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I just bought a 91 convertible auto trans non-turbo today. It is in very good condition, however it more or less sat for the last 5 years in a guys garage. The gas was about 4 years old. The car seems to be burning oil and I imagine everything that can go wrong with it from sitting has.
With that said I would like to do something clean with it and get it to a reasonable 200-220whp and would love to know the cheapest and most reliable options to get there. I found a complete RX8 motor/6spd with harness, ECU and all engine bolt ons for like $2400. Would that be my best option? Alternatively could I reasonably rebuilt the original NA motor to numbers like that for cheaper? Is it relatively easy to swap in a manual trans or am I more or less stuck staying auto?
I appologise for those questions being a little all over the place and appreciate any answers. I am also attaching pics of my new toy
first, let me say the car looks gorgeous. i'm not really a convertible guy, but the Rx-7 has always been one of a few that i felt i could see myself owning someday. yours is a beautiful reminder of why. anyway, on to your questions ...
Originally Posted by Powdermonkey1111
With that said I would like to do something clean with it and get it to a reasonable 200-220whp and would love to know the cheapest and most reliable options to get there.
is that number arbitrary or do you have some goal in mind? the two easiest ways to go about it are porting and/or turbocharging. my advice would be turbocharging because streetporting your engine might get you there (on the low end of your stated range), but it won't give you as broad a powerband as a turbo will give you. any other type of porting will give you more power, but likely take away your ability to cruise at "normal" speeds.
porting is probably cheaper these days, but it really comes down to what you expect from the car.
I found a complete RX8 motor/6spd with harness, ECU and all engine bolt ons for like $2400. Would that be my best option?
this is surely one way to go, and i think it would be cool as .... let's just say i think it would be cool. best option? i'd say, at this point, it's pretty good. compared to it's peers, the Rx-8 is underpowered, but to be honest, i love driving mine and all i really have done to it is an RB exhaust. i think your convertible is about the same weight (though probably not as rigid) as an 8, so theoretically, it should feel almost as good.
however, you have quite a number of hurdles you'd need to jump and if you don't have the resources, you will be looking at a long time just looking at the car sit (or wishing the shop would finish it) instead of driving it.
Alternatively could I reasonably rebuilt the original NA motor to numbers like that for cheaper?
again, porting is an option, and turbo engines are getting prohibitively expensive now - when you can find them. the rest of the T2 drivetrain is scarce as well. so porting is really attractive, but at the end of the day, you need to realize there's only so much performance you're going to get from a 6-port before you have to look for ways to lose weight (not easy starting with a convertible) or go bigger, race-oriented ports or turbocharge anyway.
Is it relatively easy to swap in a manual trans or am I more or less stuck staying auto?
if you know what you're doing? yes, the swap is pretty easy. you just need to secure the needed parts.
I appologise for those questions being a little all over the place and appreciate any answers.
no apologies necessary. that's what this forum is for.
Thanks for that info! As far as the number goes that just seems to more or less be the sweet spot for where I really enjoy driving cars around this weight while they end up still being reliable. I have had a 3000gt VR4 before and a couple other fun cars in the past. I sort of want to go the clean look with this one where I could show up to a local car who or something and feel comfortable. Is the auto transmission able to handle like 200 WHP without grenading? I much prefer manual but if there isnt an issue with the auto I may try it so my wife could actually drive it too.
if i recall, the Racing Beat California Roadster was automatic. they put a T2 powertrain in a Convertible and bumped output to something like 240 or so. it was a long time ago, so given the state of my memory, i might have some details wrong, now, i don't know if they did any modifications to the tranny, but that should just be a matter of some googling and maybe a phone call to RB. also, there are a handful of guys out there running modded cars with the slushbox, so if that's the way you want to take it, then i don't see why you couldn't. worst case scenario, the FD was available with an automatic as was the JC Cosmo (i think they were automatic-only), and i dare say those trannies are probably not in high demand. the point is you have options.
first, let me say the car looks gorgeous. i'm not really a convertible guy, but the Rx-7 has always been one of a few that i felt i could see myself owning someday. yours is a beautiful reminder of why.
I cannot help but agree with this. Wow, what a beautiful car! RX7's, whether it be convertible or not, always look great in white and your car is no exception!
So moving on. From years of lurking, to actually owning a T2 FC for a short amount of time, and having a close friend own a '87 manual convertible, its safe to say that there is a lot of work required in making power out of a NA 13B. If I were to do it, I'd automatically shoot for a T2 swap. The RX8 swap is absolutely doable, but you'll spend more than what that car is worth to get it to run....all for the same amount of power as a T2 swap. Worth it? To me personally, no. I'd much rather own a RX8 than own a renesis swapped car.
Turbo is gna be your best bet. However, the issue with having an automatic rotary is the carbon buildup from the lack of being able to run the car up to higher RPMs to burn it off. In an auto rotary, carbon will be your enemy long before the transmission.
That car is absolutely gorgeous and I'd be willing to bet it drives just as well, but making more power is a tough road. It has been and can be done, but at what cost? Would it make more sense for you to just buy a RX8 as a project car? The value of clean FCs is going up FAST (I saw one very similar to yours for $25k) and it might be worth it to you to hang onto it in stock form. Just my 2 cent.
I appreciate the input. I am more and more thinking of leaving it stock and just doing some look-good improvements. I wish I knew a decent rotary mechanic in my area (milwaukee) that I could hire to give it a thorough once over as it has been just sitting more or less for the last 10 years. I already scheduled a new top to be put on it. It doesnt look bad but its hard for a 30 year top to not have issues. On the note of value, do you think a manual swap would end up making sense from a persepctive of resale value? I can't imagine automatic RX-7's sell for nearly as much as manuals. Also, it would be much more fun for me to drive it in the time being I'm not specifically looking to dump it right away.
if i recall, the Racing Beat California Roadster was automatic. they put a T2 powertrain in a Convertible and bumped output to something like 240 or so. it was a long time ago, so given the state of my memory, i might have some details wrong, now, i don't know if they did any modifications to the tranny, but that should just be a matter of some googling and maybe a phone call to RB. also, there are a handful of guys out there running modded cars with the slushbox, so if that's the way you want to take it, then i don't see why you couldn't. worst case scenario, the FD was available with an automatic as was the JC Cosmo (i think they were automatic-only), and i dare say those trannies are probably not in high demand. the point is you have options.
The only issue with a JC Cosmo transmission is serviceability
While I do have the Maintenance Manual sitting on my shelf, it's entirely in Japanese and there are other, considerably larger projects ahead of it at the moment. Also, making it communicate properly with a N350 car (S5 NA) instead of the intended N390 or NF01 ECU is going to be a challenge.
A FD Automatic would be a better option since all of the info is already in English, but one still encounters the "cross-generation" conversion issues. One other option is to keep the original S5 Automatic. In Japan, they used the same transmission in every Turbo FC. If using a stock Hitachi HT-18 Turbo, you could just get a Japan-spec N374 ECU (N319 for S4) and theoretically be good to go. Once I'm done with my current projects, I can look into it further.
I wish I knew a decent rotary mechanic in my area (milwaukee) that I could hire to give it a thorough once over
Early last year I was considering moving up to that area with my now ex- girlfriend and upon further investigation, I found that you have at least one local(ish) rotary shop that has gained quite the reputation; Elite Rotary. Give them a call if you want to have it inspected, and they'll also be able to help you source parts and upgrade if you decide to go that route.
Originally Posted by Powdermonkey1111
I'm not specifically looking to dump it right away.
DON'T YOU DARE!! And if you do dare, send me a message. My girlfriend would love a white convertible
The only issue with a JC Cosmo transmission is serviceability
While I do have the Maintenance Manual sitting on my shelf, it's entirely in Japanese and there are other, considerably larger projects ahead of it at the moment. Also, making it communicate properly with a N350 car (S5 NA) instead of the intended N390 or NF01 ECU is going to be a challenge.
A FD Automatic would be a better option since all of the info is already in English, but one still encounters the "cross-generation" conversion issues. One other option is to keep the original S5 Automatic. In Japan, they used the same transmission in every Turbo FC. If using a stock Hitachi HT-18 Turbo, you could just get a Japan-spec N374 ECU (N319 for S4) and theoretically be good to go. Once I'm done with my current projects, I can look into it further.
great points.
honestly, i didn't think that far ahead, as to computer control. i was simply trying to give rotary cars from roughly the same point in time that would have automatics being used with higher output than the N/A Rx-7, in the event that that tranny was deemed/proven to be inadequate for his stated goal. i definitely appreciate you supplying knowledge and points that i did not have.
10-31-21, 09:20 PM
