and are therefore stronger and hold up better in high-rev situations.
07-20-04, 10:19 PM
#19
Old [Sch|F]ool
Does it matter when the ports will be filled with Devcon?
I don't think the intake ports are really affected by high RPM. There are much bigger concerns, like keeping the bearings fed with oil yet also keeping the eccentric shaft from rubbing them, and likewise keepign the rotors from hitting the housings *when* the shaft flexes...
I really don't see the point to mega-high revs. Better to build something that builds its power in a more worthwhile rev band.
I don't think the intake ports are really affected by high RPM. There are much bigger concerns, like keeping the bearings fed with oil yet also keeping the eccentric shaft from rubbing them, and likewise keepign the rotors from hitting the housings *when* the shaft flexes...
I really don't see the point to mega-high revs. Better to build something that builds its power in a more worthwhile rev band.
07-20-04, 10:26 PM
#20
Rotary Enthusiast
As LD said, the driving motivation which lead Mazda to employ 6 ports was the emissions and fuel economy standards. If you are not subject to emissions testing, the 4-port makes a lot of sense, especially with a non-stock intake manifold.
Why do you want to use stock turbos? These days 350 or 400 HP is fairly common for a rotary, why stock turbos?? Seems like a lot of effort if you have a clean slate.
Why do you want to use stock turbos? These days 350 or 400 HP is fairly common for a rotary, why stock turbos?? Seems like a lot of effort if you have a clean slate.
Last edited by cosmicbang; 07-20-04 at 10:52 PM.
07-20-04, 11:32 PM
#21
The thing
Thread Starter
Ok why stock turbos? Cuz I have them in hand and can't aford to go out and get up grades yet or for the next year or so and I would like to have the car running by sept. Also I am work with the 6 port because thats the motor I have and its in good working condition.
OK this is my situation; I baught a **** load of parts most new or very near, a roling chasis a 13b 6port still on stand, a 12a needs work. a front clip, 3 rears lsd, open, sun roofs windows widow luvers, wiper motors light motors, leather interior including door panels and seat, all kinds of stuff. It amouts to a 3500 dump truck completely loaded and then some. plus the car I paid $3500 for it all. Now I have to pay back 2500 I loaned off my pap, pay for school, keep my other car on the road and pay rent so that currently doesn't allow for much up grades for a while besides what I can do on my own.
OK this is my situation; I baught a **** load of parts most new or very near, a roling chasis a 13b 6port still on stand, a 12a needs work. a front clip, 3 rears lsd, open, sun roofs windows widow luvers, wiper motors light motors, leather interior including door panels and seat, all kinds of stuff. It amouts to a 3500 dump truck completely loaded and then some. plus the car I paid $3500 for it all. Now I have to pay back 2500 I loaned off my pap, pay for school, keep my other car on the road and pay rent so that currently doesn't allow for much up grades for a while besides what I can do on my own.
07-21-04, 05:48 PM
#22
first, you don't need 400+ HP to smoke a Mustang or Corvette.
second, i'm not trying to crap on your dream, but the simple fact is that something needs revision and i find that modification plans bend a lot easier than budgets. the power goals with the parts you plan to use are lofty, and if you think the fab work involved is going to be expensive, wait 'til you try to get them all to play nice with each other. it's not cheap (unless you can do everything or find someone willing to do it for next to nothing). you're already $2500+ in the hole and i don't recall any mention of what will control this twin turbo 400+ HP monster you want by September. am i missing something?
that said, you can always start simple and work your way up. you have the ingredients to make a pretty solid 4-port 13B (your other SE motor and the 12A motor). some port-work, some massaging of the rotors and shaft, some reliability mods. you can fund some of that by selling parts that you don't REALLY need. then, with that solid foundation, you can look into starting your turbo plans. just an idea.
second, i'm not trying to crap on your dream, but the simple fact is that something needs revision and i find that modification plans bend a lot easier than budgets. the power goals with the parts you plan to use are lofty, and if you think the fab work involved is going to be expensive, wait 'til you try to get them all to play nice with each other. it's not cheap (unless you can do everything or find someone willing to do it for next to nothing). you're already $2500+ in the hole and i don't recall any mention of what will control this twin turbo 400+ HP monster you want by September. am i missing something?
that said, you can always start simple and work your way up. you have the ingredients to make a pretty solid 4-port 13B (your other SE motor and the 12A motor). some port-work, some massaging of the rotors and shaft, some reliability mods. you can fund some of that by selling parts that you don't REALLY need. then, with that solid foundation, you can look into starting your turbo plans. just an idea.
07-21-04, 06:10 PM
#23
The thing
Thread Starter
All right heres the thing im not looking to go big right off the bat Yes i can fabricat most parts, for the ones I cannot I have a friend thats always looking for a reason to waste time while hes on maditory overtime, he works with stainless steel so all my turbo piping is going to be sergical stainless gonna look cool as well as last for ever. And i had no plans on getting to 400 hp by sept i just want to have the car running and reliable by then, 400 hp doesnt do much in snow.
What i figured was that once the piping was in place i can always drop in a better turbo system with minor fabrications. The major thing i was looking for here was the best way to go with the motor the 13b is good the 12a is not. how do i use 12a parts to convert a 13b 6pt to a 13b 4pt i didnt know that the parts were inter change able. there are a lot of parts i dont need here basicaly enough to build 2 good cars frame and all and still have lots left. Like i said earlier i eventualy want to get some massive gains but right now i'd be happy with 200hp and a good reliable car. that way i can sell my other daily driver and use the cash to upgrade.
My uncle whom i baught the car from swears by the 6 pt but he never went turbo. He just took out the sleves(sp) for the ports added a good Delorto carb and good fuel pump and Rb exhaust.
What i figured was that once the piping was in place i can always drop in a better turbo system with minor fabrications. The major thing i was looking for here was the best way to go with the motor the 13b is good the 12a is not. how do i use 12a parts to convert a 13b 6pt to a 13b 4pt i didnt know that the parts were inter change able. there are a lot of parts i dont need here basicaly enough to build 2 good cars frame and all and still have lots left. Like i said earlier i eventualy want to get some massive gains but right now i'd be happy with 200hp and a good reliable car. that way i can sell my other daily driver and use the cash to upgrade.
My uncle whom i baught the car from swears by the 6 pt but he never went turbo. He just took out the sleves(sp) for the ports added a good Delorto carb and good fuel pump and Rb exhaust.
Last edited by capri93; 07-21-04 at 06:13 PM.
07-21-04, 06:23 PM
#24
Originally Posted by capri93
how do i use 12a parts to convert a 13b 6pt to a 13b 4pt i didnt know that the parts were inter change able. there are a lot of parts i dont need here basicaly enough to build 2 good cars frame and all and still have lots left. Like i said earlier i eventualy want to get some massive gains but right now i'd be happy with 200hp and a good reliable car. that way i can sell my other daily driver and use the cash to upgrade.
My uncle whom i baught the car from swears by the 6 pt but he never went turbo. He just took out the sleves(sp) for the ports added a good Delorto carb and good fuel pump and Rb exhaust.
My uncle whom i baught the car from swears by the 6 pt but he never went turbo. He just took out the sleves(sp) for the ports added a good Delorto carb and good fuel pump and Rb exhaust.
all is not lost if you can't build a 4-port, i'm running the setup your uncle had and it's great all around. i still have not had my initial dyno run yet, but if everything is working as it should and i've done a good job tuning, then it's good for about 175 HP. it's not terribly fast, but it's fast, efficient and fun. 200 reliable horsepower is just a matter of streetporting it.
