Ryde _Or_Die

I just had my engine rebuilt but I used some of my old housings and some used ones. I am wanting to do the best engine I possibly can next time I do my engine so I was looking into all brand new housings. On mazdatrix's website they want $2039.78 for brand new housings for my car. Is there somewhere else to get them cheaper? Is it really worth it for a boosted car? Meaning, since I will be pushing the limits of my car(or more so than an NA engine) should I just go used, or will these last ALOT longer and give ALOT more power? Thanks alot guys.

black_sunshine

Generally, use new housings if at all possable (I assume you're talking about rotor housings and the irons).

Now, using old (worn; used) housings is okay, and can yield the same power/compression as new housings. All it comes down to is compression. Obviously, a motor making 120psi per chamber is going to make more power than one only making 80psi a chamber, thanks to thermal efficientcy (less heat is lost/absorbed).

I've seen housings with 175,xxx miles on them make just under 114psi per chamber (my old S4 NA that I rebuilt), and then I've seen housings with 126,xxx miles on them make barely 85 psi per chamber after a rebuild (my current engine which someone else rebuilt).

A good determining factor to consider when deciding weather or not to reuse housings is the depth of the groove (caused by the corner triangle). If you can see brass in the groove, that housing generally will not be a solid performer. Same goes for the intermediate/end irons. If your stepped wear is way out of spec or they have gotten warped (especially and particularly on the combusion side of them), they'll never be solid performers either.

Now, a LOT of your performance depends on the condition of the housings, but don't forget about apex seals and all 22 springs on the rotor. If they are weak (seals and 22 springs), they'll not seal properly (the reason I suspect my 87's motor only makes around 85 psi).

apex seals on used housings are a subject of much debate. In general, if you want a fast(er) break-in with used housings, use a seal without the hard-coated edge (atkins don't use this hard-coat which disappears after a few thousand miles anyways). This way, the corner triangle as well as the rest of the seal will faster take to the shape of the groove in the housing, as well as other "imperfections."

As for the performance specs, I was currious about this, so I lined the two cars I have (I sold my 88GTU [~114psi]) up and did a few side-by-side runs. Never, at any point (except above 110mph), were the two cars ever more than 1/2 a car length apart (GTU was ahead by 1/2 a car length, and above 110mph it VERY slowly walked away from me). Keep in mind that my car only was running 85psi front and rear (variance between chambers was less than 1psi front and rear), and the GTU had 114psi per rotor (variance between chambers was less than 1.5 psi front and rear).

I'd certainly like to see some dyno charts on this; I'd bet in the end, super-high compression #'s don't equate to big HP/TQ gains (judging from my experience anyhow). Anyone want to step to the plate?

Rotarded

a set of new housing, should only cost $1150. I can get them for you if you can find them. www.rx7store.net

Rotarded

Oops, left myself signed in a the RX7Store. The above post was from Zavier.

Z, ya might wanna log me out!

Mike

Ryde _Or_Die

Where can you find housings?

neptuneRX

rx7store.net etc, mazda still prints them, I checked, but they are super expensive