Secrets of the Mirage

[Native]

pulling out the back seat

Just do it.

[Loren]

New engine is in, light flywheel, baby battery, and larger front brakes. And the verdict is: It's almost fast! Much more perceptible difference than I expected.

And the numbers back it up. Previous changes added up to about 5%. This round was twice that! All told, 14% improvement over stock. That means that my 10.5-11 second stock 0-60 should be down to almost 9 seconds. The Mirage is officially as quick as a 1.6 Miata!

2017EngineAccelTest.png (31.44 KiB) Viewed 12130 times

[nathanwilliams617]

Good job Loren!

[CaptainSquirts]

So if you have the acceleration of a miata, what isn't up to par in other departments for it then compared to the miata?

[Loren]

So if you have the acceleration of a miata, what isn't up to par in other departments for it then compared to the miata?

1.6 Miata. That's 0-60 in about 9.4 seconds.

If you're talking about 1.6 Miata with an open diff, same tires, and a similar level of quality on suspension parts (cheap coilover kit), and ride height and stiffness slanted heavily toward street comfort rather than fully optimized for autocross... the Mirage should totally be on par.

[twistedwankel]

This is pretty cool. I used to race wind up rubber band airplanes as a kid. Had to allow for torque. Fun is where you find it.

So when I put a real 5.0 in my wife's 93 Crown Vic weighing 3800lbs with 460HP and a lot of torque will I feel it in my butt? Or do I have to use a seismograph?

[Loren]

Just ordered the new wider (205) front tires. Sticking with the Dunlop ZIII for several reasons. They're a tad cheaper, but not enough to matter much. But, they are also a bit narrower in section width, which is good for this application. And they're gonna last longer than RE-71R's, while delivering plenty of performance.

Don't believe me?

I ran a set of RE-71's for 109 runs. I sold them before they were completely dead, they probably made it to 150 runs. Not terrible.

This set of ZIII's currently has 97 runs. Will do another 20 this weekend, and likely another 10 on Dec 1. At that point, the FRONT tires will be about as done as I care to make them. About 130 runs... and I could surely milk them for close to 150.

I did have the front tires flipped a while back to equalize the wear. But, here's the kicker: I never ROTATED these tires. The rear tires are barely broken in! If they're 1/4 worn, I'd be surprised. They're almost full-tread with no uneven wear. So, if I wanted to completely use up this set, and had properly rotated them, I could easily have doubled that 130 runs... to well over 260! Which is insane! Over 200 runs on a set of really good tires is fantastic!

Take that, Bridgestone!

Meanwhile, the 205's are going to add .5" of tread width to the front, and .4" of diameter. That added diameter means right about 1 mph at 50. So, my actual top speed in 2nd goes up by a whopping 1 mph... from 54... to 55.x. But, as is the theme with this car, "every little bit helps".

And fkkk 3rd gear, anyway!

[Carracer]

NOOOoooo..... I wanted to see 205 RE71s on the car so badly

[SlowMiataDrew]

And the line of shame continues to get more and more difficult to beat....

[jbrannon7]

That added diameter means right about 1 mph at 50. So, my actual top speed in 2nd goes up by a whopping 1 mph... from 54... to 55.x. But, as is the theme with this car, "every little bit helps".

And fkkk 3rd gear, anyway!

What ever it takes to avoid third gear.

[twistedwankel]

And the line of shame continues to get more and more difficult to beat....

To me the line of shame for the last 2 years has been Philip in his stock crappy 96 daily driver. He had to go to M for some real competition and to let someone else win a t shirt 'cause he's a nice guy.

[twistedwankel]

Take that, Bridgestone!

Meanwhile, the 205's are going to add .5" of tread width to the front

The way you drive with ultra precision that 1/2" is going to be hitting cones for quite some time until you both get used to them. You are totally right about RE71's wearing faster BUT for my cars bigger sizes with a rebate they are still the cheapest ones other than maybe RS4's which turn to stone after a couple seasons and last forever.

[Loren]

1/4" per side. I'm not THAT precise!

[JasonS]

Totally agree about the RS4s turning to stone. The grip fell off so fast, way faster than rs3s. No bueno

[CaptainSquirts]

Eh, after 6 months I got About 12 events plus daily driving for the Rs4 to hit the wear bars. My 615k+ got about the same wear but were a lot slower at the end of life and wore a lot slower. My rs4 maybe seems to be having ok grip at the moment but I haven't reached that significant drop in performance Jason speaks of yet or I'm just getting a little better .

Anywho if I get the same wear rate with re71s I'll be content.

[Loren]

Just got back from Joe's. We straightened out the camber a little bit, I still need to set the toe. More importantly, we got the car up on the scales... and with one turn on the right front spring perch, we got the cross-weights to within 5 pounds per corner.

Total weight is 1936 w/ 3/8 tank of gas. No spare/jack, no floor mats. Competition mode.

Corner weights with driver and spare:
LF 666 (was 672)
RF 601 (was 594)
LR 443 (was 437)
RR 414 (was 421)

Cross Weights 1080/1044 (was 1093/1031)

Front Bias = 59.6% not bad for FWD

When I get around to removing the rear seat, it will be sub-1900 pounds.

[BrilloHeadBen]

Jesus, that makes me wonder if the Festy was sub 1800. I know it had that big hunk of iron under the hood, but it had way less of everything else.

[Loren]

I think the Festiva started out at around 1800. But, we may have added more weight than we took out of it with the rear beam axle support, harness bar, bigger brakes, much bigger wheels and tires, fender flares, etc.

On this car, I have a baseline weight of around 2057, and it's currently 1936. So, it's lost 110 pounds or over 5%.

The rear seat is documented as weighing 49 pounds not including the seat belt reels.

I don't think there's a lot of other easy weight to remove from this car. The hood is heavy, but even that only weighs 20.5. So, at best, there's maybe 10 pounds there. For the $500+ that people tend to want for fiberglass hoods, that would be an expensive 10 pounds. Although, I could gut it like I did the Festiva hood and probably get most of that for next to nothing.

I can get another 5-6 pounds off of the flywheel, that would be awesome.

[CaptainSquirts]

Corner weights with driver and spare:
LF 666 (was 672)
RF 601 (was 594)
LR 443 (was 437)
RR 414 (was 421)

Cross Weights 1080/1044 (was 1093/1031)

Jesus, I got 1050 at each corner in the fronts and 650 in the corner rears. Your car needs some sandbags imo.

[Loren]

You pull a spark plug wire and I'll carry sandbags.