gotdatfiyah

i have no plans of owning a tii anytime soon, if ever....but i have saw posts of people turbo charging their n/a...would the 6 port produce more power than the 4 port turbocharged? post your thoughts.

Icemark

No, the turbo motor would be better for forced induction due to the intake port timing.

rx72c

iTrader: (8)

Why wouldnt a 6 port be better, is that like turbo charging a Vtec engine.

Icemark

Mazda didn't think so when they built the Turbo.

The 6 port intake is also designed to optimize the dynamic effect, while the turbo motors have some minor dynamic effect, most of the power is generated by denser mixture that a forced induction motor is designed for.

jreynish

iTrader: (2)

the ports on the four ports are bigger also on the turbo motors, that is because they are designed to accept forced induction. where as the 6th ports are designed to "pull" in more air at upper rpms where it is needed where as on a turbo motor the higher the rpms the higher the boost. Also don't forget that the ports are placed differently on a 6 port.. Personal opinion would be that four port would be perferable for a forced induction motor.

White_FC

I disagree..
I'll bet that a STANDARD 6 port block will make more power than it's respective-series, 4 port block.
Mainly due to the higher compression, assuming correct fueling/timing of course. However, this setup would of course be much more prone to reliability issues with bad fuel/hot air temps...

But i'm still sticking by the fact that STANDARD ports (not getting into modifying the ports at all, too many vars) the 6-port motor will be making more power at the same boost level.

88ROTARY

sounds good to me.

aren't most, or all n/a engines are 6 port and isn't a power limit on a n/a block because the lack of dowel pins?

gotdatfiyah

did aaroncake t/c his 6port or do a swap?

BLUE TII

iTrader: (9)

Why wouldn't Mazda make 6 port TII or 3rd gen then. They already worked out 6 port induction, just make it fit w/ a turbo if it would have more HP, right.

But it doesn't.

The 6 port system simply allows for a smaller port in the lower rpms where an NA needs high intake velocity to make torque.

A turbo just needs a fast spooling turbo to make lots of torque in the lower rpms, so Mazda concentrated on close coupled, dual scroll, undersized turbos to spool VERY fast for low rpm torque!

OC_

i cant believe that no one said anything about the overlap on a 6-port engine. It doesnt matter if the 6-ports can flow more when your intake charge goes out the exhaust. Im pretty sure i read somewhere that theres a lot of overlap on a 6-port engine especially when the aux ports open.

casio

i don't know how different if at all the port opening times are, but Icemark did mention timing, which is what you're getting at, right? speaking of a lot of overlap, reminds me of bridgeporting. a lot of air is lost, but so much is gained, it makes up for itself plus some.

White_FC

Just to clarify my last post, i'm not saying the 6-port design is better than a 4-port design for a turbo rotor.
I'm saying that if you had the same turbo on each STOCK block that the 6-port block will make more power on the same boost level... It's intuitive, high compression and longer port timming, the only negative would be as allready said above, the intake design is optimised for intake velocity for an n/a engine.

and im not too sure about the whole thing about the 6-ports having smaller ports, I don't feel thats totally correct, i will have to do some measuring when i rebuild my S5 engine to confirm this though.

Now the only difference in port timing is that the 6-port design leaves the ports open longer(by about 20deg. if i remember correctly!!), it has exactly the same port opening time as the turbo motors.... and exactly the same exhaust timing.

BLUE TII

iTrader: (9)

and im not too sure about the whole thing about the 6-ports having smaller ports, I don't feel thats totally correct, i will have to do some measuring when i rebuild my S5 engine to confirm this though.

I simply meant the idea of the 6 port NA design is to have 2 smaller primary and 2 smaller 2ndary ports for higher velocity to make more lower rpm power-

and 2 additional auxilary ports activated in the higher rpms to aid total flow.

The primary and 2ndary ports open all open at the same time on NA and TII engines (32 deg ATDC), but the NA closes the primary port 10 deg. sooner and the 2ndary port 20 deg. sooner than the TII (respectively, 40 and 30 deg. ABDC compared to TII 50 ABDC for both).

Then at higher rpms on 6 port opens up for increased flow (over smaller 6 ports primary + 2ndary flow) and longer duration (20 deg longer- closing at 70 ABDC to TII 50 ABDC).

Since the 6 port aux ports only open in higher rpms there is no drawback to adding the 20 degrees more duration on the NA (since this would only hurt low rpm power).

So, IF the the total flow of the 6 port engine and manifold was more than the 4 port set-up it could make more power. I don't know if it flows more.

Atkin's rotary has dyno #s for ported 6 port and ported 4 port w/ supercharger here- pretty close...

http://atkinsrotary.com/dyno.htm

Of course that doensn't indicate the compression ratios of either engine, how ported the 4 ports are ( 6 ports can't physically be ported much, right?) or any # of the many many other factors that influence power.

But really, if the 6 port would have made more power turbo charged can you think of a single reason they would not have included it on the 3rd gen RX-7?

They weren't afraid to raise the compression ratio, ditch the AFM (and go prone to blowing up w/ VE changes engine management), put on a hideously complex twin sequential turbo system and completely change the engine side housings and maniflold designs- along w/ many other things.

I think it would be cool as hell to see a stock TII and a stock TII w/ 6 port engine and intake manifolds do side by side dynos just so we could see the exact differences- but that is probably never going to happen.

White_FC

Just as a bit of an aside to this all, I removed my 6-port sleeves and associated actuating crap and noticed a huge improvement in torque everywhere from about 2k to redline... although I unfortunatly don't have dyno sheets to prove this.. I wish I did though
(and YES the aus ports WERE opening up before I took them out they wern't broken before anyone asks, this was also with a free flowing exhaust and intake setup {AFM removed because motor has microtech on it.} so this could of had a major bearing on the results, im sure totally stock the actuated 6-port system would give more torque down low.)



Precisly why I didn't bring modified ports into this earlier, Waaaayyyy too many variables....



Many, Many, many reasons... namely reasons like I said before, bad fuel and/or hot intake air could cause detonation with the higher compression (ps, the 3rd gen Rx and S5 turbo have the same compression{9:1, only S4 is lower 8.5?:1..}) remember, Mazda have to cater for the lowest common denominator, ie, people who don't live near high octane fuel bowsers and/or people with hot/dry climates.

I too would love too see this, I really should have done it to mine when i turbocharged my 6-port motor, however i changed many things while doing the setup on it like modifying the inlet manifold and crap which would make a totally objective comparision with a stock TII impossible....

BlackIceGuitar

While we are on the topic of boosting n/a's, what would you guys assume is the most boost you could get away on an n/a? (and still be relitively safe)

White_FC

Too hard to say man..
Too many different variables...
You could run quite alot of boost if you have the right fuel supply to keep up with the air flow going into it.

really depends a hell of alot of the turbo aswell....

Rx7_Nut13B

iTrader: (1)

Well i was running just about 8.5psi of boost on my Turbo Na project and was putting out 260hp

Not that bad for 600.00 dollars for the hole project.

Check it out

Users2.ev1.net/~ccoutts

TURBO NA ROCKS