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

20B First Gen RX-7

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Old Jul 2, 2005 | 09:48 AM
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20B First Gen RX-7

G'day everyone,

Thought I'd post up some pics of my Series 3 RX-7 20B. Conversion is almost complete.

Engine has been rebuilt and extend ported. I'm running it naturally aspirated as first, always been keen to know what a n/a 20B would put out and was like to drive. Plus can't beat the sound of n/a.

The computer I'm using is a Microtech LTX12.

Exhaust is custom extractors to just before the diff then into a 3" pipe then into a single straight through stainless SelectMaz 3" muffler.

I'm still using the diff gears I was using with the bridge port, 4.4s

Excuse the dirty engine bay.





Click here for above pic
http://members.optusnet.com.au/rotary20b/wheels2.jpg





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http://members.optusnet.com.au/rotary20b/20b.jpg





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http://members.optusnet.com.au/rotary20b/2.jpg





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http://members.optusnet.com.au/rotary20b/3.jpg





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http://members.optusnet.com.au/rotary20b/4.jpg





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http://members.optusnet.com.au/rotary20b/3rotor.jpg





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http://members.optusnet.com.au/rotar...ncilleries.jpg





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http://members.optusnet.com.au/rotary20b/intake.jpg
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Old Jul 2, 2005 | 09:51 AM
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...............wow...............
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Old Jul 2, 2005 | 09:55 AM
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using an FB front cover? thats sick.
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Old Jul 2, 2005 | 10:20 AM
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Exactly what I eventually want to do with mine. This begs many questions, including:

Which transmission are you using?
How far back did the shift lever have to be moved?
Can the slave cylinder still be changed out without lowering the trans or pulling the engine partially out?
I'm not familiar with that differential. How does it compare strength-wise to stock?
Any firewall modifications necessary?
How difficult was it to get the 12A front mount to line up?
Who about cost invested thus far?

Again, very nice car and keep us posted re performance.
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Old Jul 2, 2005 | 10:24 AM
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aviator if u look, his front mounting system is custom, u can see the origional subframe a buncha inches back
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Old Jul 2, 2005 | 10:36 AM
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Originally Posted by Aviator 902S
Exactly what I eventually want to do with mine. This begs many questions, including:

Which transmission are you using?
How far back did the shift lever have to be moved?
Can the slave cylinder still be changed out without lowering the trans or pulling the engine partially out?
I'm not familiar with that differential. How does it compare strength-wise to stock?
Any firewall modifications necessary?
How difficult was it to get the 12A front mount to line up?
Who about cost invested thus far?

Again, very nice car and keep us posted re performance.
12A Turbo for the time being.
Not sure of exact measurement, will let you know.
I believe so.
It's a S3 diff, strongest of the first gens. Hopfully it will hold out a while.
No modification to the firewall.
Custom front cross member as shown below.



Cost.. around the 12k mark Australian ($9,000 USD) for engine, complete rebuild & porting, modifying of sump, new waterpump, computer, new S4 mounts, cross members, fuel pumps, radiator, gearbox, clutch, exhaust, thermo fan, modifying of gearbox, oil cooler, injectors cleaned, filters, oils, etc. complete.

Thank you, will do
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Old Jul 2, 2005 | 10:38 AM
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Originally Posted by Elysian
aviator if u look, his front mounting system is custom, u can see the origional subframe a buncha inches back
That's right, engine was moved as far back as possible.
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Old Jul 2, 2005 | 08:42 PM
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Anyone else have a 20B in a first gen RX-7?
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Old Jul 2, 2005 | 09:27 PM
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Originally Posted by Rotary20B
Anyone else have a 20B in a first gen RX-7?
found this in my garage 10 mins ago

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Old Jul 2, 2005 | 09:30 PM
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awesome! let us know how it drives!
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Old Jul 2, 2005 | 11:00 PM
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That's incredible. I want more info! How in God's name did you get that in there? Where's the tranny compared to where it normally is? Did you have to shorten the driveshaft? Is it a stock tranny?

Man, I wish I was in Australia.. you guys are nuts. MY kind of nuts!

Jon
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Old Jul 2, 2005 | 11:26 PM
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Originally Posted by vipernicus42
That's incredible. I want more info! How in God's name did you get that in there? Where's the tranny compared to where it normally is? Did you have to shorten the driveshaft? Is it a stock tranny?

Man, I wish I was in Australia.. you guys are nuts. MY kind of nuts!

Jon
Shifter position is in stock S3 position, just been modified

Tailshaft is standard S3, part of the reason I decided to go with the 12A box first

Yes, stock good cond. 12A Turbo gearbox.

I was going to go a 13BT box, or a supra, but thought I'd give this a shot first, if it breaks I'll go either 13bt or supra.

There's quite a few 20B in RXs over here. Think there's around 15 now, just in Brisbane.

I was almost tempted to give up half way and go 13bt like everyone else, glad I didn't.
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Old Jul 2, 2005 | 11:30 PM
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So you've got the Diff, the tailshaft and the gearbox in *stock* location, and just attached the engine to it and figured out how to mount it?

That's awesome!

There are *no* 20b's around here. Heck, I'd doubt if there were 15 on the continent!

Jon
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Old Jul 3, 2005 | 01:24 AM
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Originally Posted by vipernicus42
So you've got the Diff, the tailshaft and the gearbox in *stock* location, and just attached the engine to it and figured out how to mount it?

That's awesome!

There are *no* 20b's around here. Heck, I'd doubt if there were 15 on the continent!

Jon
Theres used to be one I like to go see race over your way, it was from Vancouver.

20B PP in a second gen, it used to race down at SIR.
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Old Jul 3, 2005 | 02:56 AM
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Is that an RX-3 front mount on your front cover? I see you had to drill new holes.

Your S4 motor mounts are a little close together for that kind of torque. Any plans to install a torque brace?
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Old Jul 3, 2005 | 03:04 AM
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Originally Posted by Jeff20B
Is that an RX-3 front mount on your front cover? I see you had to drill new holes.

Your S4 motor mounts are a little close together for that kind of torque. Any plans to install a torque brace?
It's a 12AT front cover.

The mounts have been proven to work well on another setup.
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Old Jul 3, 2005 | 03:08 AM
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Originally Posted by Rotary20B
Anyone else have a 20B in a first gen RX-7?
NOT ME! But i want one now!!!DAMN YOU!!! <<<JK!
But seriously ! i was about to get an FD ....and I saw your project!!!<<<<Guess whats going trhu my mind now!!!!
ARGHH!!! how much money i expect to spend>?
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Old Jul 3, 2005 | 03:16 AM
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Originally Posted by TurboSE
NOT ME! But i want one now!!!DAMN YOU!!! <<<JK!
But seriously ! i was about to get an FD ....and I saw your project!!!<<<<Guess whats going trhu my mind now!!!!
ARGHH!!! how much money i expect to spend>?
Cost.. around the 12k mark Australian ($9,000 USD) for engine, complete rebuild & porting, modifying of sump, new waterpump, computer, new S4 mounts, cross members, fuel pumps, radiator, gearbox, clutch, exhaust, thermo fan, modifying of gearbox, oil cooler, injectors cleaned, filters, oils, etc. complete.


Thats including parts & labor
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Old Jul 3, 2005 | 03:19 AM
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Perhaps there was some miscommunication. What is the mount that is bolted to the front cover? It resembles an RX-3 mount. It's what I used on my 20B. I think I will need a torque brace due to the narrow positioning of the motor mounts.
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Old Jul 3, 2005 | 03:23 AM
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Originally Posted by Rotary20B
Cost.. around the 12k mark Australian ($9,000 USD) for engine, complete rebuild & porting, modifying of sump, new waterpump, computer, new S4 mounts, cross members, fuel pumps, radiator, gearbox, clutch, exhaust, thermo fan, modifying of gearbox, oil cooler, injectors cleaned, filters, oils, etc. complete.


Thats including parts & labor
20B gsl-SE!!! Pm'd ya
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Old Jul 3, 2005 | 03:27 AM
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My friend wants me to help him do a 20B powered GSL-SE.
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Old Jul 3, 2005 | 04:31 AM
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I wish I had never looked at this thread. Now I have to spend more money.
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Old Jul 4, 2005 | 04:18 AM
  #23  
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New pics up








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Old Jul 4, 2005 | 01:06 PM
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Damn! Now I want to get one too. This sucks! more money lol =) How much HP dose a 3 Rotor Engine come with out mods?
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Old Jul 4, 2005 | 01:25 PM
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Originally Posted by TheLatinHeat
Damn! Now I want to get one too. This sucks! more money lol =) How much HP dose a 3 Rotor Engine come with out mods?
if i'm not mistaken the NA's are like 250hp? maybe less maybe more, i'm no expert lol... the turbo's on the other hand
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