My 1991 RX7 Build...Ford 2.3T swap, with a little twist.
 

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Here are a few shots of the car itself, picked it up as a roller with no drivetrain in trade for parts and a little cash.

The plan is of course to swap in a Ford 2.3T I had sitting around, the engine is 90% finished at this point...but I will go through a few pictures for the background of the build.
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This covers the head....The Volvo B234f cylinder head for whatever reason shares almost identical bore spacing and head bolt locations as the Ford 2.3T head....but whereas the Ford 2.3T head is cast iron, SOHC, and 8 valves...this beauty is 16v DOHC aluminum. the pictures show the necessary modification required to fit this to the Ford block...it has to be extended a bit at the back, and slightly on the side(not strictly necessary, but makes for a nicer finish) the front water port for the volvo pump needs to go, and an external oil feed line for the head needs to be installed. of course it needs to be milled down once all this is done for a flat surface for the MLS head gasket(using a cometic as opposed to the original graphite Ford gasket, this gasket is just for illustration.

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For valvesprings, this pic shows the factory Volvo valvespring to the right, to the left is a Ford 4.6L spring...what I chose to use for this build.

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but thats not all....the assembled head with..BMW ITBs? why not? a simple adapter plate makes it possible.

my xr4ti was the development car for this engine...but I have decided in my infinite wisdom the XR is better suited to my Ford 3.7L Duratec V6, so it frees up this engine to be used in the RX7

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so that is exactly what I did

On the exhaust side...
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A big Holset HE351VE VGT turbo and a 44mm external wastegate, its anyone's guess whether I can make the VGT work correctly, its rather complex with my setup.

of course 8v pistons dont work so well with a 16v head...so custom pistons are required...and if pistons, why not throw in some crower rods for good measure?
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final product....sitting in the XR...for about a year

And that brings us up to today....all I did today was pull the engine from the XR, next week I plan on ordering Granny's mount kit for the Ford 2.3T and dropping this thing right into the XR7 to finish up the build.

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A year of sitting hasnt done it much favor in the appearance department, needs minor cleaning and paint touch up before I swap it...along with installing my valve cover with the LS1 coils mounted

This is awesome, I will definitely be following this build.

Nothing much to share picture wise today...but at least I did order the 2.3t mount kit from Granny's today. They should be here in a couple weeks. I do need to rent a pressure washer though sometime soon to clean the engine bay(or just have some mobile detailing service do it for me for roughly the same cost). After that I can really get this project rolling.

some pretty awesome fab skills. love to see some video of this thing when its up and running!

well, just a little progress while waiting for mounts(should have just made them, but Granny's kit was cheap enough that it made it worth it to me not to)

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The dirty engine bay, before cleaning.

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After pressure washing with some simple green. the paint is still in sad condition...but at least all the oil is gone.

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I couldn't resist...with a clean bay I had to test fit the engine, aside from my crazy ITB air box setup(and the turbo, which wouldn't fit because the engine is currently offset to the passenger side(stupid huge exhaust housing) the engine fits like it was made for the chasis. From my measurements, I should have roughly 1/2" hood clearance at the cam gears because the factory hood bows up roughly 1.5" in the middle...the ITB air box on the other hand will protrude somewhere around 2" above the hood in front(though it should clear in the back) If I had some measurements from a turbo II hood I would be able to tell if the scoop will clear the airbox(plenum), but being offset to the driver side like it is...it would be really close. Most likely I will have to revisit the plenum and change the adapter flange angle to drop the top lower, or just redo the airbox design to be lower profile, or chop the ITB runners down somewhat....or some combination of all 3. I will be happy if I can get the thing to fit under a turbo II hood.
I am presumably getting a shifter extension for the T5 from Granny's with the mount kit, obviously the T5 fitment leaves something to be desired, we will see how the shifter extension works, if I dont like it I can always build my own. with any luck I will still be able to use my steeda short shifter base.

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This is the factory b234f intake manifold...I decided to test fit it. Its a bad design with poor TB location and the runners have a small cross section. I test fit it(just laying there...not properly lined up or attached all the way) to see how changing the angle the runners attach to the flange will affect plenum height. As you can see, this is a much more favorable angle in getting the hood to close. I should be able to duplicate this angle with a few changes to the current ITB design...namely by cutting off the BMW ITB flange and welding on a B234F flange in its place...at the correct angle. Doing this will also allow me to shorten the overall length by roughly 1". Combined with angling the back of the plenum roof for better brake booster clearance this should solve my issues nicely.

Well, did some work today on the ITB/airbox setup...cut down the airbox and cut the ITB runners at an angle...now hood clearance wont be a problem when welded back up.Attachment 620761

What kind of power are you thinking this set up will put down?

Well, thats a good question...it really depends on whether I can get the HE351VE working as it should...its a 560HP capable turbo...the engine is capable of that...but there is no way I would run a normal 500HP turbo on the street...but I will run this if I can get the VGT working to some decent degree.

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Just a pic of the airbox mods...had to flushmount and angle the back wall to clear the booster....may still have to dent the booster or use a smaller one when all is said and done.(the XR has a smaller diameter booster that may work if I need to go that route. The brake distribution block will need to be relocated and the bend on the line coming out the passenger side of the master cylinder will likely need a more severe bend.

what engine managment are you planning?

Megasquirt...have a plug and play Ford 2.3t ...ms2 sitting on the shelf, with mods to run LS1 coil packs...if I can find a place to mount them. I have another Valve cover that I have them mounted on now...but I doubt I can use it unless I find a turbo ii hood to clear the packs. I have run megasquirt on half a dozen different cars and am always happy with the results. I run MS3 on my SRT4 powered 77 Celica right now, its reliable enough for a daily driver. For this setup though it looks as if I will have to run a MAF sensor...it will make the ITB setup work much better...along with the VGT turbo(that would be a real pain to tune on speed density with the engine VE constantly changing based on turbo vane position, not a problem with MAF since it measures actual airflow...I dont much care for other issues with MAF, but its better than the tuning nightmare speed density would offer with this setup.

why do peopel swap heads rather than just use the volvo block too?

Several reasons..the Volvo block is far weaker.(after all, a Ford 302 block splits at 500HP, but the 2.3t is good to 550HP before you even start doing things like adding straps and/or partially filling the block). Also...Volvo Redblocks use a different transmission...whereas you can bolt up a T5 to a 2.3L, and while the T5 isnt the strongest transmission, it has other advatages....weight to start with...it only weighs 75lbs, plenty of aftermarket support, and they are fairly cheap, come with a wide variety of gear ratios, etc. They do survive behind 500HP mustangs for quite awhile if driven reasonably. I am sure there are other reasons too...such as a head is a lot cheaper than an entire engine...and the reason I did it...its fun to build a hybrid engine.

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What do you guys think? This is my spare valve cover, modified to mount LS1 coils. The idea behind this is the shortest path between coil and plug. A lot of LS1 guys dont like the coils on the valvecovers...I kinda like it though...it shows a priority on go rather than show. These coils make the engine a total of 2 inches taller, however it seems I will be picking up a turbo ii hood next week, so the 2 inches mean nothing since its all under the scoop...not to mention the first coil sits farther back than the cam gears.

Another no picture update. Granny's shipped my mounts Monday, so with any luck I will have them by the end of the week. Tomorrow I am picking up a turbo II hood and we shall see if the engine will fit under it. I suspect that even with the LS1 coils that the engine will clear the scoop. Also, this weekend I pulled the engine wiring harness from the XR4ti, I will strip it down to bare necesseties and use the turboford plug and play megasquirt 2 I have sitting around to run this thing. I ordered a wiring bundle from diyautone.com to rebuild the harness for this application. I will be set to go if I can find a decently priced milspec bulkhead connector for the firewall(makes pulling the engine when needed far easier)

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Well, today my Granny's mount kit. I got the basic kit, it just includes the left and right mounts and brackets, the trans crossmember and a t5 extension bracket...which I promptly installed on my steeda tri ax shifter....with this shifter at least and the bracket the shifter should come up in the stock location from what I can see. Tomorrow evening or this weekend I will see if I can get these mounts installed and get the engine and trans sitting where it needs to be, then the fun can start. In other news I finally found a mil spec connector and crimping tool at a decent price...next weekend should be wiring.

Well, tonight, I had just enough time to bolt the motor mounts in place...I still need to mark the spot weld locations for the brackets and weld them in place...also still have yet to install the trans crossmember and get the shifter installed(which will require a bit of cutting at the top of the trans tunnel). Engine fitment is great, though I do have to trim the Driver side steering rack bracket somewhat for clearance at the oil pan, very minor fabrication with this kit. I also found my huge Holset HE351VE turbo will indeed fit, with a whopping 1/4" to spare at the shock tower, its a good thing with these mounts that there wont be that much side to side movement. The problem is that the exhaust housing has maybe 1/2"-3/4" clearance. Any ideas on how to shield the paint from 1400 degree temps? All in all the engine fitment looks to be great for my needs.

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Not working on the car much today(10 hour work day) but I couldnt resist test fitting the turboAttachment 620402
Aside from the 1/4" clearance it looks like it belongs on an engine this size right?

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Finished installing the engine mounts today...it was mainly a process of spot welding them in after using the one bolt to hold them in place
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I also notched the steering rack bracket and the boss of the steering rack itself that holds the rack in place. This is because I didn't want to dent my oil pan. I found I liked this solution better.
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Had to cut a section of the top of the trans tunnel away inside the car to clear the shifter stub on the t5, after I installed the shifter extension bracket, the shifter seems to come up in a close to stock location, however I couldn't finish installing the trans since the trans crossmember granny's sent me seems to be wrong. It doesnt have the same bolt spread as the t5 trans mount to begin with, the offset from where it bolts to the body to the mount on the trans is wrong, and most importantly, it wont bolt to the body since one side is an angled mount and the other is flat. I am guessing they sent me a crossmember for a FB or FD, I dont know.

Also went ahead and test fit the stock NA hood, it wont quite close. I will have to trim just a little hood bracing to make it work. The turbo II hood will work a lot better for this particular swap.

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The finished ITB setup. Adapter plate you bought from someone doesnt work for you? Solution? Use it as a flange and weld it to the ITBs themselves. Of course there is the downside that to take the linkage apart I will have to cut the middle of the flange with a bandsaw and make it a 2 part flange....though thats neither here nor there considering that a large washer can span the distance just fine.

How do you plan on controlling the VGT?

I ran one of those turbos on a 13BT FC last year. It had some really strong points and really weak points, most of which were associated with the rotary engine.
The biggest obstacle was that a ported rotary likes a free flowing exhaust and a 70/60mm turbine wheel with, potentially, a teeny tiny A/R is bad.
All that rotary exhaust pressure also made it hard to control the VGT. I tried 4 different setups before I ditched that turbo.

I welded a nut to the lever arm for the VGT action and made a bracket that mounted to the original electronic actuator’s holes.
I tried several different air cylinders, all of which I bought at McMaster-Carr. Used a bushing and bolt to mount the top of the air cylinder to the bracket and a female rod end to bolt to the welded nut. It was a pretty crude design, but worked well, and the air cylinder end could be threaded in/out of the rod end to set just how small the static setting for the VGT.

Version 1 was a 1-1/16” bore. 1” stroke 2-port air cylinder. I connected both ports to a 2-way MAC solenoid and the common port to the intake manifold.
When I switched the solenoid, it’d allow either the top or bottom portion to see manifold pressure. This was great because at idle and high vaccum, the VGT would close and the car would be really quiet. The issue was that at WOT before positive pressure, there was no force to hold it shut and exhaust pressure would open the vanes.

Version 2 involved a 1-1/16” single port spring-return air cylinder. The spring didn’t do shit.
Version 3 was a 1.5” single port spring-return air cylinder. More effective, but exhaust would still push it open.
Version 4 was the 1.5” single port spring-return air cylinder with a check valve facing AWAY from the valve, so that it would hold a vacuum. This effectively just increased the spring pressure and helped a bit. I put a solenoid valve between the check and the air cylinder and used the ECU to turn it on/off. This allowed the vacuum to be bled off to help open the cylinder once under boost.


Honestly, I could never get it to hold shut. It always felt like a huge exhaust restriction. I actually blew off the 1/8” EGR block off plate because the back pressures were so high! Again, I know pinto motors don’t run large turbo hotsides, so YMMV.

PM me if you have questions and good luck.

Well, obviously I have no room for the controller box(which would be the easy way since they make standalone controllers for the thing now). With my space constraints my options include a pneumatic actuator(though it sounds like you had bad results...I am surprised you didnt ditch the air cylinder idea earlier), or an electric linear actuator. I plan on trying a linear electric stepper motor first...coming forward and mounted to the compressor housing. Stepper motors are easy to control with megasquirt, the main problem will be tuning...megasquirt is setup for speed density...but thats worthless when the pressure remains the same bu the volume changes...very hard or impossible to tune with speed density and a VGT turbo. I will have to convert to a MAF sensor setup. It seems to me the best way to control this thing is a linear stepper motor of some type...that way while not moving it holds itself in position...whether thats open or closed. Worst case scenario I will simply use a threaded rod and set it up as different sized turbos with different positions and make a tune for each one...at least that way I can have a daily driver setting of say 8cm and a race setting of 14cm...and switch between them in 5 minutes. How did the the spool on a 1.3l btw? It seems like it would take forever even at 8cm

I made 12psi at 3krpm in 4th. It spooled a good bit faster than my GT40R with dbb. If I set it really tight, I could get surge at really low RPMS. The drivability at the very small settings was huge. I would have to retune all my low load maps if I adjusted the VGT tighter. Megasquirt can run MAF no probem. You just need to know the 0-5V of the sensor you're using. You can also run a hybrid MAF/MAP tuning I believe. The ultimate reason I ditched the VGT, as fun of an experiment as it was, was because it cracked my manifold...in half.

Be careful with the electronics. The factory stuff was watercooled for good reason. Everything that touches the CHRA gets uncomfortably hot.

well, the only part that will touch the CHRA will be the adjusting rod, and the center section will still be water cooled, so with luck it wont be too bad...I expect temps to get to about 200 degrees or so on the rod...maybe I can find some type of phenolic hardware to attach it to the stepper motor, anyway, another reason I want MAF is the intake side of the equation...I am running BMW ITBs, and they seem to work better under MAF than they do Alpha-N or speed density. Speaking of which...I finally got the ITBs correctly mounted tonight

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I consider this a huge victory....it will all fit under the hood. I did have to swap to a Miata brake booster though...I will see how the brakes feel and if I dont like them, I will change to a smaller master cylinder.

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Another victory! While this 4 cylinder takes up every available inch of space under the FC hood, it does indeed fit. The turbo II hood closes over the engine with inches to spare(after trimming). Inches which I will put to good use by using them to mount the LS coils on the valve cover.

Well, today I spent working on porting the ITB to flange area...didnt take any pics...looks like any other porting you see, I just had to smooth the transition areas, etc. I also took a few minutes to mount my new Mazda B2200 Master cylinder...virtually identical to stock...its 7/8 as well, but its made of aluminum and the ports are on the driver side so it clears my plenum much better...it also helps I was able to flip the resevoir and gain more room there too...still not much room, but enough.

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Looks like my setup with my 4g63T swap

https://cimg0.ibsrv.net/gimg/www.rx7...4d95f36ae8.jpg

Timing Cover snuggles right in there

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Pretty sweet...does the plenum rub? You at least got to retain the rx7 booster, I would have been able to if it were a 1/2" thinner.

Nope..about 1/4" clearance. brake line loop was a bitch.

Well, today I decided it was time to fabricate a trans crossmember, since for whatever reason the one I got from Granny's didn't even come close to fitting.

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On the top is a t5 crossmember I had laying around for my XR4Ti, on the bottom is Granny's RX7 t5 swap crossmember, neither of these came close to working, so I had to fab my own.

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I hate it when I cant seem to find any of the angle Iron I know I have laying around...so I fabbed these out of flat bar stock, they form the base of the crossmember

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Here is the completed crossmember. I redesigned it a bit. I added gussets for strength. I flipped the angle around on the passenger side for more exhaust clearance(not that it was a problem before...but why not?) and the triangular area in the gusset on the driver side I opened up a bit since it lines up right where the speedo cable comes out of the trans.

As you can see, for whatever reason the Granny's crossmember didnt come close to fitting. on my chasis for whatever reason both body mounting points are flat, even though they are different heights, not so on the Granny's crossmember. I dont think this is a problem with the Granny's piece since other people have used it without issue. I think the S5 chassis is different, or that I just got a freak car with weird mounting points, its hard to tell since I dont have the original trans crossmember that came out of it.

Here's an early mock up version of my trans mount.
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Final version with retaining plate on inside of car

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Yours looks completely different...I saw that pedestal on the bottom of the car and considered using it...it just didnt look sturdy enough...so I went off the original mount holes. Was yours originally an ATX?

The original mounts where cut off by the previous owner who had done an LS swap. My setup up is pretty beefy, no issues in over 2 years. I did make some AL spacers to bolt between the mount and the floor where the pedestals end. If that makes sense.

In the top picture you can see the 2 holes where the original guy bolted his LS/Auto swap trans mount to.

More stuff came in today.
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This is Megasquirt 3, with the ms3x expander card. Or at least it will be once I assemble all the components. I went ahead and got the MAPDaddy upgrade with the 4 bar map sensor since 21psi wont be enough for this build, its the main reason I went for a fresh MS build as opposed to using the MS3X I built for my Celica...since that one also has the lower MAP sensor that runs out at 21psi(which is fine for that car...at least for the moment) but will never work once you start using Holsets. This one will be good up to 42psi...more than I will ever use. I opted for the MS3X card because I plan on running full sequential fuel and spark this time around. It looks like I will have a fun 8 hours or so of assembly(judging by the last time I assembled one).

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Finally got a day off to start assembling my MS3. This is the v3.0 blank board...same board used for either MS2 or MS3

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And here we have the first circuit mostly completed..its the power supply circuit(and of course the connectors). MS assembly pictures arent a whole lot of fun to look at, but I thought I would document it anyway since its not often seen. I stopped there for the day since I ran out of daylight and didnt feel like pulling out a magnifying glass to read components by incandescent lighting.

Lord knows how long its been since I worked on this project car...I figured it was time to finish this thing up(or at least get it running).

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So I finally finished building this MS3 unit...all up and running on the stim...have a few things to do before I can try it on the real engine.

1. Need to do a little bit of work on the ITB transition to smooth out a few areas(would kill for a die grinder for this task).
2. Since a PWM stepper motor is on my list(but need to find the exact one I need to purchase) for the HE351VE, I need to rig up a bracket to lock the vanes in some reasonable range? maybe make the exhaust housing around 9cm for now for basic get-it-running tuning purposes?
3. Need to build the engine wiring harness...this should be a fun little project since I bought a 25 connector mil-spec firewall connector for the purpose:

https://i147.photobucket.com/albums/...psmficcwlu.jpg

I guess I need to figure out something for the fuses and relays too...I really like DIYAutotune's fusebox....except for the fact that it doesn't allow an engine quick disconnect(and doesn't have a cover)


P.S. Evidently these days photobucket is so slow as to be almost worthless for hosting

Great Build thus far, looking forward to your progress

any updates? love the build!

Got any updates on that build man?

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