Miata Mongoose?

[fndrbndr]

The game calls it the Mazda Speed roadster, but it's a miata to those of us stateside (all but Ske, I think?).  Anyway, my desire to try something other than my MK2 for short, technical tracks and my interest in road racing (saw some miata racing on TV last week, looked awesome) has led me to start playing around with some other cars in D-class, ones that are good in "real life." My first project, to that end, is the Mazda Speed (but I'm going to end up calling it the Miata whether I like it or not).  Having run (and beaten) the spec races for this car, pretty much everyone will already know that it's a bit oversteer-prone.  Breaking the tires loose with 150hp is really saying something.  Since I'm making a car for short, technical tracks, I'm too worried about the low hp.  Needless to say, this thing isn't going to Nissan Speedway anytime soon (though that does sound kind of fun, in a wierd way).  Keeping it in D class means I can't add too much hp anyway (I went up to 160), but the handling upgrades should give me a quick, light RWD car that I can flick through any corners easily.  Here's what I've got thus far.

160 bhp
136 lb-ft torque
2,237 lbs

Power:  Sport intake.
Platform:  All race, Sport weight reduction.
Tires Kumho street, 225 front and rear, stock rims.
Aero:  Forza front bumper, rear bumper, and wing, Garage Valley street hood.

Setup (front/rear):
Pressure 29/29.
Gears 2.89, 1.99, 1.51, 1.20, 1.00, 0.85.  Final 3.73 (or 3.30 for "miracle lap" mentioned later)
Camber -1.0, -1.0
Toe 0, -.2
Caster 5.5
ARB 12.48, 11.47
Springs 395.2, 263.6
Height 5.1/5.1
Rebound 7.2/7.1
Bump 6.5/5.1
Downforce 85/100 lb
Braking force 47% front, 90% overall.

In case you didn't pick up on it, that's Fuerdog's suspension tuning calculator.  I'm still figuring out how to adjust some parts of my suspension, hence the shortcut for a starting point.  What I need is more acceleration.  I ran a 75.296 when I tested this setup at Diamondback.  That was far and away my best lap, using the stock racing transmission ratios, sticking mostly to first and second (noted as "miracle lap" final drive above).  It was much better than I drove the rest of the session, and it's almost not fair to compare that lap to the others.   After moving to my current final drive, I was running consistently better laps than I ran with the "miracle" setup, but never caught that top lap. 

After that session, I went to Tsukuba.  My best time was 64.406, using my non-miracle final drive ratio.  As a frame of reference, I'm in the mid-61's with an MK2.  Comparing the two cars, I'm losing about 4mph of exit speed at Tsukuba, which can really add up.  My usual solution here is to soften the rear ARB to reduce wheelspin, but I don't think that's the issue here.  That said, it is in the sweepers where I'm losing the most.  I'm only losing about 3mph exiting turn 1, and that's due in part to lack of experience with the car.  I've driven the MK2 a LOT. I suspect with time I could, but I'm just trying to get the basics down at this point.  Anyway, any help would be appreciated.

Edit:  Corrected for my confusion of understeer/oversteer.

[fndrbndr]

Tried Laguna with the default race tranny settings, 100.473.  Not bad, but again, could be better.  I felt like it handled Laguna better than Tsukuba.  My MK2 time there is 98.760, so I think for now, my goal is to beat the MK2 at Laguna Seca in the Miata.  I'll also probably use it for the snakes, but I don't want to post any more MK2 times for comparisons, in case I can't catch them.  Oh, and I said I had a little fun with the paint booth.  I kid my uncle about his miata being a wind up toy, so this seemed appropriate.

[Placard Rat]

I'm going to have to build this out for my next pass at the D-Class snakes, that's a full second faster than my 914/6 at Diamondback.

The bump settings seems a little high to me though, I'd typically run them in the region of 3-4. Though that is based more on personal preference than any solid knowledge.

Oh and as an aside, this side of the pond we call it the MX-5. Got to love those letter and number designations. 

[99-LS1-SS]

That's cool.  It'll be interesting to see which tracks the Miata handles better than the MK2.  Might not be a bad next challenge.  Imagine terrorizing people with a Miata.  

[Ske]

Actually it's called an MX-5 over here I've toyed around a bit with this car in C class, but didn't find it to be competitive at all. I don't personally build grip machines with street tires and high weight like that, but I guess it's about taste... I might see if it can cope with B class, though.

[gs shyner]

Use at own risk and I defer to those infinitely more knowledgeable.  (insert deference bow)

My recollection was the "Miadster" was way oversteery.   (tail slides out easily - ala Cobra 427/Tuscan)

I've dropped the Fuerdog calc and opted for the default / WB tune.  THANKS to Fuerdog for helping me out initially tho!
I noticed that by dropping the BUMP to half of the Rebound (that Fuerdog calcs) really helps when touching or on the rumble curbing.
(I remember reading in FMdaughtnet someone asked the developer about the "default" suspension settings and was finally able to wrangle out that they're about 90% "perfect" leaving the other 10% to individual tastes so, 90% is pretty darn good for me)

Why not keep the 3.73 or even go higher and use 3-4th?  (99%, except missle D's, of my D class cars (all of them have been run from Asia/Eur/NA) have FD > 3.5 and most are in the 3.7-4.3(AWD) range and that generally puts em at the rev limiter in 6th at Sunset Short)
Granted, even with the Race tranny/clutch, every shift costs about .05/0.1 sec so I can see why to keep shifting to a minimum but, seems that everytime I try the 2 shift idea at Tsukuba, I'm always slower than my 3 shift times.

Digression ---
I know that some like to have a tool for every track, but I'm more inclined to have a balanced car that I can use everywhere. That way, I'm used to the car tendencies and don't have to change thought processes (I'm "kinda" old) for drivabilty.

[Spiny Anteater]

Rat - hadn't realised you were a Brit too. That makes 3 of us with Moosejaw in as well.

Back on topic, I don't know if this will help, but I generally start my RWD tunes with a feuerdog set-up modified thus (don't you just love that word?

Multiply FD's spring settings by 0.9
Use 36 for the initial ARB value instead of FD's 24
Calculate rebound settings as with FD's calculator, then set the bump to half that value.

I'm not saying it's perfect, and it might not work for you, but for me it gives a pretty good starting point. Very often I don't even change the settings at all.

Incidentally, it's a long, long time since I ran the stock MX-5/Roadster races, but my recollection is more of oversteer than understeer.

[fndrbndr]

You're correct.  I was thinking oversteer, typed understeer.  Edited and corrected. 

I'll try the corrections to the fuerdog calc.  The bump settings aren't quite there, so that's a definite possibility.  I dare say that a better handling of the rumble strips could cut about a quarter second off those times, other than maybe Tsukuba, but it would help with one of my three time-losing turns there. 

And as far as that time at Diamondback, like I said, this was the best lap I've driven of anything in a while.  I'm going to try the hot lapping instead of tuning mode, see if I can post something at least that good.  I was about .450-.650 slower than that for most of my other good laps.

Edit:  Tried Diamondback again with this tune, to get a baseline.  I was right that I couldn't match that lap, at least not easily.  My best lap was 75.666.  I'll make some of the changes tonight (I think the bump change is up first, followed by tranny) and see if I can drop more time.

[Drift2XL]

Man I loved the Miata spec race.

It is exactly how I like a car to handle. Steerable on both ends.

Its not muscle/DOT tire spin. But there is a little bit of throttle control needed.

[fndrbndr]

If I could get a DOT muscle car to require that little throttle control, I'd be some sort of genius.  I've actually floored it just after the apex and NOT done a donut.  hehe

Edit:  I'd love to have a baseline for this, so if anyone else wants to post a miata time (or other RWD D Class, for that fact), I'd love to have some frame of reference. 

[fndrbndr]

Trailered back over to Laguna Seca to see if I could get closer to my MK2 time.  I could.  I adjusted downforce (I had lowered it a lot for Diamondback) and popped the tranny up to 4.00 final drive.  99.897.  This is a little over a second removed from my MK2 time.  It'll take a little work, but it's catchable.  This is the perfect combination of oversteer and stability for me, with just enough that I can power into a turn without so much that I get bad things happening.  I'm as fast as my ghost at the beginning of the track, and can get through the double apex at about the same clip.  After that, I start losing ground, and continue to do so until the end of the lap.  Suggestions would be welcomed.

Edit:  I went back to Diamondback, to see whether improvements on one track would transfer to the other.  They did, and I'm sitting at 75.053 at the moment, and have cracked the top 500 (92%).  I'm pleased with this car, but I feel like there's more there at both tracks.  At Laguna, I REALLY want to beat my MK2 time.  For Diamondback, I think I'm about where I want to be, but driving will allow me to break 75 seconds.  74.920 or better would get me into the top 400, which is about the best I can expect as a mediocre driver in a non-scoreboard machine.    Would I gain a little more stability in turns by messing with the toe, or is that a bad idea?  Also, was increasing the differential a good idea?
Oh, and here are my changes.

Final drive 4.0
Bump 4.0/3.5
Aero 65/90
Differential 68/50.

[fndrbndr]

99.416 at Laguna Seca.  I shortened the 4th gear, since I only use it in a couple of straightaways.  The new ratio is 1.24.  I also opened up the differential a bit to 55 accel, 50 decel.  I may open up decel to 45 later, but I've already wasted a morning that could have been spent on school work.  I'm encouraged, since I actually lead the MK2 through the first double apex and the onto the straight, and was within about two car lengths until the uphill straight leading to the corkscrew.  That turn (about 80 degrees or so?) has to be absolutely perfect with this car to carry 88-90 mph into that turn.  That turn wasn't.  It's not a bad time, but it's not the goal.  Actually, if anyone else has miata times (or other RWD D class times), I'd love to have some sort of benchmark other than myself in a scoreboard car.  And again, thanks for the help.  I'm starting to figure out what I'm doing with this thing, and in real life, my technical expertise stops at remembering the plug when I change the oil. 

[Ske]

I've got a pretty good Silvia S14 in D class, I'll get you some times later but I'm pretty sure I'm in the high 96-low 97 range somewhere (at Seca). I can run the Sprinter as well, should provide similar times.

You could probably get quite a bit of rubber by losing that intake, and I assume it would net you better times around Seca at least.

[fndrbndr]

Hm....now that's an idea.  Thinking the 14 hp I gain from the intake isn't helping that much?  I had gotten so focused on tuning the build I had that I forgot I could change the build.  I'll look into it at my next break.  Thanks for the tip/suggestion. 

[Ske]

14 hp on that kind of car is most likely a huge PI hit, and frankly for anything but missile tracks I'd go all the way with grip before even considering power upgrades