Gunpilot

I have been to the Texas Mile a handful of times. Mostly I have been a spectator and watched many cool cars run. If you don't know what this is, it is a closed runway where you get to run wide open for a mile straight. Record is 270 in a Fort GT. https://www.texasmile.net I did do one pass in a Mercedes S63 AMG. Hit 165 and earned my class B license. I am allowed to go to 180 now, but don't think the little Miata will do it. I have been preparing for a while and here is where I am.
- Dynoed 405 to rear wheels
- LS2 with mild cam and ported heads
- T56 from 2006 Pontiac GTO
- Getrag 3.42 from a Cadillac CTS
- Tires are a 225-15
- Added a lower lip for some down force
- Reinforced front mounted oil cooler so it does not push into condenser
- Balanced all wheels and inspected suspension
- 4 point rollbar
- hard mounted the hardtop

The car is running great and I hope to get multiple runs. Unfortunately it is supposed to be bad weather, but we will see.

GoKart

With that power you should be good for ~120 in the 1/4 mile. I don't think 165 would be too hard with another 3/4 mile.

With that said, I'm a little weary about the aero of a mostly stock Miata at speeds above 140-150 mph. The first few times I've had mine up in that range (yes, it was in Mexico ), I had major pressure buildup under the front end. Hood vents helped quite a bit, and I imagine a front lip may help slightly too.

If it were me, I'd add some sort of under tray from the front lip, back to near the front axle to alleviate front pressure. I'd also think about either cutting the rear bumper or adding some sort of rear diffuser to reduce rear end lift.

I may be talking out of my *** or worried for nothing...but after seeing my hood bulge up 1/2"-3/4" at a mere ~140 mph, I came to the realization that a stock Miata was never designed to do more than what ours can do in just a 1/4 mile sprint.

Gator Bait

I was a bit north of 150 a few times this past weekend. I have a aftermarket front nose and my rear bumper is trimmed. I have no hood vents or belly pan. The hood is straining at the pins and hinges at those speeds but it hasn't gotten 'too' scary. ...or I've gotten used to it... btw...that was with the soft top up.

We have the same gearing. I'm making 445 at the wheel and trapped 126 in the quarter.

I would sure love to do the TX Mile, but not in the cards yet again this year. :/

Gunpilot

Ill take it easy for the first 2 passes as I shake it all out. I'm using aero catch pins and am pretty confident in them. No hood vents and no belly pan either. I hope to get at least 160. Gearing will be an issue for sure.

In the picture, you can see the R package front spoiler and the aluminum bars I added to the bottom of the oil cooler. I am hoping the lip will give me just enough down force and the oil cooler support will keep it from flexing and breaking off the upper support and damaging my condenser.

I have been trying to think about all the things that will happen around 140. That is a lot of wind!

charchri4

I'd be a bit concerned about not having hood latches behind the headlights. These hoods like to lift right there at speed so at least tape the gaps around the headlights.

I ran mine past 140 a couple of times with just a cheezy JDM lip and you do loose feel of the road in the steering quite a bit that way.
After I put my wing on it got down right scary so I made a splitter this year.

This is all trial and error for me but I found a $40 hunk of plywood makes a HUGE difference after 130. I ran mine back to the steering rack mounts so it's as smooth as I can make it to the oil pan. Before I lost the feel of the road past 130 but now she feels like 100 still at that speed.




It helps for catching frogs too...


I can't wait to hear how it goes for you. Best of luck and be safe out there!

Gunpilot

I agree on the headlights. I made sure my light covers were in line with the hood so air does not ram into the engine bay. I was also planning on taping those but leave hood edges open for air to escape. Originally I was going to run with no lip, but I took it off my other car last minute and installed it for the event. I also ordered a different style lip that has a more pronounced downward edge but it is not in yet. I would love a splitter with canards to keep the front end down, but have not had time to engineer that yet.

Gunpilot

From my calculations with 5th gear at .84, rear end 3.43, 225/45/15, at 6200 RPM top speed should be about 160. Time will tell. I just hope for a dry track.

Gator Bait

How so? Too tall?

charchri4

You are on a 23" tire with 3.43s. I'm on a 25" tire with 3.55s.

Not sure if that works out to even but I'm at 135 at the top of 4th at 6500 in a 1/3rd mile run from a rolling start. And she was still pulling unnervingly hard.

Granted the difference from 135 to 170 is a heck of a lot different than from 100 to 135, but if your numbers are right I think you would be right in the sweet spot of 5th at 6200 and my hunch is the speedo would be closer to 170.

Michael what is your gut hunch on your cars speed at the top of 5th in a mile?

I feel like my car would have no trouble exceeding 160, the driver on the other hand not so much...

Gator Bait

I don't have one. My wife claims she saw the needle at 160 Sunday when I ran the Lambo, but my eyes can't refocus from road the gauges quick enough to ever get a positive mph myself. And I don't have a good idea how long the pull was (roll from ~65 in 3rd); I was concentrating on everything else too much. Way too much going on when making those kinds of pulls on these Mexican closed courses. I was in 5th at the end of the pull.

I also use the conversion box that drives the OEM NA mechanical speedo. It is dead accurate at 65 but I never tested it above that.

Gunpilot

And off I go

Gunpilot

Wow. Their are a crap ton of cars here already. Usually you can get here Thursday and get best runs on Friday while others are just arriving. Car passed tech, and I got all the window stickers I need to run. Paddock opens at 630. First run at 830. Hopefully I can get 2 in by lunch.

They have one of those jet engine drying trucks here like NASCAR uses in case of rain. They are even gonna open the track for a night run. There are no lights on the runway, so that would be strange. Going 150+ in the dark would be a rush.

Some wicked cars here for sure. I'll post pics throughout the day. They have 1/4, 1/2, and 1 mile traps. I'll post speeds as I progress.

charchri4

You have a bunch of guys living vicariously though you today! Be safe!

Gunpilot

Got up early and drove towards staging area at 600. Their are already about 60 cars waiting for paddock to open up. SOB. This is going to be a long morning.

Gunpilot

Track about to open and a small shower passed. Time to dry the track. You can see my little guy sitting third up on the right. Lol

GoKart

Awesome! Can't wait to hear the results!

Gunpilot

Finally started up after brief sprinkle and track drying. I made it up to 15 cars away and the heavens opened up. Very stron head wind. Last run got a 199.8! I bet if the wind was less, he would have made 200 club.

GoKart

I know you're probably busy out there but....DETAILS PLEASE!

How stable did the car feel at speed?
What gear/rpm did you finish at?

Put a camera in that thing!

Oh, and congrats on almost getting 200

Gator Bait

The way I read it, he was 15 cars away from getting in a run, so no run made yet. He's only licensed for 160 so would have to shut down and get an upgrade before another attempt. If he makes a pull anywhere near 180 he's go mucho ***** and would be quite the accomplishment me thinks.

GoKart

Ok disregard. In my haste leaving work it seems I misread the post. Which car in the picture were you referring to as "he"?

Gunpilot

Some clarification. I have not run yet. Last guy to run before the rain hit made 199.8, not me. I wish! Lol.

I am licensed to 199, but don't think I'll get near that due to gearing and strong head wind.

Gunpilot

I just ran. Got the rev limiter in 5th about 50 yards shy of mile mark. I'll try to get thru 4th faster next time and use 6th gear. I took it easy thru the gears so I did not miss shifts.

Gator Bait

deleted as wrong years ref, reading more on ratios for various T-56s.

Gunpilot

The way they get speed is a 2 laser trap. You cross the first laser and speed is calculated when you reach second laser. I'm pretty sure my car hit rev limiter inside the trap. I suppose my true speed was a tad bit over 150.

My T-56 is from a 2006 GTO if your looking for gearing info.

Gunpilot

Much much better. If the wind dies down, I bet I can squeeze a bit more. Had a really good launch and running of the gears. Car is strong. Got thru the gears as fast as I could. Hit limiter in 1,2,3, shifted at 6200 in 4 and 5 ran 6th out the rest with my foot on the ground. I'll post videos later. The 2 speeds are half mile and mile by the way.