Is the Answer a $100 supercharger?

RedGT, I left the timing at 25 deg. btdc. I took a couple degrees out on the dyno and lost some power but never tried adding more in. I still don't have a knock sensor but my dad and I cant hear any pre-ignition happening for what that's worth.

I also had intake air temps get up to around 200 degrees like Keith previously warned about so ill be experimenting with an intercooler setup next.

That looks like it turned out great. But I will admit every time I look at those supercharger opening with nothing over them made me shudder just a little bit. Over all, looks like fun.

I tried to keep the blower covered at all times. I just took the cover off for pictures.

Im pretty sure those superchargers are WAY less picky about small debris than the cylinders they feed.

Jack's been off at college (which is about five miles from home) and pretty busy with classes and FSAE so I thought I'd chime in with a few updates on his supercharged car.

Just before he went back to school, he installed the used RX8 injectors he bought.  He wants the bigger injectors because the car was going lean above 6500 RPM no matter how much fuel we threw at the tune, plus he's planning on trying E85 when he gets time.  As a result of the different injectors, he had to tweak the tune.  He made some tweaks by driving on the street and looking at data logs.  We haven't gotten back on the dyno to get it really clean, but it's running very well and feels great.

Soon after this, he started having some pretty big cold start issues which ended up being a bad temp sender.  He replaced it with a used sensor from our parts bin and all is well.

He also found on some hot days (maybe above 85 degrees--hot for Michigan), he was hearing some pinging.  So he dialed a couple of degrees of timing out of it.  With those intake temps so high, it's no wonder.  He's got an intercooler mounted in front of the radiator, but hasn't had time to plumb it in.  As he said before, despite Keith's advice, he wants to try that to learn firsthand.  He's also still planning on trying water injection or water/meth.  The car will go into winter storage in the next month or two, so updates may take awhile on those fronts.

Finally, he leaves it parked in a college lot quite a bit these days and it's got a really bad smell inside.  Not the normal wet Miata smell, but something more like a wet Miata with a dead animal inside.  He hasn't found any dead animals inside it yet, but keeps looking because it's really annoying.

Did you roll/weld a bead onto the charge pipe? I guess at ~6 psi it's less likely to blow off than it would be with a big turbo setup.

Water/meth would be a cool addition - just make sure you get a controller with a good failsafe, and hook that failsafe to something.

Pretty cool that it's driving and being driven. How is the drive belt holding up?

Dead animal location worth checking - Pull the rear deck carpet and pop the fuel tank access panel off and look around the top/edges of the tank itself.  Despite it being 'outside' the car, bad smells there will fill the cabin when you leave the car parked + closed.

He didn't put a bead on the charge pipe and it hasn't popped off yet.  This version of the build is really his "proof of concept" and was meant to learn lessons.  As he hones in on the final iterations, I'm betting he'll redo just about everything.  Or he'll move onto the next project, since this is just a ratty Miata with a $100 blower.  

The belt has held up fine, no squealing.

More importantly, he found the source of the smell:  dead mouse trapped in one of the seat pans.  He got (most) of the mouse out but some of the smell remains...

Let me know if he wants to sell off any of the initial build parts.     

My '91 BRG wants a SC and I'm 30 min from you.

I haven't been working on this project much since school started but, I was able to get some work done with my intercooler over Thanksgiving break.

Here's what I have had on the car for 300 miles or so.

I ordered an intercooler piping kit from Amazon and combined it with the intercooler from a used craigslist turbo kit.

Here is it all finished in the car:

Intake air temp is much better than before. Ill get some more detailed pictures and details about the intercooler setup later. 

How is driveability with this new setup?  It looks fantastic.  Very cool build.

I may be opening the hood of the thunderbood to see if I can make a mustang supercharger fit like you because of you.

so, yeah, Thanks for that. 

I'd be interested in what you had to do to compensate for the extra throttled volume of the intercooler. Usually that brings along idle droop problems.

When I first started I had some idle droop problems. I we had a similar issue on our Formula SAE team and one of our advisors showed us how to fix it with timing adjustments. I advanced timing by a couple degrees in my timing table surrounding where the car usually idles. This kept the car idling but it does not idle at a constant rpm. I'm hoping I can get the idle better with a little more timing adjustments. Unfortunately I have a couple exams this week so I might not tune anymore till the weekend.

The challenging part will likely be dealing with idle droop when coming to a stop. That's the toughest part of tuning a supercharged Miata.

I seem to recall that idle is often controlled via closed loop timing control.

I was just considering this project when a M45 popped up locally on CL. Glad I saw it.  This gives me lots of hope for possibly supercharging the 96 I've got sitting out back. I'm on the fence for a flip, or fix and enjoy.  I don't want to go down the turbo rabbit hole again, and a SC is unexplored territory for me.  Keep up the awesome work!

Keith, So far the idle droop coming to a stop hasn't been an issue after the engines warm.

Mr. Lee, Thanks for the encouragement! The car is a blast to drive with the blower!

Re the idle droop, another old school fix was to run dual throttle bodies - one on the SC, one in the standard position. Of course you have to keep them in sync...

Cool build.

Just a thought while looking at your "used CL turbo kit" photo. Would the BOV help with SC longevity the way it helps with a turbocharger? Not that I'm personally looking for turbo farts from a SC car. But theoretically there is still some compressor surge when the throttle is shut suddenly, and I would imagine the extra runner space of the IC and piping would compound this to an extent. Like I said, just  a thought.

BoxheadCougarTim said:

Re the idle droop, another old school fix was to run dual throttle bodies - one on the SC, one in the standard position. Of course you have to keep them in sync...

Cool build.

If you look at the picture of the top of the engine bay with the IC installed, you can see he's done just that. 

Good work! My old Miata had a Jackson Racing setup. Used the MSD boost referenced timing box and a piggyback fuel controller. Lots of usable power for cheap!

Following!

Mr. Lee said:

BoxheadCougarTim said:

Re the idle droop, another old school fix was to run dual throttle bodies - one on the SC, one in the standard position. Of course you have to keep them in sync...

Cool build.

If you look at the picture of the top of the engine bay with the IC installed, you can see he's done just that. 

Ah, that helps a lot. If you've got a throttle in the stock location, you shouldn't have significant droop problems. Just the drag of the blower, and you compensate for that like you compensate for AC, headlights or fans.

In reply to Keith Tanner :

I can chime in for Jack.  He still has the original throttle body in the original location, but it's wired WOT and not being used.  He left it there because he thought he might need to do the dual throttle body trick.    However, the tuning he did seems to have kept the droop and stall issues at bay.