Hi guys, im a complete novice to mx5’s so excuse my lack of knowledge but if we dont ask we dont learn.
Im purchasing my first 5 in June, probably a mk1 1.6 and have already been reading alot about turbo conversions.
The majority of the cars iv read about have gone beyond 200bhp, is there less work and/or less parts needed if I aimed more towards aroubd 170bhp as a rough figure.
Cheers
G’day Jack
If you’re looking for 170BHP then why not go the supercharger route. I fitted a JR kit to my Mk1 1.6 a few years back and got a repeatable 170 without an intercooler or large pulleys. The car was brilliant to drive, felt like the big 6 cylinder in my Holden Ute! I opted for the Megasquirt ECU but I’m sure there are better options today
Hope that helps
Hi Geoff,
Yes I did have a think about that, am I right in thinking supercharging the car would be more expensive than a turbo conversion? I guess it depends on the parts you use and labour costs.
Iv checked out the megasquirt website, doesnt seem a bad ECU to begin with.
Be interesting to hear others opinions.
Cheers mate
supercharging may be cheaper. You wouldn’t have to intercool it for that power for a start. You’d still need an ecu to run it (I use Motorsport Electronics ME221). You’d also need a better exhaust and manifold than the oem one imo. I may have a HKS stainless manifold going spare soon! Also a cobalt exhaust system which is less than a year old 
You’d also need bigger injectors, air filter,mapping done. You could have 170 bhp with a turbo but if you’re not wanting any more power than that (I have no idea why! ha ha) then a SC would prob be better for you. Instant power opposed to turbo lag, and cheaper to convert.
I’m going turbo over the next month or so and looking for about 230-250bhp. Hence why my exhaust system may soon be for sale!
at about the 170 mark there would be less need to intercool with a turbo also, not just on an SC setup. you could run it without an aftermarket ecu, but that approach is really sub-optimal and usually results in a fair bit of over-fuelling.Owing to having to retard the ignition across the entire map and having to use a rrfpr, standard injectors would possibly just about cope with 170, but they are getting towards the top end of their duty cycle there. Common replacements are rx8 yellow injectors or the even old black top rx7 ones, best options are the ev’s which are a modern design and much easier to get to idle along with more finite control of the fuelling owing to the better and finer spray pattern.
A small enough turbo would keep the threshold low. Threshold is what you’re really interested in, ‘lag’ in the way it is often used usually means ‘threshold’ i.e at what revs the turbo spools up. My T25 ball bearing job starts to spool about 2200rpm which means you don’t get so much of the ‘turbo shove’ in the back which commonly, incorrectly is referred to as ‘lag’.