well today i was staring at a 13b that me and my buddy yanked out and got to thinking... theres the little diffusers in the exhaust ports on a 6pt, they are attached to a sleeve, and if you drill the side pins out the sleeve comes out, and makes the exhaust port a whole lot bigger, and im thinking why couldnt you just take out the sleeves and run the car without them?? Someone fill me in on why the sleeves/diffuser guys are there and if you can take them out.

 

EGR takes the gas directly from the exhaust port through the sleeve.

 

Actually you can remove the sleeves and run without them, you just have to figure out the emissions and/or switch out to turbo (which would be highly recommened as all benifites of the 5th and 6th ports actuation would be lost, meaning less low end torque) AaronCake did a good write up on his page about turboing an NA. Might want to look there.

As far as I can tell (and I may be wrong about this) the defusers only stabilze airflow to help increase velocity through that portion of the exhaust system. I believe actuation occurs at 3800 rpm under load (again, i may be wrong about that). If you remove the defusers (which I've read is rather difficult because they're made out of harder metal than aluminum) you have to deal with the turbulent airflow, which would decrease your exhaust velocity. There's good resources out there to figuring it out. Depending on what your end goals are it might be beneficial to keep them, it might be better for you to get rid of them. It just all depends.

 

"Port flow is terrible if the sleeve is left out - don't do it." -Mazdatrix

I dunno if this only applies when porting, but check this page out as concerns the diffusers and porting on the Mazdatrix site:

http://mazdatrix.com/faq/6pexh.htm

 

Well i also do believe that most headers and manifolds are sized for the sleeves anyway.

 

BTW, Sidewayz, that's a sweet looking FC, some lowering springs and 1" spacers on the rear...

 

I was curious on this as well. I have a spare N/A S4 engine lying around, and thought about porting the exhaust, because I wanted to port the actuated intake ports and turbo it as well. Guess I'll be doing a load more research first. BTW excellent question OP. I'll keep an eye on this as well as check Aarons site pertaining to it. I have already seen the Mazdatrix one.

 

NO it does NOT. The EGR uses a different source.It uses that approx 3/8ths size hole below the exaust ports that goes directly into the exaust manifold.

*****figure out the emissions ***************8

The holes at the diffusers themselves are from the ACV and those holes will still be there whether or not the diffusers are removed or not. The holes AT the diffusers are where the air from the ACV is fed into the exaust stream prior to the catalytic converters.

 

The diffusers also help with reversion(keep exhaust gases from flowing back in) at low rpm's which helps produce low rpm power. If you plan on daily driving it I would leave them in. The more gases that have time to turn back during overlap in exh and int ports the worse your mileage and power at lower rpms gets. Makes it so you need to run richer in order to get the fuel to burn.


Brent

 

ook i was wondering why it wasnt more commen for people to take them out, thank you for the feedback, i can see when i looked at it again, if you take the sleeve out, the port is bigger then the exhaust manifold holes so im taking there would be mad turbulence right there if taken out. it sounds like they are there for a reason so im not gonna mess with them.

thanks for the comment on my car its got some different rims and no spoiler now, im definitely wanting to drop it around 3/4 to an 1.

 

one of the cars i bought didnt have the diffusers in it. its was turbo with an aftermarket t4 on it. i personally never drove the car but the previous owner said it ran well and he didnt even know the diffusers were missing.

 

4 port (turbo) motors did NOT have the diffusers. 6 port (NA) did.

 

i meant the exhaust sleeves sorry

 

The exaust diffusers are explained in the Emissions part of the Training manuals in one of the links below.

https://www.rx7club.com/forum/showth...ght=photobucket

http://www.wankel.net/~krwright/fil.../parts_manuals/

http://wombat.sevarg.net/RX7/RX-7_Training_Manuals/

http://www.cochran-racing.com/FSM/index.html

 

I picked up some Tein S-Tech lowering springs on eBay for $99 a while back. The handling improvement and lowered look were well worth it, (put in Tokicos at the same time though...).

You'll find 1" Mustang and Jeep Wrangler spacers on eBay for under $50 a pair which fit our 5-lugs. They widen the stance 2" improving handling and I think look great on. (1" for the rears, once lowered, without rolling the fenders you can't put too much of a spacer on the fronts, I didn't bother.)

 

i just did my rebuild and i'm running it without exhaust sleeves. i also opened the exhaust port a lil bit and imo the only difference is that it's a lil louder (kinda like a go-kart). it does run a lil smoother in the hi rpm range but that's pretty much it. just dont take out the aux port sleeves cuz you'll lose ALOT of power in the low-end

 

my actuators still work (it's a s4 so it runs with back pressure from the exhaust)

 

I would not remove them. It disrupts airflow and doesn't allow the header to seal up properly. One option is to pull the diffusers out and cut out the "wing". It's not as hard as you might think. A die grinder, dremmel tool or cut off tool will do it in 5 to 20 min.

Brian

 

it will take more like an hour to grind away the diffusers with an air die grinder with a carbide bit.

i did it my self and messed up, i hope you have it done by someone with a steady hand.

heres what mine looked like after
http://tinypic.com/view.php?pic=2aaj2fb

right now its running perfectly in my 88 gx with no evident loss of low end power.