in ye olde times Mazda had no nitriding, but they used an iron with a high nickel content. then in 1978 when they went to the Nitriding process, they were also able to use a lower grade of iron.
so lapping a 78+ iron you can expect really high wear really fast

 

in the breaking news department, in 1999 Mazdaspeed offered rebuilt engines. my picture is terrible, but its 10% more power. its a small street port



the interesting thing is that the rebuild specs were also published.
it is interesting because for only 10% more power (265 goes to 290) they specs they use for clearances are quite different from the stock ones.
the take away here is not that these specs are better, its that a high power engine may want different clearances than stock.


so translated, stock is on the left, Mazdaspeed is on the right hand side
the first group is for the side housings,
Flatness, Side seal wear Inside the Oil Seal orbit, Side seal wear outside the Oil Seal orbit, and then the Oil seal orbit
very straight forward, these are just more picky, less wear is allowed.

the rotor housing, rotor and clearances are the same 80, 79.85 and 0.06mm

the second group is:
Side Housing to rotor
Apex Seal to Groove
Side Seal to Groove
and Side to corner seal
this group has a smaller tolerance, but generally the clearances are bigger, especially the side seal

the last group are the
Main Bearing clearances, FC, FD inner, FD Outer
the Rotor Bearing
E Shaft run out
and then everyone's favorite, end play. i do wonder if they got this one reversed, but idk

the other two bits were that the tension bolts go to 3.5kgm and the flywheel nut is 50kgm, no tolerance

 

Big thing is side seal clearance, I think having properly fit consistent side seals make a HUGE difference in compression. The OEM spec is very sloppy and they don't get anywhere near the best tightness from the factory, it's really hard to do that in a very fast production environment.

Dale

 

Mazda spec is 0.05-0.15, big range, Mazdaspeed is 0.10-0.013, smaller tolerance but more clearance, isn't that weird?

 

That is odd. Are those numbers metric or standard?

I typically do .003" (3 thousandths of an inch) on all my side seals. Some people like going tighter but I've always had good luck with that and good compression.

Dale

 

its metric, they don't have standard in Japan.

i used to do 0.002" but i think that is too tight, i'm not sure how consistent my measurement is that tight, and i'm worried about binding.
so the last couple engines i've been using 0.0025" or 0.003"

0.003" = 0.0762mm

 

a bit pricey for a 1-time build and currently on backorder according to somebody waiting on an order to be filled , but cuts them in 0.01mm (0.0004”) increments perfectly square and radiused to the corner seal

You Tube

couple of good tips given regardless
.

 

Curious what the consensus is on the necessity and effectiveness of some of the additional modifications available for a 13B-REW.

For example, Chipsmotorsports offers a plethora of options, from machining O-ring grooves to CNC rotor housing cooling grooves. Mazdatrix also offers some services like balancing and metal treatments on the seals and core components. There are also more common and little things such as either an internal or external oil mod to increase oiling to the E-shaft and thermopellet replacement.

Are any of these considered an absolute improvement when say, dealing with a brand new Mazda keg? Or is it application specific?
I'm considering a new block for exclusively track in the 300 or under whp range but realized I've never considered the additional aftermarket options available from engine builders

 

At that power level I wouldn't do any of that stuff. You'll easily achieve that power level and have the best reliability on a completely stock motor.

 

A huge portion of engine build mods are for SERIOUS track use, like dedicated high RPM race car on the bleeding edge.

Really, keep it simple. Use good quality components, spend the time fitting side seals, take your time with the build and it's fine. People mainly get into trouble with all the stuff that's bolted to the engine and the tune more than anything.

Dale

 

Love this thread. Full of great information. I have been itching to rebuild my FD engine for some time. Mine doesn’t have great compression and was built about 15 years ago. It’s definitely time for a refresh.

 

+1 its a fun engine to build.

step one though is actually to price out a rebuild vs just a new engine.

 

Depending on timeline, what is damaged, and what kinds of modifications are done to your current engine (ie porting). If most of the major hard parts are damaged then yes a new engine is feasible..... but isn't the wait time for one of these ridiculous in 2023? (serious questions, arent some people waiting like over a year?) If major hard parts just need a refresh then this will be the most cost effective path. I'm currently getting ready to rebuild my engine. Fortunately I was able to get away with having one housing honed and my rear iron lightly lapped. If not I would have stolen parts from the spare engine I have laying around..... but because I would then need to have porting done on these parts (my spare engine is stock port vs the large street port on my current engine) it was a huge time saver (and cost since I likely wouldn't port this myself) that I was able to re-use all engine hard parts.

 

Just wanted to comment on this as it's something I've looked at with my own tore down engine this weekend. When you reference gouges that your finger nail can catch, are you referring to gouges other than step wear? (ie if Apex seal broke, etc)

Just wanted to note that my rear iron has step wear that could be felt with the fingernail. When I actually measured the wear with a dial indicator it was 0.002", the Mazda spec/tolerance is .0039"; so even though I could feel this step wear, it was still only half way out of tolerance. Just hammers home what has already been mentioned in this thread previously, with the way parts are increasing in price, investing your time and efforts into cleaning, prepping, measuring, etc so hard parts can be reused is all worth it.

 

this is totally worth mentioning. because its turned into a 3 axis chart (4 if you count shipping and taxes)

today the ETA on an engine is June. so if you need to fix the car NOW its not really a good option.

the second thing that is going on is that people are getting screwed by vendors and or the credit card company.
i forget where its posted, but Mazda Motorsports checks your card when you order the thing, and then periodically thereafter, and if your card bounces, you get no part.
its worth mentioning if you went to a dealer, they would either charge you up front, or at the end, so you wouldn't have this problem.

 

Could someone with old injectors + used rubber seals post a mock up pic of where they are all actually positioned on primary injectors ?
Unfortunately, shop manual artwork and details are less than great, in this section, and if there were rubber seals missing due to previous owner oversight, you're basically guessing what goes where. I couldn't properly fit the rubber seals with a hollow channel shape around the middle, onto primaries.
i asked the Mazda parts dept about this, but they never replied.
I ended up leaving them off, thinking they must be for secondary injectors, which I didn't touch, or the wrong part..

Thanks

 

check this one out! got a 3d printer or a friend with one? this looks like a good option
RX7 Side Seal Clearance Tool

 

This is slightly off topic, but I'm really hoping Mazda starts selling new "crate" rotary engines with their new technology (as shown in their rotary range extender engine) for the aftermarket and racing customers.

 

the April fools update.
first i would highly recommend building a spreadsheet or something to keep track of prices.
mine is really simple, i want to know how much things are going to cost, and different vendors have different prices, etc
happy to post pics, or even a sheet with part numbers and some prices

the goal here is to know how much its going to cost, and then since you can just buy a new engine, which one is cheaper.
for example all the seals and gaskets, plus 2 rotor housings is less than a new engine, but if you add rotors, or basically anything else, the new engine is the same money.

Second Mazda has wildly different prices in different parts of the world for the same part.
for example Mazda Japan lists the FD rotor housings
N3G1-10-B10 for 70.268 yen, which is ~$528.56
N3G1-10-B50 for 73.788 yen and $555.53, $30 difference front and rear

yet in the US the difference in price front to rear is $290, the rear housing, N3G1-10-B50 is way expensive here for some reason.

and Third, in 2023 you actually do need to take into account taxes and shipping, as these can be significant
For example, i need a 1480-13-730. my price from the dealership is $13.54, and Amayama is $12.61 easy choice right?
well Amayama wants 17.84 shipping, so its $30.45 delivered
the dealership is plus 10% and 10% tax, $16.25

 

you rang?

new engines are selling for $6100+, x% sales tax, and possibly another $500 - $600 for shipping it.

what is your total for the parts listed above plus the two rotors for the comparison?
.

 

Sorry misread your post and meant to delete this one but don't seem to be able to..... so:

I did this and it was very helpful, mine was more for tracking cost and being in Canada my parts pricing options were mostly limited (REC is essentially local to me and was cheaper than ordering from any other site due to shipping, import fees, etc).

 

I have decided that if I blow my FD's engine, I'm going to rebuild it myself because...

1. rebuild prices have become *ridiculous* in Japan

2. I've rebuilt a rotary engine before (though it was....**** me, 18 years ago)

3. working on the car is half the fun of owning it. I don't get to drive it that much, anyway.

Actually, I have decided that I'm going to start doing more and more of the work myself, like I used to, because it's fun and saves money.
You almost always at least break even buying new tools and doing it yourself, in my experience.

 

Yeah again worst case doing it yourself is you pull it all back apart and have to do it again. Yes that sucks, but BOY you learn fast that way.

It's also a huge point of pride - "I built that engine myself!"

And really, all the crap that bolts on to the engine is WAY more complicated than the engine itself. If you buy a Mazda crate engine, guess what? You're still going to have to bolt all that crap on and get it done right.

Dale

 

Yeah, but it gets a lot easier when you have a single turbo race car! Haha. Don't even have to pull the carpet to undo the harness.
I remember that simply removing the AC compressor was one of the biggest headaches of pulling my FC's engine. That, and undoing the transmission bolts without ratcheting box wrenches.

 

Absolutely plan on it when the time comes. I am intrigued with this car and can't wait to do the rebuild when the time strikes. I have just acquired this car almost a year ago. Been in love ever since. I as well have never been in the position to send a car to a shop, so good thing I was born a gearhead.