Boosted goals - grafting an Evo cast manifold and TD05 into a Miata, just because
 

Introducing me and my project:

Me - I've had a few turbocharged performance cars in the past - played with them but had the majority of work done by others. My miata is a fun hobby project. I'm not out to beat others, conquer the world, claim superiority. This project is a bit of fun, a challenge and something where I want to undertake the majority of design and work myself.

The car - I've got a standard NB 2.5. Not even sure what model it is - has plastic chrome bits, heated leather seats, 16 inch wheels, 1.8 VVT, 6 speed box and some sort of LSD.

https://cimg5.ibsrv.net/gimg/www.mia...3c3614aa63.jpg

The challenge - My friend has offered me a free Mitsubishi evo 4 cast manifold and TD05 turbo. I've done rough measurements and there looks to be enough room for the manifold and turbo to fit in the engine bay. Downpipe shape/fitment ain't going to be pretty.
The plan is to modify the car to run this turbo combo on lowish boost on the standard engine. If it is deemed a success in my eyes (reliable) - I may then build a stronger engine. Along the way I aim to learn more about mechanicals, wiring, mapping, control systems etc.

I've seen a zillion different permutations of supercharged miata with engine driven and exhaust driven superchargers, twins, compound and staged, so if anyone knows someone who has done this then that would be interesting to see and learn the pros/cons of their experience.

I'll provide updates to this thread as it rolls along.

Out to the group - will it work? Is this a great/awful idea? Why? etc.

Oh, and please wish me luck. Many thanks

As a quick check I gave the engine a leak down test to see where it is at:

https://cimg2.ibsrv.net/gimg/www.mia...f027be629a.jpg

It's happy across all cylinders. Interesting to see how it fairs with boost being sent up it.

And here is the donated organ:

https://cimg4.ibsrv.net/gimg/www.mia...297b6e8dfd.jpg

Just need to bolt it up to the miata head and I'm done... ... errr ... ...:confused:

I have an old build thread buried in the archives. (Down the rabbit hole in the search should get you to it). Let's just say free manifold and turbo is not the best reason to do this. But, hey, I've done worse.

Can't disagree with this as straight advice. I guess its part challenge part outcome orientated. I'll build the rest of the system out of half decent parts and then if required, can jump to a Kraken xyz with an EFR xyz down the road.

My current thoughts are:

Pros:
- Cast manifold for reliability;
- Fully twin scroll system through manifold, volutes and split wastegate exits;
- Proven factory hardware for bolts, nuts and studs etc;
- The evo manifold has a secondary air system. I'll most likely bore this out within the manifold to increase flow and use with a fresh air antilag system;
- Lots of cheap 2nd hand turbos for sale. The current turbo is c.350-370hp flywheel rated, Evo 9 turbo is slightly over 400hp rated and then lots of standard frame hybrids available up to 500+hp. There is a large market for the full range second hand;

Cons:
- Weight - its a heavy sucker, will need adequate support;
- Faff - I'll need to fabricate more parts (although this is tied into the challenge part);
- Danger to the standard engine - overboost and this sucker is toast. I have a spare engine to build as a further project down the line if the turbo system works out. Aim is to cap torque at 200lb/ft but hold it as high up the rev range as possible.

I'd checked how close the bore spacing between the BP and the 4G63 was ahead of taking on the idea. So I bought a BP exhaust manifold gasket and a cheap evo exhaust manifold gasket to see how they line up when centered:

https://cimg6.ibsrv.net/gimg/www.mia...671d5365fb.jpg

Evo gasket is on top. You can see how it starts to run out towards the end of the gasket as the bore spacing is slightly larger. However, the evo gasket port does swallow the majority of the mazda port. Good news.

The stud holes are all offset from each other if you turn the evo manifold upside down. This means there are no conflicts for making some sort of adapter. Good news.

I then played about with tape to visualise required transitions:

https://cimg9.ibsrv.net/gimg/www.mia...ef72697ea3.jpg

I reckon I can get a pretty good shaped transition within a pretty narrow transition adapter thickness. The transition is expanding from mazda head side to evo exhaust side due to the port size differences (evo considerably larger than mazda). Given this is turbo charged and the manifold is ruled by backpressure from the turbine - I don't think this will create a material issue compared to flowing the exact exhaust port size right to the turbine. Time will tell on this one.

So far so good. Now that it is looking semi achievable it is time to put the evo manifold and turbo in the engine bay and confirm what space is there, bonnet and strut brace clearance and any other conflicts that have not been considered before getting too deep.

If you can, space the Evo manifold so that the tops of the ports are closest to the top of the Mazda port.
Most modern V8 exhaust port set ups have a step on the bottom exactly like what you have all over the port.
It's called "D" shaped exhaust ports. It's a D with the flat surface facing downward and the manifold is a circle.
It forms a kind of "anti-reversion" step at the bottom of the manifold interface.
I've often wondered if this step will help or hurt a turbocharged application...
I know it helps a NA applications as most of the NA OEM engines have added this feature.
It usually is a significant 90 degree step and it is not blended at all.
I'd try to place this rapid increase in port size you have low to copy this feature.
Just my 2 cents and I might be wrong...

V interesting Technicalninja - I've not seen that step applied before as a feature. I think the port positioning will mainly be ruled by the mazda bolt hole placement as the adapter will be held in by countersunk bolts to the Mazda side. These will encroach on the available gasket sealing area at the evo side so I'll be looking to have the ports and holes as evenly spaced as possible to maximise sealing area between the ports and the bolt holes.

Putting the step at the bottom makes sense if required as the gas will be pushed up to the top by the curvature out of the cylinder and then looping up and then downish into the exhaust manifold on a normal V8. Cool spot by you to consider.

So are you looking to fit this with the turbo underslung (like evo run) ot top-mounted?
if underslung I'd have thought you'll have engine-mount & subframe issues (if I can remember the size & shape of the evo's turbo from working on rallycars:confused:)

Rich.

Hi Rich - to avoid conflict between the stud patterns - it will have to run with the manifold upside down so effectively top mounted with compressor and core clocked as required.

This is where the o2 housing is then pointing in wrong direction as I'm not after a wickedboi bonnet vent.

Will you be able to re-clock enough to get the drain to be downish enough to work? It was hard to tell in the picture.
in my case I bought an Evo 8 header then cut the manifold off and used schedule 10 45 degree pieces as adapters to the miata manifold. Worked great, except the turbo was setting completely wrong. I had to cut off the collector and reweld to get it where it needed to be. Geeze, I should have just built one from scratch. But at that point I wasn't going to let it kick my ass. It's been on there a few years now, so far so good. I hope your journey is smoother.

Will you be running sans hood or cutting a hole for the turbo to stick through?

If you ever wanted to learn to weld now is the time. If you want to be cheap you can even stick weld mild steel pipe for a basic log manifold.

I believe so - the core is on a V band so have 360 rotation. factory drain pipe should run between runners 2 and 3 - may need a very small bit of angle on the core but nothing I would worry about. I'll cut the evo engine side flange off and put a hose on it once its clear of the manifold heat.

From basic measurements of the space - its should fit under the hood fine. Only issue is the O2 housing exit which will point up instead of downwards. Probably means a bit of an S bend on the downpipe. Not ideal but not a deal breaker.

I'm very surprised by that. I believe there is more hood clearance on a NB but I didn't think it was that much.

I love seeing people try stuff like this. I feel like I never see it outside of the miata platform. I wish you luck.

Thank you. The innovation in this community is insane looking at some of the staged and compound super/turbo setups and the fact people are out using and racing them.

The free valve video just released on Youtube is other level if genuine.

My approach may still hit a deal breaker as I develop it. Fall back is a more conventional approach but there is no personal deadline and I'm not in competition, just a hobby to be enjoyed.

https://cimg1.ibsrv.net/gimg/www.mia...90d6c6dee9.jpg

Initial mock up in the space to see what room we have to play with and what conflicts are in there. Seems to be plenty of space for the manifold and turbo. No major conflicts - will need to do a little with the heater matrix pipe at the rear. Rear space is tight as hell for the down tube so expect a bit of modding to rear shelf.

As per rough measurements it does fit under the bonnet (notice high tech plasticine clearance checker).

Now looking at possibly canting the manifold over slightly through the adapter plate. This will give more headroom to the bonnet. Next is drawing up for manifold adapter plate designs.

Measured up and hand drew up a few designs, a friend has helped me get the ideas into CAD. Plan is to now port these into a 3D print model and then draft a 3D model to mock fit on the car.

Initial designs look heavy due to adapter plate thickness to move the turbo away from the head. The 3D prints should allow us to play with sizes. I'm aware that metal and machining are a material cost so will probably start quite simple. Get something that fits on the car and can operate and try to prove the concept.

If successful in operation, the adapter can then be finessed with more machining at a later date to knock weight off of it. Its proof of concept as main goal first.

CAD has allowed us to play with the design ahead of printing in plastic. This is an early revision:

https://cimg0.ibsrv.net/gimg/www.mia...0c7bbd920c.png

It lets you see the difference in port size, what needs blended etc.

The items of concern to me are the outer MX5 stud holes and the small distance to the evo port. We will be using countersunk cap head bolts to attach the plate to the Mazda head. The evo side can be lowered slightly to maximise the average sealing area between the evo port and the outer mazda bolt hole. I could reduce the outer studs from M10 to M8 to make the countersunk holes much smaller but then we are getting into faffing with the head which I would like to avoid. Current thought it to turn down the out M10 cap head head bolts which will allow us to reduce the countersunk hole size. This retains the M10 size in the mazda head and the bolts are only as c30lb/ft so the cap heads should be plenty strong enough.

I've done the calcs and know where I'm aiming but we will probably print a couple of different chamfer angles of adapter to see where it puts the turbo relative to the head, bonnet, strut brace, water pipes etc.

It is currently a heavy looking wedge. This will be the case for the mule to reduce machining time. If it is successful in operation then the weight and additional machining can be revisited.

So more drawing revisions then onto 3D prints. :D

https://cimg2.ibsrv.net/gimg/www.mia...f92e21bbe2.jpg

My friend sent me this picture of the first 3D print he did for me. We went with the thicker design first to see where it lands the turbo in the engine bay. It will then get refined into a second revision.

His printer wasn't large enough to do in a single print so he made little dog bones to connect the 2 halves. Its pretty cool in my opinion.

Managed to collect the 3D print, check the hole positions against a std mazda exhaust manifold gasket then invest the time in mock fitting it (car remains a runner between mock ups etc.).

https://cimg9.ibsrv.net/gimg/www.mia...0fd8828803.jpg

Tried the thicker plate with the larger chamfer first to see where it gets us. Gets the turbo away from the head and bonnet well. Comes down a little close to some of the hoses below and pushes the exhaust manifold out out to close the downpipe clearance a little too much.

I've taken dimensions from this mock up and next move is to get a slimmer version 2 print drafted and then mocked up.

Still no absolute red flags on the feasibility front.