1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

12a Carby TO -> 12a Turbo

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Old Mar 15, 2004 | 10:40 AM
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12a Carby TO -> 12a Turbo

Excuse me im a piston owner lol dont know much about rotarys...

Im looking into selling my current car mazda 626 for a s1 rx7

Whats involved in converting the stock 12a too a 12a turbo ?

Are 13bt's direct swap in ? eg mounts and box bolts up ?

What would be the most fuel efficent... and cost effecitive
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Old Mar 15, 2004 | 10:43 AM
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ok also what types of 12a turbos was there ?

i got a friend who kows about rotarys... he said there is just carby blow thru setups ? any injected ones ?
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Old Mar 15, 2004 | 11:21 AM
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Re: 12a Carby TO -> 12a Turbo

Originally posted by Aus_S1RX7
Excuse me im a piston owner lol dont know much about rotarys...

Im looking into selling my current car mazda 626 for a s1 rx7

Whats involved in converting the stock 12a too a 12a turbo ?
You need a carb that is fitted for blowthrough for sure. The stock one won't work (yet) until Carl comes up with a way of doing it. Holleys, Dellortos and Webers are available that can be modded to turbo.

Many of the people on the forum just keep the stock 12a and street port it until they can do a TII swap, which leads me to your second question:

Originally posted by Aus_S1RX7

Are 13bt's direct swap in ? eg mounts and box bolts up ?
They aren't *direct* swap ins, but they're not the hardest swap in the world. To put a 13b in a 12a's place, you need an adapter for the front mount, because the 13b's are longer. Depending on whether or not you're swapping in an EFI engine, the wiring can be a bitch. If your car comes with a 12a, it's often much easier to just slap a Holley 4 barrel onto the 13b that you're swapping in, unless you do the TII swap.

TII was the designation for a second gen Rx7 that came stock with turbo (a single turbo, it was called the TurboII because it was the second generation to have turbo in japan... 12at turbo motors can be imported, but they're rare and expensive). The TII is fuel injected, and because it's a 13b can be swapped in *relatively* easily, though it's easier to put it in a GSL-SE. The reason for this is that the '84-'85 GSL-SE was a first gen with a 13b in it stock, which was EFI. This means no modified mount necessary, and that all the wires were present for the wiring. It's still a bitch to wire, but not as much of one.


Originally posted by Aus_S1RX7

What would be the most fuel efficent... and cost effecitive
Ooh boy.. fuel efficient.... you're in the wrong crowd power comes at the cost of fuel efficiency, but there are options. The stock car gets good fuel milage, but isn't exactly suped up. If you live in a state where there aren't e-tests every few years, get a RacingBeat exhaust system. This will give you a 25% increase in hp straight off the bat. That doesn't affect your fuel efficiency much.

Past that you have porting. Porting in a rotary engine does absolute wonders for performance (but not for fuel economy). A small "street port" will be okay on gas, and up your hp even more. Besides, your engine could probably use a rebuild anyway

The TII isn't *bad* on gas like some bigger port jobs are (ie: "bridge port"), but it's not going to match the economy of your average family car.

You should take a bit of time and think about what you'd like to do with this car. There's plenty of awesome info throughout the forum, and we're always glad to help folks out. If you're daily driving the car, you probably want a mild street port with RB exhaust, DLIDFIS ignition and a rebuilt stock carb. If you're 1/4 mile racing, it's the opposite end of the spectrum. Autocross racing is more suspension oriented and is another thing entirely. Then you have what I like to call the weekend warrier. A summer car which daily drives, but can street race if prompted to (btw, that setup I gave you above for the daily driver is my weekend warrier).

In any case, have fun, read the FAQ, and don't be afraid to post.

Jon
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Old Mar 15, 2004 | 11:24 AM
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There's a thread in the archive called "TII swap into GSL-SE" or something of the like. Even though you don't have a -SE, there's plenty of good info in it that you can use to find out about TII swaps.

If you have some inginuity and some mechanic skill (and a pocket of cash) then you can do almost anything to these cars. Just think, and post, and chances are someone has done it or thought about doing it.

Jon
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Old Mar 15, 2004 | 01:42 PM
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This is what's involved to make a 250hp 12aTurbo setup. Cheapest and easiest way:


-TurboII Exhaust manifold - oval bolt holes, grind exhaust path 5mm inward on each side.
-TurboII Turbo
-TurboII Wastegate
-Nikki(stock) Carb w/mods done to handle boost
-Either a 12aT intake manifold or use an exaust manifold that places the turbo farther from the engine or else it won't fit.
-Turbo Hat for Carb
-GSL-SE Fuel pump
-Rising rate Fuel pressure regulator
-New fuel lines
-Drill hole/put in fitting in engine front cover for turbo oil return line
-T fitting where the oil pressure gauge gets it's reading from for turbo oil feed line
-Lock dizzy
-Downpipe for exhaust shop to connect the rest of the exhaust to

If you need any help or explination feel free to ask me.
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Old Mar 16, 2004 | 03:40 AM
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im just trying to see what would be the best way to get reasonably power whilst staying fuel friendly...

fuel economy in the same sentance as rotary lol....

anyway.. in all honesty im only after 150-170rwhp some people i talk too say 12at can make that power easy others say 13b n/a would be better to get that sorta power from...
What do you people think ?

My plans of attack are to upgrade the suspension brakes and drive train first before doing the engine...
am i best to just get the suspension from a s2-3 rx7 ? or is there a big aftermarket stuff out there ?

please bare with me
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Old Mar 16, 2004 | 10:34 AM
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If you're looking for 150rwhp, you can get there with an n/a 12a. A large streetport with a 48ida and a good exhaust should have 150-160rwhp, or maybe a bit more even. A bridgeport 12a with the 48ida and a good exhaust should have 160-200rwhp depending on how big the bridge is.
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Old Mar 17, 2004 | 09:40 AM
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Which would be more fuel economical ? 12a witht he mods u said or a turbo conversion?
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Old Mar 17, 2004 | 01:15 PM
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The best economy will be with a fuel injection setup and a haltech, but it will cost a lot more to start with. Best economy out of what is listed would probably be a very large streetport and a good carb and exhaust.
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