A new challenger 'The Beast from the East'

[Hobbawobba]

That's the situation I'm in aye. Would love a garage/unit to strip the whole car and upgrade/refresh everything. But I'm stuck on the driveway and can't do that

[rotarypower]

Anyone know what's supposed to go above these mud guards?
Looks like there should be some metal work or a bracket on the left hand side of these. Or do they just 'float'?

IMG_20200115_112502_resize_68.jpg (98.43 KiB) Viewed 6668 times

[rotarypower]

Not much progress to speak of on this really, I've been working flat out on the boat to get it ready for summer. (Although that's looking like it won't happen now)

However I did manage to get this done:

IMG_20200329_201435.jpg (59.89 KiB) Viewed 6212 times

That's another year closer to MOT & Tax exemption .
Nice to be able to drive it around again!

[Hobbawobba]

Awesome going there!

[ian65]

Nice one!

[myatt1972]

Always nice getting a fresh ticket

[Casey]

Well done, always good (and a relief!) to get a fresh MOT!

[rotarypower]

I've been offshore with work for 3 weeks now & before that mostly stuck in the house.
But its given me plenty of time to think about the direction I'd like to take this project in & because I've got a few hours spare I thought I'd share some of my musings plus research.

I had mentioned in a different thread that I was thinking about swapping in an inline 4, maybe a Honda K engine (which is a great engine still), but the more I've thought about it the more I felt that I'd quite like to keep the rotary.

My goal for this car is to drive it every day reliably with the odd track excursion & the odd road trip. To make me happy it needs more power, some bigger wheels around 15", suspension refresh and the usual stuff like sorting out the paint, good stereo, central locking etc.
I've not given up on my dream of a rear IRS, but that still needs a lot more research.

But it makes sense to think about what to do engine wise first as this may involve modifications that I'd rather do before getting the car beautiful. I did think about tuning the 12a, but realistically its on borrowed time, parts are getting harder to come by & going EFI (which I would like) would involve a good bit of work for not much return.

So going forward I've tentatively settled on 2 possibilities:
- 13b Turbo from an FC
- 13b-msp Renesis from an RX8

The 13b turbo has the advantage of easy power, somewhat easy fitting, especially if I went the FC front subframe route & being able to utilise a few of the bits I have lying around.
The downsides are the fact that I won't be able to turn up the wick too much without serious upgrades to the rear end, the engines cost a fortune now even for none rebuilt ones & a loss of low down torque due to the lower compression.

The 13b renesis has the advantage of 230hp which is a nice figure, NA reliability, probably not too bad fuel consumption in a car light as ours, a nice 9krpm redline & great idling and drive ability, also the engines are still readily available and cheap.
Downsides are longevity not as good as older NAs (although I think it can be alleviated by turning up the OMP), getting it to actually run (more on this later, its now a lot easier than it was) and if I want more power in the future then it will cost more & reliable turbo setups are super expensive.

At the moment I'm erring towards the Renesis but here are some thoughts on fitting either of those two engines.

13b Turbo
- You need the engine & gearbox (as the FB gearbox won't last long with turbo torque)
- Custom driveshaft & gearbox mount
- If going FC subframe then the mounting is sorted
- If not then a GSL-SE front cover, Oil Pan & Racing beat mount brace
- S4 OMP (which I have) to replace the electric OMP with.
- Megasquirt or some other stand along
- EFI fuel pump, upgrade all the fuel system & hoses
- Turbo back exhaust.

Renesis
- Engine, the 12a gearbox might hold out with it, power is higher than the turbo, but I think it makes less torque. Many people don't rate the Rx8 6 speed as especially strong
- If using 12a gearbox then a lightened 12a or 13b(na) flywheel, rx8 automatic counterweight. 12a or 13b na clutch and pressure plate can be used.
- Custom engine mounts, Renesis is mid mounted so some form of custom brace / mount to be made
- You can use the 12a front cover, but then you lose all the electric OMP & other bits + piece (custom engine mount preferred option here)
- To run the engine in the past required a full swap of the RX8 cluster PCM modules etc. A real PITA.
- BUT Adaptronic now make a full plug & play stand alone ECU, it can control all the standard engine functions, variable intake, OMP etc and has the capability to tune if required in the future. All it needs is a VSS signal
- To get the VSS signal an MX5 gearbox VSS can be used, but I need to swap the RX7 drive wheel onto it.
- With an electronic VSS then the speedo needs to be converted from cable driven to electronic. There are a few guides knocking around on how to do this using other car's speedo's and integrating them into the cluster.
- Fuel system would need to be upgraded as above but the Renesis uses a returnless system.

Bit of along post & I've probably forgotten a load of stuff there as well, my heads full from endless browsing of rotary forums.
If I've missed anything obvious then feel free to chime in!

Neither way looks particularly cheap, but engine swaps (and classic car ownership) never are.

[gt_james]

Great that you're thinking of sticking with rotary power!

Just thought I'd add a few comments, Dailying an RX7 is do able, but realistically you'll be in a constant battle with rust! Even if you bare metal the underside and use the best products, after a few years of exposure to salt things wont be looking pretty. Get a cheap winter hack and daily the RX7 in the nicer weather!

I still think forget the whole IRS thing, just go with a stronger rear axle and a parallel 4 link set up with panhard or a properly engineered watts, or if you want to keep it easier and minimal fabrication, a tri link with panhard. I have some good literature on setting up the RX-7 suspension if you want to improve handling. Also on that note, I personally think the FC subframe creates as many problems as it solves, I hope to be designing a rack conversion soon, I have a few Ideas on how to add a rack, but anyway don't expect an FC subframe swap to have perfect geometry, it wont.

I agree with the thoughts on modifying the 12A, and to an extent a 13Bt conversion, they aren't exactly plentiful! The MSP is the obvious answer for an upgrade while staying rotary, availability, more power than most ported 12A and NA 13B set ups and much better drive ability. Although not sure where you got the idea that the 13BT compression will mean a loss of low down torque, compression ratio really has very little effect compared with things like intake design, exhaust system, turbo selection, porting and mapping.

an MSP wont really give you 230hp, but you can expect 200-210hp from what I've heard, which is still very respectable for an NA 2 rotor with great driveability.

you could use an RX8 gearbox with a 13BT, the RX8 gearbox is very strong, I have heard of people run many 10second 1/4 mile passes on stock RX8 gearbox with a big turbo FD.

Mounting either engine is very simple really in the stock cross member, the 13Bt will bolt in with a 12A or GSLSE cover, cut and extend the brace and GSLSE sump. The renesis is a bit more work to fit the 12A cover, the CAS drive gear is reversed and on bolt is out of place, and the sump will need cutting and welding.

Don't bother with OMP, just premix.

whilst megasquirt is a good ecu, better to think who will tune it and what they are happy working with.

[rotarypower]

Hi James, cheers for the thought's they're always appreciated.

When I mean daily I mean daily through Summer. (and the odd nice winter day)
Basically from when they stop salting the roads through to when they start again. Although that said the underside will be getting epoxy treated the same way I did my FC & some raptor shield on top of that.

For the moment rear end wise I'm just going to refresh what I have, I've got the parts to refresh the diff (which does need the bearings & lash doing) and also the full suspension bushing kit to do.

I've actually got the beginnings of a plan for IRS that wouldn't involve any cutting whatsoever. I've been working with some measurements & the issue isn't that an IRS won't fit in the space that's there, its that the subframe won't, however it may be possible to build a tubular subframe that would avoid the structure of the car, pick up on the existing mounts at the forward end and the aft end would only require some studs, anti-crush stand offs and perhaps some extra reinforcement welding in, nothing cut out, so it could return to standard if required.
However that's all very theoretical at this stage in time & quite possibly won't work.
Even if I never do this stuff, I still enjoy brainstorming it, measuring it etc.

The low down torque is mainly from my experience of Japanese turbo cars of the era, both my MR2 Turbos were pretty laggy until they came on (at which point they were very rapid indeed), my friends GT4 was the same (hardly surprising as its the same engine), I've heard the same said about the Rx7, and that the high compression turbos that some people have made are generally much better in this respect.

Unfortunately the RX8 gearbox is a no, from my research the gear shifter will be far too far forward, okay on an S1 but not on the S2/S3. They also don't have a speedo drive (comes from the wheel sensor on the Rx8) or an easy mount as they use the PPF as per the MX5. Presumably there are ways around all of this, but if I can keep the existing box for the present then it makes sense to me. Maybe I'll change my mind later.
Premix I will avoid if at all possible, I may chuck some in when I'm doing a track day but day to day I'd rather not.
As I understand it from my emails to Adaptronic, their ECU will control every stock aspect of the Renesis (even down to being able to run the dash in another car if you so chose), since we don't have to worry about emissions, it should be possible to increase the oiling amount.
The other advantage here is a get a perfectly useable stock tune, later down the line I can have it dialed in to extract as much power as possible.