So, I've been doing quite a bit of searching for a TII drivetrain and am finding that it may be nearly impossible to source the engine, tranny, and diff for a NA -> TII conversion even with 15-20k to invest (this includes the shop costs, as I don't have the shop space or knowledge for a full swap). With that said, what kind of performance could I get out of the NA while avoiding full on race spec tech? The whole point of this resto/swap is to have a FAST, but fun car. Emphasis on fast.

What do y'all think?

 

There is one S5 TII motor on ebay. 88-91 MAZDA RX7 FC3S TURBO ENGINE 5 SPEED MT TRANSMISSION JDM 13B-T 13BT MOTOR | eBay but man prices have really gone up. Also you would need to plan to rebuild that engine as the condition of those JDM rotary engines can be suspect. Also if you're not out doing drag launches and such the N/A rear end should last awhile. Just get a torsen LSD from a Miata to replace the open diff you have, which is something you'd want to do anyway.

Now on to your original question. I don't know from personal experience as I'm still on the stock ECU, but from what I've read on here around 200rwhp with a street port. 200rwhp also seems to be max for the stock intake manifolds. I know some ITS racecars have made 200rwhp on stocks port but there was a lot of time tuning on the dyno and tuning the exhaust on the dyno to get there. I'd say 160 to 180rwhp is more realistic on a stock port. Also all these numbers are using a standalone ECU. As to a street port with a different intake something like ITB's I'm not sure as there doesn't seem to be a lot of dyno charts for them. The 6-port isn't the best base to start with due to the port timing so it's just hard to get much more than 200rwhp on them.

 

it's really going to be a matter of what your definition of fast is, so for less generic answers, you might want to fill in those blanks for us.

with the right mods (suspension, tires, brakes, etc.) you could probably build something (based on a streetport) that could run real nice, ... and be reliable! you could "daily" it if you so chose. the next step up from there would be to build something based on a more radical port, that you could keep streetable (though that's a little more open to interpretation), get more performance out of, but may not be something you'd want to daily.

just keep in mind that i'm giving you hypotheticals in a vacuum. what i mean by that is: this is if you're just building a car for YOU to enjoy as an owner/driver. if you're building something to race or beat your friend's (inset car here), then you may need a completely different plan.

 

I saw that but thought it was the wrong one because i didnt see any top mount intercooler. I guess i really need to educate myself more. I'm still so new to this rx-7.

You make a great point. I need to determine what "fast" means to me. My daily driver is a 2019 accord touring. The 2.0 turbo makes like 250 hp and is plenty of fun when I step on it, and weighs 700lbs more than the rx-7. My thoughts were originally to get 300whp with a TII, but maybe a full tune and port on an n/a might work.

Bottom line, i need to keep learning about whats possible with an N/A, and how to correctly identify the parts I need.

 

To directly answer your question, I want to get to 60 in under 5 seconds and a high 12 quarter.

 

You may want to look in the build thread section for infernosg's build thread.

Look on page 7 for his dyno results. 250rwhp and 160 ft-lbs of torque at 9000rpm. This is with a street port (4 port irons, so it necessitates you finding T2 irons and doing a rebuild), T2 housings (or grind out the diffusers in your NA housings), ITBs, defined autoworks header, standalone EFI, aftermarket coils, etc. The car still has a partial interior and so I wouldn't call it entirely "race spec" but it's quite all out as far as streetable cars go.

Since you're probably looking to use the stock block (as you mentioned the trouble of finding T2 parts these days) I concur with the others that 160-180rwhp is more likely. Maybe 200.

I'd also look up the dyno sheets section. You can find one there with an S4 streetport in a 1st gen and that car made 184whp. I believe this was with stock intakes still.

Turbocharging the NA engine is very possible, but if you're looking to have a shop do the work I'd be very surprised if they wanted to take on the project.

 

I think you will want to go turbo. Not saying it's not possible n/a but I think the porting will need to be more aggressive than just a street port which will hurt it's "streetability". Also you would be better to start with a four port engine like in the build that was linked so you have to buy a turbo engine anyway. If you look up some fast( 12 sec or less) n/a drag cars they are not running 6- ports. They are bridged 4-ports or peripheral ports The turbo engine seems like a lot of money on front end but to get a n/a that fast you'll most likely end up spending just as much.

 

another option to consider is an Rx8 drivetrain, 232hp with a 6 speed. shop labor would be really high, you'd be the first one to do it. car has potential to end up lighter, emissions legal (if needed) and as quiet as you'd like. engine mounts would need to be made, ecu wired up, etc.

i'm working on FD engine swap #2. its got more power potential, its easier to find parts, can be emissions legal. the cons are lots of fabrication work

Mazda does still make engine parts, so its totally possible to build a 13B-T, and its stock, so shop labor would stay normal. the downside is finding all the little stock parts you need, like intakes/fuel rails, etc

 

Build up a t2 engine over time. Look for deals but use good new internal parts.

I take my car to the canyons and do drifting with my fc and I think the power is borderline enough, sitting around low 300’s.

My setup is:
stock port rebuilt s5 t2 engine
os giken twin disc clutch
bnr stage 3 hybrid turbo
apexi power fc ecu
walbro 255 fuel pump
720cc primaries/ 850cc secondaries
fmic
hks intake
greddy profec b spec 2 boost controller with max boost at 15psi


Definitey run an electronic boost controller so you can spool the turbo faster, and start to close the wastegate when boost tapers off.

 

I have been researching and recently found a possible donor TII drivetrain. I think im gonna go the full swap route. I found a shop that will so the full conversion and I think the ease of pushing higher whp from a TII as opposed to the significant tuning and fussing to get N/A up there will be worth it.

Pictures and more to come when I start the project in earnest. Still have to get all the cars and parts together!