Adding Supercharger to '92 (1.6L)

40% sounds about right; that would be ca. 35 rwhp. I've only driven one 1.6 with a Sebring kit. It may not have been set up correctly, because it was a total dog off idle, like five A/C units had kicked in at once, and a challenge to drive smoothly until it had built enough boost to overcome the compressor load. Above 4k, it was slightly faster than my stock 1.8, enough to notice but nothing dramatic. I imagine the 1.6 clutch wouldn't tolerate more power in any event. I had been thinking about a supercharger, but that drive convinced me it wasn't worth it. Remember, it requires at least 91 octane, and the provided air filter is a mickey-mouse piece of junk (just ask Leon). IIRC, when Leon drove his car to Alaska, he disabled the supercharger for the duration to minimize reliability worries.

Rich, Don't flame me but I'm just asking as allot of people (usually folks who are more accustomed to V8's) don't realize that you really need to use the full rev range to get decent performance out of the miata engine. You are using the full rev range correct?

I don't remember anyone describing the 1.6 with a SC with as bad a drivability as Lanny describes here. I would think that was more likely a bad set up. Hopefully some others will jump in here, I always wanted to do the SC on the 1.6 having read that it was a pretty wonderful 'plug and play' set up for decent power gain.

Chris

99BBB

I think I know what Rich Is after. He wants some pull in traffic, not performance on a track or in autocross. Like me, he wants more low end torque, not high RPM horsepower. Neither of us are likely to drive around town revving the engine above 5000 RPM, even though this is where it is most happy. Most after market modifications make themselves felt at high RPMs, not in the 3000 and 5000 RPM range. Of the changes Rich has already made, only advancing the timing makes a noticeable improvement in the low to mid RPM range.

Wanting the same thing, in 3 Miatas in the past 11 years, I find that my choices are limited. In order of the most significant improvement in the low to mid RPM range (and also cost!): Buy a Vette, Porsche, or other car with lots of torque Drop in a ford V8 - $16,000 + your car, but great fun to drive! Supercharge and add a controllable ECU - $3-4,000 for a decent improvement Put in adjustable valve gears - $200 but only a modest gain

FWIW, one man's opinion, Randy

The timing may have been set too conservatively. There is a significant boost, even at low rpm. But after I got my M45, (Sebring/JR), I did feel the need for a timing device to allow better performance at lower rpm. The Miata engine does not seem to do well at 8 BTDC.

92 rather.

It was on mine, no dispute.

No, because I could not get 87 octane, let alone the 93 octane required. And on the Alaska and Cassiar there is no option to go to the competition. If you need 93 and they have 84, the mind boggles.

Leon

You don't consider holing a piston a reliability issue? :-)

Not a reliability worry. Holing will be quite reliable, if you use 84 octane with 6 psi boost.

Leon

Since the 2006 model requires 91 octane or higher, does this make it impossible to do the same trip in your new MX-5? Also, are there any warning signs for no high octane gas or anything like that? A lot of vehicles require higher octane than 84 or 87, it seems like they would get stranded up there.

Pat

The knock sensor should retard the timing enough to run safely on regular gas, with some loss of power. Or use an octane booster additive.

Dunno what it's like in Canada, but I've only seen 84-85 octane fuel in the mountains. At high elevations, the octane requirement is reduced, at least for normally-aspirated engines. You just buy "regular" or "premium," same as usual, and ignore the numbers. I've never had pinging with 85 octane in Colorado, even at 14 BTDC.

That makes sense, thanks.

What would be the difference with FI? I already put 93 octane in at just over sea level. Would I be SOL with 84-87 fuel in the mountains without octane booster?

Pat

Pat, I don't have a 2006 Owners Manual, but I'll bet if you read it like I did my 2003 book, you will find that it tell you that you "may" run lower grade fuel, but the performance is less when you do. Section 4, page 2 in the 2003 Manual and Section 4, Page 2 in the 2004 Manual.

"You may use a regular unleaded fuel with an Octain Rating from 87 to 90 (91 to 95 RON) but this will slightly reduce performance."

It ain't gunna blow up on you if'en you use a lower Octane !!!!!! :-)

I run 87 in my 2003 and I just checked the milage. 254.0 miles on

8.35 gal. = 30.419 MPG.

That is filling to the vent hole each time. Some in town ( two Parades, up and down hills ) then some cross town stop and start 26 miles each way (6) of those, the rest the rest is short trips to the store and Highway to and fron the Parades. These are not "power runs", just driving the car normal.

If you are in a Drag Race or Autocross, 87 is not the grade to run. If you just drive the car, 87 works well.

Bruce Bing '03 LS

Thanks Bruce, good information.

I don't drag race anymore after having a hose slip while suffering a high heel blowout, very dangerous. That cost me first place, I even had to drag myself across the finish line by my painted fingernails. ;-)

Pat

The 2006 Manual states:

"You may use a regular unleaded fuel with an Octane Rating from 87 to 90 (91 to 95 RON) but this will slightly reduce performance. Fuel with a rating lower than 87 octane (91 RON) could cause the emission control system to lose effectiveness. It could also cause engine knocking and serious engine damage."

I wouldn't think so. As Doug points out, Mazda specifies 87 as minimum. And the air density on the Cassiar and Alaska is not by far as low as in the mountains, so there is a likely problem.

However, I would think if you pussy foot it, you should be OK with 84. I have driven quite a lot with audible knock, because of various problems, and if you back off at the first sign of it, it seems to be OK. The official line is that knock destroys the boundary layers that insulate the engine from the hot gasses. That is a process that takes a bit of time. (Knock can also affect the forces on the pistons, but I would surely think no one is going to ignore that. Somehow, anyway, in my experience that seems to be related more to high air temperatures, though I have no scientific explanation why.)

I would not be averse of trying the trip, :)) but it seems self-evident that I will not have much time this summer to drive, let alone to Alaska. :(

Knock has a clear sound, but it is not as obvious as some people claim it is. Initially, I though it was the exhaust.

Leon

Thank you for the explanation. That makes sense to me. I am still wondering, though, what effect a turbo would have. I would obviously not have the option to disconnect it the way you did with your SC. Could that trip be done in my car? Also, many other cars are OEM turbos. Do they just not get driven regularly in the areas with low-octane gas?

Problem solved. I have the time and can give a full report of your 2006 model's performance after I return from Alaska. I will keep a full log. See you Wednesday, that will give me enough time to get to Florida. Can I borrow your gas card too? ;-)

Pat

In addition, the lower air pressure in the mountains is not as helpful for a turbo either. The thing just starts spooling up faster.

How low can the wastegate be set? Like zero? I will leave it to someone else.

All I can say that Miatas and similar are very rare and far in between there, let alone boosted ones. It is mostly trucks, big vans and SUVs in those areas. I guess word of mouth spreads what works among buyers, and that car dealers are leery of products that may get them into trouble. The Mazda dealer in Fairbanks had lots of Miatas, though, including two

10th anniversary editions when I was there. But that is in a big city with decent gas (though I do not remember any 93 octane there too).

No, and you will have to replace the tires with identical new ones. I do not think there would be anything left after that many miles. :)

Leon

[snip]

Thanks Randy. Exactly what I'm looking for. Will the SC provide that low end torque? Lanny's experience suggests not...

-rich-

A SC should increase output across the rpm range by about the same percentage, but it won't alter the shape of the engine's power curve. So yes, you'd get a bit more low end, but a 6 psi Miata still won't make serious power below 4000 rpm. OTOH, at 15 psi there could be more than enough torque to cause traction problems at almost any speed in the first three gears.