hi guys,

I'm planning to get a 5MT RX8. But can you guys enlighten me what are the differences between 5MT and 6MT besides the extra gear and extra horsepower?

Was told that the 6MT uses a 6 port intake, while the 5MT uses 4 port intake. How big is the difference for these 6 port and 4 port intake? Can I upgrade the 4 port intake in 5MT to a 6 port intake?

Any other difference for the LSD, traction control, undercarriage, anti-roll bars, suspension, etc for the 5MT and 6MT?


thanks in advance

 

The attached .PDF file from Mazda UK should help.

 

thanks, looks like they are some how the same. Except the 6port and 4port intake.

 

The intake is where the extra HP comes from and you have to basically replace the whole engine and ECU to update it. If you want the extra HP in the future, buy the 6 port now.

 

Or rather, if you want the extra HP in the future, pull the 4port, rebuild, and port.


A 4port, when ported, will always flow more than a 6port. A 6port CAN be made into a 4port to achieve the same goal, though.

 

why no one wants to do that then ?

 

A good majority of the 2nd gen RX7 guys (the majority of all 6-port engines) get their 6ports ported out to be 4ports. ESPECIALLY the ones who are looking into turbocharging, as the 6ports are hard to keep operational with a turbo, and cause a restriction when not opening properly. Flow potential is greatly hindered by the 6ports.

Renesis guys just haven't had to do many rebuilds yet, it'll happen eventually :-P

 

any guides for porting a 4 port to gain better performance than 6 port?

everybody is saying 6 port is better and we can't do much on the 4 port. If modding 4 port enging could gain better power than 6 port, I would certainly go for 5 MT 4port. Why would everybody pay for so much extra for 6port?

Thanks for your advice, as i'm more interested for the 5MT 4port bcoz of the price difference.

 

all the JDM 5MTs we see here are lower spec also .
Smaller brakes
Smaller Rims
No DSC
Softer suspension
Can't remember all the differences but basicalliy it is an inferior car to 6MT

 

Here is an informative post from RG:

https://www.rx8club.com/series-i-specific-performance-mods-97/heres-why-engine-has-less-power-potential-than-6mt-20148/

Both wil not get much more power until you add forced induction it seems. Only time will tell which engine is better for turbocharging, but it seems like in this part of the world the 6 port is winning by default. No more 4 port for the USA.

 

I read that b4 as well and that post really ruin my hope of building a cheap Sideway RX8 without FI

Until I heard AdRoCK3217 said that 4 port is better than the 6 port when comes to porting...

 

Your right Brett, I remember when I was looking for my car and doing the research that there is heaps of difference between the jdm type E and type S - Rim size, suspension, Brakes, headlights, super torsion lsd (or whatever its called), intake as well as the obvious horsepower and gearbox!

 

I wouldn't say the majority of rx-7 6-port motors have been ported out to 4 port ( I know of like 5, mot race only motors)

or that 6-ports dont work with turbocharging (this is a clearance issue with the rx-7 6-port LIM, not a port issue)


They do cause a restriction when not working properly, this is true.


I would'nt say flow potential is greatly hindered by 6-ports, even the 6-port FC motors outflow the 4 port T2's bar for bar.


Keep in mind the renn also has contoured sleeves andno actuator arms dead in the middle of the port like the FC motor does.


All tht would happen if removed the 6-port system on the renn is youd loose craploads of low rpm torque...

 

Here in Greece and Europe in general, we actually got a pretty sweet deal on the 4port 5MT RX8. We got everything the 6port 6MT has minus the engine, the 6MT box and the xenon headlights.

So my 4port 5MT has the big brakes (front-rear), the 18" wheels, sunroof, leather, electrical seats/windows/mirrors, heated seats, plus I ordered the MP3 player (I could also go for the Bose).

Differences between the gear boxes is different number of gears , different gearing, different throw, different feel, same final ratio.

Difference between engines is the VFAD, 6 vs. 4 ports, SDAIS works in different RPMs, additional injectors, different fuel maps. Oh, and about +40HP, and -1Kgm torque for the 6port Extra HPs are of course due to the higher RPM range.

 

wow!

Think I'll get the 4-port 5MT and reflash the ECU to raise the rev limit up from 7500 to 8500. And I would possibly gain 20 - 30HPs by doing that.

 

Speaking of raising the RPM limit.

Would the Interceptor-X for NA be able to do this?

 

Don't think that will get you that much extra power - you will be restricted by how much air you can get into it .

The Greddy turbo size is probably more ideally suited to the 4 port than the 6 port .

 

Stock fuel-cut for the 4port 5MT is 7800rpm. You need to have done some intake/exhaust mods to actually see any benefit from raising the fuel-cut above 8K rpm. And I think that 8500rpm might be pushing a little bit....the torque curve is dropping REALLY fast past 6-6,5K rpm....