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Last track day was rad, no major issues, but some things that need addressed.
First, spark blowout when the car is hot. After a few laps I can't run more than 12psi or so. Last time this happened it was a failed COP. I'm tired of it, and replacing COPS every few years, so enter LS coil setup:
Just A mockup, installing later this week.
I also had an issue with uneven steering. I.e. the weight to turn left vs right was different, and wheel wouldn't self center after turning right.. initially thought alignment was bumped off but not the case.. long story short im pretty sure my steering rack was damaged in the wreck, it makes a slight clunking noise and has some free play that is not related to the steering u joint or telescoping column. So I'm doing a depowered rack conversion with a properly depowered rack i bought like 10 years ago. Felt good to pull the PS pump, its honestly been fighting me for years on the track overflowing fluid, inconsistent feel, etc.
Funny that you mention that you had issue with COPs and them dying. I just had the same issue with the Toyota COPs I've been running the last year. Scared the hell out of me.. Had me thinking I somehow blew my motor. I just bought LS coils and will be installing them this weekend along with some fuel system upgrades.
I also went with a properly depowered rack and am super happy with the feel. Low speeds it can be heavy but I kind of like it that way. I'm sure you will enjoy it!
LS coils installed! Wow, that was super painless. I kept them batch fire for now, they really should be strong enough that it doesn't matter all that much, and they wired right in.
The COPS had a tach output and the LS coils don't. I thought I'd have to run another wire for the tach signal on my TruboKitty ms3x, but I looked at the pinout and found that it was already wired into the black/yellow tach signal! All I had to do with enable tach output in ms3x and the tach started working again. And now the tach is way smoother and more solid looking, it used to get twitchy sometimes. Really neat. I also relocated the catch can in the newly free'd up space that the PS pump was taking up.
You can see the new rack here, and the SuperPro poly bushings I went with.
Another Friday night at the shop. Glad that the GTX has a built in party table (all 100% legal here in the great state of NM).
And a fresh alignment. Not as aggressive as before, but I wanted it more balanced. I.E. I've always liked how the car handled with 2.5* front and 2.0* rear, so I kept that f/r ratio and went with 3.0* front and 2.5* rear targeted. Also dropped the caster because no-PS.
And holy **** the car feels dialed! Uneven steering 100% cured. I know I've read this before, and it's cliche, but this de-powered rack conversion is the best thing I've done to the car in a long time. It feels GREAT, over 20MPH it literally feels like power steering just more linear. Parking lot speeds it's definitely heavy, but this car is a toy not a DD (though I do drive it to work sometimes). I really enjoy how linear it feels, my PS wasn't the best example because it was worn out, but PS always was inconsistent in its power delivery. My old rack was also found to have a LOT of play on center, I think the pinon itself was worn out, this new rack is so nice in comparison. It really has me amped on the car right now, it's crazy how far this thing has come.
A bunch of updates here but I'll make this short and sweet.
Pictures are out of order but here goes. Cars been on the dyno and had 2 track days since my last update. Last track day in August, I ended up running some 1:31.x's and ended up in 4th place in my class. Not bad, but not quite where I was at, still working my confidence in the car and myself back up, but drove safely with no issues.
After years of "tuning" my own car (thanks Vlad for the timing map), I finally manned up and paid a pro to dial it in. I got an EBC hooked up, already had a flex fuel sensor wired in (but never used it), and went to the dnyo (which is in a city 2.5 hours away - near where I go to race).
The car was tuned using flex sensor for timing, fuel, and boost curves. This makes it super easy to just fill it up with whatever fuel is available and go, so road trips, etc. in the car can still happen. With "allofit" on e85 we made just over 300whp. Note that the PSI ratings are a little off due to how the dyno was calibrated (basically we're starting at ~80KPA (5500 ft) and the dyno thinks anything over 100KPA is in boost). The runs that show 13.8PSI were actually 16-17 psi on the gauge, which as you can see is where the turbo (old skool gt2860) started running out of air. We tried giving it more EBC duty cycle to hold boost on the top end but we could only get a peak and fall curve, so we pulled that extra boost back out to keep a nice flat curve where the turbo was happy. The blue run is where we left the car for an "allofit" tune. The car made 243whp on 12psi on my map on 91 octane. The tuner played around with timing, added some fuel, and we settled on 254whp on 91 octane before switching over to the e85 map. 250whp on 91 seemed good enough and safe for the car. The car immediately made 275whp on 12psi wastegate when we switched to e85 +more timing and that's where I left it for track use with a switch in the cockpit for the "allofit" tune. The tuner seemed to know his **** and dialed in timing until a degree was only giving us a few HP, so we stopped there and pulled the timing back out once we reached diminishing returns.
He did all the pulls in 3rd gear for whatever reason, and assured me the dyno was properly setup to do pulls in that gear. I'd rather of seen the curve in 4th just because it looks really lazy in the graph when it's really not that bad. Full boost on a 4th gear pull is under 4k rpm, which has a great powerband for track use.
The next track day was 2 days after the dyno. Again, on the track I'm sticking with the 12psi/e85 tune which resulted in about 275whp, and I ran another 1:30.2x, which is near my PB and I was pretty stoked. This netted me 2nd place at the event. The car felt super dialed and easy to drive, so I can't wait to get back there to break sub 1:30.
I also installed a supermiata hybrid mount, which is AWESOME. A bit more NVH and buzz at idle, but it actually isn't that bad once the mount broke in. Other than the idle, you really don't notice the extra stiffness during cruise, etc. and at the track it was a huge upgrade. There was one particular right hander that would consistently cause my downpipe to rub against the steering column and that issue is gone, which makes the car feel way better.
You gonna be at Sandia on the 1st? I am trying to make it up there from Las Cruces.
Yeah! That's the plan, the cars all sorted, though I think I bumped the alignment off last track day. I should easily have that sorted in time.
Seeya there! Should be fun, I'm super stoked to see a new group of people and cars out there. Make sure to come by and introduce yourself. Will you have a car there? I know you hang out with the TF dudes, who else is coming from that crew?
Been a while since my last update. Had a blast with ddwelch, tftyler who came up to the track even. Nice cars boys and good driving!
I ended up with 2nd place in C class for the season closer, and a 3rd overall. Good fun, stoked for next season for sure.
Got some quickjacks to make racecar stuff much easier. I.E. rotating tires, brake maintenance, etc. Now with black fender.
The car has been running great on E85. Still been running low boost on the track, with high boost settings for fun on the streets.
MC brace from NAPP motorsports is pretty sweet. I dig it.
Got and installed a 9 Lives Racing Street **** and a spare trunk. It's a wild look but I'm digging it, looking forward to seeing how it helps on the track. First event is in a few weeks.
I have a bunch of little stuff in the works. Changing out my 550f / 300r springs for 800f / 450r. Still on stock billies so keeping it budget for now. Working on some more minor aero tweaks, with tire spats for the front wheels integrated into my front lip. Eventually hood vents. The goal this year is to get the aero / exterior setup and paint or wrap the car at some point. Hardtop needs some work too.
It may be just the photo, but that wing is a looong way back, not only is it loading up the rear tyres, it is levering the front up. Any plans for upgrading the front DF, I reckon the spats will need some help?
It may be just the photo, but that wing is a looong way back, not only is it loading up the rear tyres, it is levering the front up. Any plans for upgrading the front DF, I reckon the spats will need some help?
Ha, it's not just the photo, it sticks out like 7" past the bumper. I totally get what you are saying about leverage on the wing, that leverage increases downforce, but also the rear wheel acts as a fulcrum and can add some lift on the front. I'm no expert, but AFAIK that's part of the design. A smaller low drag airfoil mounted further back to give it more leverage/downforce for its size. It's supposed to be "balanced" without a front splitter or major front aero. They said it generates ~200lbs of downforce so nothing too extreme. I'm also bumping to 450# springs in the rear which should help.
We'll see! Do you think it needs front aero to balance out? Looking at pluca's simulations I'd say my front end is already somewhere similar to #3 (hopefully better?), which means the front end of my car went from -106 to ~60 lbs of downforce. Reading the massive DIY aero thread on this forum I learned that much of the lift in the miata is in the rear, so I'm kinda hoping things will get close to balancing out without having to run a splitter, since I street drive the car fairly often. The rear is always moving around on track so that's what I'm trying to eliminate. In the end I'm not looking for major DF with this setup, just low drag and zero lift, and maybe a bit of DF.
First up, changing springs will not alter the aero balance or lack thereof. It will alter handling at the rear (especially in the slow stuff), but the leverage on the front and DF on the rear will be unchanged (I think, someone correct me if I have this wrong).
To me, the notion of tweaking wing location/size to reduce the need for more DF at the front seems inherently flawed. However that presumes a balanced car to start with - if I had a loose rear end that I wanted to tame a little, I'd use a MSM-type spoiler. I did that, went from a stock NB boot to an MSM-equipped boot, and a 170kmh corner stopped being a bum-tightener that required constant corrections and became much more manageable, and that little bit quicker. This was an aero issue, car was fine on slower corners (as you say, they generate lift at the rear). If I had a beast that wanted to swap ends all over the place, I'd take all the aero off, and ensure that the chassis was dialled in, producing at least acceptable if not great handling in all conditions I was likely to find on the tracks I use, and then look at how much faster I wanted to go and aero up accordingly. That gets complicated when it is also used on the road, but there are plenty of ways of doing quick removal splitters etc.
Ultimately you need to decide what is most important - bringing home pots from the track, or having fun on the road. If the latter and you are going to get frustrated not being more competitive on the track, it is time for a dedicated racecar.
First up, changing springs will not alter the aero balance or lack thereof. It will alter handling at the rear (especially in the slow stuff), but the leverage on the front and DF on the rear will be unchanged (I think, someone correct me if I have this wrong).
To me, the notion of tweaking wing location/size to reduce the need for more DF at the front seems inherently flawed. However that presumes a balanced car to start with - if I had a loose rear end that I wanted to tame a little, I'd use a MSM-type spoiler. I did that, went from a stock NB boot to an MSM-equipped boot, and a 170kmh corner stopped being a bum-tightener that required constant corrections and became much more manageable, and that little bit quicker. This was an aero issue, car was fine on slower corners (as you say, they generate lift at the rear). If I had a beast that wanted to swap ends all over the place, I'd take all the aero off, and ensure that the chassis was dialled in, producing at least acceptable if not great handling in all conditions I was likely to find on the tracks I use, and then look at how much faster I wanted to go and aero up accordingly. That gets complicated when it is also used on the road, but there are plenty of ways of doing quick removal splitters etc.
Ultimately you need to decide what is most important - bringing home pots from the track, or having fun on the road. If the latter and you are going to get frustrated not being more competitive on the track, it is time for a dedicated racecar.
I agree the car should be balanced without aero, as well as with. The spring rate change is not just rears, I'm going from 550F/300R (definitely undersprung for my tires) to 800F / 450R, The spring rate was not changed because of the wing or aero, it just needs more spring in general.
As for aero balance, I'm pretty sure the car is aero unbalanced without a wing coupled with my GV lip, with more lift in the rear than the front. Of course I have no way of proving that, just the conclusion I came to after reading the aero thread, seeing some aero simulations, and feeling the car on the track. The car is nicely balanced in lower speed corners, but over 80mph the rear end "wiggles" or feels "twitchy" and wants to come around.
I went with this choice of wing because it's supposed to be aero balanced with no front aero, and I also happen to like the looks compared to a huge wing that would definitely unbalance the car without a large splitter. It's stated that this wing "stops rear lift", so my understanding is that it's not adding massive downforce to the rear cantilevering up the front. We'll see if that's true soon enough!
I always appreciate the input though! And this car has to be a balance of street and track, I don't have a trailer, let alone a tow rig to make a dedicated racecar happen at this point. I drive 3 hours to the track, race, and drive 3 hours back. It's not ideal, but it's where I'm at right now. So the idea for now is mild "street" aero, targeting zero lift, with the idea that I'll upgrade to full aero package down the road. We'll see what kind of front modifications I need to keep up with the rear, but according to people who know more than me this should be aero balanced with no front aero. This wing is part of the 9lives racing "low downforce kit" which is coupled with only a bolt-on front lip. They even go so far as to say that front aero is super easy to achieve on a miata, and that if I do a splitter/dam setup I'll be unbalanced with this wing and they recommend their big wing for that.
Understand. BTDT with progressively building a racecar that was street driven, then building a trailered dedicated racecar.
Agree front aero is 'easy' initially, I guess I would (did) choose a different path to fix the rear end lift issue (never occurred to me that a high-mount rear wing might be an option, but that was a while ago). I will be really interested to see how that works out when the rubber hits road so to speak.
I'd disagree about suspension tuning vs aero. But it depends on the level of commitment. If you're going to be seriously increasing grip with aero you're going to be able to make a shitload more in the back than the front on a production car, so you're either going to have to limit your max total downforce to keep the car balanced or you're going to have to change the suspension so that they car would be undrivablely loose without the aero.
I'd disagree about suspension tuning vs aero. But it depends on the level of commitment. If you're going to be seriously increasing grip with aero you're going to be able to make a shitload more in the back than the front on a production car, so you're either going to have to limit your max total downforce to keep the car balanced or you're going to have to change the suspension so that they car would be undrivablely loose without the aero.
Good discussion going on here. Ideally aero is fairly balanced F/R (so that the car handles the same way at slow speeds as high speeds), so the spring rate f/r ratios should stay the same, but the rates are increased to handle the extra loads of the downforce + the extra grip the car will make.
In my case I have some 450's laying around that used to be on the front of my car, so I bought 800's to go with them as an experiment. First, can the Bilsteins handle them at all, this might rattle my teeth out or suck on rough parts of the track and make me go xidas after the first few drives. Second, will this F/R ratio work well with my car and aero setup?
Here's some data on that wing (mine's actually 48" which is V2 of this but the same mounting style with a bigger airfoil).
And the data from some common front end simulations:
#3 is close to mine, and I'm doing some fender spats and going to connect the lip to them like in #4 (but without with the big splitter). I think this setup should be fairly balanced, but if not I'll be moving more towards #4, or doing #5 on my car eventually.
Oh that wing is making less downforce than I assumed and certainly isnt a mega downforce wing like mine was, I was more like 300 pounds at 70mph and the style 4 lip but extended to the style 6 length forward, it wasn’t even close. And remember what’s not shown in the downforce data is the straightening effect from the end plates and those wide section mounts.
You could always revalve your billies at home with restackor. I’vebeen doing that with my mtb stuff and it’s the same concept.
07-21-2022, 02:22 PM
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