Afternoon all

After some long thought and consideration, also seeing that it had been done before I decided I would not be running a turbo Mazda engine but a Cosworth lump.
I am currently(slowly) building a track MX5 and going through the process of removing rust, seam welding etc before building up.

My original plan was to run with a standard 1999 engine on megasquirt through a 6 speed box and lsd. While in the background I would build a fully forged engine to run 320ish bhp and once ready this would be swapped over. Quite a bit of faffing around and on a drivetrain that would not like the abuse for long.

Now my plan is to build the car up over a longer period and install the Cossie lump along with diff and gearbox. Fabrication of mounts etc is not going to be an issue, wiring is not my strong point and neither is Cossie tunig at this stage.

Can you advise on the following please to get the brain working.
- What is the going rate for a standard good working order engine?
- What is the difference between the 7" & 7.5" diif? Would the 7" be ok in the MX5
- What issues can anyone see?

I will post pictures up of how the car has propressed so far.

 

a friend of mine had a forged 99 engine gt28rs turbo megasquirt etc 400bhp in a mx5 and it was very fast would be a lot cheaper than doing a cosworth conversion in my opinion

 

I'm sure it was on here I see a blue MX5 running a YB engine and type9

 

I can't see that a GT28rs on a MX5 engine would produce 400bhp. You would be 50bhp short. You would need one hell of alot of work to get to 400bhp on a 5 engine.
Please tell me if my Cossie prices below are wrong but I dont see that it would cost much more.

MX5 Diff - £350 + shalfs
Cossie - £300 = shalfts

MX5 box - £450
Cossie - £300 + Prop

MX5 management - £400. Selling my megasquirt
Cossie - £200 for L6 ecu?

MX5 engine - £550 for later engine or £2500+ for fully forged, + £1000 for turbo + £500 for absurdflow manifold.
Cossie - £1000 for std engine with the intention to run a chip to get me to 250ish bhp. Tuning will come later.

I know there are other factors to consider but not large cost items.

All advice welcome.

 

I'd go a bit more on a nice standard 200 block motor say £1500 or so but I think your prices are fair.
Maybe (and I mean MAYBE) cheaper to get a full motor and recoup the money a bit in the other parts ie shell,interior etc.

 

You'd struggle to get a YB for a grand, even £1500 would need a rebuild IMO.

 

What would be a fair cost to pay then for a half decent engine then?

 

I'd expect to pay 3k odd for a good engine and box

 

Plus it's a heavy old boat anchor. I'd go sr20det my self

 

As above, I'd be looking at an SR or something similar. If you want a challenge, 4AG4 from an EVO, 4WD would be interesting!

 

value for money wise id build a 1.8 turbo lump with kms management cusco diff far cheaper easier than getting a cossie lump in there. As far as im aware flyin miata us still make the best turbo kits i have had a manifold off them for mine and the quality was great

as for the sr20 the good ones are few and far between (and getting expensive) due to the drifters blowing them all up lol

cossie route your looking 3-5k dependent on what you want and will need hubs it may be easier to get the whole rear beam in there dependent on width, you could always buy a rotten 2wd keep the parts you want and break the rest

 

or an rb20/25det could be a better option gtsts are getting cheap

 

Another long heavy engine. Or a supercharged curated, that will bolt up to your gearbox and is all alloy so light

 

I am not convinced the cossie engine is much different in weight to the MX5. The MX5 is a heavy old lump.
I am not a fan of the sr20 engine and the skyline engine is too long for an easy install.
Zetec/duratec turbo? Is that a good choice.

 

Ok now. If I was to ever build a mx5 it would be running a 13B rotary turbo.
Mazda engine in a mazda car. End of story!

 

Duratec is a Mazda engine. Easily super charged. Weighs fuck all and will boltno your gear box

 

IF I did go duratec and modded to extract 350-400bhp would I be any further ahead than going cossie YB?
Looking at engines and cost anything decent is going to cost 1500 then modding on top to get additional power adds another big chunk.

 

now thats a good idea an alot of aussies seem to be tuning the v6s to over 400hp iirc there not much heaver than a zetec ive seen an mk4 escort running one with twin turbos but dont know if it was ever finished

 

2.0 fiesta st engine is a duratec. Supercharge it to 300 ish bhp pretty cheaply

Looking 300 for an engine and about 2k for a complete supercharger set up.

You ent getting 400 bhp out of any of the suggested engines for less than 4-5 k.

Cheapest way would be omega rwd gear box and Saab 2.3 red top turbo.