Stredrotor's RX4 Coupe * Project 20B *
 

Thought I'd start a thread on my 1974 RX4 hardtop.

I bought around 2 years ago after previously having a 13b turbo 1973 RX4 hardtop and an '86 Series 4 RX7 turbo over the last 15 years.
The car had a carby 13b and first gen RX7 5 speed, it ran well but I needed more power. I think of the RX4 as mazdas "muscle car" so it needed a engine with the muscle, hence a 20b :reddevil:

The RX4 as I bought it....

http://img511.imageshack.us/img511/5...pefrontmg4.jpg
http://img140.imageshack.us/img140/1...peseatsjw6.jpg
http://img116.imageshack.us/img116/3...upereardr6.jpg

Striped and painted the crossmember and replaced tie rods, sway bar and bushes.
http://img364.imageshack.us/img364/3...smemberyh9.jpg

All installed!
http://img171.imageshack.us/img171/2...smemberku0.jpg

The next acquisition for the 20b project, a series 5 gearbox :D .

http://img205.imageshack.us/img205/7...gearboxas8.jpg
I got a awesome bargain the other day, a bloke at work tipped me off to some 16 inch F90 Simmons at a second hand shop. A bit of bargaining and these were mine for $140. :D

http://i28.tinypic.com/2s6lymd.jpg
All 8 inches wide.

Picked up a Microtech LTX12, coils, loom and Eboost
http://i30.tinypic.com/2zi901g.jpg

Just got the engine in place to work out the engine and gearbox mounts
http://i30.tinypic.com/28mnss4.jpg
http://i29.tinypic.com/25rcrqs.jpg

For Fathers Day I asked for some kid free time to work on the Mazda, so I got around to doing the old shorten shifter housing mod......
http://i227.photobucket.com/albums/d...nedshifter.jpg

Modified the gearbox cross member to suit the old RX4 one.....
http://i227.photobucket.com/albums/d...arboxmount.jpg

Made some plates to mount the engine off and exhaust manifold flange :D ......
http://i227.photobucket.com/albums/d...nginemount.jpg
http://i227.photobucket.com/albums/d...nginemount.jpg


Now I just have to install the engine and box and fab the mounts off the suspension crossmember.

Here's the prototype mounts:)
The engine and gearbox is mounted 50mm further back than the 13b to help with clearance at the front of the engine bay.

http://i227.photobucket.com/albums/d...nginemount.jpg
http://i227.photobucket.com/albums/d...inemount-1.jpg

RH engine mount now finished
http://i227.photobucket.com/albums/d...ginemount1.jpg
http://i227.photobucket.com/albums/d...ginemount2.jpg

And test fitted.
http://i227.photobucket.com/albums/d...ountfitted.jpg

Left hand mount completed, sits quite nice .


http://img42.imageshack.us/img42/5561/lhmount.jpg

Should be strong enough :!: :D

R/H side mount installed.....

http://i227.photobucket.com/albums/d...a/IMG_0943.jpg

...and L/H

http://i227.photobucket.com/albums/d...a/IMG_0942.jpg

Getting there

http://i227.photobucket.com/albums/d...a/IMG_0941.jpg

My latest purchase 60mm Tial waste gate and a GT42, ball bearing, water cooled A/R 1.06 exhaust. Now have to get in and make the exhaust manifold.:)

http://i227.photobucket.com/albums/d...a/IMG_0940.jpg

WOW! What a project you have there. :icon_tup: Looking forward to updates.

Very nice fab work on the engine mounts, but how come you didn't throw a gusset or two on the inside of the L shape on them? Looks like there's plenty of space for a few gussets, though maybe that'd be overkill given the thickness of material used?

And a GT42?! Wowzers, how much power are you planning to make? :)

Trans mount really needs some rubber thrown in somewhere, or it's liable to have massive vibration issues.
Otherwise, awesome project.

Yea, it's now got a 10mm thick piece of rubber between the mount and gearbox bracket plus the crossmember is rubber mounted as well.:)

A bit more forward progress.....

Got the pipe layout sorted, think it will flow ok :D

http://i227.photobucket.com/albums/d...anifoldfab.jpg
http://i227.photobucket.com/albums/d...nifoldfab3.jpg
http://i227.photobucket.com/albums/d...nifoldfab2.jpg

Just got to sort out the transition piece on top

Couldn't help myself and did a test fit in the engine bay

http://i227.photobucket.com/albums/d...rbotestfit.jpg
http://i227.photobucket.com/albums/d...botestfit2.jpg
http://i227.photobucket.com/albums/d...botestfit3.jpg

Now have to have a think on how I'll plumb the wastegate.

This is a great build you have going here.

Nice!!! keep up the good work!!
Cant wait for more updates!

Great build i like whene people put new tec on old school car,hay ma keep up the great work nice looking rx4....

Finally got a few days to make this manifold

Tacked manifold to 25mm plate to help stop distortion......
http://i227.photobucket.com/albums/d...tackeddown.jpg

Welded and turbo bolted on.....
http://i227.photobucket.com/albums/d...dwithturbo.jpg

Fitted to engine to see how it fits.
http://i227.photobucket.com/albums/d...nginefitup.jpg

Now to fit the wastegate pipe! .

After a lot of thought decided to plumb the waste gate straight off the collector under the turbo.
I know it's probably not the best location for flow but there was really not enough room to run three separate runners.

Here's the pipe tacked up.......

http://i227.photobucket.com/albums/d...egatefitup.jpg

...and test fitted in engine bay.

http://i227.photobucket.com/albums/d...da/testfit.jpg

Pipe welded on and wastegate fitted :D

http://i227.photobucket.com/albums/d...tialwasteg.jpg
http://i227.photobucket.com/albums/d...edda/ohyea.jpg

And bolted onto engine :drool5:

http://i227.photobucket.com/albums/d...edtoengine.jpg


Next is step is to send it off to get the mounting faces machined flat.