Doppelgänger

iTrader: (12)

Thank you. I like having a car that performs as well as it looks...it's quite the challenge.

I'm running a FM rear bar on the middle setting and a FM solid front on the soft setting...though i've thought about going hard to see what happens. The car is ver sharp and stable on entry but I was having trail-braking issues that hopefully my Brembos will take care of. As for transitions, I can get the car to do what I want with the throttle pretty easily. But remember, I did do a lot of competitive drifting for quite a number of years so I naturally like a tailhappy-ish setup....on-throttle rotation can be fun and impress the "old dogs" at some events

I wouldn't mind having someone else drive the car to evaluate it though...someone who knows the game well.

flier129

iTrader: (7)

Poly bushings!

Chris Swearingen

iTrader: (1)

I am running a Walbro-255 in the tank and what used to be a rising rate fuel pressure regulator that was on the car when I bought it. If you don't connect the vacuum line, viola' it becomes just a fpr.

I have not been able to find much information on the MS traction control. It wasn't terribly popular in the MS-I which is why it didn't make it to MS-II originally. You may have found my thread on MSextra.com where I have been lobbying for its return.

My off season is hopefully pretty light this year. I am most likely going to upgrade to 1000cc injectors. If they appear to balance the EGTs I won't add the individual gauges to each cylinder. I am swapping out the popups for fixed headlights. I need to redo some mounts for the passenger side Kirkey seat and get the stocker out of there.

Then..... depending on what I think the total weight difference may be I might put in a cage and fuel cell. I am definitely going to run SSM another year. (I am glad to see more Miatas coming into the mix) After next season, the car is going to see some time trials, time attack and maybe some door to door track activity. That means I need the cage at some point. If I can do the cage/fuel cell and stay within 20 lbs of non caged weight I will do it this year. There is still more HP and torque hiding in the motor. If that number goes up to 350+ I will probably be okay taking the weight hit for cage

They way I read the rules (somebody make sure I am not just reading what I want to hear) I can gut the doors and door panels to install nascar type bars on both sides. That will offset the weight somewhat. Then I just need to figure out a dash bar. I am thinking of making it a low hoop over the existing dash, so that if the windshield gets removed at some point for XP or track stuff I can just remove the dash under it. Any thoughts? I don't want to hijack this thread. If you want me to start a new cage one I can, or since it is sort of a SSM debate, weight versus stiffness maybe it should stay here.

webby459

iTrader: (8)

Chris, not a thread hijack at all, so don't sweat it. Obviously for the most part you will be building the cage for the wtw racing ruleset; what class/sanctioning body would you be looking at? If you don't have your own source of info for it, I can get in touch with a guy I know that builds and races SMs and get his total cage weight and tubing specs, and what weight he saved/gained from gutting the doors to add the nascar bars. I think quantifying the additional stiffness from cage installation may be difficult, but I'm sure it is substantial.

Chris Swearingen

iTrader: (1)

Double post, see below.

Chris Swearingen

iTrader: (1)

The more data the better. If you don't mind asking the weight question I would appreciate it.

I am looking at the SCCA GCR rule set, but a supercharged Miata really doesn't have a "good" place to play. ITE-U is kind of the catch all. Part of my issue is the front hoop. If I leave the windshield, the continuous hoop "should" follow the windshield header. I am betting I remove it in a couple of years so I want a lower front hoop.

Patience may be the key. Trying to keep the car SSM legal limits me. IF I were going the full XP route, I could take a lot of stuff out of the way and do things differently.

I have been in a few Spec Miatas and didn't like the cage placement near the drivers foot. I am still trying to figure out if there is a way to have the front hoop terminate at a spot on the floor, so that I can use it as the dead pedal and not have it against my ankle.

In a perfect world, I would have a cage that is a) SAFE, b)SSM legal, c) XP legal, d) functional with or without a windshield and dash and e) legal for SCCA ITE-U, NASA, Redline Time Attack, and Formula the D word we don't use around here again with or without a windshield.

I am just starting to toy with the idea, so I really haven't done enough of the research to know if all those goals are attainable.

I agree that the chassis will be noticeably stiffer but, back to the SSM content, will that increased rigidity offset the weight penalty? It would be great to know how much the CG of a Spec Miata goes up with the installation of a cage.

The setup will have to change a little as some of the chassis flex that used to dampen body roll and wheel inputs will be gone.

webby459

iTrader: (8)

When I talk to my contact, I will update. He said he prefers to buy a 'seasoned' tub for some of that flex you mention above.

About the windshield header bar being lower than the windshield header itself, do guys building XP cars do this? It seems that, especially in a track situation, you will have helmet broomstick clearance issues by putting the front of the halo any lower than maximum possible height.

About the front hoop to floor, I know the autopower off the shelf kits have that bar in front of the dash, in a terrible location wrt driver's leg. Take a look at this from miatacage.com: http://www.miatacage.com/images/lowe...c562d477f98e3f
This looks like instead of acting like a dead pedal, this cage clears your leg well and won't obstruct a real dead pedal. Their cage has a bar behind the dash, I have no idea if that's SSM legal, but it should be SCCA/NASA, XP, RTA, and FD legal, I would think. I will try to get a pic of my contact's SM cage wrt down bars, too.

Getting back to your car, reading your post in the brake thread made me think to look at your brake setup. Have you ever thought of going to a bbk, specifically with a two piece rotor/hat, like what Emilio is selling now. He quotes a 12# total weight reduction over stock, of course unsprung. I am not adding lightness at this point in my build, but this combined with a tubular suspension arm (so do we have to follow the SP one arm per corner rule 15.2.E?), could really reduce unsprung heft for you guys at the top end.

One more thing for everyone, what kind of chassis bracing are you using? I have frame rails, which are a no-no and will be removed in the off season. I will miss them, as they WORK. Something as simple as the 949 front and rear sfc's? The triangular beatrush is illegal, I think, because it connects the rear subframe and ppf together, right?

Chris Swearingen

iTrader: (1)

A true "XP" build would only have a roll bar not a cage. Look at DP. The broom stick has to clear the helmet from the front hoop to the rear hoop. You can adjust the height of the rear hoop if needed. It may look a little funny with the windshield still attached, but it only stays on for SSM.

The dash bar should be legal, but with a low front hoop it may not be necessary. Running the braces through the dash/firewall forward may be more difficult with the dash still intact.
I have considered it. Just haven't done it yet. I would be afraid that it will push the bias back forward. It will probably happen before the first non time attack type track event.
Correct on all assumptions. I am just using the stock lower braces and calling that good enough for now.

webby459

iTrader: (8)

Guys, the thread on the other boad, 'So SSM now...', got me thinking about what a money no object(ish) SSM Miata build would look like. Do you think an NB is intrinsically better wrt a bit of a larger tire fitting? How much of a problem is getting heat in the tires for you? What about a bit of a heavier car to fit the min weights with a bigger tire, to heat the tires better?

I know a real money no object deal would be some sort of 4 rotor or rotary with turbo monster, but what about with a miata engine? Midtenn, if you're still out there, in your convo with Jeremy Schuster, he kind of glossed over 'intake' in his email. Any idea what was there? Looking at high-powered build on this board, the intake MAY be the limiting factor in making huge power in this engine.

My thought is 1.9, 99 head, ported at the flow bench, cams selected and degreed on the dyno, custom intake, ~2860RS or a serious s/c like what Chris has) on a shortie, short charge pipes (a la the tube front drifter on this board), v-mount ic, maybe water inj (I don't think meth is allowed per the rules?), tune optimized for race gas. CSP style flywheel/dual plate clutch (high idle, anyone). Maybe we could source a sequential gearbox so that the engine could be a little peakier than normal.

ECU, something with high resolution tables and a VSS based real traction control. AEM, adaptronic?

Suspension, similar to what Chris has, with custom made chassis bracing. Maybe have a second set of dampers and springs, heavy/light setup depending on site quality: 800/~475, 1200/~650. Largest tires avail/practical as per 1st paragraph.

Brakes, try to source a small 2 piece rotor and lightweight alum caliper.

Add in what you think. Have fun.

Chris Swearingen

iTrader: (1)

There was a pretty long thread on SCCAForums.com about a year ago on this subject. SCCAForums.com - SM2 NA/NB Miata Build

Midtenn

iTrader: (15)

Jeremy ran an ITB setup with a custom plenum.

I have to disagree with starting with a NB chassis. If you're running SSM seriously, just be prepared to cut the fenders and bolts on some flares. the NA chassis is inherently lighter to begin with, so starting with a 90-93 and doing a 99+ swap is your best best.

webby459

iTrader: (8)

I read this a while ago, and read it again today after your post. I was kind of thinking of taking that further. Example, in that thread it was said TC, but not how to implement, assumed 275 was the tire of choice, assumed that the GT28 was the turbo, etc.

FYI, I messed around with rev control in my MS1 the other day at my shop. Just to get it so it wouldn't cut power in first gear in a controlled roll-out, you would probably have to set it to cut at ~4000 rpm/sec or more. The question is if this threshold is enough to do anything in second gear. Effectively, without having vehicle speed sensors, a way to switch it on/off once you are in second, or have it know what gear you are in, you will have to basically give up acceleration in first gear in order for it to do something in second. Again, this is without doing much work, or even reading much on how the system works, so I could be off base.

Anyway, I posted this after thinking about what was going on in the thread on the other board re SSM. I find it hard to fathom why an SSM car wouldn't have a CSP car beat on the autocross course. The assumption would be that the extra power with fi in the SSM car ruins the car's balance because of weight or power delivery. Is this really the case? If that's so, could it be possible that I am better off with my little 1.6 making 220 than a much more radically tuned 1.8 bored to make ~300? Would a well-prepared CSP car with a well done fi system be a class-killer in SSM? Would a maxed out n/a engine be better, as is being discussed on the other board? 1.8 stroked to 2.0, high comp, cams, ecu with a radical tune and a huge redline?

Further, what about Bill S's question about running a bigger tire on the car? It doesn't seem that there are any tires wider than the 275 with a diameter equal to or smaller than it. And Chris, you said that you contact your bump stops at the same time as your tire hits the top part of the inner fender? Is this in the front or rear?

I have my set of 275's in the basement, wheels will be on order within a week. The '90 will get a 1.8 engine transplant, new exhaust for my GT2560R, then it will go to the body shop for whatever it takes to fit those 275's under the fenders. If it's roll and pull, so be it. If it's flare, so be it. The question is, will it fit a bigger tire than the 275, and will it benefit from a bigger tire and the additional weight per the weight rules for the class?

And, in the end, can it beat the RX-7s in the class?

Midtenn

iTrader: (15)

It is yet to be seen. The 3 top RX7's in the class have years of development behind them (with Dan Chadwick's have even more improvements to be made). I basically plan on nearly cloning Jeremy Schuster's car as a starting point (with many of his "old" parts actually, haha) and he was definitely competitive back when he ran Solo.

Doppelgänger

iTrader: (12)

Well yesterday finished up the season for me. I got second (a whopping 1.064 behind first). I secured 2nd in SSM for the year out of 23. Got 22nd fastest time out of 150 people.

I need that fuggin OSG diff.

Chris Swearingen

iTrader: (1)

I was talking about the rear.

You can't put a bigger tire in the rear at any reasonable ride height without having essentially a 0" back space, because you can't alter the tub inside the hub face.

I really hope the answer to the last question is YES. I have spent a couple of years trying to prove it but haven't had much success yet. The goal for next year is minimal changes, lots of free wine courtesy of Bill, and having something to keep the rx-7s thinking about.