apsolus

iTrader: (2)

So it seems ive been polishing a turd, my 87 NA motor has a blown coolant seal. It needs to be deflooded every time i start it, loosing coolant out the overflow, slight overheating etc.

Anyway i was brain storming doing a V8 swap but decided ill give the rotory at least a chance so the hunt for a good motor started. Found a guy on craigslist with a few rx7 cars and he offered to sell me just about everything to do the NA to turbo swap except the driveshaft for 1000 bucks. the motor he is selling me had a lack of power concern he states and he decided to just do a V8 swap. So we checked out the engine and spun it over. it spins freely and i laid eyes on all 6 apex seals, rotors look to be in good condition at least not carbon fouled. he thinks an apex seal got stuck in the slot by the rotor locking down on it. So im seriously concidering buying everything off him even down to the hood and rebuilding the motor. turbo and manifold been ported and the twinscroll deleted, turbo trans exeddy clutch.

I seached and it seems using the NA wiring harness is the better route but yeah what do you all think? sound like a deal?

RotaryEvolution

iTrader: (30)

if he modified the turbo that is probably why is is responding poorly. but you can get used turbos relatively cheap still.

Evil Aviator

I think it is worth taking a chance on it. If you open up the engine and see major damage, then you can probably sell the parts for nearly what you paid, or you can buy replacement parts for the rebuild. A crummy used J-spec engine and transmission sells for about $1,500, so I think that this is a decent deal.

Almost all of the original driveshafts are toast now, so you would want a new one anyway. You can send the turbo to BNR to see if they can rebuild it, and if not, then just buy a good core turbo that can be rebuilt. I would also look into getting an Rtek upgraded ECU.

apsolus

iTrader: (2)

Dude states he got the engine from japan and showed me some tags and oil filter all have japanese writing so i belive him. Also states the intercooler is jspec cause it says "rotory turbo". Dude told me he was on the highway and ot felt like he "dropped a piston" hes guessing stuck apex seal. So he just removed the engine and trans and decided v8. He stated the engine still idled just lacked power.

So a ported manifold and turbo with twinscroll delete is no good?

Evil Aviator

Not if it was modified by a goon. Does the owner have a receipt for that work to show that it was performed by a professional and that it is covered under warranty?

It sounds like the owner bought a crummy used J-spec engine, hacked it up a little bit, and drove it until it finally broke.

apsolus

iTrader: (2)

Modified goon special. He does have a un touched turbo as well. Anything else i can look for before i commit? Based on what i saw engine seems rebuildable, but im very new to rotory.

dwb87

iTrader: (22)

Even if it's blown... I would say get it. But I would personally rebuild it. $1,000 for a TII swap (without driveshaft) is cheap. Your decision should be based on YOUR expectations of the car and YOUR financial well being.

Evil Aviator

^ This

Plus, see how much the guy wants for the unmolested turbo.

You can price the turbo rebuild levels here:
BNR Supercars - Bryan Nickell's Rotary Supercars - Mazda RX-7 2nd Generation (1987-1991)

apsolus

iTrader: (2)

alright seems i can get a fresh turbo rebuild for around 400 bucks with all the mods. seems likely this is the route ill take.

pick up the parts, rebuild the motor, replace fuel pump with walboro255, replace rear end and trans with turbo 2, install clutch, custom drive shaft made, modify the original wiring harness for the new motor, replace motormounts and transmount with poly bushings, install turbo hood and stock intercooler. also ill need an aftermarket boost gauge.

for the motor, dude states you can run up to 14 psi with the module that fools the computer to ignore higher than stock boost which is included in this deal. does this sound smart? he states i can make upwards of 270 crank hp with 14psi and stock intercooler. well i like power but longevity is number 1 in my book. ill have the money in a few weeks at most for the parts, then the wait for more money to afford the engine rebuild kit and all the other bullshit ill need.

anytips from the people in the know?

Furb

iTrader: (2)

Running anything above 10psi with stock injectors, ecu and intercooler pretty much equals a blown motor..

Evil Aviator

I think we now know what happened to the engine, lol. That device is called a "fuel cut defenser (FCD), which bypasses the car's overboost fuel cut safety feature. This is fine as long as the car has the supporting fuel pump, fuel injectors, aftermarket fuel computer, and turbo and intercooler modifications, but otherwise 14psi is going to blow the motor.

You may want to just disconnect the FCD and get the car running at the stock boost level until you have the time and money to install high-flow injectors and a fuel computer, and tune the engine. Also, the engine is rated for regular unleaded fuel if you run it at the stock boost level, so you may just want to keep it that way in order to save money. Most people are quite happy with 0-60 in 6.7 seconds.

You don't need a custom driveshaft if you have a Turbo II transmission and Turbo II rear end. The custom driveshaft is for when you have a mismatching transmission and rear end.

I like to perform these mods when I buy a used RX-7:
- Replace the pulsation damper
- Replace the two o-rings under the oil filter pedestal
- Send the fuel injectors out for cleaning and flow testing
- Install a Fumoto oil drain valve (F106 without a nipple) so I don't need to deal with the oil drain plug and crush washer.
- Check to see what else needs to be replaced due to age or damage from the former owner.

apsolus

iTrader: (2)

sound advice. pushing the motor doesnt sound like a bright idea. so ill run stock and get myself schooled up on running with a turbo, then slowly i might build up the power.

i already have a turbo pulse damper so thats done, and the rest i can do with the new motor when its out on the stand.

so knowing he blew the motor due to overboost do you guys still think its salvagable? he told me he was cruising when the power failed. and remember i did lay eyes on all apex seals. im one paycheck away from getting everything bought.

wthdidusay82

iTrader: (15)

If he was over boosting the Turbo there's a good chance it needs a rebuild.

The limit on a stock turbo is 12psi, anything higher is inefficient and will cause it to blow its seals and to run that you need upgraded ecu, fuel pump and upgraded secondaries.

The most you should run on a stock setup with a fcd is 9psi, fuel system can't really handle more and stock ecu won't retard timing beyond 9psi boost.

If he was running 14psi he's not too smart. Only a hybrid (modified) stock turbo can efficiently see beyond 12psi

At minimum check the end and side play of the turbo if you can inspect it, if it has either it probably needs rebuild.

Rotary >Pistons

apsolus

iTrader: (2)

oh yeah thats easy enough, i check turbos all day long at work. plus he has everything tucked away in a closet so yeah ill check the turbos out. im leaning on getting the stock turbo he has as opposed to the one he ported out and modified just to keep things simple first time around.

wthdidusay82

iTrader: (15)

I got a nice s5 Turbo setup for $200 shipped here on the forum in like new condition. No end or side play.

Have to replace my stock turbo because its in bad condition, I'll be selling it after I remove it.

Rotary >Pistons

apsolus

iTrader: (2)

cool. running the s5 turbo for more power? i should be fine with sending my s4 turbo out for proper mods via the link i was giving by evil right?

wthdidusay82

iTrader: (15)

S5 has better boost control and was told boost comes faster, as far as power they're both going to give you the same power.

It has a better wastegate design so it controls boost creep better (comes from bigger exhaust and upgraded intake), though most people port the waste gate on both s5 and s4. S5 has a dual waste gate design with 2 holes, s4 has one.

The link he showed you is pretty much where everyone on here upgrades their turbo or gets it rebuilt, they're very well known on this forum.

Rotary >Pistons

apsolus

iTrader: (2)

thanks for the tips, well haha im starting to lean more toward just repairing the motor thats in it. infact the main reason im thinking the turbo swap is because my transmission is pretty well shot and he had the trans to sell me too.

so next question, could i install a turbo transmission to the na? im sure i could right? that way i can leave the rear end, driveshaft alone and not have two motors taking up space in my one car garage currently holding the car and 3 bikes. all in all, my goal is to have a nice running rx7, turbocharged or not. sorry to be bouncing back and forth i guess time changes minds.

RotaryEvolution

iTrader: (30)

it's gonna cost more than $400 to rebuild it by the sound of it. multiples of that if you have someone else rebuild it, maybe even if you do it yourself.

be prepared, and no i'm not on the bandwagon that this sounds like a great deal the more i hear of it.

the S5 turbo only spools faster due to the higher compression engine it originally came on. it will spool slower than a proper twin scrolled S4 turbo on the low compression S4 engine.

wthdidusay82

iTrader: (15)

Why would it spool slower? Everything Ive read regards the s5 as can upgrade over the s4 on an s4 car.

Yes the compression is higher on an s5 engine that's a given, so it'll spool faster on it.

Rotary >Pistons

RXSpeed16

iTrader: (41)

You need to read the FSM. Twin-scroll works, but it was made unnecessary by the S5 divided manifold. I'd rate them pretty close, but removing a moving part from inside the exhaust stream is always a good idea.

junito1

Sounds like bad idea. You are lining yourself up for bad rotary experience.

wthdidusay82

iTrader: (15)

I dont understand what you're trying to say, so it really doesn't answer my question.

Ive never read of there being drawbacks to using the s5 over the s4.

Rotary >Pistons

apsolus

iTrader: (2)

me or wthdidyousay? im tryin here!

wthdidusay82

iTrader: (15)

I'm pretty sure he's talking to you, there's nothing wrong with me using an s5 turbo.

What you're doing is going to be a lot of work, is what he's trying to say and maybe more than you're thinking.

I personally got my Turbo2 for $1000 with blown coolant seals, there are some deals on turbo project cars if you look around and be patient.

No matter what you do I'll do what I can to help.

Rotary >Pistons