So...I just bought an RX-7 Turbo II, School Me

The opportunity came up to pick up a decently clean FC RX-7 Turbo II for challenge money. It has some nice mods, ~100k miles, and was being sold by a local autocrosser...how could I say no?

I can't even explain why I did this. I already have a V6 MR2 project. I currently am in-between houses. I barely freaking fit (6'6")...I've never owned a rotary and was curious I guess. It runs well, will occasionally stall which I believe is due to the aftermarket tune. No real smoke to note and pulls pretty hard, so I believe the engine to be healthy, but I have absolutely no reference point. Suspension feels/drives great. 

So, what do I need to know? It seems like the cooling has been mostly addressed via mods. What are the other weak points?

More importantly, what should I do with it? HPDE car? Autocross? $2018 Challenge (from Colorado)? V8 Swap? Help me enjoy my new spinning Dorito.

Holy cow, you got a TII in that condition for challenge money? If that's a genuine TII, that's worth considerably more unless it's a flintstone mobile and doesn't show in the pics.

I'll leave the rest of the gang to suggest V8 swaps and will suggest to keep it rotary. This looks like it's got most of the usual problem areas addressed, so I would keep make sure to warm it up properly and then drive it like you stole it. Personally, I also tend to use Idemitsu premix for a little added safety margin.

Those have gone up in value a bunch lately. Fix and sell for a big profit. They are getting rare. I would hate to see it get turned on to a v8.

I love that us folks around here buy first and ask later when we are serious. But when aren’t serious, we make a “what car” or “learn me” thread. Lol. Only here on this forum

BTD said:

So, what do I need to know? It seems like the cooling has been mostly addressed via mods. What are the other weak points?

 

More importantly, what should I do with it? HPDE car?

Too many weak points to list, probably best to just sell it to me and be done with it.  Challenge money you say? 

Definitely bring it to the Challenge!

You got that thing for Challenge money?!?! E36 M3, I would have bought it just for the suspension parts and diff at that price.

Mine is LS1 swapped and it is spectacular, but a TII in that condition and running well I think I would be inclined to leave alone, at least until you blow the rotary up. But if/when the time comes, they do swallow a V8 remarkably well and there is a lot of info and parts support available for the swap. 

you got quite the deal there... I have wanted one of these for a while for no reason I can confidently identify. 

Damn!

I want!

Did I miss the blown apex seal or frozen turbo? At challenge money you got it for at least half off. 

I would detail the heck out of it and take it to some import nights and stuff.  Pretty cool and kinda rare to see on on the streets anymore.  Then I would autocross it, keep it mid-pack and just have fun with it.  

Leave it Rotary, stay out of the redline, maintenance it religiously, and have fun! 

I kept reading waiting for the "it's not running" part of the post... you seriously scored deal of the millennium. If it truly is as clean as it looks, you bought it for 1/3 price at least.

What would I do with it? Keep it as is, maybe put some aftermarket wheels on it (keep those stock wheels nice) and a small removable ducktail and that would be about it. Keep it topped off with fluids and occasionally autocross it. It seems like whoever owned it had a good idea what they were doing mods wise.

Just remember that you DO NOT want to baby a rotary, a redline a day keeps the mechanic away!

Keep an eye on your oil and coolant levels and monitor that temp gauge. Maybe add an oil temp gauge if you are going to do HPDE or track days.

Oh yeah, and there are a ton of groups on Facebook for rotary cars.

Well done sir - seems like a tune and enjoy plan to me.  These look so good in white.

Nice car. Looks like an '87.

My memory believes the S5 (89-91) differentials were viscous, I'm not sure if that's an "upgrade" from the S4 clutch pack diff. The S6/FD differential was torsen.

I'm not sure why the exhaust has two catalytic converters. Yes they came that way from the factory, but the pre-cat was in the downpipe. In the OEM configuration the pre-cat was restrictive, but things have changed in the last 30 years so an aftermarket replacement could be better.

I would confirm that the "relocation" of the oil cooler makes sense. These cars rely heavily on oil cooling.

A S4 with those modifications should have sky high boost. What peak boost do you see?

Thanks for the kind words everyone, I'm pumped about it as well. If I can make the challenge work, I'll be there. It's a far drive from CO to FL...

Snrub said:

Nice car. Looks like an '87.

My memory believes the S5 (89-91) differentials were viscous, I'm not sure if that's an "upgrade" from the S4 clutch pack diff. The S6/FD differential was torsen.

I'm not sure why the exhaust has two catalytic converters. Yes they came that way from the factory, but the pre-cat was in the downpipe. In the OEM configuration the pre-cat was restrictive, but things have changed in the last 30 years so an aftermarket replacement could be better.

I would confirm that the "relocation" of the oil cooler makes sense. These cars rely heavily on oil cooling.

A S4 with those modifications should have sky high boost. What peak boost do you see?

 

Correct, it is an '87! I'm no expert on the rear diff, that's just what the P.O. told me. The exhaust has two cats because it failed emissions with only one. I have a car delete pipe but the second cat was needed the last time the previous owner registered the car. 

Where would you reccomend the oil cooler be located?

I'll have to double check on boost, it was above 10psi but I'm not sure of the exact number. I'll take it for a spin later. 

TheRX7Project said:

I kept reading waiting for the "it's not running" part of the post... you seriously scored deal of the millennium. If it truly is as clean as it looks, you bought it for 1/3 price at least.

Keep an eye on your oil and coolant levels and monitor that temp gauge. Maybe add an oil temp gauge if you are going to do HPDE or track days.

I cheated a bit with the first picture and only showed it's best side. Not to say that it's in bad shape, but it's a much better 10' car than it is a close-up car. Pictures below, it's got some dents and dings and such. Nothing that affects the car, but some stuff that will probably be harder to fix. 

The car has an EGT gauge along with a wideband Air/Fuel and a fuel pressure gauge. Maybe I'll add an oil temp gauge as well. 

It also came with an extra set of Kosei wheels and NT01 tires, so it's pretty much ready-to-run as it sits.

Photos to show it isn't perfect:

I played with buying it, but at the end of the day, I just don't have space in my garage for it, or a use for it.  Looking forward to seeing what you do with it.

I do regret missing on the nice NB Miata that was on rmsolo for $1200 awhile back tho!

I lived near Pete Townshend back when that car was new and he had one just like that, though I think I remember a spoiler on the back of his.

You bought THAT for challenge money?! Wow, I'm envious. Very cool car!

Temp gauges on these are useless. If they move above normal you have probably toasted the motor. Install an aftermarket one. I drilled and tapped the boss on the housing for the thermostat. I used a manual gauge and it worked great.  

Also don’t start it and then move it 20 feet and shut it down. Rotarys hate that. Always bring it up to temp before shutting it down. 

The injectors like to leak.  I installed a kill switch on the fuel pump so to shut it off I would kill the pump and let run out of fuel pressure  this also makes a nice security feature  

the oil injection pumps like to fail.  Keep an eye on them.  If they fail you will toast a motor.  I just got rid of them and went to pre mix.  I liked that I was running clean oil in the fuel instead of the dirty stuff from the case.  There is also an argument that you should not use synthetic oil in these due to the injection of oil and it needing to be Dino oil.  Running two stroke oil let’s you run synthetic in the case with out worry about what is getting burned in the motor.  

The only other thing is don’t speed shift them .  The synchros will not last  even rev matching will not help.  Use the clutch.   

Other than that have fun.  They are great cars.  Another car that is more than the sum of its parts. 

BTD said:

Correct, it is an '87! I'm no expert on the rear diff, that's just what the P.O. told me. The exhaust has two cats because it failed emissions with only one. I have a car delete pipe but the second cat was needed the last time the previous owner registered the car. 

Where would you reccomend the oil cooler be located?

I'll have to double check on boost, it was above 10psi but I'm not sure of the exact number. I'll take it for a spin later. 

I cheated a bit with the first picture and only showed it's best side. Not to say that it's in bad shape, but it's a much better 10' car than it is a close-up car. Pictures below, it's got some dents and dings and such. Nothing that affects the car, but some stuff that will probably be harder to fix. 

The car has an EGT gauge along with a wideband Air/Fuel and a fuel pressure gauge. Maybe I'll add an oil temp gauge as well. 

It also came with an extra set of Kosei wheels and NT01 tires, so it's pretty much ready-to-run as it sits.

Photos to show it isn't perfect:

Even with the scuffs, it's still a great car and a wicked car for the money.

Interesting about the two cats, but I suppose that's one way to do it. They weren't the cleanest cars out there :) and they typically run richer AFRs than many other cars for safety. I'd be tempted to run 0-1 cats most of the time. In that setup with your 3" exhaust and turbo inlet duct (3" initially?) you might hit 15psi+. The wastegate on the S4 turbo is pathetically small. It's a common modification to port the wastegate to keep the boost to sane levels and then use the boost controller (if necessary) to bump it up a bit. These cars came from the factory with 182hp, but a good 3" exhaust can bump it up 50-60hp and potentially more with your TID and tune. People don't like turbo lag, but it can actually add to the entertainment factor when the boost hits this hard.

Regarding the oil cooler, the factory location is front bottom. I'd just make sure the new location seems like it will get a lot of air flow. It's also important that the under tray is intact so air doesn't simply bypass the oil cooler and radiator. The under trays seem to be more fragile than in some other cars.

Based on your outline, your car seems to be properly modified. The only thing I'm not necessarily in agreement with is the pulsation damper removal, but that's controversial and I don't know if it's reasonable to expect to have a reliable one in a 32 year old car.

The one thing that is kind of neat about these cars is they were pretty much the fastest thing on the road in their day (balance of performance attributes). C4 Corvettes were faster, but other than that, it was only exceeded by rare/fragile exotics. In many ways they're a seriously beefy car. There's a picture Mazda took during the development where they launched it off a ramp into the air to ensure durability. There are people putting 600hp through essentially stock drivetrain and engine.

Careful with anything much above 10 psi.  The stock turbo can do 12 psi without too much inefficiency.  However, the air temps start to rise faster than teh boost at that level.

Opening up the exhaust can cause CRAZY boost creep.  This CAN hurt the engine.  

If you open up the exhaust (even replacing a cat), keep an eye on your boost the first couple of times you drive it.

With a 3" downpipe and a 3" exhaust, I could get to 14 psi with a fully ported and welded wastegate (cut hole bigger than flapper and weld a big washer on it).  I actually had to put in a fairly restrictive resonator to get boost back down to around 10 psi.

Rev the piss out of it on a regular basis.

Also, the S4 temp gauges work fairly well.  The water temp gauge should sit about 1/3 of the way up.  If it gets to half way, shut it down and let it cool off.

If you didn't know, those are s5 tail lights.

That car is in VERY good shape.

Dont remove anything plastic from the interior.  It WILL break.  Be Super careful doing any interior work.  All the clips like to break off.

Quote

Even with the scuffs, it's still a great car and a wicked car for the money.

Interesting about the two cats, but I suppose that's one way to do it. They weren't the cleanest cars out there :) and they typically run richer AFRs than many other cars for safety. I'd be tempted to run 0-1 cats most of the time. In that setup with your 3" exhaust and turbo inlet duct (3" initially?) you might hit 15psi+. The wastegate on the S4 turbo is pathetically small. It's a common modification to port the wastegate to keep the boost to sane levels and then use the boost controller (if necessary) to bump it up a bit. These cars came from the factory with 182hp, but a good 3" exhaust can bump it up 50-60hp and potentially more with your TID and tune. People don't like turbo lag, but it can actually add to the entertainment factor when the boost hits this hard.

Regarding the oil cooler, the factory location is front bottom. I'd just make sure the new location seems like it will get a lot of air flow. It's also important that the under tray is intact so air doesn't simply bypass the oil cooler and radiator. The under trays seem to be more fragile than in some other cars.

Based on your outline, your car seems to be properly modified. The only thing I'm not necessarily in agreement with is the pulsation damper removal, but that's controversial and I don't know if it's reasonable to expect to have a reliable one in a 32 year old car.

The one thing that is kind of neat about these cars is they were pretty much the fastest thing on the road in their day (balance of performance attributes). C4 Corvettes were faster, but other than that, it was only exceeded by rare/fragile exotics. In many ways they're a seriously beefy car. There's a picture Mazda took during the development where they launched it off a ramp into the air to ensure durability. There are people putting 600hp through essentially stock drivetrain and engine.

wvumtnbkr said:

Careful with anything much above 10 psi.  The stock turbo can do 12 psi without too much inefficiency.  However, the air temps start to rise faster than teh boost at that level.

Opening up the exhaust can cause CRAZY boost creep.  This CAN hurt the engine.  

If you open up the exhaust (even replacing a cat), keep an eye on your boost the first couple of times you drive it.

With a 3" downpipe and a 3" exhaust, I could get to 14 psi with a fully ported and welded wastegate (cut hole bigger than flapper and weld a big washer on it).  I actually had to put in a fairly restrictive resonator to get boost back down to around 10 psi.

Rev the piss out of it on a regular basis.

Also, the S4 temp gauges work fairly well.  The water temp gauge should sit about 1/3 of the way up.  If it gets to half way, shut it down and let it cool off.

If you didn't know, those are s5 tail lights.

That car is in VERY good shape.

Dont remove anything plastic from the interior.  It WILL break.  Be Super careful doing any interior work.  All the clips like to break off.

So, took the car to get emissions today. It fast-passed, which is great!

Some things I noticed:

1) It's boosting to ~8psi according to the aftermarket boost gauge that's in there. This seems low based on what I'm reading in this thread, but maybe it was tuned down a bit with the RTek7?

2) Idle Air/fuel fluxuates between 16.5-17.2. This seems really, really lean to me. I assume that additional tuning is needed? The car runs ~14.7 (stoich) under light load while cruising and ~12.5 under heavy load/boost. 

So far, I really REALLY enjoy this car. It's night and day different from my V6 MR2 which has gobs of torque down low but falls on it's face up top. 

Engine bay photo:

Those AFR seem off to me. I'd check the sensor first and see if it might need recalibration.

BTD said:

Quote

Even with the scuffs, it's still a great car and a wicked car for the money.

Interesting about the two cats, but I suppose that's one way to do it. They weren't the cleanest cars out there :) and they typically run richer AFRs than many other cars for safety. I'd be tempted to run 0-1 cats most of the time. In that setup with your 3" exhaust and turbo inlet duct (3" initially?) you might hit 15psi+. The wastegate on the S4 turbo is pathetically small. It's a common modification to port the wastegate to keep the boost to sane levels and then use the boost controller (if necessary) to bump it up a bit. These cars came from the factory with 182hp, but a good 3" exhaust can bump it up 50-60hp and potentially more with your TID and tune. People don't like turbo lag, but it can actually add to the entertainment factor when the boost hits this hard.

Regarding the oil cooler, the factory location is front bottom. I'd just make sure the new location seems like it will get a lot of air flow. It's also important that the under tray is intact so air doesn't simply bypass the oil cooler and radiator. The under trays seem to be more fragile than in some other cars.

Based on your outline, your car seems to be properly modified. The only thing I'm not necessarily in agreement with is the pulsation damper removal, but that's controversial and I don't know if it's reasonable to expect to have a reliable one in a 32 year old car.

The one thing that is kind of neat about these cars is they were pretty much the fastest thing on the road in their day (balance of performance attributes). C4 Corvettes were faster, but other than that, it was only exceeded by rare/fragile exotics. In many ways they're a seriously beefy car. There's a picture Mazda took during the development where they launched it off a ramp into the air to ensure durability. There are people putting 600hp through essentially stock drivetrain and engine.

 

wvumtnbkr said:

Careful with anything much above 10 psi.  The stock turbo can do 12 psi without too much inefficiency.  However, the air temps start to rise faster than teh boost at that level.

Opening up the exhaust can cause CRAZY boost creep.  This CAN hurt the engine.  

If you open up the exhaust (even replacing a cat), keep an eye on your boost the first couple of times you drive it.

With a 3" downpipe and a 3" exhaust, I could get to 14 psi with a fully ported and welded wastegate (cut hole bigger than flapper and weld a big washer on it).  I actually had to put in a fairly restrictive resonator to get boost back down to around 10 psi.

Rev the piss out of it on a regular basis.

Also, the S4 temp gauges work fairly well.  The water temp gauge should sit about 1/3 of the way up.  If it gets to half way, shut it down and let it cool off.

If you didn't know, those are s5 tail lights.

That car is in VERY good shape.

Dont remove anything plastic from the interior.  It WILL break.  Be Super careful doing any interior work.  All the clips like to break off.

So, took the car to get emissions today. It fast-passed, which is great!

Some things I noticed:

1) It's boosting to ~8psi according to the aftermarket boost gauge that's in there. This seems low based on what I'm reading in this thread, but maybe it was tuned down a bit with the RTek7?

2) Idle Air/fuel fluxuates between 16.5-17.2. This seems really, really lean to me. I assume that additional tuning is needed? The car runs ~14.7 (stoich) under light load while cruising and ~12.5 under heavy load/boost. 

 

So far, I really REALLY enjoy this car. It's night and day different from my V6 MR2 which has gobs of torque down low but falls on it's face up top. 

 

Engine bay photo:

6 to 8 psi is stockish and should be good for long life.  

Id say those AFR's are about perfect.  Under load 12.5 or under is good.  Just cruising, they can be all over the map (literally).

Wow, a turbo with the stock air pump.  Unicorn!