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Rebuild/Full Restore Project
Hello my name is Ethan and I have been roaming around the forums now for about a few months. I just recently purchased a 1986 NA FC and I will be doing a complete overhall and revamp as well as boosting. I already have a completely decked out asubaru WRX that I did all myself and this is my first rotary. Im planning on a 250-300whp setup with good mid range ... I dont need top end power and low end would be much more what im looking for. I plan on drifting in this guy (depending on how I feel about it once it looks pretty) So im trying for a more reliable punchy mid end power band hoping to be sitting on the 4-5k rev range most of the time.
My first question is, is there a premade guide to building a FC? I feel like ive seen a simple mod list floating around with very detailed hp gains and cost of products but I have yet to find it again!? 2nd question, I know nothing of fuel systems in these cars it seems way different then my subie. Is there a guide/manual that tells you how much cc injectors/ fuel pump/ turbo are needed to make a certain hp point? I asked a local guy around my area If I could put my subaru turbos on the engine. ( I figure a 140whp 4 cyl making 150+HP on the vr22 would be sufficient to hit 250-300hp on the 120whp rx7) my neighbor told me that the turbo would be waaaay too small. I find it wierd that the 1.3L needs a bigger turbo then the 2.5L my Subie runs. So im getting kinda confused with the fuel systems and turbo setup. Im already tearing apart the engine and mild porting the guy ive been just working on smoothing and rounding everything nicely. Ive been told the bridgeport (although it sounds cool) is bad for lowend so as far as I am aware I am just doing a nice street port. I was looking at a GT35r turbo ... is this too big or small for what Im trying to accomplish? I will probably be doing e85 and I am still deciding on the brand on injectors I want. All recommendations are appreciated! Sorry if any of this sounds soooo Newb but I truly have been around here alot and Ive been reading a Haynes manual every night before bed xD. Thanks for any help guys. |
Originally Posted by Ethan Adams
(Post 12224237)
Hello my name is Ethan and I have been roaming around the forums now for about a few months. I just recently purchased a 1986 NA FC and I will be doing a complete overhall and revamp as well as boosting. I already have a completely decked out asubaru WRX that I did all myself and this is my first rotary. Im planning on a 250-300whp setup with good mid range ... I dont need top end power and low end would be much more what im looking for. I plan on drifting in this guy (depending on how I feel about it once it looks pretty) So im trying for a more reliable punchy mid end power band hoping to be sitting on the 4-5k rev range most of the time.
My first question is, is there a premade guide to building a FC? I feel like ive seen a simple mod list floating around with very detailed hp gains and cost of products but I have yet to find it again!? 2nd question, I know nothing of fuel systems in these cars it seems way different then my subie. Is there a guide/manual that tells you how much cc injectors/ fuel pump/ turbo are needed to make a certain hp point? I asked a local guy around my area If I could put my subaru turbos on the engine. ( I figure a 140whp 4 cyl making 150+HP on the vr22 would be sufficient to hit 250-300hp on the 120whp rx7) my neighbor told me that the turbo would be waaaay too small. I find it wierd that the 1.3L needs a bigger turbo then the 2.5L my Subie runs. So im getting kinda confused with the fuel systems and turbo setup. Im already tearing apart the engine and mild porting the guy ive been just working on smoothing and rounding everything nicely. Ive been told the bridgeport (although it sounds cool) is bad for lowend so as far as I am aware I am just doing a nice street port. I was looking at a GT35r turbo ... is this too big or small for what Im trying to accomplish? I will probably be doing e85 and I am still deciding on the brand on injectors I want. All recommendations are appreciated! Sorry if any of this sounds soooo Newb but I truly have been around here alot and Ive been reading a Haynes manual every night before bed xD. Thanks for any help guys. I'll start from the top and try and answer your questions in order. 1) If you want 250-300 whp, sell the NA and find a Turbo 2 to start. Swapping and building on the NA base usually ends up costing more in the long run because you have to think about the whole package. -The NA engine is possible to turbo and it's been done many times, but the higher compression and port volume works against you in low end and driveability. -The transmission is not suited for the higher output and torque for the long run. The clutch diameter is smaller and can't withstand the extra power without going to exotic materials. The T2 transmission can support well over 500whp stock. The NA one, not so much in the long term. -The rear diff is probably an open diff with a smaller ring gear than the Turbo 2 unit. You need turbo axles to work with the T2 diff, and axles are rare and expensive to find used. -You will not be sitting at 4-5k with an NA turbo, more like 5-8k Rpm. The power comes on much later. 2) Go to FC3Spro.com There is a great list of mods and things you can do to upgrade your car, but the site is geared toward T2 cars. As far as prices, people usually do not list prices because they vary from region to region. -Aaron Cake has a good website on how he turbo'd his NA, but he has come on the forum and stated that it's not a recommendation for everyone. Just how he did it. aaroncake.net 3) For fueling, go to the Single Turbo Forum. Howard Coleman has multiple posts about injector sizing, fuel pumps, and turbo sizing. Most of his lists are geared toward 500+whp. For a stock-ish turbo making 300whp, a Walbro 255, Stealth 340, or Supra TT pump works fine. I believe the FD pump would work as well. I'll get to your turbo sizing soon, so bear with me. 4) Bridgeport is not ideal for the street and porting the NA will not get you very far. In the NA Subforum, they have lists and documented results as to where porting will get you on NA. The port volume on the 6-port is already so large that porting the secondaries only gets you more peak power and the low end suffers. 5) This is where I address turbo sizing. The Subaru turbo is already too small for a Subaru. I know the displacement is 2.5l on a subie, and the RX7 is 1.3, but you need to understand how the rotary works first. A piston engine has 1 power stroke per 720 degrees per piston. On a four cylinder, that's one power stroke every 180 degrees. On a rotary engine, there is one power stroke per rotation of the eccentric shaft. You basically get double the exhaust volume vs a piston engine. A rotary engine in racing is counted as double displacement, so a 1.3 is treated as a 2.6 instead. Because of the exhaust volume, a Subaru turbo would choke the engine out. A GT35R is a great turbo, if you are chasing 400+whp. For 300whp, it's too big and will be laggy. If you want around 300whp, a hybrid T2 turbo is great for that and will get you there for under a grand if you already have a turbo. You want the S5 turbo and manifold, because they flow much better and prevent boost creep. BNR Supercars does hybrid turbo services. The Borg Warner SXE 7670 is also a great turbo for around 300 whp. 5) E85 is really only viable if you are trying to push 450+ whp. You need 33% more E85 to make the same power as gasoline, so you will suffer major fuel economy losses and finding E85 is a pain in most areas. Your tag says Portland. I'm guessing Oregon. Not too many E85 stations in the PNW, so good luck having any range or fun at all. E85 has a very short shelf life because it absorbs water from the air, even when sitting inside the vehicle's tank. E85 is useful for knock suppression and you can run more timing, but you need a special fuel pump to push the volume. A Walbro 400 E85 would work. You also need injectors that can handle the ethanol content, so ID injectors in the 1000CC primary and 2000CC secondary would likely be needed. That's about $800 in injectors alone. Plus fuel rails, lines, regulator, etc. Running E85 would require a standalone PCM, so theres around $1500-2000 for a controller and all the things needed. You need it tuned, so dyno time is a must and that can get upwards of the thousands of dollars. I'll summarize what you should do here: Enjoy the car. Drive it stock and enjoy it. Figure out its limits and drive the car. I've had mine on stands for over 3 years. I wish I just fixed what was wrong so I could drive the damn thing. I'm already balls deep in a full restoration, so I can't enjoy my car. If you really want a car with 300 whp and turbo, sell the NA and buy a Turbo. Don't swap it. It's seriously too much work, expense, and time to track down every little thing you need. Trying to half-ass it and cut corners will only bite you in the end. With a stock T2, you can have a decent base to begin and put some bolt-on onto it. Get an S5. Do not get an S4 because you will be limited as to what you can do in the long run. I get that some people enjoy building cars, but too many are started and never finished. You say you've been around, well your questions and plan of attack show that to be inaccurate. There are threads asking your exact question that have been covered hundreds of times. I'm not trying to be an ass, but I'm being realistic. Reading a Haynes manual doesn't get you anywhere in this game. Reading what other people have done and what has worked is where you should start. Check build threads and look at what the payouts end up being. You will notice most of them fall off the face of the earth and usually end up getting parted. There is a wealth of information and going head first into a build with no plan and direction is a sure way to fail, or spend far too much money and end up jaded. I know the suggestion to JDM turbo swap will come up. Expect ANY JDM engine you get to be a boat anchor. Too many members buy engines from overseas and end up scrapping most of the rotating assembly. They sit for years in lots, then sit for months in container ships, then potentially years again once they get here. I just looked up and read your post again. You already pulled the engine and tore it down, so driving it now is out. The rebuild kits are about $1000 on average, so pick what you will do wisely. I still think your best plan of attack is to start with a Turbo 2 and build from there. |
Sounds like one hell of a build. I would see some benefit starting with the Turbo II - my dad bought one of these new and my whole family still remembers that being one of the fastest cars we've owned. He only sold it to upgrade to a 928 (because he "needed" a back seat to put the kids in).
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Originally Posted by ACR_RX-7
(Post 12224282)
I'll start from the top and try and answer your questions in order.
1) If you want 250-300 whp, sell the NA and find a Turbo 2 to start. Swapping and building on the NA base usually ends up costing more in the long run because you have to think about the whole package. -The NA engine is possible to turbo and it's been done many times, but the higher compression and port volume works against you in low end and driveability. -The transmission is not suited for the higher output and torque for the long run. The clutch diameter is smaller and can't withstand the extra power without going to exotic materials. The T2 transmission can support well over 500whp stock. The NA one, not so much in the long term. -The rear diff is probably an open diff with a smaller ring gear than the Turbo 2 unit. You need turbo axles to work with the T2 diff, and axles are rare and expensive to find used. -You will not be sitting at 4-5k with an NA turbo, more like 5-8k Rpm. The power comes on much later. 2) Go to FC3Spro.com There is a great list of mods and things you can do to upgrade your car, but the site is geared toward T2 cars. As far as prices, people usually do not list prices because they vary from region to region. -Aaron Cake has a good website on how he turbo'd his NA, but he has come on the forum and stated that it's not a recommendation for everyone. Just how he did it. aaroncake.net 3) For fueling, go to the Single Turbo Forum. Howard Coleman has multiple posts about injector sizing, fuel pumps, and turbo sizing. Most of his lists are geared toward 500+whp. For a stock-ish turbo making 300whp, a Walbro 255, Stealth 340, or Supra TT pump works fine. I believe the FD pump would work as well. I'll get to your turbo sizing soon, so bear with me. 4) Bridgeport is not ideal for the street and porting the NA will not get you very far. In the NA Subforum, they have lists and documented results as to where porting will get you on NA. The port volume on the 6-port is already so large that porting the secondaries only gets you more peak power and the low end suffers. 5) This is where I address turbo sizing. The Subaru turbo is already too small for a Subaru. I know the displacement is 2.5l on a subie, and the RX7 is 1.3, but you need to understand how the rotary works first. A piston engine has 1 power stroke per 720 degrees per piston. On a four cylinder, that's one power stroke every 180 degrees. On a rotary engine, there is one power stroke per rotation of the eccentric shaft. You basically get double the exhaust volume vs a piston engine. A rotary engine in racing is counted as double displacement, so a 1.3 is treated as a 2.6 instead. Because of the exhaust volume, a Subaru turbo would choke the engine out. A GT35R is a great turbo, if you are chasing 400+whp. For 300whp, it's too big and will be laggy. If you want around 300whp, a hybrid T2 turbo is great for that and will get you there for under a grand if you already have a turbo. You want the S5 turbo and manifold, because they flow much better and prevent boost creep. BNR Supercars does hybrid turbo services. The Borg Warner SXE 7670 is also a great turbo for around 300 whp. 5) E85 is really only viable if you are trying to push 450+ whp. You need 33% more E85 to make the same power as gasoline, so you will suffer major fuel economy losses and finding E85 is a pain in most areas. Your tag says Portland. I'm guessing Oregon. Not too many E85 stations in the PNW, so good luck having any range or fun at all. E85 has a very short shelf life because it absorbs water from the air, even when sitting inside the vehicle's tank. E85 is useful for knock suppression and you can run more timing, but you need a special fuel pump to push the volume. A Walbro 400 E85 would work. You also need injectors that can handle the ethanol content, so ID injectors in the 1000CC primary and 2000CC secondary would likely be needed. That's about $800 in injectors alone. Plus fuel rails, lines, regulator, etc. Running E85 would require a standalone PCM, so theres around $1500-2000 for a controller and all the things needed. You need it tuned, so dyno time is a must and that can get upwards of the thousands of dollars. I'll summarize what you should do here: Enjoy the car. Drive it stock and enjoy it. Figure out its limits and drive the car. I've had mine on stands for over 3 years. I wish I just fixed what was wrong so I could drive the damn thing. I'm already balls deep in a full restoration, so I can't enjoy my car. If you really want a car with 300 whp and turbo, sell the NA and buy a Turbo. Don't swap it. It's seriously too much work, expense, and time to track down every little thing you need. Trying to half-ass it and cut corners will only bite you in the end. With a stock T2, you can have a decent base to begin and put some bolt-on onto it. Get an S5. Do not get an S4 because you will be limited as to what you can do in the long run. I get that some people enjoy building cars, but too many are started and never finished. You say you've been around, well your questions and plan of attack show that to be inaccurate. There are threads asking your exact question that have been covered hundreds of times. I'm not trying to be an ass, but I'm being realistic. Reading a Haynes manual doesn't get you anywhere in this game. Reading what other people have done and what has worked is where you should start. Check build threads and look at what the payouts end up being. You will notice most of them fall off the face of the earth and usually end up getting parted. There is a wealth of information and going head first into a build with no plan and direction is a sure way to fail, or spend far too much money and end up jaded. I know the suggestion to JDM turbo swap will come up. Expect ANY JDM engine you get to be a boat anchor. Too many members buy engines from overseas and end up scrapping most of the rotating assembly. They sit for years in lots, then sit for months in container ships, then potentially years again once they get here. I just looked up and read your post again. You already pulled the engine and tore it down, so driving it now is out. The rebuild kits are about $1000 on average, so pick what you will do wisely. I still think your best plan of attack is to start with a Turbo 2 and build from there. Another option I could do is before I decide to go all out get a T2 engine setup is just roll with the Stuff I have. Once I put it all together and get her rolling work on all the kinks, then I can start the turbo build? As far as If I do go HAM and just get the turbo engine right away ... does it need a special exhaust or can I run the NA exhaust until I find the turbo Im looking for? I know there is a difference between the 2 engines on the exhaust port where you cant use a turbo 2 manifold on the NA model because of a clearance issue. But I have yet to see if you can run a NA manifold on the turbo model. Of course I will be getting a turbo but I wont have the downpipe/turbo when I first get the car running and its in general just easier to work out all the kinks when you have less to work with. Sorry for the long wait time on responses I work and go to school full time. And thanks for all the insight feel free to say anything on your mind xD Ill take it as a learning experience. |
As far as the E85 is concerned I have E85 here and I wanna use it just for reassurance. I know the setup is much more costly and I know my setup will not require it but I also enjoy the Idea of dealing with less detonation chances. Which Ive heard is the number one fault in most rotary failures.
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And as far as my drivetrain is concerned I actually have a S5 T2 shell with all the drive train ready to go. Axles, Diff, suspension, hubs, all the goodies. The only part im missing is the tranny.
I was going to work with this S4 NA but after a few of the things youve said I will prolly just go with the Turbo model which I WAS looking at but eventually decided against it ( Im not sure why??) I can buy a used turbo engine for about 800$ for the S4 and prolly sell my NA for what 200-300? But now that im looking into buying a whole new engine im now sitting here trying to decide on generation xD I know the S5 can handle more HP but since im staying in the 250-300 whp range and S4 should be able to deal with it. And Id rather keep my costs reasonable on the engine and spend extra on reassurance mods and make sure she runs right. |
If you can get a running Turbo engine for 800 I will eat my underwear!..
No matter which way you slice it though any build is gonna cost ya...I'd be starting with a good TII foundation though. |
It wont be a rebuilt one but it will run ... Please dont eat your underwear xD. All said and done it will probably cost around the 1.8-2k range with new seals if that settles your appetite better xD
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Originally Posted by Ethan Adams
(Post 12224766)
It wont be a rebuilt one but it will run ... Please dont eat your underwear xD. All said and done it will probably cost around the 1.8-2k range with new seals if that settles your appetite better xD
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The reason I recommend the S5 has little to do with power potential. It's all about future proofing.
The S4 turbine housing will boost creep with almost any aftermarket exhaust. Too much boost, you run lean, engine goes boom. The S5 has a much better wastegate to prevent this AND the S5 is twin scroll. The later S5 engines had a much stronger rear iron with a thicker dowel casting that prevents cracking above about 350-400whp. The main killer in rotary engines is detonation, but that is almost always caused by a poor tune. A properly running and tuned engine will run indefinitely. The rear dowel casting design on the later irons is just to help cope with the twisting of the housings that the engine goes through under peak torque. Again, don't waste your time or money on E85. The tune is what matters and at 300whp, you won't run into any detonation issues if the engine is tuned properly. Like I said, most E85 users are pushing over 500whp.If you want assurance, go with water/alcohol injection instead. The systems help keep the internals clean via a steam clean effect, prevent knock as well as E85, long term it's far cheaper, and it doesn't require you to run an exotic fuel pump and injectors. E85 is not available everywhere and filling up constantly will get old real fast. My old FB had a bad distributor that caused misfires and an air leak. I got 10-12 mpg for about a month before I got around to fixing it. That fuel economy only gives you about 150-160 miles of range. No fun at all. besides, if there is a meet anywhere outside of E85 range, you are SOL. Don't underestimate how much effort is really involved. People always come on here and say they can "do all the fab themselves" and in the end, they usually go with a premade kit (turblown, glease, IRP, etc) or they go hybrid turbo with stock manifolds. The number I keep seeing thrown around and the number that is usually reasonable for a start-to-finish turbo swap runs between $5k-10K on average. I've broken it down before on other posts I have made, but here's the short list with all of the parts you likely need: -Engine and rebuild $2-4k This is because JDM engines are a gamble and anyone with a running T2 wants MINIMUM $1500 for a running engine - Fuel system $1000 I'm figuring Walbro/Stealth pump at around $140 plus soft hoses, tank gasket, and clamps. You want a fuel filter, more soft hose for the bay. Do you have T2 fuel rails? If so, you need to remove the fuel pulsation damper (fire hazard) and replace or eliminate. You need injectors, seals, potentially the injector diffusers (lots of threads on those) and a regulator of some kind with standalone. -ECM and harness $1500-2000 The price varies based on which controller you go with, but you will need a wideband O2 sensor, all of the peripheral sensors (air temp, coolant temp, MAP, etc.) And they all add up. The stock sensors can work ,but aftermarket GM types are the norm and are fast-acting. You also need to take into consideration the actual construction of the harness, the connectors, tape, loom, clips, etc. Building a harness well takes time and requires you to test your work. -Transmission, flywheel, and clutch $1000-2000 This really depends on how cheap you can get a transmission and if you can get a flywheel for a reasonable price. Aside from cost, there is no reason to stick with the NA transmission. The clutch diameter is smaller, the transmission is weaker, and you will end up needing a heavier clutch by power than a turbo clutch. Basically, a stage 3 NA VS a stage 1 Turbo clutch. The higher stage clutches are a pain to drive daily, or in traffic, and cost more money. I bought a transmission for $300 in unknown condition and I have a lightweight flywheel that came with it. I'm pretty sure both pieces are gonna be junk, but that's my problem. Basically, figure $500 for the trans, $2-400 for clutch, and look for a factory flywheel THAT FITS THE ENGINE SERIES YOU HAVE. S4 and S5 flywheels are different and are not interchangeable for the engine. The flywheel is the counterweight and the wrong flywheel will destroy the engine from imbalance in the long run. -Engine Cooling $4-500 pump, hoses, radiator, coolant, clamps, and fan (if you don't have the stock clutch fan and shroud) How dressed is the turbo engine you end up with? Will you need brackets, alternator, thermostat/water pump housing? Front cover, OMP, pulleys? All of these things really add up fast and get away from the goal of driving the car. Will the engine you get have a functioning turbo and manifold? How many pieces inside will need to be replaced? In reference to your question about the exhaust. The ports are the same distance and diameter on the housings. The NA housings have a diffuser and the port volume is smaller inside, but where the manifold bolts is exactly the same. You can bolt on a NA manifold to a turbo engine and drive it, but why? The turbo engine has much less compression than a NA engine and it will drive like a dog without a turbo. Like i said, it's possible, but not really practical. Also, you would have to plug the oil feed port in the front iron that would feed the turbo if you had an NA manifold. If I could start over on my car, here's what I would do: Step 1: Buy a Turbo 2 series 5. Step 2: Perform all fluid and reliability maintenance Step 3: Drive and enjoy the car Step 4: Refer to step 3 Step 5: Buy another engine and build it in the garage on the engine stand with all the trimming (big turbo, standalone, etc) Step 6: Dump in built engine and goodies in the course of a couple months. Step 7; Refer to step 3 If you want a good exhaust and downpipe for a stock turbo, you can't beat the Racing Beat full exhaust systems. Complete with downpipe to muffler tips. A really good system for around $1000 |
All this thread has made me do is think about buying a Turbo II for the last three days.
It does seem to always end up more cost effective to start with the closest thing to what your end build will be (turbo start turbo) so I can see where costs would add up quickly. I had a Mark III supra and for some reason people were always starting builds with N/A engines and hoping to turbo them later and it always ends up being a money pit. |
It almost always is better to start off closer to the goal. Also, early S4s didn't come with 5 lug hubs and 4 piston calipers, so that is another consideration. honestly, if you wanted to start with a non-turbo base, have a complete Turbo 2 sitting around and swap it all over. The early 86 cars were among the lightest available with no sunroof, wiperless hatch, no power anything, etc. You could feasibly have the T2 shell and swap all of the important bits, but that takes two separate cars.
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TII engine and drivetrain (easiest to get a TII to start with).
Stock or mild street port. GT3076R Standalone FMIC Stock 550CC primaries, 720 or 800CC secondaries 300RWHP all day long with a great midrange, no engine stress. No need for E85. |
Hello! back with progress report on my stuff! Sorry havnt posted here ive been actually recording my progress and YouTubeing it. Just listing where ive gotton in the build.
Engine has been torn apart. One of my irons had a blown sidewall for the coolant so it was a goner. Looked around and found some good shape S4 NA irons, Ported the irons and the housings. My housings have very mild chrome wear but will work for the build at the moment. Rob at pineapple racing said they were very usable and should last a while with the expectations Im planning. Grabbed some S4 Turbo low compression rotors with low miles, well low for my standards (80k). |
Here are some before and afters!!
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For the past few days ive been cleaning up the extras and today i finished up the oil panhttps://cimg7.ibsrv.net/gimg/www.rx7...ebc6c78a2f.jpg
https://cimg8.ibsrv.net/gimg/www.rx7...1d93865f46.jpg https://cimg0.ibsrv.net/gimg/www.rx7...99dff6c676.jpg https://cimg6.ibsrv.net/gimg/www.rx7...982cf19610.jpg https://cimg9.ibsrv.net/gimg/www.rx7...0c99014dc2.jpg https://cimg5.ibsrv.net/gimg/www.rx7...bd80cc49ec.jpg https://cimg4.ibsrv.net/gimg/www.rx7...8640464794.jpg |
Im in school and working so I dont get much time to work on it but when i do I make sure im taking it slow and putting lots of detail in it. Hoping i do it right the first time and dont have to deal with messups in the future xD. Next ill be working on the Intakes and matching up a s5 turbo intake to the 6 port NA. Hopefully ill get to stitch welding the chassis soon but depends on when i can borrow my dads truck to haul it around xD
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flipping awesome
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