Leeroy_25

I pulled this image from an old post. Someone was using it as a dummy engine
What engine is it? The rotor housings look to have some kind of factory peripheral port or is it just a very tidy job done?



Cheers
Lee

RIX-7

iTrader: (2)

looks like a 12a with factory (mazda Racing) PP housings to me. Rix

mannykiller

iTrader: (93)

possiblty a renesis?...

MountainScreamer

Looks like it's a mix of things. the rear iron is from a 4 port while the front is from a 6 port if I'm not mistaken. Also those are probably factory pp housings.
It looks like it has a dry sump kit on it.

Definitely not a renesis.

Very interesting, though. I hope some of the more knowledgeable members will chime in!

-Max

jgrewe

iTrader: (1)

Just a mix match of parts to fill the hole for a mock up. I don't think you could call it anything.

peejay

Rotorhousings are definitely MFR housings - besides the obvious cast-in intake ports, the exhaust studs are a lot closer together than street housings.

Dry-sump front cover, too.

I agree, it's not a running engine, just a collection of parts that are engine-shaped. (plus - durr - there's no eccentric shaft!)

I assume that it is just a mockup thrown together with a couple tension bolts in order to figure out where the engine mounts, exhaust system, intake, and oil lines have to be. It's good to try to do them all at once, so you don't, say, mount the engine in a location that doesn't give you enough carburetor clearance.

As a guess, the rear end housing is FD or possibly twin turbo Cosmo (intake port at a high angle, rear turbo oil drain, but I didn't think FD had the top start mount anymore?), the center housing is from a GSL-SE or whatever the non-US market equivalent is (tiny inlet ports, no EGR valve, and the funky boss at the bottom that means you have to modify headers to fit) and the front end housing appears to be from a European N/A FC (no possibility for a sleeve in that aux port!)

Leeroy_25

Thanks for the feedback people.

I was really interested in the rotor housings as I hadn't seen them before. I have 3/4 of a spare FD engine and need replacement rotor housings, possibly rotors. I was thinking of doing a N/A 13b PP engine. and wondered if the PP housing was something readily availalble.. I guess they might be factory race ones from what I have read..

I realised it has a dry sump front cover and was probably a bit of a mis-mash other than that.. but all interesting.

Will I get enough compression for a N/A PP engine with my turbo 13B setup or should I be looking to get N/A rotors?
I also thought looking at the pics those exhaust ports look small compared to the FD 13B ones? Could jsut be the camera angle though.

Cheers
Lee

peejay

I am not expert but I understand that MFR (Mazda Factory Race) rotor housings require the carbon-aluminum apex seals, since they do not have a steel inner liner. Direct chrome-on-aluminum, heavy apex seals can damage them.

I've seen that high compression rotors do not increase peak power because at high RPM the internal engine airflow characteristics are hurt by the smaller rotor depression. I have also "heard" of people making ridiculous high RPM N/A power using low compression rotors, maybe for this very reason.

I don't know how "large" the MFR exhaust ports are, but they actually open later than street exhaust ports, and the street exhaust port runners are actually way too large for best power - lots of people have had good results in making smaller I.D. exhaust sleeves, or just crushing the existing ones down to a more favorable size. (I assume Mazda did what they did because a rapid expansion helps cut noise)

mannykiller

iTrader: (93)

Def not a renesis...my bad..

Leeroy_25

Would like to know some more on the port size theories.. Most people I have seen doing rebuilds admittedly not on PP engine have opened up the exhaust ports. That said I guess they were probably all turbo motors and that would probably account for wanting a larger exhaust port? (more gas to get out) What about the inlet on and NA PP motor. Is there some kind of rule of thumb to size the port? I would guess you are going to want something quite large to allow more air to get drawn in wihtout the forced induction but then too big is going to kill it at the bottom end? Guessing there might be quite a fine line there?

Cheers
Lee

jgrewe

iTrader: (1)

The biggest issue with the exhaust ports is turbulence from the roof of the port expanding too quickly to keep the air flow attached. You can make great power with a sleeve that keeps the port the size of the hole but you will burn holes in stuff eventually(think of a torch flame being focused)

Leeroy_25

When you say keep the port the size of the hole I presume you mean the stock exit in the rotor housing? So what about a compromise of increasing the port size slightly and maybe reducing the sleeve diameter a touch? Or for a N/A motor do you need to try an reduce the port and sleeve equally?
Or are you just as well leaving it as it is?
It's all very well trying to gain loads of power but not at the cost of reliabilty for a streetable car?
Anymore points of view on this?

Lee