20B First Gen RX-7
Thread Starter
S3 RX-7 - 20BT 450 RWHP
Joined: Dec 2004
Posts: 312
Likes: 0
From: Brisbane, Australia
Thread Starter
S3 RX-7 - 20BT 450 RWHP
Joined: Dec 2004
Posts: 312
Likes: 0
From: Brisbane, Australia
http://www.rotary20b.com/1.wmv (972kb)
http://www.rotary20b.com/2.wmv (334kb)
http://www.rotary20b.com/3.wmv (433kb)
http://www.rotary20b.com/4.wmv (605kb)
http://www.rotary20b.com/2.wmv (334kb)
http://www.rotary20b.com/3.wmv (433kb)
http://www.rotary20b.com/4.wmv (605kb)
Last edited by Rotary20B; Apr 6, 2007 at 01:23 AM.
Thread Starter
S3 RX-7 - 20BT 450 RWHP
Joined: Dec 2004
Posts: 312
Likes: 0
From: Brisbane, Australia
Couple more vids.. just cruising up to 60
http://www.rotary20b.com/20b-1.wmv
http://www.rotary20b.com/20b__2.wmv
http://www.rotary20b.com/20b-1.wmv
http://www.rotary20b.com/20b__2.wmv
Originally Posted by luiml73
I found this one over at www.ausrotary.com, but I can't find the thread now.
Thread Starter
S3 RX-7 - 20BT 450 RWHP
Joined: Dec 2004
Posts: 312
Likes: 0
From: Brisbane, Australia
Just got the car back after upping the boost a bit and it now has a S4 turbo box with a quick shift and new clutch etc.
I believe it made 450 rwhp on 9psi, smoking the tyres on the dyno, I only have 205's on the back now.
Gearbox feels great, clutch is very heavy so apart from the diff the driveline should be sorted now.
Its a real handful now, should have some in car vids up soon.
Thanks to Craig Dyson for a top job as usual.
I believe it made 450 rwhp on 9psi, smoking the tyres on the dyno, I only have 205's on the back now.
Gearbox feels great, clutch is very heavy so apart from the diff the driveline should be sorted now.
Its a real handful now, should have some in car vids up soon.
Thanks to Craig Dyson for a top job as usual.
Joined: May 2002
Posts: 5,972
Likes: 37
From: Ottawa, Soviet Canuckistan
I'm drooling over both your N/A *and* your turbo build. They're amazingly impressive. You aussies sure know how to do justice to a rotary build project.
Jon
Jon
Rotary20B, you've gone to a 3" exhaust system I take it.
I'm doing a 2.5" system for my NA 20B.
Did you already change out the 3rd member to an LSD? What gearing? Hope it's not still the old one-legger 4.44 you had with the 12A bridgeport.
I'm doing a 2.5" system for my NA 20B.Did you already change out the 3rd member to an LSD? What gearing? Hope it's not still the old one-legger 4.44 you had with the 12A bridgeport.
Thread Starter
S3 RX-7 - 20BT 450 RWHP
Joined: Dec 2004
Posts: 312
Likes: 0
From: Brisbane, Australia
G'day, hows your 20B coming along?
Still 2.5", will change to 3" a bit later on, will no doubt gain more hp with that.
Diff is now stock S3, same diff as your GSL-SE's. I'm now running 3.9s though, open wheel as it is stronger than running the S3 LSD. I'll be changing to a Hilux soon though.
Never had a 12ABP, always had 13B BPs in it before the 20B
Ah, it must have been your friend with the 12A.
My '83 is still on schedule for 12A removal some time in July or August for test fitting the 20B. To be ready, I've been working on a CD23C Cosmo (RX-5) as tearing into the RX-7 will leave me without a daily driver. Gotta get the Cosmo done soon. It was unreliable with the automatic so the manual conversion should help tremendously. Plus the engine's getting swapped for a fresh rebuild because it was leaking out of the rear eccentric seal. Might as well swap the tranny and the engine at the same time.
Hey I'm glad to see you made that much power on 2.5" exhaust.
I must admit I had a few doubts in the the back of my mind when I worked out my diameter to 2.5". Not anymore. I'll let that be a lesson for everyone else who think they need 3" on their 2 rotors.
Go with 2" or at the largest, 2.25".
I've got the LSD in mine. Stock gearing for '83 (3.9something). The tranny will most likely stay at the stock position for easier access to the oil filter and clutch slave. It also makes future tranny and driveshaft swaps easier.
I roughly calculated the best position for the oil pan. I'll know more once the 12A is pulled. I'll definitely need to reverse the crossmember and add something up front between the swaybay and the main crossmember for the front cover mount.
My '83 is still on schedule for 12A removal some time in July or August for test fitting the 20B. To be ready, I've been working on a CD23C Cosmo (RX-5) as tearing into the RX-7 will leave me without a daily driver. Gotta get the Cosmo done soon. It was unreliable with the automatic so the manual conversion should help tremendously. Plus the engine's getting swapped for a fresh rebuild because it was leaking out of the rear eccentric seal. Might as well swap the tranny and the engine at the same time.

Hey I'm glad to see you made that much power on 2.5" exhaust.
I must admit I had a few doubts in the the back of my mind when I worked out my diameter to 2.5". Not anymore. I'll let that be a lesson for everyone else who think they need 3" on their 2 rotors.
Go with 2" or at the largest, 2.25".I've got the LSD in mine. Stock gearing for '83 (3.9something). The tranny will most likely stay at the stock position for easier access to the oil filter and clutch slave. It also makes future tranny and driveshaft swaps easier.
I roughly calculated the best position for the oil pan. I'll know more once the 12A is pulled. I'll definitely need to reverse the crossmember and add something up front between the swaybay and the main crossmember for the front cover mount.
Last edited by Jeff20B; Jun 30, 2007 at 11:04 AM.
Thread Starter
S3 RX-7 - 20BT 450 RWHP
Joined: Dec 2004
Posts: 312
Likes: 0
From: Brisbane, Australia
Here's a short video of what its like accelerating, stock diff gears (speedo is accurate), 2nd gear from 70 - 120 km/h.
http://www.rotary20b.com/2nd.wmv
http://www.rotary20b.com/2nd.wmv
Speedo is accurate but your tach isn't.
Is it reading three pulses per rev instead of the two pulses it was designed for?
My ignition will output the proper two pulses per rev so the tach should be accurate.
Is it reading three pulses per rev instead of the two pulses it was designed for?My ignition will output the proper two pulses per rev so the tach should be accurate.
Thread Starter
S3 RX-7 - 20BT 450 RWHP
Joined: Dec 2004
Posts: 312
Likes: 0
From: Brisbane, Australia
haha I was just about to jump back into my post to explain that the tacho isn't calibrated.






