4G63 FC RX7

mike000 · Post by **mike000** » Mon Jun 30, 2014 10:36 am

I just joined Project Zero G today, after having found the site a few times over the years. Here's a little bit of background...

I started out as a strong advocate of RWD Japanese platforms years ago, but have moved to the generic FWD, econocar concept as I grew up. I had an itch last year to do some drifting at a local track here, and bought my first RWD car in 5 years and was hooked again. That car has since been trashed, but I'm looking to replace it with a convertible FC3S RX-7. For those who don't know, the FC3S is a great handling small platform, with a huge amount of aftermarket support and a rigid chassis (rigid by convertible standards).

After learning through Project Zero G, that a stock FC3S transmission will bolt to a 4G block with use of a Mazda truck bellhousing, I was hooked. This means: stock transmission, stock transmission mount, stock driveshaft in the Mazda. Of course, this is only 1/4 of the battle, and I'm sure it will still have it's handful of challenges.

Now, there are a few things that I have learned about the Mazda/Mitsu trans orgy, but I am a bit fuzzy on the details, so if anyone has input that would be phenomenal!

Plans:
S5 FC3S Chassis
1G DSM Head
1G DSM Engine Harness & Computer
4G63 Wideblock
Mazda B2600 Bellhousing
Stock FC3S trans/driveshaft/transmount

Now, from what I've read, I don't THINK that a there is an option to use the Mazda RX-7 trans with a narrow block through any combination of parts, can someone verify this?

Anyways, this is my thought process now, and I am entering the "piecing together" phase of my project. Thanks again to all of those who contributed to such an awesome site, with some extremely helpful information.

mike000 · Post by **mike000** » Tue Jul 01, 2014 8:12 am

mainstream wrote:You've got everything right supposing your vert has been swapped to TII transmission. The 13B NA trans does not have a removeable bellhousing. If you aren't swapped already, swapping in a TII trans will require a custom driveshaft unless swapping entire drivetrain. TII stuff is bigger and beefier. You are correct there is not a narrow block option. Mazda used only the 2.6 (which is the wide pattern) and only for 2 years, 87-88.

Kane

Ah, I didn't know that there was an external difference between the TII and n/a 13b trans. I always assumed it was all internal. That's something I'm going to have to look into before diving too deep into this project. Thanks for the info!!!

Post by **DJpowerHaus** » Tue Jul 01, 2014 1:36 pm

Also, the B2600 Bellhousing on the RX7 transmission in the RX7 will tilt the block to the exhaust side by several degrees. Not a bad thing really, puts the turbo lower making the downpipe routing easier. Might need to do a top mount turbo though.

http://www.4g61t.org/forum/viewtopic.ph ... d94835c177

Or you just rotate the transmission up to straighten the motor. Lots of other pictures on google image search show this method.

mike000 · Post by **mike000** » Wed Jul 02, 2014 10:09 am

DJpowerHaus wrote:Also, the B2600 Bellhousing on the RX7 transmission in the RX7 will tilt the block to the exhaust side by several degrees. Not a bad thing really, puts the turbo lower making the downpipe routing easier. Might need to do a top mount turbo though.

http://www.4g61t.org/forum/viewtopic.ph ... d94835c177

Or you just rotate the transmission up to straighten the motor. Lots of other pictures on google image search show this method.

Thanks! I am so glad some information surfaced about this car. I wish there were more pics and a bit more information, but very cool! I stumbled across a pretty generic bay shot of this car on google image a month or so ago.

As far as the motor leaning, I am not too upset about it really. The Mazda has a very low header/downpipe due to the rotary motor design, so having the down pipe down low, similar to factory Mazda, will likely make routing it way easier. As far as the oil pan goes, does the 4G63 utilize a front sump or rear sump pan? I had thought from my searching that a front sump was the norm for a 4G, yet one of the pics in that link shows a stock (looking) rear sump pan on the short block in the Mazda bay.

SOB Racing · Post by **SOB Racing** » Wed Sep 17, 2014 4:31 pm

I had mine running for acouple of years.

http://s890.photobucket.com/user/SOB_Ra ... 9137782007

Somebody was just asking me about my setup so here's a few of the step i went through.

-Fab'd a adapter plate to go from narrowblock to b2600 bell. I set both my engine and trans vertical
-b2600 bellhousing needs to be machined in depth to position pilot on trans in correct engagment with pilot bearing.
-Flywheel was machined for rx7 pilot bearing.
-Rx7 TOB sleeve needs to be lengthen to poition TB correctly with clutch fingers.
-Clutch fork ball needs to be extended.
-Adapter plate is machined for proper starter engagment location-stock 1g starter

Used Fidanza AWD Talon flywheel, ACT Talon clutch and Miata disk

I fab'd new engine mounts, trans mount and a rear sump pan and pickup