J.S.J

I am new to rotaries however it seems most owners tend to send out engines to builders for their engine overhauls. The rotary market is so specialized most auto machine shops don't do rotary service work. The surfacing of side housings is much like a any automotive surfacing, flywheel, cylinder head so, does anyone know of a machine shop who will surface side-housing. The rotary market seems to me to be overpriced in some areas which are understandable, but machining or resurfacing a flat surface seems much the same as any other cast iron chunk of material. Comments welcomed, opinions wanted here. John

luneytune

It's not just the machining, which must be done exactly. Its the measuring, for instance, side housing and end housings must be within 0.0016" in warpage acrross the entire surface. Side seal wear limits 0.0039", side seal overlap of oil seal 0.0004" limit. These kinds of numbers are outside the range of piston engine machiners and should be left to those that both understand the engine, but also have the shop to do the work. IMHO

Redrotor

DON'T machine side housing.
it has special coating on it with out coating it won't last.
also machining gona change o-ring grove.
only side housing that is machinable is 1st gen rx7
which doesn't have coating and o-ring grove is on the rotor housings.

RonKMiller

They can and should be lapped, it requires a special machine and they need to be sonic cleaned before reassembly. The tolerances allowable are insanely small, I seem to remember .003?

You need to find someone who does this all the time on rotaries, the accuracy of the job is going to depend 100% on the machine operator.

J.S.J

I see there are some close tolerances. The numbers you have given are surely attainable but for the 'coating', is not that a case harden treatment which penetrates a bit below the surface? Surely not far but there are some guidelines and leeway with lapping the surface. Please don't think I disagree with the complexity here. Just coming from a person who will try anything once I get all the facts/data I just think we spend a lot of our money on things due to ignorance/lack of knowing or asking/trying and yes exparementing.... I have this illness, I really feel I can do anything. I don't want anyone to think I can but I do expect to succeed and often I do surely not the first time. I do appreciate the dialog and am new here so maybe after a few grind up motors I'll see things clearer. I have been a drive-ability guy for 20 years and have not run from challenges often. There are some I wish I had passed on but along the way we all learn concepts/and develop skills even in failure. I will sit down and consider the subject. I have a brother in law who has a machine shop and talk it over there. Hope you all has a good Thanksgiving, John

rockshox

iTrader: (3)

any good machine shop can meet those tolerances. they have the same kind of tolerances on heads and block decks. there are big tolerances in the water seal groove so the housings can usually be reused several times.

i have also heard that the hardening doesnt actually have an appreciable effect on wear. a shop built 2 race motors and one had the housings lapped through the hardening. these were 10k rpm race motors that were run for 200 dyno pulls or something like that. after that the wear was exactly the same.

the issues with lapping will be the same at a rotary shop or any other. they need to have sharp cutters and they need to control the traverse rate or the housing will measure flat but have grooves in it. you should look at a sample of something they have cut beforehand.

luneytune

Some warpage can be machined off the side housings but again the groove has to be measured if it still is ok after the machining.

Generally though, you can do it yourself, it just comes down to are you willing to try and possibley waste big bucks in gaskets, the kits aren't cheap. Are you willing to buy the measuring tools and learn the process. And when you find warpage you must either replace it or machine it. I'm not sure about coatings but you could find a shop that has "Ion" hardening capabilities (don't know the proper name). We rebuilt 12A's that don't have the grooves, but we never started with a warped core so we didn't need to machine. The rotary is a pretty strong engine as long as its not overheated.

I would not rebuild an overheated engine just for the problems you can encounter.

We rebuilt cores that were good, bridge ported them and raced then for 1 or 2 seasons, then rebuilt them again - but we never overheated them. IMHO

t-von

iTrader: (8)

Ok! So if the plates are within spec, how much metal can be machined off. I myself plan on rebuilding my own engine in the near future and I as originally going to send the plates off to Mazda Trix. I would like to have this done locally if possible.

clayne

I would just like to add that this kind of work/project is great as it decreases the dependency on the few shops out there that do rotary specific work - which is keeping the rotary's popularity and associated costs where it is now.

The tolerances mentioned above are child's play for a machinist.

luneytune

If the plates are in spec. no machining is required, if its the overlap and side seal thats just over then lapping them would be all thats required. I have heard of people lapping it manually with compound but I would think you need a tool that is large and flat enough? I may have to do this to the block surface of my wifes Supra as it has a failing head gasket and if I want to go HKS copper then I will need a very flat surface. Piston engines have much more tolerance when your using big fat squishy stocker head gaskets. IMHO

Sesshoumaru

iTrader: (1)

my main tollerance is if ur finger nail catches it- it's done.

Not scientific but does the job.

there are other criteria but for side housings that's what i go by.

eurautodave

you can do your own rebuilds but with factory remans for 2.4k why bother? i certainly could have done mine but the econmics just didn't make sense. as for the machining, you just have to think outside the box a bit. any decent industrial machine shop can easily handle the side housings. just have them cut and lapped(you need to give them the specs in microns) and they should be able to deliver if you are willing to pay.

Sesshoumaru

iTrader: (1)

b/c you can have a rebuilt engine for 600 dollars with a street port

eurautodave

with the close to 20 hours i was going to have in the r&r i wasn't willing to risk it. third gens are too complex for me to want to take a couple swings at getting a motor right. i see your point and god bless if it works for you, but i got chicken when it came time to do my own. maybe when i feel more comfortable that this thing is going to reliable for a while-next winter-i'll pull it out to do some porting. i went to a track event at mid-ohio this fall and spent too much track time working on my car. i'm the kind of person who likes to work on their car at the shop and go to the track to drive. i'm even wondering if i got the wrong car for track use.

Sesshoumaru

iTrader: (1)

I just said that b/c u said "the economics just didnt' make sense".

If you can do it you will save alot of money and you learn alot.

I love knowing I built the motor myself. I also think it's reliable b/c of it.

eurautodave

i think your asuming that no machine work is required. i'm going right to worst case. i didn't tear down my old motor and kind of wish i had. then i would have known for sure what i was up against. i just feel that if a person is paying someone to work on their car....a factory engine may be the most certain fix.

luneytune

Have you or have you heard of anyone doing a Bridge Port on a 13B-REW?, heard of lots of street and strip porting. It would be lots of work and the exhaust port would have to be pretty radical also and a new turbo manifold to boot.

clayne

It's a principle thing.

Just how long does everyone expect to be a Slave To The Reman?

That same fear you had before tearing your motor down is what keeps this entire process of send back and replace continuing. Had you torn it down, you would have seen, during the process, that the engine/turbo design of the 13B-REW is not as complex as it's made out to be. However, that fear on your part is understandable.

The amount one learns during an engine rebuild/restoration is greater than any other thing you can do to your car. You form a bond with the engine and there's a sense of purpose obtained when doing something like this yourself.

As far as relying on a "factory" engine - their parts and procedures will be no different than what you will do during the rebuild process.

The more people out there doing this form of work on their own cars and engines will result in a greater overall understanding of the rotary engine and an easier time for everyone.

If you wonder why it's so much easier for piston engine guys is because there are more piston engine people attempting "harder" jobs on their own cars. They can do this because the knowledge and understanding is already out there. It took people doing it themselves in order to get that knowledge out there in the first place.

Smitty-RX7

I'm taking a tool and die course at BCIT (a technical college in BC, Canada) and the tolerances listed .003 (3 thousands of an inch) are very doable... but when you start talking about toleranced in the .0003 (3 microns) range your costs skyrocket because that can only be attained by a CNC machine, manual machining you can get accurataly within a thousandth of an inch, but your costs willl still be super high if you need it to one thou. The smaller your tolerance the more it costs... from 3 to 1 thou will easily double the price... @ an average shop rate of 90-100 dollars an hour (canadian currency).

luneytune

Have you or have you heard of anyone doing a Bridge Port on a 13B-REW?, heard of lots of street and strip porting. It would be lots of work and the exhaust port would have to be pretty radical also and a new turbo manifold to boot.

t-von

iTrader: (8)

Poetry in motion. Very well said!

Sesshoumaru

iTrader: (1)

i said street port not bridge port...............

Sesshoumaru

iTrader: (1)

yes if you chunk a apex seal i will cost a LOT more.

but i'm talking about colant/oil rings.

93BlackFD

you can take off four thousands until you have to re nitride the side plates

rynberg

Most rebuilders use a special machine to lap the side housings. You can send yours to Racing Beat to have them lap the housings.