I'm thinking of doing this, but wanted to know what other's experiences have been after swapping them or grinding the diffusers out.



Did it affect low-end torque, fuel economy, noise output, ect...?



I've heard of a few reasons Mazda put the difusers in.

Are they for keeping proper backpressure(sounds stupid to me), reducing noise(I thought they made silencers and muflers for that), and/or to disrupt exhaust pulses going from one port to the other(maybe they thought to hard on that one)? https://www.nopistons.com/forums/pub...IR#>/wacko.png





Thanks,



New

Hasn't anyone swapped out the turbo sleeves or ground out the difusers? https://www.nopistons.com/forums/pub...1047683561.gif https://www.nopistons.com/forums/pub...1047683561.gif https://www.nopistons.com/forums/pub...1047683561.gif

if memory serves correct, it's just to reduce noise.

it would make sense, since there's no turbo to dampen the noise

[quote name='Old Splatterhand' date='Aug 25 2005, 12:12 AM']if memory serves correct, it's just to reduce noise.

it would make sense, since there's no turbo to dampen the noise


[/quote]





I am planning to go with a presilencer of some kind and a nice big cat to help keep the noise down.

I would really like to know what others have experianced and done to keep the extra noise down before I start grinding or swapping the sleeves...

I do it on every n/a motor I build. Whatever the reason for the sleeves, be it noise reduction, they are an exhaust restriction. I can't tell you an increase in db, because every car I have done has had a complete different setup, and you can never get any two cars the same.

how are NA rotor housings different from turbo rotor housings... aside from the diffusers in the sleeves?

No coolant passage for the lim.

the noise tone changes, and it might sound a bit more annoying to some, but its nto a major diffrence, atlest nothing that cant be fixed with an extra presilencer. most peopel run loud exhaust on their cars anway so i dont see this bothing people. unless they were very concerned with the noise in teh first place.

[quote name='kahren' date='Aug 26 2005, 12:48 PM']the noise tone changes, and it might sound a bit more annoying to some, but its nto a major diffrence, atlest nothing that cant be fixed with an extra presilencer. most peopel run loud exhaust on their cars anway so i dont see this bothing people. unless they were very concerned with the noise in teh first place.


[/quote]





Yeah. I'm a little concerned about the noise. If I want to autocross in the Atlanta region I need to keep the noise below 96db.

Someone was going to give me the turbo sleeves, but I guess they forgot about me. https://www.nopistons.com/forums/pub...O_DIR#>/11.gif

Oh well.



What's everyone's favorite way of grinding out the difusers?

[quote name='Newguy707' date='Aug 26 2005, 07:56 PM']

What's everyone's favorite way of grinding out the difusers?


[/quote]



in my opinion that should be the last resort, try to get the turbo sleeves.

atleast thats my favorite way of grinding them, to answer your quastion.

Most people will tell you to stay away from grinding on them, they are hard as hell, and trying to grind them out almost always causes damage to the housing in the process.

[quote name='89 Rag' date='Aug 26 2005, 06:53 PM']Most people will tell you to stay away from grinding on them, they are hard as hell, and trying to grind them out almost always causes damage to the housing in the process.


[/quote]





I definitely don't want to damage my housings. I was hoping ther was a special grinding bit or something to get the difusers out easier. I remember reading in one of Aroncake's threads were he seemed to grind them out fairly easily. https://www.nopistons.com/forums/pub...IR#>/blink.png



Looks like I'll be posting on the For sale/Wanted section for some sleeves and factory tranny mounts as well. (Yes, I am a tranny swapping purist. i.e. ripp out interior, weld in stock mounts... https://www.nopistons.com/forums/pub...1047683473.gif )





As a last resort, I'll take them out and then grind away the difusers with whatever works.



I would still like to see/here of any performance increases that others have experianced from removing them, and also the best method to keep the noise down (96db).



So stop passing this thread by, whoever-you-are, and help a worried rotary noob out! https://www.nopistons.com/forums/pub...1047683329.gif https://www.nopistons.com/forums/pub...1047683329.gif https://www.nopistons.com/forums/pub...1047683329.gif

if you want to keep the noise down, and also want to get rid of the diffusers.. you might want to get a resonator or presilencer like kahren said in a previous post.

[quote name='FikseRxSeven' date='Aug 27 2005, 08:52 PM']if you want to keep the noise down, and also want to get rid of the diffusers.. you might want to get a resonator or presilencer like kahren said in a previous post.


[/quote]











I plan on doing something like that, but I was hoping some people had specific recomendations for the best setup. I'll do some searching on the subject of exhaust tuning and setup and see what I can find. I really don't know much about the usage of cats, silencers, and resonators in tuning the exhaust. i.e. How big, how long, how many, which is first, which is last... and so on.



Like I said before, I am a definite noob in this area. https://www.nopistons.com/forums/pub...1047683664.gif

our ITS car passes sound with this setup:



stock port 6 port engine, with turbo housings.



custom header into 3" piping



rb turbo back pre silencer http://www.racingbeat.com/resultset....tNumber=16425P



and a magnaflow muffler



setup is actually really quiet (on the track) and sounds like a denist drill at 9000rpms https://www.nopistons.com/forums/pub...#>/biggrin.png

That's an awsome sound when you know the engine can handle it. https://www.nopistons.com/forums/pub...1047683473.gif

Sometimes I can't resist reving my little die grinder like an F1 racer. It gives me a glimps of the light at the end of the tunnel, so to speak.

My car and motor have been sitting in the garage for almost 2 YEARS!!!



Your setup is impressive. What is the sound limit you have to adhere to?



Youv'e got me thinking now...

I like the look of Rx7.com's streetable header. It has fairly even runers and the O2 sensor is where it should be. http://www.rx7.com/store/rx7/fcexhaust.html



I hope putting a dual canister catback sys will muffel it enough. I really don't want to draw too much attention while dding, and I just think being loud is dumb.

Unless your'e on the race track of course. https://www.nopistons.com/forums/pub...R#>/tongue.png





Thanks Guys!

[quote name='j9fd3s' date='Aug 28 2005, 11:17 PM']our ITS car passes sound with this setup:



stock port 6 port engine, with turbo housings.



custom header into 3" piping



rb turbo back pre silencer http://www.racingbeat.com/resultset....tNumber=16425P



and a magnaflow muffler



setup is actually really quiet (on the track) and sounds like a denist drill at 9000rpms https://www.nopistons.com/forums/pub...#>/biggrin.png


[/quote]





Of course you realize the engine is illegal with turbo housings?

Why would it be, the housings are the same essentially.. There is no advantage to swapping TII housings over N/A housings with TII sleeves..



Only specific casting difference is the coolant passage at the peripheral intake area..

Because it's a turbo engine part that was not available on the NA. Would be like using RX-8 rotors. There is also the possibility that the diffuser inhibits flow giving the illegal turbo housing a flow advantage. This one has been through the tech shed before. This engine is not legal for SCCA's ITS class.

[quote name='C. Ludwig' date='Aug 29 2005, 10:44 PM']Because it's a turbo engine part that was not available on the NA. Would be like using RX-8 rotors. There is also the possibility that the diffuser inhibits flow giving the illegal turbo housing a flow advantage. This one has been through the tech shed before. This engine is not legal for SCCA's ITS class.


[/quote]







I don't know the racing class rules, but that sounds weird. Would the only "legal" way be to grind the N/A diffusers out? https://www.nopistons.com/forums/pub...1047683358.gif I would think the housings are equivalent to a piston engine's cylinders, which are the same between N/A's and turbo's, right?



Ahhh, the joys of all the rules against the rotary engine...



Why don't they just ban the rotary completely? ...Like they did in the 24 Hours of Le mans... Punny piston lovers!

[quote name='Newguy707' date='Aug 30 2005, 07:58 AM']I don't know the racing class rules, but that sounds weird. Would the only "legal" way be to grind the N/A diffusers out? https://www.nopistons.com/forums/pub...1047683358.gif I would think the housings are equivalent to a piston engine's cylinders, which are the same between N/A's and turbo's, right?



Ahhh, the joys of all the rules against the rotary engine...



Why don't they just ban the rotary completely? ...Like they did in the 24 Hours of Le mans... Punny piston lovers!


[/quote]





Within the confines of the SCCA's rules for ITS the only legal thing to do is use the unmodified NA housings. I'm sure other classes and other sanctioning bodies have different rules. But j9fd3s specifically referred to ITS.

Ahhhh like the old saying "It ain't cheating if you don't get caught" people have been adhearing to that rule since the beginings of automotive racing.

[quote name='C. Ludwig' date='Aug 29 2005, 06:53 AM']Of course you realize the engine is illegal with turbo housings?


[/quote]



yep, but we run nasa, and didnt have any good na housings

[quote name='C. Ludwig' date='Aug 30 2005, 10:29 AM']Within the confines of the SCCA's rules for ITS the only legal thing to do is use the unmodified NA housings. I'm sure other classes and other sanctioning bodies have different rules. But j9fd3s specifically referred to ITS.


[/quote]



we run nasa, ps1 is the class which is supposed to be the same as its, but nasa doesnt print rules so we dont know.

What's wrong with running sp or gt-1?

[quote name='89 Rag' date='Aug 30 2005, 07:49 PM']What's wrong with running sp or gt-1?


[/quote]



we're there if you pay for it

[quote name='j9fd3s' date='Aug 30 2005, 08:50 PM']we're there if you pay for it


[/quote]



lol, well other than that aspect!



back in the 90's most of the rotary guys in this region were running gt-3 and were out of control, to say the least.

I'm not trying to be an ass but you could certainly be leading some people down the wrong path. The NASA rules are published ( http://www.nasaproracing.com/rules/ps.pdf ) and the intent of the PS rules is to adhere to the SCCA ITCS except where exceptions are made by NASA. This particular part is not one of them. Your engine is illegal for NASA PS-1 as well.