My RX7 rebuild (Not 56K friendly)

First off Hi, my name is Richard and I've known Tom(Toad) for a while now and I was down the farm on Saturday and he said I should put a project thread together, so here I am.

A little bit of background first...
I bought the car a couple of years ago for next to nothing because it was due a rebuild and was already showing signs of water seal failure, basically there was a bit of white smoke/steam out of the exhaust when it had been sat overnight and it drank a lot of coolant.

Since I knew I would have to rebuild it anyway I decided I would do the modifications to the engine at the same time as rebuilding the engine, I did all the work myself, with some help from a spanner monkey called Dan who was a legend when it came to motivation and knowledge.

So it all started on November 2006 when I took the car apart, this was the beginning of the steep learning curve that I was about to go through.

Engine before we started...
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The draining of the life giving fluids. You can also see coolant dripping from the sub-frame, this was a sign of the radiator hose leaking.
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Remove the engine undertray.
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Remove gearbox undertray and then clean it, not a bad result for 13 years of dirt.
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Remove the battery, this was done with extreme prejudice since the battery was being relocated to the boot anyway.
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Remove intercooler pipping and inlet elbow, no longer needed so straight in the bin.
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Remove induction pipes into to the turbos also no longer needed.
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Get of rid of the intercooler, that wasn't going back in.
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Alternator comes off, not completely necessary but it did make life easier for removing other parts. You can also start to see the rats nest underneath the UIM (Upper inlet manifold).
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Powersteering and AC pumps removed from the engine brackets and then moved to the side.
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Unplug the three fuel lines, two bottom lines are fuel in and fuel return the top pipe is fuel tank air pressure that plumbs into the boost network. They were plugged into the three shiny nozzles in the centre of the pic.
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Well mistakes sometimes happen, and also do small leaks.
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More, I NEED more

So what turbo(s) are on it as standard?

Sorry more is on the way, work keeps getting in the way.
There is a twin turbo in the form of a turbo pack on it as standard, very small for fast spool but no real power.

Next was the starter motor.
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This small gearbox access panel is all you have to get access to the clutch....curse those Japanese with their small hands.
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We have to spin the clutch round un-doing each of the 6 bolts as we go until the clutch is free of the flywheel and the engine.
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Remove the air pump, the air pump was a crafty way of fiddling the emissions as it all it did was draw in fresh air and pump it straight into the CAT.
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Prop up Gearbox so that we can undo the bell housing bolts.
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Remove the Y pipe which joins the air from the two compressors on the turbos together.
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And reveal the downpipe, the removal of which was a complete B@5t@rd!!!!!
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And finally remove the engine.
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Start stripping the engine down.
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Our thoughts of waterseal failure are confirmed on the rear rotor which is looking slightly damp.
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Remove sump and oil pickup.
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Now for the awesomeness that is, what is otherwise known as the rats nest, which controls the twin turbos in a sequential format. They're awesome when they work but a pain to fault find if you get a boost leak. lol
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Remove the rats nest and consign most of it to the bin, as I was going single turbo I wouldn't be needing it.
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Keep removing bits.
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Until you have, as if by magic just the block, yes that really is all there is to a rotary engine. I could lift it up all by myself without that much effort.
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A little while later we took the engine down to RE:Worx who are the local experts and they kindly removed the 54mm flywheel nut and the slightly more tricky to remove 20mm pulley nut. Back in the shed a few days later we took it apart.
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Remove the oil pump housing from the front of the block.
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Remove the oil pump itself.
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How the oil pump works.
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Take out the stationary gear from the front plate.
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Turn the engine around and remove all the main block bolts which hold the whole sandwich together. Notice the puddle of coolant coming from the rear rotor housing....Waterseals have definitely gone.
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Remove the back plate to reveal the rotor.
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Another picture of hot rotor action.
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A rotor covered in carbon.
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Most of the little bits that make up a rotor.
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Remove rear housing in preparation to remove the centre plate.
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Finally engine now in bits, where it stayed for nearly a year while I was waiting for my shopping list to arrive.
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Is that a counter balance off the 'crankshaft'?

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So I've heard that the rotors need to be refaced relatively frequently IIRC. What is involved with doing that?

I'm guessing that the cooling is done around the whole block and there is an inner and outer thin rubber seal that look orange in the second to last pic?

Yep that is indeed a counter balance, there normally isn't one on the rear side because of the weight of the flywheel which is attached to that side, however I have installed a lightened flywheel so I now have a counter balance at both ends of the block now.

The rotors don't need refacing as such, the only part of the rotor that touches anything is the toothed cog on the rear/front of the rotor depending on which rotor you're looking at. What does wear out and need replacing are the apex seals, which stick out of the tips of the rotors, these come as part of a full rebuild kit and I replaced them when I rebuilt mine.

Yep if you look at the second to last pic on the previous post you'll see that there are holes running all around the plate and housings, this is the water jacket which cools the entire block. The orange seals you pointed out are the inner water seals, which in my case is what went, there is also an outer black seal that runs around the outside of the water jacket as well.


Next there came a very long period where I waited for parts so I set about cleaning bits and generally sorting the car out.

Using the old plates I practised porting so when the new ones turned up I didn't trash a £300 plate.
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Clean the rotors, which came up quite nicely considering they were black when I removed them.
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While I waited for parts to turn up I took the dash out as it was looking rather used.
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...and repainted it, here it is being undercoated.
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Removed the AC completely from the car and consigned it to the bin.
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Removed a lot of the no longer necessary wiring from the car.
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At some point in late 2007 early 2008 the parts I'd ordered began turning up.

I got a full set of new plates, here is one of them.
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Two new housings.
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A full rebuild kit.
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New aluminium VMount intercooler and radiator.
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New clutch and lightened flywheel.
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A little box of tricks costing just over £1k, why are ECUs so expensive.
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Turbo kit finally turned up.
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...and the wastegate as well.
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Now all the bits had turned up I cracked on with getting the engine built, although first came the porting as I wanted to run more than standard power.

I first enlarged the exhaust ports which are apart of the rotor housings. Here is a comparison between my port and a stock port.
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There are three plates that make up 2 rotor block. The two end plates have on big port per plate that the secondary fuel injectors fire into, the middle plate has two ports one for either rotor housing and these are small ports that the primary fuel injectors fire into. Here is one of my ported primary ports.
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A comparison of the stock primary channel to my ported primary channel.
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To build a rotary engine you'll be needing lots of this.
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I changed the oil seals on the rotors, these allow the rotor bearings to be oiled without letting the oil into the combustion chamber.
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To fit the side seals you have grind them to length and they need to be accurate to within 0.05mm, so out with the feeler gauges. The side seals stop combustion gases going down the side of the rotor on to the oil seals, this also helps to improve the compression.
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Now that the rotors were built and everything was prepared, I could build the block back up.
Firstly you start with the front plate and build up a like some sort of awesome burger. Adding the front stationary gear to the front plate first.
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Using lots of Vaseline add the inner and outer water seals. Vaseline is used because it holds the waterseals in place while you put the engine together and if there is any excess makes it to the engine then it just burns off.
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Add the first housing, covering everything in 2 stroke oil so the first turn of the engine isn't dry.
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Slot the dowels in place to hold the sandwich together.
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Add a rotor with all it's seals already in place.
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I mentioned in a previous post that the part of the engine that wears is the Apex seals, now there are 6 of these in total, 3 per rotor, and they stick out from the corners of the rotors to provide a seal for compression.
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Fitting an apex seal, the two springs allow the apex seal to adapt to the contours of the housings.
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Apex seal in place, ta da.
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Oil up eccentric shaft, which runs the length of the block and drives the front pulley and the flywheel.
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E-shaft in place.
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Fit centre plate.
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Rear housing is fitted into place.
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Add final rotor and repeat the Apex seal process.
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Add rear plate and the main block bolts, which require being done up in a certain order so as not to warp the block.
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Do up 54mm flywheel nut to 300ft/lbs, for this I contacted a mate of mine who maintains engines on big boats and he lent me this torque wrench. He said that if it didn't work he had a bigger one.
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Turn the block on to it's side and on the front the plate add all the oil bearings on and tighten to 80ft/lbs...
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Test the end float to ensure you haven't trapped anything internally.
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Take it apart again and put the oil pump housing on once you know the end float is good. Then take the new block to a pro to have it checked it over.
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How much are the new plates and housings? Can't you re-use the old ones when doing a rebuild, or did you just want to do a complete rebuild anyway?

Awesome write up mate! If you don't mind me asking, how much did those housings and end plates set you back? Were the originals beyond repair?

EDIT: Ha ha, Stu beat me to it.....great minds think alike obviously!

The plates and housings are about £200 each, however I did get a little bit of discount off of that so wasn't to bad. Normally you can reuse them, however the rather helpful person who owned the car before me had been using tap water in the radiator system which unfortunately causes a lot of corrosion to the water jacket so mine had to be replaced for the engine to last more than a year. The ideal thing is distilled water and coolant in a near 50/50 mix.


After the block was check out by pros, I took it back to the shed to put all of the other parts back on the block. These included the fuel rails, the wiring loom, water pump, clutch and flywheel, alternator and the boost hoses.

A start was made.
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I had to remove the hot side of the turbo to get it attached to the manifold.
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Fitted the rest of the turbo kit.
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After seeing the state of the thermostat I had to change it.
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As if by magic and also by lacking a camera man, I have an engine.
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Since I had gone single turbo, I no longer needed a lot of the what controlled the sequential twins, however this left holes so enter the home made blanking plates.
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With the block made I just had to fit it. However this was during summer 2008, so it was raining, firstly we built a garage....it could be considered some what temporary.
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I tried to look as cool as Elvis while I transported the engine from the shed to the garage.
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We lifted the engine on the engine hoist and added the sump and engine mounts.
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Some of you might be able to spot the technical wiz that is my father hiding behind the engine hoist.
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Curse swear and generally hate the world, until you have this.
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So there I was fitting the wiring loom back through the fire wall to plug into the ECU, which is in the passenger foot well, when I hear Dan behind me saying I wonder what else it will lift, well I turned around and saw this.

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What made you go down the F-CON route as opposed to the usual Power FC? That's a neat little manifold too, where did you get that kit from? My 7 had plain water in the cooling system when I bought it and I know my plates are going to be like swiss cheese....but I'm hoping beyond hope I never have to open my engine up to see it! She's not showing any signs of water seal failure tho so I've got everything crossed that it stays that way.

I went the FCon route because it's much better for tuning when it comes to power of over 400bhp, the pfc can't map the fuel fine enough and you get break up. So I was left with the choice of FCon or Motec, went with the FCon in the end as it came highly recommended.

I broke all the rules with the turbo kit and went to the states for it, normally this is a bad idea as they make them for LHD cars and that means the manifolds foul on the steering rack. However I got my GT35R kit off of a company called A-Spec tuning who not only make RHD versions of their manifolds, but also do the GT35R on a T4 flange. The exchange rate at the time made it a steal as well so I had the down pipe and the manifold ceramic coated for an extra £90 while they were at it.


Ok this is the last of the picture heavy posts of the build, as this should bring everyone up to date with the cars current condition.

I needed to open the clutch master cylinder to change the seals over because the new clutch was a push type not a pull type clutch. However after near on a week of trying to undo it, I gave up and asked my dad to help me, within 15 minutes he had it open. I obviously loosened it for him.
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Next I got the screamer pipe and wastegate into position and tightened up.
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Removed the CAT and put in a straight through mid pipe.
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Fitted the VMount, hooked up the radiator and bled the coolant system.
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Added the boost controller solenoid.
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Added the new FPR (Fuel Pressure Regulator).
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Build tempoary garage Mark II, which at this point the rain stopped and the sun came out.
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The first firing of the engine.


Find that the water pump is leaking like a rusty boat and change it.
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Remove clutch slave cylinder and rebuild it.
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Climb under dash to ensure boost hose to gauge and controller are in place, also wire in the boost controller all the while cursing the previous owner for butchering the wiring.
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Two years in the making I give you, the finished article.
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I don't like this car...

I flippin luv it.
I can appreciate all the work that you have put in up until now.
Much respect.
I'm going to have a proper read through when I get home from work.

That's some really nice work, I bet she sounds awesome with that screamer pipe! Are there many companies about that can map the F-CON?

As it happens RE:Worx who are just down the road from me are experts at mapping the FCon. So no worries for me, but I have heard that there aren't many people who can tune them.

I've been at college today, and was going to badger you to knock a thread up when I got home tonight, looks like I don't need to really...

Awesome work Rich, all the time we gave you hassle at QGate I never thought you'd be getting on with it like this... Finished article looks bloody good. FMIC seemed very efficient on Saturday.

thats allot of work there mate,good to see inside one of these motors,good write up

So, what sort of power are we torque-ing (hehe) about?

Well I'm not 100% sure what I'll get when it's finally tuned by RE:Worx. The turbo is good for 600bhp ish, but the porting I have done is a lot milder than required for that sort of power.

My hope is 400bhp at the wheels at about 1 bar, I'm going to get it tuned up to 1.2 bar, so hopefully will have a little bit more to play with too.

Have you put it to bed for the winter yet Rich?

Not completely to bed no, I should do really as I doubt there will be many dry days until about April next year. I'm also refurbishing the alloys, 2 piece split rims myself, hopefully before Christmas.....what could possibly go wrong.

StormBleeder wrote:Not completely to bed no, I should do really as I doubt there will be many dry days until about April next year. I'm also refurbishing the alloys, 2 piece split rims myself, hopefully before Christmas.....what could possibly go wrong.

Lets see some pics then? How are you planning to refurb them?

Fantastic write up and an awesome build I've spent so much time in VW world that I've forgotten all the other great stuff that is out there.

You're absolutely right about it not being 56k friendly though

I was talking to a mate of mine at work today and he is really good mates with a guy who races RX-7s. The guy runs a GT35 on his Mazda, but more interestingly he has his intercooler mounted the other way up i.e. at a 45° angle facing forward rather than backward. At first thought this is counter-intuitive, but apparently that way up it actually aids the aerodynamics as the air is forced through the intercooler at 90° and actually ultimately forces the car downwards. Not only that the air is pushed through a vent in the bonnet, much like those found in Mitsubishi EVOs and thus aiding handling. As yours currently is, the air is forced into and underneath the engine. Maybe food for thought?

Here is a link to the guys website, although there isn't a clear picture of the intercooler fitted, but you can make out the bonnet....

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just read through again.This car is sOooooo alien compared to your average vw.
An excellent contrast to all the german engineering on here.
Especially liked all the pics of the wankel.
Are these engines very robust?