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.

I got the exhaust manifold back from having the sealing faces machined flat so I have been able to make the 3 1/2 inch dump pipe, a tight fit but it clears :D . Just have to make the flanges to bolt the exhaust system to it. (When I make the exhaust system.)

http://i227.photobucket.com/albums/d...a/IMG_0037.jpg
http://i227.photobucket.com/albums/d...a/IMG_0034.jpg

After I weld the flanges on, the turbo exhaust housing, manifold and dump pipe will be sent off to be ceramic coated. Should help keep the heat down and looking good.

.....also mounted the coils

http://i227.photobucket.com/albums/d...a/IMG_0038.jpg

Awesome build!

good luck get some videos up when its finished!!!

damn dude, that is gonna be sick!

Damn nice build, ive always had a soft spot for Rx4's and this one is sure to be the nicest ive seen.

A bit off subject, but will a RX4 bellhousing fit a 20b? And what does a series 5 trans come out of? Nice build by the way.

An RX4 bell housing would fit a 20b but the later FC Turbo models onwards gearboxes run a larger flywheel so have more friction surface the clutch to grip.

Sorry, you guys know the series 5 RX7 as the second version of the FC RX7 model. It is often related to in Australia as First Gen RX7 as Series 1,2 and 3 Second Gen (FC) Series 4 and 5 and Third Gen (FD) as 6,7 and 8.

thanks for the info. I looking for options on transmissions to hold a 20b's power.

We use that to. We usually just say "S5" though.

Amazing. Updates? :)

Haven't had much time to work on it lately:(. I have decided to remake the dump pipe it came a bit too close to the brake lines.

I am chasing a throttle body so I can make a start on the water to air intercooler setup.

Plus I said yes to make a 20b turbo manifold for a guy in Melbourne :banghead: but it's extra cash and I learned a few things from making mine.

Excellent work man! I look forward to seeing some updates.

What are you going to do for brakes and rear end?

Not sure yet, like to have a good disk brake setup.




Here's a bit of an update not much but it's one step at a time :) .

Lashed out on a Westside Exhaust and Custom radiator and oil cooler combo.
http://i227.photobucket.com/albums/d...a/IMG_0100.jpg

Also a PWR barrel cooler, heat exchanger, filler spout and water pump I scored for a good price off ebay.
http://i227.photobucket.com/albums/d...a/IMG_0099.jpg
http://i227.photobucket.com/albums/d...a/IMG_0101.jpg

Now have to make some mounts for the radiator and heat exchanger and plumb up the barrel cooler.

Getting there ever so slowly.

Found a bit of time this arvo, so with the mounts welded on I mounted the radiator and made some trial mounts for the heat exchanger radiator.

Also had a bend welded onto the end of the barrel cooler to bring it in line with the radiator.

http://i227.photobucket.com/albums/d...a/IMG_0107.jpg
http://i227.photobucket.com/albums/d...a/IMG_0108.jpg
http://i227.photobucket.com/albums/d...a/IMG_0109.jpg

Waiting on a 135 degree bend from plasmaman to go up to the throttle body to finish it off the intake side.

.

Shaping the end of the tube to match the chopped off snout.

http://i227.photobucket.com/albums/d...a/IMG_0128.jpg

Trial fit up.

http://i227.photobucket.com/albums/d...a/IMG_0126.jpg

Spent a few hours sanding out the casting marks on the snout and the hammer marks on the tube.

http://i227.photobucket.com/albums/d...a/IMG_0130.jpg
http://i227.photobucket.com/albums/d...a/IMG_0131.jpg
http://i227.photobucket.com/albums/d...a/IMG_0132.jpg

Now just have to get my mate Troy to weld the pipe and snout together. (Don't have an AC tig to do Aluminium)

Hey guys, today I moved the wastegate outlet which fouled on my new radiator :blush5: .

Cut it off and shortened it........

http://i227.photobucket.com/albums/d...a/IMG_0158.jpg

Then welded it up!

http://i227.photobucket.com/albums/d...a/IMG_0170.jpg
http://i227.photobucket.com/albums/d...a/IMG_0171.jpg

The pipe from the barrel cooler to throttle body now welded.

http://i227.photobucket.com/albums/d...a/IMG_0162.jpg

I made a mount for the coils. I think they should work there :confused: .

http://i227.photobucket.com/albums/d...IMG_0159-1.jpg

Here's a pic of the dump pipe, just tacked up at the moment. When I get the lower flange cut and tacked I can see if the flange will fit past the engine and steering box :dunno: .
Then I can weld that up as well. :D

http://i227.photobucket.com/albums/d...a/IMG_0160.jpg

the only problem you might experience with the coils so low is if you ever run into rain or a larger puddle getting them wet. I would make sure to make some sort of shield or something along those lines to keep them dry. Nice project so far cant wait until i can dig into my rx2 more.

Nice looking project... will be nice to see a vid of it runing ...:)

I plan not to drive it in the rain as much as possible. A sunny day driver.:)
Don't worry I'll post up a vid of it running:biggthumpup:

I am a worst case scenario kind of guy :D

Awesome car. I can't wait to see it completed.

Just a quick update guys, with a few jobs around home keeping me busy I haven't had a lot of time on the old girl. So while I am waiting to get a bit of cash together for the stud kit and the rotors to be machined I have managed to sneak out to the shed a few times. Wore my fingers a few centimeters shorted by sanding and polishing the intake manifold and throttle body snout.

http://i227.photobucket.com/albums/d...a/IMG_0413.jpg

Still needs another sand I think to get a few more scratch marks out. It's not going to be any show car but I always wanted a car with an engine bay I was proud of. :D

awesome

Just a quick update. Didn't get much done over the break, had a lot of stuff to do around the house.

But I did acquire some coil over struts and S4/5 calipers and slotted disks. :D
http://i227.photobucket.com/albums/d...a/IMG_0557.jpg