O-Ring failure - Considering Options (RX-6 vs 99 Twins)
 

I just found out the O-ring on my engine failed. Since I am going to have to have the engine rebuilt, I am considering upgrading the turbos at the same time (the old ones are leaking oil and have 70K miles on them). I want to keep the car emissions legal and streetable, since it is my daily driver. My shop, Mazcare, is suggesting the 99 twins because they have had good luck with them. I was wondering if it is worth looking at Apexi's RX-6 single kit instead. I know the RX-6 kit is more expensive, but I would like to improve the reliability if I can (get rid of the rats nest).

I currently have an M2 Medium Intercooler and Power FC (as well as a Downpipe and CWC intake that would need to be removed). The engine will be rebuilt by Roger Mandeville's shop, and I am probably going to keep stock porting. What else would I need to install the RX-6 kit (ex. Upgraded injectors, fuel pressure regulator, fuel pump, special piping to make it fit with the M2 intercooler, etc)? Also, has anyone with the RX-6 kit passed emissions/kept the airpump?

Thanks,

Jim
94 MBM (Being rebuilt)

The easiest thing would be to buy new twins. If you go single turbo, you'll need to spend more money that just for a turbo kit. You'll also remove your airpump which will make you fail emissions.

Not with the RX6 kit you won't. I would go with a small single, but not the RX6, something that uses a turbo that is easier to get parts for and rebuild in case you have a problem in the future. I know the HKS kits allow you to keep the airpump, also the A-Spec kits with a little work would allow you to keep the airpump as well. Both utilize standard Garrett turbos.
You could get rid of the rats nest and clean up the engine bay.

Go single instead of the 99 twins, once you do you will never want to go back.......

you have to upgrade your fuel system, re-tune for the single ..

Re-tune probably, upgrade fuel system, not necessarily. If he tends to keep the boost near stock levels he would be fine. I don't see why some standard drop in upgraded injectors and an upgraded fuel pump wouldn't be enough to boost up to 15-16 psi with one of the smaller turbos. That's about as high as you would want to go on pump gas anyways.

Have mandeville port the motor if he's going to have it apart.

also, you may want to look in to the BNR twins if you are interested in bigtime power.....the 99 twins can't hold a candle to the potential of the BNRs. Check this link:

https://www.rx7club.com/time-slips-dyno-121/finally-bnr-stage-3-high-boost-dyno-results-442095/

That's funny, your post sounds almost identical to one I posted about 3 years ago. :)

I was in the same boat, about the same amount of mods, had blown my engine, turbos had 120k miles on them and were cracked, so it seemed time to do turbos too. I'm a power freak, so it didn't take much to talk me into a small single. Decided on the RX6 so I could keep all my emissions equipment.

I think that would have probably been all fine and dandy, but I also got 850 primaries at the same time to help support my new fuel needs. Unfortunately, these weren't tuned properly when I picked it up, resulting in a VERY rich idle. Turns out that rich idle, combined with an air pump blowing air into the header causes it to glow red and melt your wiring harness when sitting stopped in traffic.... So I ended up disabling the air pump, which meaned then I needed a midpipe, and then I headed down the slippery slope of changing from a relatively stock car to a highly modded one.

Point being, I don't regret it. I like the RX6 a lot, and I think stock sucks anyway. :) But just be prepared for it to turn into a lot bigger of a job than you first anticipated. It seemed like one thing just lead to the next. I suppose I was a little naive for thinking I could just swap in a single, pick up the car, and everything immediately be all fine and dandy. Maybe your shop can do that for you, but I wouldn't count on it.

Good luck, whichever you decide!