ORX-800

Having tracked both ORX-626 & OMX-596 for a number of years it was time to build myself a pure track car!

Both cars have their pros & cons and as they are quite tidy (many, many hours spent on them) registered cars, the last thing I'd want to do is have a red mist moment and damage them. Neither of them have a roll cage/bar or harnesses so that also held me back from getting the most out of them when on the track. They are two completely different vehicles, with the 626 having ample straight line speed and braking capacity, the MX-5 having fantastic balance and handling. The brakes on the 5 are perfectly OK as the car doesn't have a particulary high top speed that may require larger items.

So the recipe for the track car was quite simple, take all the good points of both cars and put them into one vehicle. So the chassis choice was quite simple....MX-5....but which series..NA, NB or NC. As some of you may have gathered, I'm quite partial to the rotary engine, so which chassis would accept a 13B the easiest? Having done plenty of research, it was obvious that the NC was the best solution. As you may have read in other threads (other forums included) regarding \"rotarising\" MX-5's/Miata's, the main issue with installing a rotary in either an NA or NB is the lack of room available for positioning the engine and gearbox where it really should be without substantial modifications. This is primarily due to the high centreline of the rotary's eccentric shaft (crankshaft) when compared to a piston engine. The other reason for going NC is that it is soooo new.

Anyhow, having now decided on the chassis and engine combination I'd better start acquiring the necessary items.

So in August '06 a suitable engine became available....'03 model RX-8 13B MSP with 6-speed and engine loom and under 15,000km on it.










In September '06 a suitable damaged chassis became available in Japan. An '05 model NC in Winning Blue (my favourite colour) with less than 3,000km on it :shock: . It was the base model fitted with 16\" wheels and 5-speed...however it did have the Bose audio option. After a few anxious e-mails I'd secured it!






Then not a lot happened until January '07 when the bare chassis finally reached our shores....as you can see I also picked up a hard top and a second-hand front bar.


















Once again not a lot happened until September '07, besides acquiring various bits and pieces like Tein Flexes with EDFC, headlights, quick-shift, mazdaspeed pedal rubbers and gear ****, and an Eaton M90 supercharger!






As previously mentioned, I wanted the punch of the 13BT in the 626, but this time I'd try something different with the forced induction route. I'm an advocate of the \"area under the curve\" on a power versus rpm graph (rather than just maximum hp), and I really wanted the massive torque available throughout the rev range that can be provided by a positive displacement supercharger. I'm more than happy to give away peak horsepower for a wide and flat torque band....especially on a track car. It will be intercooled via an air to water unit not unlike the one I designed for my 626.

ORX-800

Not completely true as I forgot that it was in October '06 that I found another NC that was complementary to the Winning Blue one...ie had most of the bits I needed for the repair.

It was also an '05 base model, however it was Wine in colour and had taken quote a hit on the drivers side at the A-pillar and drivers door. It also had low km, only 9336km.














Now fast forwarding 'back' to September '07 when it landed on our shores, I promptly stripped it out so that the chassis from the firewall forward could be unpicked is readiness for the transplant.









Quite a hefty hit!!!

ORX-800

Struggling to keep things chronological here...

In August '07 I got the chassis rolling by slinging both front and rear subframes in place so that it was easier to get it to the panel beaters....a forklift made light work of this.


Running-gear less shell on a two-post hoist....




Raising the front subframe into place....



....and installed.




NC rear subframe (multi-link) ready to be fitted...




Rolling and ready to go for surgery......









October 2007 saw the first project milestone after the front end damage was repaired.


Loaded and ready to go to the panel beater.




Here's some photos that detail what structure was removed and how it was replaced. 8) Where possible, the chassis' original spot welds were replicated as opposed to just cutting sections and butting them together.















In the first week of November '07 it returned looking like this.....absolutely sweet!!!

ORX-800

I thought some of you might be interested to see the detail Mazda now use for the front uprights on MX-5's.....an unboltable hub/bearing unit (subsequently the same as RX-8 ).








Back to regular programming.....

In November '07, after having the body work repaired the next step was to strip out the interior to a stage that allows my sub-conscious to start working on designing the roll cage.




The factory 'torque box' roll bar will be discarded for something a bit more substantial but not dissimilar in concept.










Bits!!!




I also then re-installed the brake booster & master cylinders...it is envisaged that the ABS system will not be part of the final brake package.



December, 2007 was a great month for progress...to be continued.....

rotarenvy

this is a massive project! I'm glad you started the thread I was too lazy to go to the mx-5 forums.

Revolver

Top stuff Danny.

Keep us posted on all developments. Love the photographic record.

I hope the torque and power does not overwhelm the wheelbase!!

skc

Thank you for your detailed description of your track car project. It is very interesting indeed. I will be keeping a keen eye on your progress.

skc

matt13b

That is insane!Top effort.You are attempting what so many of us said mazda should have done but we don't know how to do.Well done.Can't wait to see and hear the end result..

Revolver

Such a shame it won't be street legal.

It would definitely scare the crap out of some of those who like to call the MX5 a girl's car or hairdresser's special. I'd love to see the look on bogan boy's face as his precious dinosaur V8 gets dusted!

mikeyr

Awesome Danny, will be hanging on for the next "episode"!

mdr

Danny you are hard core.

Well done.
Let me know when you are ready to take her to the track I would love to come a long and watch it in action.

takahashi

Wow cool Danny

It is like looking at a NC **** story, one blue (male) mating a red (female) NC... it has a female head

No it is just the face... me bad.

The brain has to be the ECU haha...

matt13b

I thought there was a place called "Bullet" in Adelaide or something that puts Lexus V8's into MX5's and have done 13b turbo's before as well..I'm sure they were street legal too.

ORX-800

Thanks for the positive feedback guys . As you can see it's quit a big job, but by no means insurmountable. Just need to find more time to spend on it.


Me too Matt! I was blown away by the performance of the RX-8 out of the box on the track...it just reinforced my decision to do such a conversion as the NC is at least 250kg lighter.


The up shot is that the conversion (sans supercharger) is legal if I was using a locally delivered/registered NC. .


Matt, the Bullet was made on the Gold Coast under the ICV (Individually Constructed Scheme) managed by DOTARS. Unfortunately, they weren't just an MX-5 with different running gear....to comply with the prescriptive requirements of the ICV scheme, a separate chassis (pretty poor and heavy) was made and the MX-5 chassis (less the front rails) bolted onto it.

Cheers,
Danny

ORX-800

In early December I started giving consideration to the supercharger installation by beginning with drawing the Eaton M90 in Solidworks. Many, many hours were spent practising and working out the best way to create the model. This solid model will give me a good basis from which to design the air to water intercooler and the intake system manifolding.




I had some free time to play cars over the Xmas / New Year so I got stuck into trial fitting the powertrain. In the last container from Japan my stainless steel extractors arrived, so I took the opportunity to install them prior to dropping the engine in.






Here's some more views of the Eaton M90 solid model....if you look carefully you can see some filleting detail that I just couldn't get to work .

ORX-800

Here's the engine ready to be lowered....



.....and sitting in position!




The next step was to fit-up the gearbox & see where the gearshift resided...and you gotta be happy with this!






Here's some photos showing the fit of the 13B MSP in the NC chassis.










I then spent some time re-installing the standard engine bay items (eg. header tank, fuse/relay box, CAI etc.... to see how they interact with the engine.










I also threw the Flex's in the rear....






On New Years eve the NC radiator and cowling was installed.








I also had a look at what differences exist between the NC & RX-8 differentials.







As you can see the RX-8 diff is somewhat bigger.

Revolver

<me reaches for some more popcorn>

Gyro_Bot

+1 This is a very interesting production you have going. I'm humbled by the level of knowledge and accuracy involved with this extreme project.

Looking forwards to seeing more pictures!

Superb!

maskedferret

iTrader: (1)

Mmmmmmmoooooooarrrrr!!!!!!

swoope

iTrader: (5)

very, very wow!

beers

ORX-800

In late January I got some spare time to look at fitting an RX-8 differential into the NC rear suspension subframe. After putting a tape measure over both the NC and RX-8 diff 'ear' brackets I found that the RX-8 diff ear bracket mounting centres were indentical to the NC. NC diff ear bracket on right in below photo.




I also found that the studs in the diff housings also had the same spacing. However, the RX-8 diff housing has an extra bump that prevents the NC diff ear bracket from fitting. Note the narrowed section with ribbing on the RX-8 bracket. Net result.....I purchased an RX-8 diff ear bracket and bolted her in!




The next step was to look at a suitable solution for reinstating the structural connection between the gearbox extension housing and the nose of differential (better known as the PPF - Power Plant Frame). The NC like its predecessors uses a pressed aluminium section for the PPF (FWIW - NA & NB is a C-section whereas the NC is a Z-section). The RX-8 uses a fabricated steel member not unlike the item used in the FD RX-7. Besides being made of steel, the RX-8 PPF also has some torsional capacity as it is predominantly a closed section. I only needed a quick look at the NC PPF to realise that major rework was necessary to make it fit to both the RX-8 gearbox and diff attachment points. Once again the solution was to use the RX-8 item as this would give me the correct end connections....but it is also a nominal 370mm too long because of the shorter wheelbase of the NC. The next question that needed to be answered was where to remove this extra length. The RX-8 PPF section changes its shape all along its length so the goal was to find two positions along its length that were as close as possible in cross-section. The below photos show the end result. I used a diaphragm plate to assist with reconnecting the two slightly different cross-sections.

Once I fully weld it out, the excess diaphragm material will be removed back to the silhouette of the PPF cross-section.










In January I also began laying out the supercharger, air to water IC core and inlet manifold header plate to get a feel for the required manifolding and the necessary space.




Here's the progress made in March '08......

I firstly tidied up the PPF join detail...later on I'll add a couple of little plates to clean up the force transfer between the two slightly different section profiles.






I felt like I needed a quick win...ie. look like I was achieving something :| so I fitted the headlights and front bar. :P








I also bolted a lot of the standard NC engine bay components to see how the 13B interacted with them. With minor mods an RX-8 suspension tower brace fitted in.




My goal is to have the car ready to race at the beginning of next year, however work was getting in the way of making the much needed progress on the supercharger front. So after stumbling across a new Blitz non-intercooled supercharger kit I decided to put the R & D of an intercooled Eaton M90 supercharger on the back burner and purchased the Blitz kit.





The installed kit looks like this....not pretty, however it will save me lots of time (that I don't have) and still get the fatter torque curve I'm chasing. IIRC the Blitz kit boosts at around 6 psi which adds quite an acceptable amount of area under the power/rpm curve. :D




Which is about half of the boost pressure I expect that the Eaton M90 can deliver. :twisted: Thus it needs intercooling.

rotarenvy

do you have any shots of how the belts are arranged on the blitz SC? I'm still searching for some inspiration

ORX-800

Hi Jarl, I have a pdf copy of the Blitz installation instructions...in Japanese only of course . I can e-mail it to you if you like....it may help?!!

Cheers,
Danny

rotarenvy

send it through I love reading installation manuals

Andy Wana

Mate, do you mind if I link you thread to another forum?
This is just too good not to be shared around.