Vk304s Mazda rx7 s4 discussion thread

[Vk304]

On 13/01/2024 at 17:14, mjrstar said:

Is there any chance that mx5 light motors would be the same?

Yes my thoughts too and they work fine but not the same mounts

[rotormotor]

Pretty hefty exhaust leak that, my leak was just the gasket after the downpipe.

If you after any emission stuff or airpump let me know 

[Vk304]

Yea ay, was one of the majors to fix, no im good thanks lol 

[cletus]

Adrenaline r are good, I have a single 3.5" at the back on my car

When I was doing noise testing they were a muffler that actually worked, rotaries usually needed a couple of them though. 

 

[Vk304]

Yes i have a maxfab 3.5 resonator in the front, cheers, if thats not enough i might have to run 2 resonators 

[rotormotor]

I have currently a twin pipe setup with resonators x2 and some JDM brand rear mufflers..mufflers hang far too low.

Assume twin muffler etc quieten down the rotor moreso?

[Vk304]

Yea i currently have a surge tank and pump occupying the other side haha so thats not an option, but ill get around to doing it properly soon

[dabuzz]

For exhaust, I removed a stainless adrenalin R off my RX4 as I couldn't stand the sound it made, horrible tinny and had a resonance at a certain RPM that just drilled into my head.

Not a fan.

I had a custom "Manawatu mufflers" mild steel boiler made to suit the space available, huge difference, really nice deep sound, slightly quieter, way happier.

[Vk304]

Heard they are good, cheers will keep them in mind...

[Jusepy82]

Looks mint

[kiwi808]

Probably the front Iron has cracked by the water jacket. It’s a common weak point from casting. That was the cause of my first rebuild.

[rotormotor]

My irons were all mint with no corrosion so I got lucky it seems.

Welcome to rebuild time 

[Vk304]

Hope its not too bad but yea should be cool to see what its like, when it got real bad it sounded like 1 rotor was going and lots of backfiring and water pushing out of the radiator, did a compression test but nothing really stood out there, if its cracked there does that mean buy a new one or is there a way to save it?

[rotormotor]

My engine builder said 

" Normally it's lack of coolant and I would replace ( if irons cracked). Not worth a dodgy repair taking everything out.
I'd be putting it down to corrosion, rusty coolant passages my guess "

[shizzl]

Could be caused by a number of possibilities really, cracked housing, blown water seals, cracked plates. 
they usually still comp test fine too.

Atleast you know it’ll be good after a rebuild

[kiwi808]

My irons were mint with no corrosion at all but the metal between the water jackets and the seals is pretty small. Apparently it’s pretty common for it to break.

[shizzl]

Yup also common for the water seal groove to disappear 

[Vk304]

Yea we will see, just need to get a 54mm socket now and i can split it

[shizzl]

That sux to see. 
maybe someone’s dropped the Torrington bearing at one point

 

[rotormotor]

FYI FD irons and housings are the superior items, Irons more meat to port for one.