How hard would it be to... (full build imaginings)

[Nexus]

I'm wondering what I'll do for a larger vehicle down the track. I kinda want to build something. Having thought about how much fun an MX-5 would be, it occurs to me that it's just not a practical all purpose vehicle like the 3. I want more practical and more space.

Then I get to thinking that mazda 6 wagons look pretty good. And then I get to thinking that a mazda 6 MPS wagon is what I'd want. And I'd be happy to build one.

Hard part is finding a donor mps6, and then having the gall to dismember it. Wrecks would be the go, I suppose - main parts are nose panels and chassis bracing + drivetrain, brakes etc and some trim....

Finding a wagon shouldn't be that hard? Add some further bracing to compensate for being a wagon...

and then some more because I want it to be tow capable, too.

In theory this should be straightforward and pass all engineering. And then for the perf mods..

which is another "how hard would it be to?" question - twincharging - adding diagrams first . I've thought it through. Not sure there's sufficient space. Not easily in a 3 anyway :|, but a 6 - please don't just shoot it down without discussion; looking for engineering feedback. There's any number of ways to plumb systems like this, I've narrowed it down to a couple of variations, and now there's a couple of specific points to query and discuss. Diagrams soonish.

Target outputs along the lines of troy's jamboree winner; but uber-streetable pull and reliability. Full build to accomodate the design targets.

Hope fully not just a daydream in the long term, thought it might be interesting for discussion regardless...

[laser beam]

hmmm yes please.

Shouldn't be too hard to find a mps6 with rear damage at an auction. Question is, will the driveline and engine drop straight in or will you have to go on a hammer rampage?

As for the twincharging.... how big is your bank balance?

[Scaredycrow]

I guess it's one of those things, until somebody try's nobody knows. On the face of it, given time effort and budget are sufficiently available, it should be achievable. But be prepared for all manner of stupid little setbacks.

Apart from that, I'd have a good hard look at the differences between a 6MPS chassis and the 6 Wagon chassis. I doubt they are all that similar, and if there's no provision for AWD there already, you're going to have a devil of a time.

Good luck though, don't want to discourage anyone with the creative to dream big

[Nexus]

It's the sort of thing I'd tackle just for the joy of it. Right now I don't have the bank balance for it, but I'm patient.
(1) First thing to check is chassis differences.
I'm expecting relatively minimal. i.e. they're both GG chassis...

(2) twin charging.

The point here is to get fairly big numbers - i.e. troys benchmark - in a reliable and controlled package. Big turbo's are all very well and good but with this we can eliminate boost control issues by using a positive displacement SC - specifically a sprintex S150 - fed by an appropriately chosen TC ~ prob not much more than a BNR stage 1 but possibly slightly different wheels - more on that later, I expect...In essence rather than a turbo needing to push 25PSI on it's own, the TC needs to push up to 19 PSI - about same as stock - but with slightly (?) higher flow rates. The SC then multiplies that to ~25PSI. S150 chosen because it'll do this at 90% efficiency over most of the engine rpm range geared at 2.5:1 = 16000 SC rpm @ 6400 engine rpm. 16000rpm is the SC's continuous operation speed redline. The ratio is also ideal for the SC to produce ~6PSI with max efficiency.

The plumbing is where all the questions arise. Not so many, I think I have them sorted, but I reckon it'll make for interesting discussion. What makes the plumbing complicated? Two words : positive displacement. At idle, the SC pumps the equivalent airflow of WOT @ 6PSI boost. If you're throttle plate is closed, boost builds and builds until your traditional TC bypass valve opens. It causes significant parasitic losses etc. It makes throttle control a bitch. It needs it's own bypass solution to address parasitic losses, closed throttle and fine low boost control (instead of 6PSI on or off with no linearity between).

S150 has one built in, and this is, of course, the simplest option. It is not hugely controllable, but it's simple. It might cause pressure backflows that are bad for your turbo sometimes. Prob not, but maybe. Linearity in less controlled. Engineering-wise bypass is not always needed - there is another alternative, but more so - there may be benefits to an "external" SC recirculation.

Diagrams coming up.
#1 Internal SC bypass.
#2 Insert secondary throttle plate prior supercharger. SC bypass then redundant, as secondary throttle controls airflow to SC.
#3 Insert secondary throttle plate in bypass plumbing to TC inlet - this is my preferred solution - may have some significant +'s in terms of throttle response and how it affects the turbo. Some potential to enhance lean cruise and off throttle conditions as the bypassed supercharger airflow will induce the turbo to spool which in turn will have a scavenging effect on the off-boost turbo's exhaust flow, thus recovering the slight parasitic losses of pumping the recirculated airflow, and potentially recovering more than that, gaining efficiency.

Drawing a few diagrams now...

[2XS]

That all sounds to easy.

Forget the twin charging, go for a GTX 30/71r, .64 housing and 18-19psi boost, build the engine (properly) have it tuned, by Chiptorque, manifold, DP etc, FMIC to elminate heatsoak issues. Theres the power sorted.

Under body bracing will sort out the stiffness, fit some coilovers (DGR)

I know where there's a rolled 6 MPS. You just need to find the wagon.........................
$10k for the conversion, $5k for mods, $5k for the engine build +$ for the wagon.

[Nexus]

I figure it's a very practical build. If I had the $, I'd be looking for the wagon right now.
There's one more criteria that might warrant the twin charging - towing capacity. I expect the twincharged solution will have some advantages there; very much appreciate the +ve feedback on the overall practicality of the wagon conversion.

Wait for a moment for diagram - troy prob doesn't need the diagram - and consider the added desire for it to be a tow practical vehicle...

I like the engineering challenge, even if it's just thinking it through...

That all sounds to easy.

Forget the twin charging, go for a GTX 30/71r, .64 housing and 18-19psi boost, build the engine (properly) have it tuned, by Chiptorque, manifold, DP etc, FMIC to elminate heatsoak issues. Theres the power sorted.

Under body bracing will sort out the stiffness, fit some coilovers (DGR)

I know where there's a rolled 6 MPS. You just need to find the wagon.........................
$10k for the conversion, $5k for mods, $5k for the engine build +$ for the wagon.

[Yeldarb]

I didn't read much of that sorry, but I'm all for fast wagons.

Monster challenge. Good luck!

[TD]

What/why would you tow with it? A $1500 Falcon wagon would shit all over it for towing duties, and you're buliding in inherent compromises by even thinking of that as one of your targets.

Otherwise, cool idea. Would be a good build. No idea why you would want to twincharge, there is such a thing as overcomplication...doing everything else would be more than enough.

[Nexus]

#1 and #3 rough diagram. Perhaps it's be good for a higher well controlled boost level over broader curve, and apart from being an engineering challenge, would be better for tow solution?

I am expecting a standback or similar might be needed for some additional control lines (bypass TP and valve) above and beyond OEM ECU tuning.

Love the red one. Not so low. Yeah sure I could buy a falcon, why would I want to?

Please exuse roughness of diagram.

It's an engineering exercise at the moment. Llooking for constructive feedback on engineering it. I don't mind recieving it, but I'd rather work through the engineering challenges.

i.e. lower compression ratios higher boost to deal with the expected loads without detonation, better compressor wheels to meet the targets - are the targets too conservative for a twincharged solution that wants more than the top end punch and long spool times a bigger turbo produces?

Not talking dedicated tow, but making it a consideration...You should imagine a lightweight but rigid (i.e. not fold-out canvas) travel-trailer. Mostly for the joy of doing it (and doing it a little bit differently...

[Nexus]

#1 and #3 rough diagram. Perhaps it's be good for a higher well controlled boost level over broader curve, and apart from being an engineering challenge, would be better for tow solution?

I am expecting a standback or similar might be needed for some additional control lines (bypass TP and valve) above and beyond OEM ECU tuning.

Love the red one. Not so low. Yeah sure I could buy a falcon, why would I want to?

Please exuse roughness of diagram.

It's an engineering exercise at the moment. Llooking for constructive feedback on engineering it. I don't mind recieving it, but I'd rather work through the engineering challenges.

i.e. lower compression ratios higher boost to deal with the expected loads without detonation, better compressor wheels to meet the targets - are the targets too conservative for a twincharged solution that wants more than the top end punch and long spool times a bigger turbo produces?

Not talking dedicated tow, but making it a consideration...You should imagine a lightweight but rigid (i.e. not fold-out canvas) travel-trailer. Mostly for the joy of doing it (and doing it a little bit differently...

Think of it this way...instead of thinking "tow", think bigger engine ~3L with a fast spooling turbo as the desired driving feel that would satisfy the "tow" requirement whilst being suitably high performance. Throttle response, linear easily controlled boost...all performance results that have the side effect of being "tow" worthy )))

I'm thinking a 9.2:1 Ratio so's detonation is staved off a little and 25PSI is good and practical over broadest range.

Now I'm thinking it would be nice to do this year. Not sure how I'll manage that

---------- Post added at 10:57 PM ---------- Previous post was at 09:49 PM ----------

I think there's some real potential for solution #3 - a throttle plate controlled bypass for excess SC flow.
turbo recirculation should recover the remaining pumping losses...and then some, hopefully.
I'm seeing that as the most fuel efficient configuration; it should certainly exceed a turbo alone if the scavenging effect operates as predicted. I know it will. It's not a 1:1 linkage, the turbo gathers energy from the airflow, and the effect of that is exhaust scavenging above and beyond - I expect by a significant stretch - what would normally take place in the same cruise conditions. That can only do very good things for economy. Everything runs cooler...On that note I'd take the SC bypass from closer to the throttle body than what I have in the diagram - just before the traditional bypass valve.

[kmh001]

This is a fantastic project concept and I hope you see it through to completion.

My advice would be to begin by sorting out the structural issues. My understanding is that the MPS and sedan chassis are essentially the same, apart from the undercarriage itself, the bracing is the main structural difference. So the question becomes, is there a difference in the rear end locating points between the sedan and wagon?

The following diagrams seem to suggest the two body types may not be all that different in terms of locating points. This is good news. If it's a simple matter of bolting up an MPS rear end under a wagon with almost no fabrication that's the biggest hurdle crossed right there. God I hope it's that easy.

You still may need to cut the floor and do a custom fuel tank but that's easy.

wagon rear suspension


awd rear suspension

[Nexus]

This is a fantastic project concept and I hope you see it through to completion...

SO DO I !
At troy's suggested build spec and an '04 wagon that's an MPS spec wagon at ballpark $30K-$35K.
That's more attractive to me than anything on the market at a similar price...even after adding some significant twincharging R+D costs.

[raymondato]

sounds awesome, good luck with it.

[bd581]

That idea is crazy. I love it.

Not knowing if there is any differences in the actual floorpan makes a exact plan of attack a bit more difficult. Must remember the little things like mounting points may/will not be there on a wagon floor, then there is things like a hump to fit the diff etc, the best option if that was the case would be to unpick the floorpans and swap. Without access to chassis jigs i wouldn't even consider this.

Other option.

Rather than turning a Wagon into a MPS, why not turn a MPS into a wagon?

That would solve the vast majority of structural reinforcement issues aswell as most engineering issues such as fuel tank, mountings etc.
With a written off wagon (probably more common than a MPS) some creative welding and measuring should see it relatively easily done.

Other advantage to that would be the legalities of it, i'm not sure, you would have to check, but i'm sure that the fun police (engineers and RTA) would look more kindly at a MPS with a hatch welded onto the back than a Mazda 6 converted to AWD and turbo charged. Yes, technically much the same, but we know how government departments are.......

[Caffeine Fiend]

We need an Australian Chip Foose to tackle crazy stuff like this

[2XS]

We need an Australian Chip Foose to tackle crazy stuff like this

We already do It's called "Rad Rides by Troy"

We just need people with the funds to want to complete it.

[Caffeine Fiend]

Hahah!! I'll have one x Quadradeuce then please Mr Trepanier


Sent from my iPhone using Tapatalk

[Nexus]

I'm pretty keen. I'll be watching wagon's on carsales.com
Obviously the floor pan specifics at the rear are the main concern, albeit fairly minor. I would expect it to be an easier and still a perfect engineering pass to start with the wagon on it's existing chassis and then start transplanting. Very little is expected to need alternative parts. Fairly confident that functionality by way of transplanting from one GG chassis to another GG chassis and demonstrating equivalency and exceeding the OEM solutions will pass.

One question, though - is there a panel between the rear seats and the boot on an MPS6, or can you fold the seats down and access the boot? Something like that COULD be a spanner in getting an easy pass, because it's clearly difficult to create equivalency. Pretty sure I'm thinking of the RX-8 re: boot panel?

Having said that, the main focus here in QLD will be how the functionality is added - GG chassis to GG chassis, mazda OEM parts swaps, all of same build model... Chassis bracing not being an exact match would not be an expected build killer, although I can understand a paper pusher liking the idea of an MPS chassis with a Wagon body, reconciling that would be just a bit more submission paperwork and not so much a problem, I think. This is also where the light to moderate tow capacity holds some weight - we add some bracing to deal with that on top of the MPS bracing...yes, Mr Vehicle Inspector Man, it does weigh just a little bit more but it's braced up to exceed the source MPS chassis so as to deal with some moderate tow loads.

I'm going to look into the requirements a bit further. Step one is getting the wagon AWD chassis registered. Engine build etc, unless donor engine shot can come second...

In the meantime... Obviously I'm thinking full build - high-spec rods, pistons with the heat reflective stuff on top etc, bearings, balanced etc, etc.

Dropping the compression towards 9:1 to make it a more reliable high boost solution?

Troy, is there a slightly different turbo combination that you would suggest considering the suggested specs? Could an OEM have the headroom to flow sufficiently ? Stage 1? Stage 2? Custom compressor and impeller combination, or just the compressor wheel, or not necessary? I guess you'd be sizing it as say a small responsive turbo for a 2.9L with 18 PSI target?

[kmh001]

The 6MPS rear seats can and do fold down, but only after removing the trim pieces that are in the way. Mazda put a lot of diagonal bracing behind the rear seats which left a much smaller opening so they decided to just cover it over and delete the folding seat feature, however the folding mechanism is still there.

Here is the full list of structural differences quoted from Mazda documentation:

• Torsional rigidity has been improved by approximately 50% over MAZDA6
• Local reinforcement on sub-assemblies to limit weight ,increase rigidity
• Advantages include overall rigid feel, improved grip of rear suspension, and steering response
• Four angled diagonal brace members added behind the rear seats (eliminating the fold down function)
• The cross members atop the floor join the left and right sides of the cabin to support the damper mounts
• The strength of the suspension mounts at the rear of the body was increased to support the greater damping force of the new rear dampers
• Increased size of the reinforcements for the inside of the bumper section strengthens the joint to the body
• The cowl has been lengthened on both ends and connected directly to stiffeners on the front damper mounts
• The numbers of joints between the instrument panel members and body were increased to create a stronger, more rigid assembly
• The body mounts for the perimeter frame to which the front suspension and engine are mounted were strengthened
• Reinforcing gussets were added to strengthen the left and right roof rails and header sections of the upper body

It's an incredibly rigid structure. It feel's like other cars do after they've had a roll cage installed. Coupled with the wishbone front suspension, this is why the 6MPS will go through a corner quicker than most other cars (if you know how to drive it properly). Reminds me why this car is a keeper.

[2XS]

Are you still stuck on the idea of twin charging? I can't go that far.

Otherwise, go for a stage 3 with built motor.

Bolt it all in, transfer the brakes etc. Simple build, then a towbar won't even be considered by DOT.