Doing some drag
 

My goal with this car has been to get an 11 second pass out of it on a street tire. The car is finally starting to make the power to do it and I'm getting all the kinks worked out. I took it out to a local crappy 1/8 mile track to see how it would do before I drive 100 miles to the nearest 1/4 track.

Traction was terrible, I was spinning into 3rd gear, but the mph seems decent. Really hoping it'll hook up a little better on a decently prepped track.

https://www.miataturbo.net/attachmen...ine=1450102628

That's moving, congrats :)
Assuming the online 1/8 to 1/4 converter is accurate, that car should definitely hit 11's on proper tires. You'll likely need slicks though if you don't want to break stuff

It traps high enough to run LOW 11's.

Thanks, I was pretty happy with the trap. The tune is actually still way rich, and I'm gradually leaning it out so I think there's a little more power in it. The trick is going to be getting off the line.

There was a Cobb AP tuned GTR trapping 90mph, and a C7 that was trapping 92mph pretty consistently. Made me feel pretty good that my shitbox had more topend than those two.

Here's the virtual dyno numbers. Blue pull was the first pull to redline on a new fuelpump. Red line was the tune I drag raced on (like I said, still pulling fuel in boost).

https://www.miataturbo.net/attachmen...ine=1450192670

Wasnt it your rule that online automotive calculators = cock slap? :fawk:

Your MPH is high enough, but your ET is not.

Quit fooling around and get some tires. 2.XX 60' times are the most boring thing ever on a drag strip. 1.7 and faster will start to put a pretty good grin on your face.

I've looked at drag radials a few times, but I just hate to spend that kind of money on a tire I really only intend to use for one trip to the drag strip.

If I did go that route, what would you suggest? My 205 Kumho V720's are mouted on 15x8's, but I hate to mess with those and I really don't want to buy more wheels. It looks like they're coming out with a 225 in that tire and I considered swapping out the rears to gain 10% more thread, but I don't know how much that would help. I've got a spare set of 14x6 NA wheels I could use. It looks like Nitto makes a 555r in 205/55/14 that's reasonably priced. Would that be a good option or do you have a better suggestion that's not going to set me back +$500.

Troy will say wrinkle wall slicks, I bet.

I would suggest Spec Miata Hoosier takeoffs as a compromise because they are free or nearly free. They will be slower than wrinkles but will be streetable. The rain compound is even softer and not hard to find, but does usually have a tread pattern.

I'm cheap.

I wouldn't do that.

My buddy tried this many times and they sucked more than his street tires.
He couldn't understand how slicks can be so bad, but road racing slicks are quite different and really not meant for this sort of thing (IMO)
You want soft wall, hard will just make it worse even if the rest of the tire is "slick"
Wrinkle wall or go home

Looks like the Nitto's I was considering are no more; not listed on the Nitto site and everywhere that lists them for sale is "out of stock". All the full slicks I could find are +$200 a tire. I would have thought there would be something out there in that size (or similar) for the Honda guys.

Agreed. I put Mickey Thompson ET Street radials on my 99 a few months ago, best thing ever. Went from spins from a roll on concrete to hooks in 1st. Now I have the power turned up similar to OP and it still barely spins 1st. I drive them on the street, luckily Houston is pretty dry.

ryan still spun, but at least the car stayed intact, just sayin

https://www.miataturbo.net/attachmen...ine=1370804071

Is that shit running?! and no updates?

wtf bros.

haha nah that was from a long time ago at only 360whp :)
it's not running with the new 1000whp setup....yet

Damn.

Yeah A6/7s and R6/7s are no bueno for drag launches. Best I can do on unprepped surface with them is 1.9xx, usually 2.0s and 2.1s if I suck. Never done it on prepped surface, but other people say its bad.

My best launches have been in 2nd gear and leaning heavily on launch control and post launch boost and timing corrections in MS3. The car hopped something fierce otherwise, 1st gear was pointless, to the point that I was expecting the torsen to give up the ghost

The clutch is not an on/off switch. I learned that lesson the hard way.

+1

I was about to say, "so did aidan" :giggle:

:fawk:

Using road race slicks for drag racing is like wearing hockey skates to play football. You got to wear the right shoes for the sport you are playing.

You are right about my recommendation though. In a car that is already making enough power and clutch to utilize them, no other modification will knock more time off your ET per dollar spent than a properly sized set of slicks.

I ended up ordering some MT ET Streets in 215/60/14. Going to put them on my stock na8 wheels and see how they do.

Are axles usually the first thing to go or is the rearend? I though about buying an extra axle so I could just swap it at the track if I break one.

Wheelhop will break torsens at 220hp.

Troy was breaking them when the wheel hub center was not aligned with the diff due to ride height. The axle shaft should be in a straight line and the cv joints not bent for best results.

I can't help but think that "The axle shaft should be in a straight line and the cv joints not bent for best results" should include the words: "at squat on launch"

Just got home from the 1/4 mile this time. Car ran fantastic 100 mile drive there, made 5 11 second passes, 100 mile drive back home.

I couldn't get the car to launch for crap. It was either bogging really bad or blowing the tires off. I think with a halfway decent driver it would have been sub 11.5 all day.

Best ET was 11.68, Best trap was 124.18.

https://www.miataturbo.net/attachmen...ine=1452971919

DUDE!!

That's FAST!

Congrats. :likecat:

Very nice! That's damn fast. What tire/LSD were you running at the time?

215/60/14 ET Street Radial on a stock NA8 wheel. 3.90 torsen and a 6 speed.

I may try again in a month or so. The alignment is maxed out in the rear at -1.8 degrees and I can see a lot of wear on the inside of the tires. If I go back I'm going to raise it an inch in the back so it'll bring the camber downs some and hopefully help get off the line a little.

yeah, many drag guys actually run positive so that when it squats the wheels are at 0* and the axles are perfectly horizontal. there's lots of little tricks to it, but you're already smoking fast. c6 z06 fast.

I think you can do a lot better on those tires. What tire pressure are you running?

I'm running that same tire on a 225-50-15 on stock wheels and I've run a 1.76 60' when I had 35 PSI pressure in them. I aired them down last night to 16 PSI and found out these things hook like crazy when aired down, enough that I smoked my ACT XT trying to launch it without bogging at 20+ PSI on launch control. I'm at -1.3 camber in the rear.

They're at 15psi.

I think setting up launch control and leaving in 2nd would be my best chance for a good '60, but also my best chance to scatter chunks of drivetrain all over the track. I definitely need to figure something out because there's certainly more left in it. I'm just totally lost when it comes to setting up a car for drag racing.

If you have any datalogs of the launches I could look at them and see if I can find anything to improve your launch. I launch in 1st on my car. If you car spins in 1st you can setup launch control to pull timing to soften the power in 1st for traction/drivetrain happiness.

Also I'm guessing you were not using launch control? If so, that will help 60' a ton, turbo car without launch control is HARD to get a good 60' because no boost...

if 2nd helps you leave softly without bogging or wheel hopping, it likely wouldn't be any harder on the drivetrain.
hard bog/hop is what kills it the fastest

you'd have to really up your LC rpm tho

Correct, I wasn't using launch control. I've played with it a few times on other cars but never could get it working right. I'm pretty much retarded with megasquirt with anything beyond adjusting a fuel/ignition table. I didn't datalog any of the runs, in retrospect that probably would have been a good idea.

First off, amazing results so far, and congrats on accomplishing your initial goal, not only did you run a good 11second pass, but you dove deep into the 11s compared to where you were before. I'm certainly no drag racing expert, however from my personal experience here are a few ideas/ tips to possibly help you out.

First thing id suggest is making small changes to the setup at any given time, like 1 change at a time, then go out and make a pass. The more changes you make, the less effective your progress is going to be. If you choose to change tire pressure, only change tire pressure so you can diagnose your time slips on comparison to your previous slips.
Learn how to read, and analyze your time slips, it helps you to learn what you did or did not do correctly on particular passes.
As others have said, a proper launch control is going to help you a lot in the long run, it's one less factor you need to take into consideration while launching and will also help you remain consistent, consistency is key here.

Another thing to keep in mind is that if you focus on lowering that 60', your end et/ trap will significantly be impacted by that, for every fraction of time you can take off of the 60' it will reflect 10fold by the end of the 1320. A 1.7 or 1.6 60' with a clean run would have likely put you into the 11.3/11.4 range assuming you hit all of your shift points.

Buy yourself a digital tire pressure gauge and check pressure before and after each run, also the taller the tire you can fit, the better that will help your gearing out.

What gear did you cross the line in and at what RPM?
Post some pics of the car with the track tire setup, I'm interested in seeing it :)


Best of luck to you the next time you head out, and remember that the only person you are in competition with is yourself.

I cant read.

This is what your car will launch like with your tires once you get launch control setup and dialed in. It makes ALL the difference. This was a 1.74 60'.


This was a 1.75 60'


Pic from one of those videos:

https://www.miataturbo.net/attachmen...ine=1453709147

hahaha picking up the nose like a boss :likecat:

Will it do a 45 degree wheelie? :)

--Ian

It doesn't have enough power to do that. But I was launching the piss out of what it has!

Needs moar powah. I want to see wheelies! :)

--Ian

Agreed. I think another 100whp or so it would pull the wheels in 1st if it hooked. Hmm....

I'm really shocked at how soft your suspension is! even just from a small tap of the throttle, the car rocks back.

30 lbs of love.

That's hookin' up! :party:

Finally got a couple in-car videos uploaded of my runs.

The AMG staged with the back wheels in the first run, I wasn't expecting them to run us like that so I wasn't ready and left super late.



A bunch of people told me they recorded videos but I can't get anyone to send them to me or upload them. I don't feel like my car squats at all, certainly nothing like Pat's is doing.

Nice run! It sucks when they let someone stage on the back tires, I've had that happen to me too... Funny to see you running down a AMG!

Your car is part of why the Whipple is coming off and the turbo going on. How much boost are you running?

Noiceee!!
That car will do 10s with well set up lc/ffs

Thanks, yeah I felt good to end up catching him.

For those runs it spooled to 14psi then gradually creeps up to 19psi (crappy wastegate design).

https://www.miataturbo.net/attachmen...ine=1454552792

I swapped it back to a lighter spring now and trying to tune EBC so I can raise the boost when I really need it. I feel like I'm going to kill myself if I keep trying to drive it like that all the time on street tires.

If it's creeping due to poor wastegate flow, then the spring isn't going to get you less boost at the top. What WG do you have?

I keep thinking that one of these days I should take mine to a drag strip just to see what it's like. :)

--Ian

@pdexta - what's your rear spring rate? Based on your videos vs. Pat's - it looks like there's a big spring difference.

It's a Tial MVS, the concensus was that the location was bad. It creeps ~5psi from 3500-7000 regardless of what spring is in there, just starts from a different pressure.

https://www.miataturbo.net/attachmen...ine=1454595997


Whatever BC Coilovers come with, I think they're 8k (450lb) rear springs.

fwiw- I've read that your WG port location is ideal. I've seen it on a lot of race cars- including AAR's Toyota prototype (long tube manifold.) But what I don't know is to what degree the angles of the port impact the performance. Or what putting the EWG so far of the port does. The AAR gates were on a short stub at ~45 angle iirc. Need to find the photo/story.

Wonder what a softer rear spring would do for your launch/60ft.

I made a thread a while back about the creep and everyone seemed to agree that the 90 right off the turbine housing was the issue.

From watching Pat's video softer springs would definitely help, but I was happy with how it ran and don't have any plans to swap suspension out. They were already threatening to kick me out if I went 11.49 without pants, firejacket, and 5pt harness so if I do go again that's my only goal and I think that's possible without any changes.

You need more power on the launch, not less spring. Car bogs hard on your launch. I'm on the bump stops anyway when I launch. Launch control around 15 PSI one pass would get you kicked off that track. :)

I think the gas velocity where your gate ties in is very high, and you have a sharp 90 there. Putting it at the manifold (slower velocity, easier for exhaust gasses to turn into the pipe for the gate) or maybe porting the turbine with a round edge going to the gate would help. Short of making a new spot for it.

The best passes I made were when the car bogged, if I launched harder it would spin and I'd have to peddle it and end up being slower. I think you're absolutely right about launch control though. I'm just too dumb to figure it out without some major hand holding.

I've got a brain built diypnp that has 4 output wires; power, ground, o2, and ebc. I've read into adding launch control a few times but as soon as I take the case off the MS I start crying and frantically try to put it back together.

Yeah without launch control setup, you can't launch very hard without blowing the tires off.

I can't tell you how to wire it inside your computer, but I'll help you get the settings dialed in, I know how to do that.

Launch control is building boost that pdexta's rev-n-clutch-drop is not?