Tore my engine apart today and found the most glorious surprise:


and that was before I cleaned the surface of the housing. According to one rebuilder, the SE housings chrome are just moments away from chiping away to oblivion. I was considering a re-grind, but I have no chatter marks or much of anything wrong with either rotor. what makes the newer style housings less likely to flake?

 

not SE housings...... nice turbo ones tho

 

when u tap on the pic it shows different ones ?

 

They are GSL-SE housings. the diffusers were not added until the FC. As for tapping the picture, I'm not sure... It should only be the one photo.

 

 

I should have prefaced my comment that the NA housings had diffusers starting in 86. They look real nice Ray!

 

the housings in the pic ray posted are not gsl-se housings. the se housings will have the O-ring groove in them.

 

I wouldn't do anything to it.

For the 2nd generation RX-7 and 12A turbo Mazda used an additional surface treatment on the housings that put microscopic channels on the chrome surface to aid in oil retention. I think it was switching to 2mm seals that really helped reducing flaking.

 

I don't know so much that they are. Remember that they are used with the 2 mm seals and dual springs, so my guess is that that's why you may not see them in the same condition as you might the older 13B housings.

 

Who cares about chrome flaking by the exhaust port.... You aren't making any compression there.

Tell your builder to look at the 6 o'clock and 12 o'clock positions on the housings. That is where the apex seal passes during the (for lack of better words) compression stroke begins and power stroke starts to end. Once the apex seal has made its way to the exhaust its not sealing anything. Another words look for chrome flaking there because that's where its detrimental; flaking elsewhere isn't as much of a big deal.

Besides looking at that huge port you are putting into those turbo ii housings you are going to end up grinding off any chrome flaking in the GSL-SE housing anyway. If you end up porting that aggressively.

 

Let me clarify, this is a picture of Richard Millers housings (not mine!).



I found it along with a bunch of others by scrolling beyond the click on the first photo he posted above.

And yes Richard is right, they look real nice!

 

This is odd, as these are not mine. The ones on the workbench are mine... The ray green picture is not me either. I don't even have the one in my library.

 

Another unwanted feature that was implemented without anyone knowing it? ... effing related threads and infinite scroll anyone?

That little nick in the surface shouldn't cause an issue. It's when you get flaking on the edges of the housing, that's when you start measuring to see if it fits within the mazda spec for a rebuild.

Anyone know if there is a spec for inclusions/porosity on the face of the chrome?

 

It is odd Richard, I just assumed it was your picture because it's in the same "folder" as the first picture you posted.

You should be able to see this for both your first picture and the one I posted by simply clicking on the picture and then scrolling left or right.

Your original picture is two scrolls to the left of the picture I posted.

Baffling for sure, those mods are always trying to confuse us.

 

Those rotor housings look GREAT. I would leave them alone. "Regrinding" would just take away chrome and make them more likely to have problems later on.

Do, however, make sure all coolant scale/crust is removed from the water jackets especially in the spark plug areas. And take a very small fine file and gently touch up the edge of the chrome surface all the way around. Think "deburring" more than beveling. The reason the chrome flakes at the edges is because of the rotor housings flexing back and forth across the side housings, so if you trim the chrome just a tiny bit, it stops a worse problem from happening.

 

I am hoping to bead blast the surface and sonic clean after. I will be protecting the trochoid surface with aluminum HVAC duct tape.

 

I would avoid any and all bead blasting of rotor housings. Especially in the coolant seal groove area. Why? Have you ever taken apart a lot of engines? The rebuilt ones that had been bead blasted are really bad with a lot of corrosion in this area.

 

thanks for the warning. never thought of the sealant grooves. good advice.

 

I have glass beaded them with no problem. Glass beading doesn't hurt a dang thing.

I do avoid the chrome, mostly because I don't want to risk embedding glass in the chrome surface.

 

oh boy, the plot thickens.

 

Gotta say I don't do any major sanding or anything abrasive to the coolant jacket. I nock off the chunky build up, scuff it with a green scotch brite pad, spray it with some carb cleaner and call it good. I don't see any spikes in temp or problems with sinking heat from the motor. Granted I am not racing or getting extremely accurate temp info, but as for DD usage (with occasional rompings) I haven't' had a problem.