Show full size 924Board.org
Discussion Forum of 924.org
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
 Technical FAQ924 FAQ (Technical)   Technical924 Technical Section   Jump to 924.org924.org   Jump to PCA 924 Registry924 Registry

Project RX924 begins!
Goto page 1, 2, 3, 4, 5, 6, 7, 8  Next
 
Post new topic   Reply to topic    924Board.org Forum Index -> Engine Transplants
View previous topic :: View next topic  
Author Message
Andrew NZ  



Joined: 22 Jun 2004
Posts: 744
Location: New Zealand

PostPosted: Wed Nov 28, 2007 8:02 pm    Post subject: Project RX924 begins! Reply with quote

Hi Guys,

My apologies to the purists, but it's time to do something I've wanted to do for a long time - install a 12a bridgeport

So far it's looking quite promising, with the 924 clutch disking fitting perfectly with the RX7 pressure plate and flywheel, and the 924 spindle being exactly the right diameter for the Mazda spigot bearing.

Other than making a bellhousing, the only other major is going to be modifying the crossmember, which is going to need a lot of altering to allow the engine to fit, unless I shorten the torque tube about 100mm to allow the engine to sit just behind the cross member.

I'll keep you all informed of the progress as it happens, but it's probably going to be a long term project!!
_________________
Andrew
1977 RX924 rally car
12a bridgeport
www.race4-dcup.co.nz


Last edited by Andrew NZ on Sun Oct 10, 2010 6:46 pm; edited 2 times in total
Back to top
View user's profile Send private message Visit poster's website
v8carreragts  



Joined: 05 Sep 2003
Posts: 661
Location: Tucson, AZ

PostPosted: Thu Nov 29, 2007 5:53 am    Post subject: Reply with quote

Sounds like a cool project. I thought about this swap in the past but since I don't know much about rotarys, I didn't try it. They can be modified to make a lot of power and they rev high.
The only thing that I know about rotary swaps is they are hard to cool. This just means that you need a big radiator.
Back to top
View user's profile Send private message
Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11343
Location: PacNW

PostPosted: Thu Nov 29, 2007 6:43 am    Post subject: Reply with quote

Why not a 13B? My buddy had one in a first gen RX7, and all he did was put a header and a Holly on it, and god was it fast. You could also watch the gas gauge drop every time he floored it. . .it got about 5 MPG when driven hard.




rasta
_________________
Toofah King Bad
  • Shaggy (1980 931) - Got Boost?
  • Red (1987 924S) - Pro44/Spec944
  • Weiße Scheiße (1987 924S) - In Progress
Back to top
View user's profile Send private message Visit poster's website
Rich H  



Joined: 10 Jun 2007
Posts: 2665
Location: Preston, Lancs, UK

PostPosted: Thu Nov 29, 2007 7:54 am    Post subject: Reply with quote

Rotary weight
Rotary power
Rotary economy
_________________
1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec
Back to top
View user's profile Send private message
Andrew NZ  



Joined: 22 Jun 2004
Posts: 744
Location: New Zealand

PostPosted: Thu Nov 29, 2007 8:09 am    Post subject: Reply with quote

v8carreragts wrote:
Sounds like a cool project. I thought about this swap in the past but since I don't know much about rotarys, I didn't try it. They can be modified to make a lot of power and they rev high.
The only thing that I know about rotary swaps is they are hard to cool. This just means that you need a big radiator.


I've already got a bigger radiator, so shouldn't be too much of an issue as it's bigger than an RX7 radiator.
_________________
Andrew
1977 RX924 rally car
12a bridgeport
www.race4-dcup.co.nz
Back to top
View user's profile Send private message Visit poster's website
Andrew NZ  



Joined: 22 Jun 2004
Posts: 744
Location: New Zealand

PostPosted: Thu Nov 29, 2007 8:15 am    Post subject: Reply with quote

Rasta Monsta wrote:
Why not a 13B? My buddy had one in a first gen RX7, and all he did was put a header and a Holly on it, and god was it fast. You could also watch the gas gauge drop every time he floored it. . .it got about 5 MPG when driven hard.




rasta


Two reasons - There's a big weight penalty for a 13B in the race class I'm going in, and the 13b's are 20mm longer, which will make the crossmember even harder to mod!

Because the engine angle and centerline are limited in a 924 by the torque tube, I can't sit the engine on top of the normal crossmember. With a rotary the eccentric shaft runs through the middle of the engine, not near the bottom like a piston engine.

I've had 5 RX7's, 1 RX5 and 2 RX2s, so I know all about the fuel usage!!
_________________
Andrew
1977 RX924 rally car
12a bridgeport
www.race4-dcup.co.nz
Back to top
View user's profile Send private message Visit poster's website
Peter_in_AU  



Joined: 29 Jul 2001
Posts: 2740
Location: Sydney, Australia

PostPosted: Thu Nov 29, 2007 10:40 am    Post subject: Reply with quote

Make sure you take lots of big, clear pics.
_________________
1979 924 (Gone to a better place)
1974 Lotus 7 S4 "Big Valve" Twin-cam (waiting)
1982 924 (As featured on Wikipedia)

Learn to love your multimeter and may the search be with you
Back to top
View user's profile Send private message Send e-mail
Andrew NZ  



Joined: 22 Jun 2004
Posts: 744
Location: New Zealand

PostPosted: Thu Nov 29, 2007 11:36 am    Post subject: Reply with quote

Peter_in_AU wrote:
Make sure you take lots of big, clear pics.


Will do!
_________________
Andrew
1977 RX924 rally car
12a bridgeport
www.race4-dcup.co.nz
Back to top
View user's profile Send private message Visit poster's website
Petrovich  



Joined: 27 Sep 2005
Posts: 235
Location: Rockville, MD

PostPosted: Sat Dec 01, 2007 5:55 am    Post subject: Reply with quote

Is the crossmember clearance problem due to oil pan, or the actual engine block?

IMO rotary is a great swap motor for 924. Light, small, exhaust on the same side - just let us know how you do the bellhousing, that's the hardest part, pretty much.
_________________
1982 924 Turbo, now Lemon
Back to top
View user's profile Send private message
Andrew NZ  



Joined: 22 Jun 2004
Posts: 744
Location: New Zealand

PostPosted: Sat Dec 01, 2007 6:39 am    Post subject: Reply with quote

Petrovich wrote:
Is the crossmember clearance problem due to oil pan, or the actual engine block?

IMO rotary is a great swap motor for 924. Light, small, exhaust on the same side - just let us know how you do the bellhousing, that's the hardest part, pretty much.


The crossmember clearance is mainly due the engine housings rather than the sump.

The bellhousing looks pretty straight forward, I have a S1 RX7 bellhousing ready to cut about, and the spacing back to where it needs to bolt to the torque tube is identical to thye 924 (150mm). The hardest bit I can see now is going to be changing to a hydraulic clutch.

I have an engineer freind coming around tommorrow to look at the bellhousing for me, so I'll let you know.
_________________
Andrew
1977 RX924 rally car
12a bridgeport
www.race4-dcup.co.nz
Back to top
View user's profile Send private message Visit poster's website
endwrench  



Joined: 07 Dec 2002
Posts: 1629
Location: Victor, Montana

PostPosted: Sat Dec 01, 2007 8:33 am    Post subject: Reply with quote

This is going to be great project to follow! Mostly because I know your not "all talk". You get shit done Plus, you don't have a bottomless bank account so we're bound to see some pretty good "ingenuity"

Todd
_________________
'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....
Back to top
View user's profile Send private message Send e-mail
Petrovich  



Joined: 27 Sep 2005
Posts: 235
Location: Rockville, MD

PostPosted: Sat Dec 01, 2007 8:58 am    Post subject: Reply with quote

Have you considered making the engine a stressed chassis member? Bascially, remove crossmember and install short bars on both sides that will make your entire engine your new crossmember. I'm probably talking out of my ass because I never looked at the crossmember all that much, but it got me thinking now.

I wonder how easy it is to convert to a 944/931 master cylinder, and whether it will work fine with 7's slave. Would be something I'd investigate first.
_________________
1982 924 Turbo, now Lemon
Back to top
View user's profile Send private message
jamez  



Joined: 03 Nov 2002
Posts: 401
Location: Chehalis, Wa

PostPosted: Sat Dec 01, 2007 9:28 am    Post subject: Reply with quote

The stressed chassis member is an awesome idea, I wish I would have thought about that when I did my conversion, the motor could sit alot lower.

edit : the only problem I see with this is the steering rack. But a new steering rack mount could be made and the engine would still be able to be a few inches lower than if the cross member where there.
Back to top
View user's profile Send private message Send e-mail Visit poster's website
v8carreragts  



Joined: 05 Sep 2003
Posts: 661
Location: Tucson, AZ

PostPosted: Sat Dec 01, 2007 2:46 pm    Post subject: Reply with quote

It's not that difficult to convert an early car to a hydraulic clutch. I did it on an early 77. You need the hydraulic clutch pedal, the clutch master cylinder, push rod and associated hardware along with a flexible hose to connect to the slave cylinder and the brake resevoir from a 924t or 944 (it has the connection for the master cylinder feed). In my case, I used all 924 turbo parts.
You will need a chassis punch to punch the hole, I think it is 1" diameter. The left front wheel well needs a little dinning with a hammer to make clearance for the front end of the master cylinder. You will need to drill two holes for the master cylinder attaching bolts. And a VERY important thing is you will need to make a backing plate for the master cylinder to distribute the load from the pedal. Trust me, you need it. Mine worked for a few months until the master cylinder pushed through the firewall. Then I made a 16 ga. plate and welded two bolts onto it (for the master mounting) and put it behind the firewall. Starting sometime in 1979 this area had an added piece of sheet metal spot welded in for this purpose. Then you just swap the pedals and mount everything.
After I added the plate, I drove that car every day for about 8 years without any problems. I did this so I could put a 944 transaxle in the car. On my 79, I just used a late Mustang disk in the 924 n/a clutch to fit the 944 transaxle. On the 79, everything was in place for the hydraulic clutch except for the two mounting studs for the master cylinder. This included the mount for the spring and nylon bearing that helps reduce the force of the pedal. You really don't need the spring. I didn't use it on my 77 and never had any problems.
Back to top
View user's profile Send private message
jamez  



Joined: 03 Nov 2002
Posts: 401
Location: Chehalis, Wa

PostPosted: Sat Dec 01, 2007 3:42 pm    Post subject: Reply with quote

v8carreragts

I did the same with the backplate for the master cylinder on a '77 924. I used a cylinder from a corvette.
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    924Board.org Forum Index -> Engine Transplants All times are GMT + 11 Hours
Goto page 1, 2, 3, 4, 5, 6, 7, 8  Next
Page 1 of 8

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group