My 1974 REPU Project

[chickenwafer]

So I spent a few hours stripping down the long block to inspect everything I have. First task i wanted to accomplish was to pull the turbos and manifold to peak into the exhaust ports to check condition of the rotors and internals.





Side note, a REPU truck bed and a 20V DeWalt cordless impact make this a breeze!

Stopped taking pictures here but I got it down to the keg. Looking in through the exhaust ports the front rotor looks MINT, the housing and iron surfaces appear great. This is be expected as that rotor was making excellent compression. The rear rotor doesn't look as bad as I anticipated given it was making 0PSI. I can tell the housing has a little chatter but I can't see any massive chips/dings thus far. And the rotor looks fine and all apex seals are intact. I'm wondering if it's just worn out? Should still make a little compression. Oh well.

So far the build plan is:

13B-REW Block
REPU Front cover and oil pan
Banzai GSL-SE oil pan brace
Full Function Engineering CAS Trigger kit
Street Ported Irons/Race port exhaust
RA Classic 2mm apex seals
Atkins Rotor & Closing O-Ring/Seal kit with Atkins Solid Corner seals
Probably have the irons and housings refinished/resurfaced
Stock twins converted non sequential
All emissions deleted
Adaptronic new Modular PnP ECU
Upgraded secondary fuel rail with 1680cc injectors and FPR
This should be good for 350-400rwhp on pump gas
Do a burnout

[chickenwafer]

Little update:

So after looking at the apex seals through the exhaust ports and finding them all in pretty good shape, me and Matt where talking and wondering why it wasn't making compression. I felt the seals through the ports and sure enough two of them weren't springy/moving and completely stuck, leaving only one in springy shape, which would yield zero compression.

So I soaked the stuck seals in WD40 and rotated the engine by hand, a lot. After this I worked the stuck seals with my fingers pressing them down and rocking them in their groove. Sure enough one seal started springing back to life! (Bad pun intended). The more I rotated the engine the more is started to move and seal. So I hit the starter and sure enough I was getting compression in one chamber now, strong compression too. So I left the last stuck seal to soak in a liberal amount of WD40 and set the rotor facing up so the WD40 could soak/drain into the seal.

That was last night, so this evening after work I went back out and started massaging the seal some more and soaking it in more WD40. I then added some motor oil to the mix and ran the engine on the starter for a solid minute. During the rotating the engine "chugging" noises got stronger and stronger. I felt the last seal and it's moving now! Sweet. I'm now getting two strong compression pulses and a third weaker one. The seal isn't 100% but it's still kinda odd I would have 2 strong pulses...could indicate a stuck side or corner seal.

So I left the last seal which isn't 100% to soak so hopefully overnight it loosens up more now and I might not have to end up rebuilding the engine afterall.

[speedjunkie]

I would think it would have to be the side seal since a corner seal would most likely yield the same results as an apex seal. But I could be wrong.

[Shadowden]

For us who have never worked on a rotary engine or tore it apart, was the WD40 used to somehow revive the seal itself or something else. I googled a bit and it seems as if there are springs under the seals? If so, was the goal of the WD40 to get those moving again somehow?

I'm getting more and more intrigued by the rotary engine and just trying to understand.

This is what I read:
http://www.racingbeat.com/mazda/perform ... seals.html

[chickenwafer]

Yes, there are two springs (longer and shorter) under the apex seal that allow the apex seals to move up and down in their groove on the rotor tip. What had happened in my engine was the apex seal was stuck in the down position, compressing the springs fully. This obviously reduces the height of the seal and thus the seal it can make against the rotor housing, allowing air to escape past it.

Like if a piston ring was sucked too close to the piston so it no longer made contact with the cylinder wall and air/compression could leak past it, or blowby.

I'm guessing the seals were stuck because of carbon build up and sometimes this excessive carbon will accumulate around a seal and as it builds it will force the seal down. It's rare but carbon can sometimes build up under the seal as well, and this would usually indicate a failed corner seal.

The WD40 was more to just lubricate the springs/seal and loosen any carbon to get things moving again. This is why carbon build up is the death of any rotary engine as it's common for a seal to become "stuck" with too much carbon build up. This is why rotary engine typically love to be flogged- redline em all the time (once warmed up, please), and just generally beat on them in a way that would make any piston head cringe. This theoretically gets EGTs and everything hot, which burns off the carbon. Idling a rotary and generally driving it like a grandma promotes carbon build up and is really bad.

Every seal in the rotary engine has a spring behind it- Apex seals get all the attention but there are other seals as well that are very important- Side seals and 1 spring under them, these obviously seal the sides of the rotor and combustion face. There are 3 per side of the rotor, so 6 total per rotor. In a 2 rotor you then have 12 total side seals and 12 side seal springs.

The there are corner seals and they have a single "spring" under them- more like a bent C-Clip. These go are circles that go into grooves and seal the edges of the apex seal and the junction of two side seals. There are also 3 corner seals per rotor side, 6 per rotor, so 12 total in a 2 rotor.

Lastly there is oil control ring that seal against the opening where the eccentric shaft passes through the rotor. The rotors are filled with oil when the engine is running, so you don't want oil getting into the combustion chamber. These are essentially metal discs with a groove that have a rubber o-ring in them to prevent the oil from seeping out of the rotor itself into the combustion chamber. There are two per rotor per side, an inner and outer, so total of 4 per rotor, 8 per 2 rotor engine, with the exception of the RX-8 Renesis 13MSP engine which adds a 3rd Oil "Scrapper" o ring. Each has a spring underneath it as well.

Not sure if you wanted to know all that but there ya go LOL.

[Shadowden]

thanks!

probably more than I'll ever need, but the touge monster fd with an NA 20b had me looking into them. seems like the turbo cars are fun, but the heat is an issue on track. get some good power and torque out of the three rotor, more linear throttle response and a good reliable rotary track car is born...but I really don't know.

[speedjunkie]

It seems that a lot of people do an NA rotary in their race car, usually peripheral port, either 2 or 3 rotor. I'm not sure if it's because of class rules, reliability (which is laughable because a PP doesn't last long anyway), or because of throttle response or something else related.

[chickenwafer]

thanks!

probably more than I'll ever need, but the touge monster fd with an NA 20b had me looking into them. seems like the turbo cars are fun, but the heat is an issue on track. get some good power and torque out of the three rotor, more linear throttle response and a good reliable rotary track car is born...but I really don't know.

If I was building a dedicated rotary track car, it would be NA, with the exception of a drag car or top speed/standing mile car. NA rotaries last much, much longer than turbo cars generally because of less heat and just because they make less power. An NA rotary that gets detonation from running lean usually doesn't blow either, whereas a turbo rotary running lean is almost always catastrophic. A properly built/clearanced NA rotary can make good power and last a long time surviving at sustained high RPM abuse.

[chickenwafer]

So I did some work on the twin turbos for my JDM engine. I've decided to keep the twins, for cost reasons and to make sure I can keep up with my time table, and I will run them non sequential to keep things simple.

So I set out modifying the turbos for non seq. I obviously removed the turbo control door in the factory manifold, as everyone does. Didn't take any pics of this. I then wanted to take things a few steps further since I really want to maximize the power potential of the setup.

So I started with this:



Stripped off the oil and coolant hoses and heat shields:



Separated the turbine housings from the down pipe collector:



Here is the turbine entry of the secondary/rear turbo. You can see it is "divided". This is because there is a door in the manifold that covers the right opening when the secondary turbo isn't operational. That door gets removed when converting to non sequential. Because of this, there is now the "divider" or bridge of cast iron material in-between the pre-spool door and the turbine entry disrupting exhaust flow. So I ported it out, which was a bitch:



Rough porting after cutting out the bridge:



Better porting:



I did some better porting but didn't get a pic. My air compressor was running FOREVER when I was running my die grinder and I kept having to stop to wait for it to catch up. Didn't help this was after the kiddos went to bed (only free time I have to wrench anymore) so I couldn't keep going. I really need a good electric die grinder because this took forever.

Also I removed the secondary pre spool door, which diverts exhaust gas through a channel in the OE manifold and "leaks" a little exhaust flow into the secondary turbo, prior to it coming fully online so when the main door opens it isn't "shocked" on. Again, this is a restriction and most people just wire it open. I choose to remove it. I had to plug a hole where the shaft for the door passes through. So I drilled the hole out a little and found a big bolt I wrenched in as hard as I could, then cut the bolt flush to provide a leak proof seal:



Still some more work to do but overall happy with how it came out, just wish it didn't take so long thanks to a slow compressor. Hopefully I can crack 400rwhp with these

[chickenwafer]

So yesterday Eric once again came up all the way from the Springs to give me a hand with some of the hard work on Project REPU! Thanks dude!

I had the engine/trans combo sitting in the bed of the truck on the pallet it was shipped on, but needed to move the engine to my stand so we could do some more work on it. Too heavy to do myself. So Eric and I separated the engine and got the engine on the stand only to dump oil and coolant all over my driveway haha. We also were able to break the 200ft-lbs torqued front hub bolt off the new engine and my old REPU engine. The older 13B's must not be torqued as crazy as the newer engines because it came off pretty easily.

The old REPU motor was caked in so much dirt it was hard to access the front cover bolts but we managed too. So scavenged the front cover and oil pan from the REPU motor to transfer to the new motor so it would be an easy drop-in affair to bolt into the REPU. To my surprise, the old REPU engine looked super MINT under the front cover and oil pan! Stuff looked virtually brand new! This is supposedly a virgin unopened 1974 motor from what the guy I bought it from told me, and it doesn't appear to have been rebuilt since there's no RTV or gasket goo squeezed out of anything. Sweet!

I was hoping to have Eric help me drop the motor into the REPU but we unfortunately ran into a small snag. I needed to drill and tap the front cover for the primary turbo oil drain and before I could do this we needed to track down a 5/8 hose barb fitting. After going to ACE and Lowes and we came up empty on trying to find a good fitting that wouldn't half ass it. And since I can't drill the front cover with it on the engine without sending metal shavings into the oiling system, and the engine can't be mounted without the front cover, we were stuck. Always stupid little things like this that hold you up!

I was able to find all the parts I need to customize the oil drain online so I ordered them last night along with a few other things. Some key parts to complete the swap will be rolling in here in the next couple weeks so I'm pretty pumped! My goal is to have the engine/trans mounted before it gets stupid cold so I can focus on the tedious wiring mess during the cold months. Then she might even be ready to roll this April/May! Ideally maybe even March but with two kids it really depends on how much free time I can devote to the project.

[RX-7 Chris]

So why not go with a GSL-SE front cover? That way you can run the oil injection system out of an SE or S4.

[chickenwafer]

Mostly because 1 ) I have a REPU front cover just sitting here not doing anything for free, and 2 ) GSL-SE covers are about $300-$500 USED and that's if you can find em. For me, there really no reason to run one as my REPU cover is fine and spending crazy $ for a GSL-SE cover poses no benefit as I'm not going to an run an OMP anyways. I'd still have to drill and tap the GSL-SE cover for a turbo oil drain just like the REPU cover.

[chickenwafer]

Finally some time to update!

Parts rolling in:



Full Function Engineering Hall sensor crank trigger kit. Quality of this stuff is INSANE!!





Also, scored an AMAZING deal on a used Haltech Platinum Sport 1000 ECU WITH a fully terminated Haltech 13B harness setup for GM LS1 ignition coils. Couldn't be happier I got this for a great price:





Also got to work wrapping the lower and upper intake manifolds in DEI Reflect-a-gold heat barrier. I don't know how much it will help with temps but it's mostly for looks as I painted my manifolds black before and didn't want to do the same thing as last time:



LIM wrapped:



Upper wrapped:



GOOOOOOOOLLLLLDDDD!!!



Also painted the REPU front cover, drilled a tapped an oil return fitting, and installed it along with the oil pan, LRB oil pan baffle, and oil pan stud kit:



Front cover on:



This is so baffling (lol) and note the studs:



Dirty ass pan installed:



Of course I also ordered a can of Permatex "Right Stuff" RTV sealant specifically to install the oil pan with since I was doing it without a gasket. And of course I couldn't get the nozzle to work and ended up leaking the entire can LOL. That was $25 down the drain. Luckily I had some other good RTV laying around just not as good. All wells.

The engine is now almost ready to drop in!

I did discover that when I ordered my FFE crank trigger kit I got the kit for an older style 13B, so it would fit the front cover I have. But apparently the FD has a different front hub than the older 13B engines, so the crank trigger won't fit. I emailed them tonight to see if I can hopefully just exchange the wheel I have for the proper one. Otherwise I'm going to have to track for a different front hub (or maybe my old REPU engine has one??)

[speedjunkie]

GOOOOOOOOLLLLLDDDD!!!

This is so baffling (lol) and note the studs:

Bad Dave, BAD! lol

[chickenwafer]

LOL

So minor hiccup:

The FFE trigger wheel doesn't fit the REW front hub, so I swapped to the REPU front hub and it fits! Sweet, right? Except now the FD crank pulley doesn't fit...grrrr. So looking at FFE's website the REW trigger wheel is flat, and mine is bolted to wheel/gear thingy. I need the REW flat piece. So I emailed FFE about the problem and asking to exchange the trigger wheel I have for the FD one. Simple, right?

I get a response saying swapping front covers "messes things up" and this "may require custom pieces". I emailed them back, 2 times now, and haven't heard anything in 2 days. WTF? I thought FFE was a good company? Their products seem top notch. All I want to do is exchange a trigger wheel. I completely own this as my own fault since I'm doing something a little "custom" although I'm hardly the first person to put an early (often refereed to as a GSL-SE front cover even though this isn't one) on an REW block. Kinda shocked right now I'm not getting good customer service at all from them!