locost mx5 project
 

Right before anyone jumps on me I've done a good search so hopefully don't ask too many bone questions....
I'm starting a locost 7 style project based on an mx5 donor. At the moment the donor is a bog standard '96 1.8 and obviously want to make a turbo system for it
I will be running a megasquirt 2 kit to control everything.
Will be using equal length header and probably stock supra injectors or similar.
Possibly water/meth sprayer run off the megasquirt.
Probably a top mount intercooler due to the amount of pipework required to run FMIC.
All this needs to be done on a budget so turbo will be a used stocker off another car or a chinese turbo but I'm not forking out for a new garrett.
I'm after 200hp with minimal lag. Is this realistic?

What turbos would fit the bill. Garrett website seems to recomend 2254 but I can't find anything stock that runs them. Someone suggested one from SR20DET and I'm guessing most any stock 2 litre-ish car would work. All the chinese turbos I've seen look big and laggy.

t25 from a s13 sr20det. It is almost exactly 2554 sized and will support your 200whp goal with minimal lag.

Thanks. Forgot to ask will stock internals deal with 200hp reliably? What about the gearbox and diff (7 inch open but I'm looking for a torsen). I'm guessing stock clutch wont be happy.

torque breaks internals. 1.6s are good to 200-225, 1.8s are good for 225-250 ROUGHLY. It all depends on your tune, abuse, and luck.

Luke, have you considered td04l-13t from Subaru applications?
These turbos can handle 220+whp and spool from 1500 rpm on a 1.8.
They are inexpensive second hand and are incredibly tough.
Also I am curious about using an equal length manifold as typically you wont see any benefit at 200 hp over something like this
[IMG]https://www.miataturbo.net/attachmen...ine=1371465135[/IMG]

Thanks Sturovo - a quick look on ebay shows that the td04/05 is much easier to get then the sr20 one! They have an unusual flange too don't they? As for the manifold - I'm open to advice but I thought if I was going to make a manifold from scratch I might as well go all the way and make them equal length even if the benefit is minimal. And also expect I'll have plenty of room to work with. Did you stick weld that manifold? Looks like you've done a bloody good job with rather crude equipment...

some have that "unusual" flange, some dont. the TD04H has a 4 bolt rectangle pattern, and is just as easy to find... not the BEST turbo out there, but it is very reliable... more than suitable for your goals

Actually Sturovo the more I look at your manifold the more I like it...simple, compact and looks like it flows much better then a standard log.

The td04-13t from the wrx has kind of a weird flange, but I feel like it should actually be easier to make one with hand tools than a t25 flange, since all the holes are round.

Thanks Luke, I like the look of it too. :cool:
There are a few issues with long runner manifolds (expensive/difficult to manufacture, significant radiated heat, susceptible to cracking, ps/ stock coolant incompatibility) which made me look at alternative designs.

I made drawings for Subaru flanges in case you need them.

Stock parts for 200 in Locost is fine. Just like any junkyard parts you will take chances.

Miata motor is tall as it is, you cannot have intercooler on top without big scoop interfering with drivers view. The hood rests on oil filler cap and still is several inches below bottom rail.
Equal length header is nice thought and theory, but the steering and the narrowing frame of Locost makes it pretty difficult on top of previously mentioned challenges, the brake and clutch may be an issue in the general area as well.
I like to think it in a way of heat, the long tubes of header lose some of the heat making the delta t between turbo inlet and outlet less. The temperature replaces missing flow.

Just got a tdo4 subbie turbo for...nothing. Been sat in my mates garage a couple of years so not sure if its good but if nothing else it gives me something to build around.
Didn't think about the height of the engine so good point there HRK. Maybe I can side mount intercooler. Theres really no where to front mount it and the radiator is from a nissan micra...so it will need all the airflow it can get. Maybe water cooled exchanger? But I'm not so keen on putting extra water and a pump on something that relies on being super lightweight.
Steering, brake and clutch isn't a problem though because its right hand drive

I have a galaxy/sharan/alhambra intercooler that should fit in setups where space is at a premium.
It is 55mm tall and is 680mm between the piping connections. The connections are 50mm which makes it it easy to tie to the turbo outlet and throttle using flexible hose.
It was used in 140hp turbo diesel applications so I am not sure of the cooling capacity. I plan to try it in an under the rad 200 hp setup.