faulty

I'm looking to pick up an 86 or 87 RX7 in the near future as a winter project car, and I've got a few questions, likely most of them n00bie ones. Prob. not the most organized post, but hopefully it'll answer the gist of my questions so I can plan my winter.

Quick background on me so you can get an idea for my general experience level.

First car was a Mazda Tribute, left it stock and sold it after a year. Then I bought 3 Volvos in a row - 1 wagon which stayed stock and got sold, then a sedan which I've converted into a drag car (AWD conversion, built motor, twin turbos, etc.), and my current daily driver is another wagon which has a +T (aka adding a turbo to an NA motor) All work done myself. Both the wagon and sedan are running on MegaSquirt 3. By day, I'm an IT guy, by night I'm a car modder.

Enough background - now for my questions.

I plan to do a performance-based build that will be sane enough to roll as a summer daily driver, but I want it pretty hard-core. My likely plan is to buy a super-cheap RX off CL - like under 2 grand. My main things are it must not be a rust bucket and must have a clean title/not been crashed.

That said - I've seen a lot of people say "don't do a full bridge or a big PP as it's not streatable" - I need someone to define "streetable" - my wagon gets 15 MPG highway on a good day, and the drag car is lucky to get 3 MPG, so millage isn't even remotely on my list of stuff. As far as tons of rough idle (brap, brap, brap ) it's no biggie - my wagon has huge cams and my idle vacuum is on the verge on not being usable with SpeedDensity. (I think I get like 8 or 9 inches )

I read through Icemark's motor rebuild thread last night and I'm pretty surprised how simple the 13B is compared to the straight-5 Volvo motors I'm used to working with are. The rebuild looks super-easy.

One thing that got me was the weird oil pump - chain drive? WTF was Mazda thinking?! Does this hold up well at high power levels?

With that in mind, it seems that people are running pretty big turbos on these motors. I have a pair of Holset HX52's on my drag car, and I saw someone who has a single on an 13B. Given you can buy cores on ebay for under $200, that would be my choice for a turbo. Not sure on the hotside though - if someone could give a suggestion on what my expected spool RPM would be, that'd be good.

For anyone who's done a +T, in case I get stuck with using NA irons, how do I deal with oil feed/return?

On that note - oil metering pump...If I wind up with an S4, I'm fine. S5 might be an issue. Anyone who's binned it on an S5 and running 2-stroke oil - if it comes to it, what's the best mixture?

Ignition coils - it seems that the leading coil is a normal wasted-spark coil, but the trailing is some goofy "switched logic" coil - what the heck is it, and am I stuck with the factory trailing coil, or am I free to run something different? (GM LS2 truck coils come to mind)

I think that's all I can dream up now for questions. Hopefully this will be a good jumping off point for me as I miss my Mazda.

p.s. - my family is Mazda-heavy. We've owned the Tribute, an MS Protege, a 3, and a CX-9 - all since 2001. I'm dying to get back into the group.

exnissanguy

Dont let the small physical size of the engine fool you, the rotary engine produces an exhaust pulse like that of a v8. Take a look at turbine housings sizes and they will be in the .96 and larger depending on port for these engines. With these engines ive had great luck with divided housings and dual wastegate setups to handle the boost creep

I think your best choice would be to just pick up a tII shortblock. with that you get the lower compression rotors too.

There a alot of great bottled pre mixes out there, just do a few searches on the board. I liked the klotz caster bean stuff. Pre-mixing isnt a bad idea even with the omp still working. its cheap insurance for a part that fails every now and then on these engines.

I have seen lsx coils used with haltech s1000 standalones


Hope that helps!
-ricky

faulty

Thanks! That helps me a lot! I looked and apparently I can get a TII shortblock, brand new from Mazda for $3400. I'll try to find a used one first, but if I can't, that price isn't all that bad. Only thing that sucks is to buy a brand-new motor, then the first thing you do with it is to take it apart to get it bridgeported.

The ignition coil info is good news. I've got literally PILES of LSx coils around here, and I know that they're super-cheap and very reliable.

The current turbo I've got is a Holset HX52. .88 turbine, 1.14 compressor. Divided T4 exhaust inlet flange. I've got a single 60mm wastegate, but I can add a second one if I need to.

I found a car last night which is in good shape, trans. is good, and the motor is alright. It'll rev. to redline w/o any issues, but can't idle...my money is on the idle adjustment screw needs to be turned a bit. Guy wants $850 for it, so I might pop down and check it out this weekend. Hopefully it'll turn out good and I'll have it in my driveway by next week.

funkjaw

iTrader: (3)

To answer one of your questions, it's not a bad idea to pre-mix any rotary to be honest. I personally have had any issues with the OMP myself, but at the power levels you want to go, you'll want to pre-mix just as cheap insurance.

exnissanguy

Ebay has tons of s4 and s5 turboII complete with trans, and all accessories and most have compression tests and warranties for 2grand. If you are gonna port you might as well save some cash maybe even make some back from selling uneeded parts.

faulty

Mk. I guess I'll need to get used to leaving a bit of room in my tank before filling it up with gas. No biggie.

Good point. Never crossed my mind to buy the motor off ebay. I'll look into that for sure!

faulty

OK, some updates and more n00bie questions.

After looking around quite a lot, I've decided to hold out and try to find an FD coupe. Reason being I like the looks MUCH more then then the FC's.

Now for my n00bie questions.

A) Still un-answered from the first post: half-bridge vs. full-bridge...does it really matter if I get a full bridge in a street car? Again, I'm used to barely idling from huge cams, and since this will be a performance built, full bridge would seem to be the more logical choice.

B) As far as my turbo goes, what powerlevels can I expect to see? It's about the same as a GT4202R, and some YouTube videos I've watched are averaging around 600whp. Is this reasonable to expect, or will it be a long shot?

C) Does anyone have suggestions for a good widebody kit? I've seen a few on eBay and the like, but I'm guessing the quality is pretty dodgy.

D) What's a good size FMIC to go with? I've got a 24x12x3 floating around, but I think it's a bit big for an FD. I've got a 20x20x2 and an 18x16x2 around as well, but those are likely of even less use.

E) I've got 1 SSQV BOV, but I've read some places that with a turbo this big, 2 BOV's are recommended. Can I stick with 1, or should I put a second one in for safety's sake?

F) Exhaust. I'm thinking just a 4" straight pipe. No issues with noise - I've got a 3" side dump on my wagon at the moment, and it's loud, but nowhere near unbearable. Emissions aren't a concern to me.

I think that's all I can think of right now. I'm open to any suggestions/ideas on how to make this car awesome, so feel free to throw them at me.

(note to mods, you might want to just move this to the general FD forum...prob. getting too off-topic for the new member forum now, lol)