Need advice for JRSC M45 NA8 build
 

Hey everyone,
This is my first post and hoping not to get too roasted. lol..
I bought a 94 M edition in Montego Blue (M8) with 132k on it about two months ago. I bought it for a few reasons:
It was cheap enough
I love the color/tan interior
It had tons of maintenance done

I bought a M45 supercharger off FB Marketplace on a whim about 3 weeks ago. It was a good price and I guess was one of the later models because it has a water cooled charge pipe.
I've read quite a lot on this forum and it seems that basically everyone says two things:
Turbo is better than Supercharging
and Megasquirt is always the answer.

Before everyone tells me to just sell the SC and buy a turbo setup let me tell you what I want out of the car and my driving.
I will NEVER track this car. I will also likely never autoX it either. I will drive it on nice days to work always withn the top down (11miles each way) and occasionally take it for short pulls in the twisty hills that are nearby. I doubt I'll ever push the car for more than 5 minutes at a time.
I don't have crazy power goals (150-170whp) and want to spend more time driving it than working on it.
So that brings me to some questions.
It seems the SC with 5 psi will get me to roughly 140-145whp. The car was dyno'd a few years back at 118whp but who knows now.
Ideally I don't want to have to intercool it. I'm hoping the charge pipe is enough considering I'm not going to beat on it. Will a TDR heat shield help?
Ideally I don't want to have to deal with Megasquirt. I want a normal idle, I don't want to have to re tune the car for cold starts when the weather changes etc. I just want the car to work. I've read multiple times that the MS is going to take tens of hours and months to tune right. Can I get away without it? Would a piggyback ECU perhaps suit my wants?
In order to get closer to 170whp I imagine I'd need injectors? turn up the psi on the SC with different pulley size? Will this then be the point that I need an intercooler? I've seen a youtube videos of a M45 with 6 psi and a ME221 putting down 174whp and it didn't seem to have a intercooler.
Is there another upgrade I can do to eek out a few more HP without affecting reliability? Already have a racing beat header, magnaflow exhaust and advanced timing to 14 degrees.

Please, any advice besides sell the M45 will be appreciated
Thanks!

Install the m45 as described in the instruction manual, which google should find for you. The JRSC was very refined in its day.

The TDR heat shield is good for charger reliability.

Anything that makes you thing you will get 174 whp out of an m45 at 6psi is an unreliable source.

An injector change will require a differnt form of engine management.

The m45 makes a decent amount of heat, anything beyond the stock pulley it's recommended to add an intercooler. You can mess with water/meth injection but an intercooler is easier in my opinion for various reasons. You can search for yourself on that.

My car when I had an m45 has a good stock clutch and would slip in 1st and sometimes 2nd gear with the stock pulley. You'll need to budget for that if you haven't already.

MS takes a learning curve but it allows you to get what you want out of the car. The m45 is notorious for having a bad return to idle and is one of the main reasons I got rid of mine. I was using the jackson for and an msd box which was great driving but the idle wasn't great. A powercard is a good alternative for your use but not sure if that'll fix your idle.

There's a lot of avenues to take but to check all your boxes you'll need to compromise on either price or ease of use.

I've done the M45. My advice is as follows: Install it and ignore horsepower goals. Anything to try and push the M45 beyond it's basic components has a very low return on investment. If you get bit by the horsepower bug.. well, that's where the "sell the kit" advice comes from.

Are you me? I just bought an M45 off facebook, even though it makes everyone here scream and pull their hair out, but it was a good deal, I similarly don't intend on tracking the car with any frequency or have delusions that its a race car. I wanted the supercharger like 80% for the glorious whine they make.
I have the MS3 pro for my ecu, a squaretop manifold, and happy meal clutch already, there's plenty more bits I still need, I want to run an intercooler and/or water injection.

Another new yorker here - But I just yanked my M45 off and am trying to offload it.

or turn it into a coldside SC and add a turbo.....

Thanks guys for all the advice.Special thanks to gooflophaze as thats probably the best advice is to just ignore HP goals.

A few more questions.If I did decide to buy a MS PNP does it really matter if I do a MS2 or MS3? I don't care about traction control or launch control but if it's actually easier to turn or comes with better base maps then its probably worth the extra money to me if I did decide to go that route.

As for an intercooler-would you guys recommend a TDR air to air which are like $900? or can I get something significantly cheaper? Would a certain intercooler be easier to switch to a turbo car or not?

And I plan to put a 6 speed in it and at the same time swap the clutch. Any thoughts on which to go with? I planned to do an Exedy because I have a buddy who can get 40% off. Does it make sense to do a lightweight flywheel? I heard to stick with a heavier one for some reason.

I have the Spec flywheel in my car that tdr sells. With the SC it loved to stall if the AC was on, worse still AC and headlights. The idle droop is less pronounced without the SC now.

MS3, the fueling is way better, as well as the community support.

Back in the day my stock 90 with just the JRSC M45 made 155whp with Konig britelites with 195-50-15s. You might get in the 160s with exhaust, lighter wheels and a few tricks. The SC really pepped up the car.....most notably the torque. However I found myself wanting more almost immediately. If you're not power hungry and just want a more peppy driver, I like the JRSC choice. If you will ever want more than 150-160whp, I'd recommend just saving up a while and doing it once......I.e., a rotrex or similar, or a turbo.....imho.....

I love my FM stage 1 clutch. Super soft pedal and has held up great to ~330wtq. Holds my torque without really any trade off in comfort or driveability....

the M45 is notorius for being a pain to get to idle and tip in properly, so adding a lightweight flywheel can exacerbate the problem and make rolling from a stop annoying at best.
a MS3 is loads better then the MS2, and would help further improve the known issues with the M45

I ran an M45 on my 1.6 with an MS3x, dual throttle body setup, intercooler, and stock exhaust. Made... 155hp at 11psi.

Do the stock pulleys, don't bother with an intercooler. Put in an MS2 or MS3 (I say to with the 3). Tune it and don't do anything you can't sell with the supercharger setup if you get the itch for more. It was fine, it pepped the car up, and I had to upgrade the clutch.

As a comparison, I am making 192hp at 10.5psi on my turbo setup, and it makes more boost and torqur at a lower RPM than the super did, it just feels a little softer below 4k rpm.

You were spinning an M45 up to 11 PSI? i thought they hit the rpm limit before that. what kind of intake temps were you reading, above 8psi I would think an intercooler would be warranted.

Guys,
This really clarifies a lot of things for me.I'm going to install the SC and see if it's enough for me and if I'm having issues with the idle drop. It came with a dummy throttle body which i believe is supposed to help with that? I think I'd be super happy with 150-155whp if I don't have to do an intercooler. Stick with the OEM flywheel, and upgrade the clutch. I think the 6 speeds closer ratios should help it feel 'quick' too.
Next step would be a MS3- Does it make sense to buy one of these new? A used one should be just as good right? What about the few members who make them like Rev and Braineack? What should I expect to pay for a used one?

As a heads up, I had a 13lb flywheel and had zero idle issues once I got my idle tune dialed in. But, sticking with the stock flywheel is way cheaper.

I was waaaaay over spinning it. But never spent much time arround red line because it ran out of puff by 6300rpm or so. 150mm crank overlay and a 62.5mm nose pulley. I was seeing cold side temps upwords of 160F post intercooler.... Basically, I got all the supercharger stuff cheap, built it like a turbo system so all I had to do was swap the supercharger and bracket for a turbo and manifold, and had fun with it before selling all the supercharger stuff for a profit and going turbo. I miss the whine and super sharp blow off noises it made though...

They all came with the dummy. That's what leads to the lag - the air volume between the throttle body and the valves are what make idle tuning difficult.

MS3 - buy new, or buy from someone reputable (rev or brain). I've seen it happen that someone snags a used MS for a "great deal" only to not have the technical knowledge of how to adapt it to their year car and pinout. Overall it's not something you want to cheap out on.

Put the SC on and try it. Just do it, and don’t waste time on “prepping for boost” mods, EXCEPT for a Wideband

If you want more power, consider selling it. Seriously, if you add up the price for MS, injectors, MS accessories, intercooler from TDR, you’ll be sad that you just burned a wad of cash for like 15 more rwhp. It’s out of headroom without clever ($) tricks by 8psi, or even pullies to support it properly (belt slip and SC pullies small enough). Some may argue you can get by on the cheap DIY, but these are people familiar with these platforms, or have done days’ of research. if you’re asking these questions here on a 30 year old system, you probably are looking for more off-the-shelf solutions.

If you like the power, just not the idle droop, you want a dual throttle body mod. All that money for an aftermarket ECU won’t fix it 100%, which is why x_25 still did it, even with MS3. It’s very difficult to fix a fundamental hardware problem by tuning. Plus it’s a Miata specific supercharger issue. Guess how many tuners or MT.net MS members can help you?

I would highly recommend learning to install it yourself. It’s not hard and gives you better insight Into troubleshooting if needed, or even preparing for other forced induction kits.

I did the dual throttle body setup because I had an intercooler with a ton of extra piping and such. With just the original crossover tube, it wasn't that bad.

The dual throttle bodies did make it idle like stock, but I had all sorts of other issues with the hand off between the two throttlw bodies. I never got it dialed in right....

Oh! Important note, if it did not come with one, you need to put a one way valve in the line for the IACV if you are plumbing it anywhere other than post supercharger. They leak a good bit of boost.

Basically, it all boils down to, run the JRSC setup as it came in the kit, maybe with a slightly smaller pulley, and a good ECU. If you ever decide you want more power than it makes like that, just sell it and go turbo. Moding them just isn't worth it.

Yeah, if I'm going to buy a megasquirt I'd make sure that its a PNP model already with the pins needed for my 94. Someone has a MS2PNP for sale on FB marketplace near me for $599 new in box which makes it hard to swallow $1200 for the MS3.