[TheMightyElk]

Hello, I looked at the title of my car and realized on 5/11/2023 I will have had my MX-6 for 20 years. Allow me a short story time and then ill explain my build plan.

I had 4 RX-7's and 3 MX-6's at the time that this one went down. I had it pretty extensively modified. running an MSD with the internal coil (which worked great) but the MSD after a while had a broken diode which I didn't know. I didn't have time to fuss with it and my friend tried to be nice and took it to a shop. I asked them to not hook up any diag equipment due to the custom harness but they did and fried most of the electrical. couldn't get the thing running after all that to save my life. my other MX-6 got the engine and trans and I kept the shell. Years passed and it sat with no engine or trans but I always wanted to do my "crazy build" I just got my stepson rolling in a 95 LS I picked up in a divorce and it reminded me how much I adored my MX. So to the point.. here's what I have now.

Block, head, and internals for a 2004 protege 5
millina S supercharger
megasquirt 3
no trans currently
new clutch and flywheel.

the plan is I have a buddy that does metal fab, he owes me a manifold and I was intending to fab a manifold to direct bolt the supercharger to the intake of the head. long enough pipes to add injection. run standalone coils (protige5 head means no mechanical distributor). this also means I get to keep my AC because I live and drive in central WA in the summer. The protege 5 engine had an issue with the cyl walls being out of spec so they'll probably need to be bored and honed. I'm looking for advice from all you people like me who love these cars.

Bottom end:
What should I look for that is a good product for the purpose? not intending to get more than maybe 250hp out of it as I want to drive it around on the street.

• Piston/connecting rod suggestions
• Do I need a new crank? or would the crank from the protige5 work

Top end:

• New valves or keep the original
• new cams or same, keep the original
• debated doing better than stock valve springs but I am open to suggestions.

been about 16+ years since my last engine build. and.. well over 20 since I built anything with pistons and I know tech has changed a lot.

thanks all for the advice and I hope this post is aligned with all the rules. if not I did read stuff but I have a properly garbage memory.

 

[Sundot]

You have always loved and supported me with all your heart. Cheers for completing 20 years and creating wonderful memories together. Happy 20th anniversary.

 

[Mazda Carnage]

Bottom end:
What should I look for that is a good product for the purpose? not intending to get more than maybe 250hp out of it as I want to drive it around on the street.

• Piston/connecting rod suggestions
• Do I need a new crank? or would the crank from the protige5 work

Top end:

• New valves or keep the original
• new cams or same, keep the original
• debated doing better than stock valve springs but I am open to suggestions.

been about 16+ years since my last engine build. and.. well over 20 since I built anything with pistons and I know tech has changed a lot.

thanks all for the advice and I hope this post is aligned with all the rules. if not I did read stuff but I have a properly garbage memory.

The Millenia 2.3L v6 runs a 6" crank pulley and a 4" supercharger puller, so it runs a 1.5:1 supercharger speed and makes 5-6psi boost. With the same size pulley's on the 2L you should make 1.15X the boost (5.75 to 6.9psi).
The 2.0L FS makes 130bhp and 135ft/lbs, the Millenia 2.3L V6 makes 210bhp with the supercharge.
What is the maximum RPM for the supercharger?
You would have to run at least an 8inch crank pulley and run the supercharger at a 2:1 supercharger speed.
I don't think this will get you to 250bhp, my math says you would need about 13.57psi manifold boost to make 250bhp.

For the engine:
I say pull the pistons, clean them, gap the rings for boost, hone the cylinder walls and ignore the out of spec cylinder walls.
Run the full factory bottom end. Your power goals aren't unreasonable, tuning will play a bigger role in the engines survival than performance rods and forged pistons.

Keep the original valves and cams. Add 0.06" valve spring shims to increase valve spring pressure. You don't need to build the engine when running forced induction, let the boost do the work until you reach the limits of the supercharge or turbo charger or rods then throw money at the head for more power or upgrade the supercharger or turbocharger or rods and run more boost.

Personally I think you should sell the millenia supercharger and run a turbo, you don't have to run the turbo directly off the manifold, run 2" pipe off the manifold to the turbo (wherever you can fit it without interfering with the A/C stuff).
A turbo is far more reliable than the Lysholm Twin Screw supercharger and allows for simple boost changes without having to make custom pulleys, it's also smaller than the supercharger assembly so wherever you where going to put the supercharger put a turbo there instead, you can run full water injection instead of an intercooler or water/meth injection for more octane, you can run a small water to air intercooler under the hood instead of a front mount air to air cooler.

A supercharger is fixed to engine RPM, so at 3000rpm a supercharger with 2:1 pull runs at 6000rpm, at 6000rpm the supercharges spins at 12000 rpm. So a superchargers boost curve is progressive.
With the right sized turbo you can have it spinning 200 000rpm at 3000 engine rpm and hold it to redline, full boost across the rpm range.


I also like to work with what I have but sometimes the results aren't worth the time and effort, for example you build around the millenia supercharger and push it harder than the miller V6 would trying to get a bit of performance out of it and it disintegrates what do you do? Buy another used millenia supercharger and cross your fingers or run less boost? Redo everything to install a better supercharger or turbo...

Don't get me wrong I think it's cool you want to use the old millenia supercharger and if you said you where installing it in a zero $ build and if you only get 35 more wheel hp your cool with it I would say "That's awesome, do it".
But when you mention forged pistons$$$, performance rods$$, engine bores$, valves$ and valve work$$, performance cams$$ and spring upgrades$ to run a small unreliable Lysholm twin screw I have to say "What?".

If you want do to something different and think turbo's are done to death and everyone runs them just remember that 35years ago some people said everyone runs a blower or supercharger, I want to do something different and run a turbo.

If you want a supercharger why not get a centrifugal supercharger that can be sized reliably for your power goals with different available pulley sizes to run different boosts.