Im rebuilding my 87 na and doing a mild streetport on the intake and exhaust. I did a search and came up with more questions than answers about removing the exhaust inserts, grinding the baffles out of the insert, or using tII inserts... Is completely removing them a bad idea? Where do I find the tII inserts? I know that it will be loader without the inserts (or with the tII inserts) any advice on this would be greatly appreciated.

 

You can get rid of the baffle with a plasma cutter and then grind it smooth. Easier way, just get some TII inserts. Don't remove them and leave them out!

Inconel is some hard ****, if you try and grind the baffles out....I hope you are patient and have lot's of bits. If you can't get a hold of a plasma cutter, just get some TII inserts.

 

would it be bad to put the inserts back in after porting? would that counteract the porting?

 

The N/A inserts minimize exhaust gas reversion. They improve fuel economy, reduce noise, and widen the power band. You shouldn't port the exhaust on a street driven non-turbo engine. I would leave the stock non turbo inserts in the housings and do a mild port job on the intake ports.

 

too late for that..so should i put the inserts back in?

 

Yes.

 

The N/A inserts minimize exhaust gas reversion.

Ignorant here. Reversion, does that mean exhaust gas going into the intake stroke charge?

 

Ummm, I have always been told, even by the guys a rotary performance, that the keep the engine from being too noisy by delaying full exhaust port opening right off the bat.

 

I thought so. Illogical?

 

Assume you're using Turbo housing for N/A Engine, would street porting it :

- suck *** fuel economy (if its not the worst already, how much less mpg should I expect?)
- loud as f!@# (will it turn the car into a cop magnet ?)
- narrower power band ? (so only mid range rpm usable now ? or higher rpm ?)

Cuz Im thinking should I do a full street porting (intake & exhaust using Turbo housing)

 

Thats what I thought, if it just about noise im not too worried about that. is anyone running without them?

 

I have no baffles, but I have the inserts still there. Dont run without them or you'll have fluid dynamic problems with exhaust gas I wont get into. I also have slightly ported exhaust ports (not quite a street port, but not stock either). My intake is left unchanged.

Low rpm suffers a tad but 3k and above is MUCH better.

 

No. Just saying I don't KNOW. Just wondering, that's all. Made sense to me.

That online training manual shows what is shown in the attached jpg. Mentions something about smoother exhaust flow. I still like the reversion idea though.

 

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

For what it's worth, I put turbo exhaust sleeves into my S5 6port block when I rebuilt it. Also polished the exhaust ports and smoothed the intake runners. Port matched the intake manifolds. I can't comment on power gains because the engine was tired before the rebuild. It eventually lost an apex seal due to carbon buildup.

I have a main cat only on stock exhaust. I don't think it's loud but again, I don't have a benchmark.

 

well i got the plasma cutter out and got to cutting and grinding, sanding. about 4 hours later, they look pretty good. (good enough for the ****** I go out with) I can post pictures tomorrow.

 

Cool. I want to see.

Did you actually port them or just remove the diffuser?

 

To answer your question, yes, there are people who run without them. I don't know much else about the subject though. I do know personally I'm going to keep my turbo inserts (on my turbo motor). If I ever do anything else with them I would port/polish them. I also plan on keeping a turbo on the motor, so this really doesn't apply to me...

 

Don't run without them. It tends to kill velocity at the port and leads to higher coolant temps.

 

I've removed the diffuser with an endmill but decided not to use them because of the large square hole in the insert. It looked like it would hurt performance wise more than help it...

 

Sorry, let me clarify. I meant not to remove the sleeve. The diffuser I can't say for sure if there is any effect on power, but it certainly makes the car a crapload louder. Mazda's primary reason for including them seemed to be to cause a more gradual opening of the exhaust port to reduce noise.

 

here are the inserts after a lot of grinding

 

since someone mentioned Inconel, here's a neat, brief read on the stuff
http://en.wikipedia.org/wiki/Inconel

 

every ported motor i've ever dealt with has been built from mostly NEW parts, and was also using some kind of tunable ecu/fuel control.

-fuel economy. this is more dependent on pumping losses, free up the exhaust and MPG improves, and it doesn't seem to matter what port you have. my friend had a bridgeport 13B with a holley, and it got 26mpg, which is just as good as my old gsl-se with RB exhaust.

-on a turbo car it will make more noise from the intake. the other thing is a ported engine needs to have a freer flow exhaust, which is usually louder.

- again, using new parts, they usually make more power everywhere. mazda's papers show that you do trade off low end for top end, so maybe new rotors, irons, and rotor housings make up for it? my friends old mild port S5 t2 motor was great, with a 60-1 turbo it made more power @2000 than my stock port stock turbo car, we both ran the RB turbo back. he made 392@12psi

 

so how did I do on the inserts? they should work out huh?

 

Thx for clearing that up

One more question tho, I wonder if Stock ECU/tune would be able to run Street ported engine, at least for a while.

Cuz some family issue came up and I don't think I will be "Free" to get it tune or change the ECU to some stage1/2 setup for a while. but I can still push it/drive it without blowing it up? probably worst mpg ?