FWIW ive driven 20 miles home from PIR on a 5 speed that only had 1st and 4th

I had to go back and look at the time slips. On nitrous I made mostly 1/8th mile runs. I was about 4 miles per hour faster than my best N/A 1/8th pass (84.09 versus 80.50mph) . That would put me about 104 to 106 trap speed in the 1/4 on nitrous according to 1/8 mile to 1/4 mile convertors. I hurt the motor the day I went down the 1/4 on nitrous, and went 100.91 on the last pass. Broke a piston on that run. My healthy motor was very similar to sonofthehill's best mph. The point being he would be a great candidate for a conservative set of slicks.

The key to running slicks, is choosing the right sized tire. For a Miata running 100 to 110 mph you need a surprisingly small tire. Anything bigger makes the car slower, and may contribute to broken parts. Way back when I was running nitrous, there was a 20x8x14 that would fit my factory 14" wheesl. That is the tire that took me to 1.71. That tire is no longer available. When I made my best N/A pass, I was running a 22x8x15. Really too much tire for my N/A setup. I had to pump up the pressure to get the car to work properly, but it still bogged slightly. Because he is making more power, I think it would be a good choice for sonofthehill. I think a better option would be the M&H brand in a 23x7.5x15. That is my next tire to run N/A.

[[i]threaddriftfuel] I can comment, at least for used 5spds that were in good condition as installed. After ~2k miles on the first 5spd with 250 wheel ftlbs the input shaft had enough resistance that it took two hands to rotate it in neutral. The problem became apparent when coasting in 5th gear felt like the handbrake was not fully released. The second 5spd at 280 wheel ftlbs has nearly 3k miles on it now and 2nd gear is seriously whining but the input shaft was spinning freely when reinstalled 150 miles ago. I have not done any hard launches on either of these transmission- no burnouts or clutch dumps. The stress has come from full load runs from low rpm in fourth gear (tuning) and typical runs through the gears, full load acceleration, no speed shifting. [[i]/threaddriftfuel]

The idea that shouldn't be lost in all of this is that wrinkle wall slicks do a very good job of absorbing shock load and translating it into a smoother, more even force on the drivetrain components. And they are very unlikely to wheel hop compared to rigid sidewall tires.

Wait...so you treated 5 speeds nicely and still broke them? For some reason I dont think "mechanical empathy" is going to save my 5 speed from a gt3071 and e85. Well over 300 hp 300 torque. Probably closer to 400 if I can keep the engine intact. Im screwed lol

I was next to a street only Miata when it sheared the teeth of 3rd in a 5 speed. It had been making 310 at the rear at one point, was down to 280ish. Throttle stuck open in a 3rd gear pull and sheared the teeth off (that car is possesed. Hence why it is named Linda Blare...). It is well cared for too.

So all those times we told you it'd blow up, and now after dozens of posts about it and several months later, you're finally coming to terms with this reality?

lol

There is an off the shelf solution for 99% of problems when trying to make a reliable high hp miata. BESIDES a bolt on trans solution. Hurry up Trackspeed! Ill donate to R&D! Wait no.. im too cheap

Huh? You must have me confused with someone else. Ive been planning out this "rods only" build for a long time. And its happening as we speak. I just never really considered the 5 speed to be an issue until i break it. I just cross bridges when the time comes bc im stupid i guess

Maybe I am.
They are cheap enough to break a couple.........for "science"

Thanks Aidan! Actually worth a ton, perhaps I may be so lucky.

Couple things to remember about my car.

It's inching closer to 250k so it's on borrowed time already.

That being said it was unusually well maintained by the PO.

I still have the original 5 speed but it is noisy as hell.

I see an early 1.6 tranny on Craigslist for $50 right now but it's a bit far.

I have the full intention of going the 5 speed consumable route.

Last but not least my car seems to have been blessed with unicorn semen at one time (does too exist, I am near SF.) :rofl:

Yeah thats my take on it. Not really worth trying to sell it before i break it because they arent really worth a whole lot. Especially in my area. So when i break it, i guess ill be hunting for a 6 speed

Yes, no beating and the 5spd was showing wear. It still worked but was very hard to rotate the input shaft. The only reason I've been using them is because I have/had so many.