Cracked rear iron... I think

[ElTeeFauci]

so this:
http://rx7.com/cgi-local/2ndgencalc.cgi

tells me that 720/720 is able to support 350 at 85% duty cycle...

If I keep my 720 injectors (currently secondaries), swap them over to the primary rail, and throw in some 1000's on the secondary, are there issues when the secondaries come online? The only real reason I'm asking is that the above mentioned calculator says so... but I can think of people running even 1600cc secondaries without issue.

Guess its all in the tune.

Anyway, getting the engine tomorrow... cant wait. Though it will be a while until I swap it in. Gonna throw in new front/rear main seals for the hell of it, order some new exhaust gaskets, and of course a pair of bigger injectors. standing by for recommendations on injector size. I'd like them to fit the stock secondary rail.

[Rotary Evolution]

that calculator is bogus, the figures are too high for rotary engine applications. perhaps it was carried over from piston engine calculators.

stock 550's good for 262whp at 85% duty? i don't think so.. it also claims FD 550/850's would do 342whp at 85% duty? right.

and i'm not sure why i have to keep repeating this, a turbo S5 engine does not guarantee a thick cast rear iron. they are actually quite rare even on j-spec blocks. if you wind up being unlucky and get the thin cast i would suggest studding the engine or keeping the power levels reasonable(sub 300whp) until it needs to be rebuilt and then reinforce it.

[ElTeeFauci]

I think I'll shoot for 720/1000s then to be safe. I dont see myself ever getting a bigger turbo, at least with this particular car anyway.

Ben... I believe you on the rear iron. I just happened to find an engine about 4 hours away. It'll provide me with spare engine parts if I ever end up REALLY blowing an engine and not just cracking an iron.

I'll check to see if it has the little gusset going from the iron to the oil pedestal - I think thats one of the telltale signs of the thicker dowel area, right?

[Rotary Evolution]

nope, the extra rib does help but i have still broken those irons easily. the thick cast rear iron protrudes quite a bit outside the "L" edge of the rear rotor housing. look at the front iron versus the rear where it meets the rotor housing, the thick cast iron will be easy to spot. if they look the same F+R then it's the thin casting.

[ElTeeFauci]

Thanks. Maybe after I get to Monterey and get this thing back up I'll take it down to Vegas and have you play with the tune (if you want to mess with a MS2). Dont pack up the shop yet! I imagine I'll be done sometime around July-August.

[Rotary Evolution]

i'll be around, i won't be leaving here for at least another year. we may be looking at houses down there in the next few months though.

[ElTeeFauci]

Picked up the engine... definitely has the thick dowel area. I don't like the front rotor pulses at the exhaust via the poor man's compression test, so ill be rebuilding.

[ElTeeFauci]

The front rotor has a blown apex seal, with some rotor damage. Haven't seen the inside of the housing yet... but I'm sure it ain't pretty!

But the back is good!

[ElTeeFauci]

pic of the front...

[ElTeeFauci]

Tore the engine down today... the donor engine is near immaculate, with the exception of the front housing and rotor.

The front and rear irons both have the thick dowel area. From what I read, I thought it was just the rear.

Question number 1: God knows what this engine has been through, its a JDM s5. When I tore it down, I found 3 piece apex seals, but the funny part was that the corner seals had FD springs. Anyone know if the JDM engines came with these?

Should I keep the front iron too?

pics attached... somehow.

[Rotary Evolution]

it was probably rebuilt many years ago before mazda went to the 2 piece seals in around 2004-ish, after the remaining stock of 3 piece seals was depleted. no original FC engine ever came with the FD type corner seal springs.

[ElTeeFauci]

Originally Posted by Rotary Evolution

it was probably rebuilt many years ago before mazda went to the 2 piece seals in around 2004-ish, after the remaining stock of 3 piece seals was depleted. no original FC engine ever came with the FD type corner seal springs.

Good to know. I've decided that instead of selling these irons with the exception of the rear iron, I'm going to use them in my rebuild... may have the engine studded... though I cant fathom how I'd reassemble it; I'd have to look at the process... I haven't gotten that far yet.

Just waiting on a dial indicator to get here to check the step wear (though I strongly doubt it'll even be measurable). Then its the Atkins kit for me... and Ben, I'll likely be ordering a set of the goopy seals.

I cant imagine that the plates and housings that are in the car now are i better shape than these... but we'll see!

[Rotary Evolution]

since you got the thick iron you should be fine, studding is more for the weak thin cast rear iron blocks. the front iron can also crack in the same spot but it is a rather rare occurrence. if you ever want to push over 450whp i would suggest then thinking about studding it for future goals.

[ElTeeFauci]

Just spec'd out the irons... .002 is the biggest step on them, so I'm good to go as far as irons are concerned!

I also picked up a cherry picker and engine stand yesterday, adapter plate is on the way...

[ElTeeFauci]

So since the last post... I've moved to CA, set up the garage... and...