Why not a dedicated set of slicks for the track?

Maybe in future but at the moment cars are sending me broke

i think theese yokohamas will be more than my axels can handle has anyone tried the 400hp units from the drive shaft shop ?

Can confirm these things stick.

Damn the budgets. Slicks will be the best dollar you spend if you get the right ones.

You will find drag slicks are foregiving, even more so coupled with an auto trans. Don't worry about axles until you start breaking them.

It will happen its all a learning curve as iam not a seasoned drag racer

i think suspension will be equally important as well

im thinking about stich welding the door frame and solid mounting this hardtop before i go

Suspension becomes important when you get really competitive, or when trying to get radials to work. Today's drag tires are really really good. I do plenty of drag racing, and experience has taught me there is no better investment than the right tires.

The key is choose wisely. Most people make the mistake of going too big. The right tire for a Miata will look shockingly small depending on power.

I am taking your advice and getting M&H slicks when I have a few more bucks.

I run Mickey thompson ET Street R's, 225-50-15's on my setup. What do you think of those? They are bigger than stock. Seem to work best around 18 psi pressure.

what boost do you launch yours at pat

Around 20-25 PSI with a manual transmission, RPM's vary from 4,200 to 4,800 depending on track conditions.

Ok maybe the drive trains stronger than i thought in my head 10-12psi max

my ultimate goal is a 10.99 but i dont know if 400hp and auto is enough

I think all you need is the 7.5-23-15 for your power level. I think it will be capable of 60' in the 1.6 range. Going bigger will only slow you down on the big end.

I think it is a good tire, but drag radials are less forgiving and require a lot more suspension tuning, particularly with manual trans. Once you get it right, they are actually faster than bias tires. Are you getting wheel hop? I get none using bias ply.

my ultimate goal is a 10.99 but i dont know if 400hp and auto is enough[/QUOTE]
That is plenty of power to break in the 10's if you launch hard enough.

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Productive day i got a mint condition hardtop with perfect seals and rubbers with frakenstien bolts and demister wiring cheap well cheap for us in oz

side latches are missing but my intention is to solid mount it

i also wired up my auto thermo fan to my unused fog light switch works a treat

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my bluetooth module has arived so i can have music again

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Has anyone thought about bumper cuts to reduce drag?

sorry about the video quality i will make more

tyres hook up well on high boost its so much more grip

Finally a video!

Really looking forward to a video at wide open throttle going through the gears!

With a manual it would cut low 1.7 60' times, but the reason for that was mostly to do with the clutch. I swapped to a puck clutch and choose not to slip it out of the hole as I knew that would destroy it fast. It would wheel hop if I tried to dump the clutch out of the hole over about 20 PSI or over 4,500. I could fix that with air, but it slowed me down on the big end. Drag radials are meant for auto cars, not manual, so it should be better now, though I'm sure it won't launch as well until I get a higher stall in it and whatnot. One thing at a time!

Bit worried about the converter at the moment went behind home put it on high boost and raked out third from 80kmh it sat at 6,800rpm and kept pulling like a train

if got a bad feeling converters slipping or maybe 3.63's are too tall for 80 in third

im new to this auto thing on a plus auto holds 25psi and grip

Does it slip in all the gears the same under high load? Just wondering if it's the converter or the clutches in the trans slipping. The rear gears shouldn't matter.

i doubt it would be clutches the box is well rated higher and proven in much higher applications

iam going to put it on a friends Dyno tomorrow and see what power it makes and what the curve looks like i think we can work out converter slip with it i need to look it up

You got me worrying how much my stock 99 auto is going to hold. Will found out soon enough.

No offense, but I can't think of a worse gear ratio than a 3.63 for dragstrip use with your power level. I understand the desire to have a comfortable street car, but you are leaving an awful lot on the table.

my friends who have experience in drag racing say the more power the taller you go for more mph as you have the power to hit limiter with shorter ratio's

and if you look at the ratio's of the jatco i needed more legs

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i could be wrong i bought the 3.63's when it was manual i may go back to 3.9's depending on how it goes on the track i just spoke to my auto builder asking about the thing revving to 6,800 rpm he said some cars do it they build your converter to the cars specs there are two ways to check mph on the track and Dyno and check rpm vs wheel speed

How tall of a tire?

225/50/15 is the tyre and so far feels like it sticks well

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Ok so everything works a treat hits limiter in third at 132mph so gearing seems perfect it comes on hard on the dyno with the converter

the intresting things we tried 2 more psi got some blowout but the dyno line jumped up a silly amount so i might have to regap plugs or upgrade the ls coils thats at 27.1psi i want 28psi in the end

the fuels are pretty good there is one dip we want to clean up we also might throw some more timing in it see what happens

i want 300rwkw back

343whp/460wtq for those curious.

Day-um! Am I reading that right, 625 Nm of torque?

Did you figure out if the converter is slipping?

We dont think it is slipping

torque is a little higher as we were doing 2nd gear runs

but my friend who owns the dyno said it wouldnt be much less

If tq is high then so is hp. One is a mathematic function of the other.

between 2nd and third low boost runs was .5rwkw so if they are relative im am guessing it wont drop by much at all

next thing is the run it down the quater i may just turn it up before i go

this does not sound correct

Could be. Old style autos can result in some weird dyno readings. My buddy in the old turbo dodge minivan would usually have a graph that was shaped a lot like that, with somewhat similar numbers.

I guess we'll find out when it runs the 1/4 mile.
I never quite understand your time slips down there, there always seems to be a 1264 foot mark or something.
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well it feels quick i am keen to run it down the track but not sure when i can go cause the closest track is two hours away and i work the weekends

it at least feels very quick and its fun to drive i might go out and bench mark it with some friends with a few v8's and see how it goes

He later mentioned he dyno'd in 2nd not 3rd (3rd being 1:1 gear, 2nd being I dunno but > 1:1) So power is right, torque is off as we here quote wheel torque in the 1:1 gear and he apparently dyno'd in 2nd not 3rd.

UPDATE !!
 

Box has to come out

My auto builder called me as we had a discussion earlier in the day and there is an issue not a big one but its costing me power and not coming on properly oil pump in the box might need modding or changing he will also change the converter slightly

he thinks converter is flaring due to lack of oil pressure but is an easy fix

then we can turn it all up

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its up and exhaust is out i need to have it all apart by Tuesday and they will have box all moded within one week

not how i planned on spending my weekend

What do they think is wrong? What changes are they thinking of making to the oil pump?

He thinks there is not enough oil pressure or flow iam not sure which one which is screwing with the converter it should climb a little more power wise iam just happy i have got onto someone that has the time to help get it right as it is all trial and error to get it bang on he has said once its right i cant change turbo's as the converter will need to be changed

he thinks he left the stock MX5 oil pump in the box he will upgrade it to the Holden VL Turbo model which is the car they build these boxes for or modify the stock one which iam not sure of what entails he is also going to tweak the converter as he has said it may be a little loose

Could you get me the contact info for the guy building your auto? I'd like to get in touch with them.

Also, if you get any more info on what the difference is between your current pump and what they change it to or modify it, I'd love to know. Port it to flow more? Or raise pressure? Or just a bigger pump for more volume/pressure?

message Goran he is a legend contact@gzm.com.au

Thanks I sent him an email.

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this is the tail shaft i had made upgraded uni's and upgraded tube heaps heavier than the old unit i never put a photo up for those who are curious

the rule of thumb is you want to cross the finish line asclose to redline as possible. My math with a 24.1" tire, 7000 rpm, and 3.63 gear comes out to 138mph. If your car is not capable at trapping at that speed, you have too tall a gear. My suggestion is get all the bugs worked out, and send the car down the strip to see what it traps at, then change the gear to what is appropriate.

Looking forward to seeing this thing run.

I messaged him a week ago but never heard back. Just messaged him again. I sent him these two vids of my car cars auto in boost at 20 PSI.

How does this compare vs the auto you had built? Mine slips on the 1-2 gear change, but seems fine on the 2-3 change. Once in 2nd it holds 20 PSI no problem.

That acceleration ! my gawd! how much boost was that?

the difference is night and day every gear change is firm direct and quick but that is what you would expect on a manualised built gearbox the only issue i was having is power loss which i should have fixed when the the box back next week

my auto guys only specialise in Jatco's so the Ln471b only

when i get mine back next week i will put my go pro up and video the dash how did you video yours ?

If that was directed at me, wastegate 20 PSI. I have a bigger turbo up front now so it's a lot stronger per lb of boost vs before. This hits 55% duty on my injectors at redline at this boost level.

Interesting. Yeah I think I'm going to buy a low mileage auto and either swap it in, or just build it and then swap it in. Do you know if the guy that did yours deleted the accumulators? Or just modded them?

I talked to one auto company that builds performance transmissions and he quoted me a pretty high price and said he could only guess that it might hold 350whp. Not confidence inspiring. Going to call level10 on Monday, I called and they said he won't be back till next week.

I just filmed mine by holding my phone with one hand.

i have no idea what they do i believe automatics are a black art so i don't ask questions i just pay the experts

and mine also was not cheap but to get a reliable setup i was willing to pay the money how much did they quote you for 350hp ? id go a jatco my guys rate the box for 460hp on the 4 speed and alot more on the 3sp

yeah i tried to hold the phone there and iam too worried about when it shifts gears 1-2nd guaranteed to spin tyres 2-3rd on low depending on the surface and that is only with 199rwkw on low boost

3,200 USD parts and labor (4,211 Australian dollar) if I ship them a trans to build, plus shipping back to me, and when I asked him how much it would hold once he built it he said "I can only guess, 350?" Not what I was looking to hear. Would like to know that it will be strong and not break, not a guess at what it might hold... I don't mind paying for good work if I KNOW it's good work and going to solve my problem.

well mine was $4,000 AUD to build including converter i think they may have under quoted the work they have to do all iam hearing is time for a Jatco can you get them in the states they are out of eunos import here is Australia ?

I think I'm just going to build a 99 trans myself unless Level 10 says they can build one that will hold 400-500 reliably. I don't want to pay 3,200 + shipping both ways + tax = way over 4,000 USD for something that might hold 350.

If that does not work, Jatco. Hopefully they guy building yours will email me back. :)

On your box is that 460 flywheel hp or 460whp it's rated for?

all there stuff is in RWKW's mine is rated for 350 rwkw dont forget torque is the thing that breaks stuff that is a rating from a heavier car and 3ltr 6cyl turbo so my theory is can go a fair bit higher in a mx5/miata

350RWKW is 470whp. And my guy guesses at it maybe taking 350whp. Big difference there. I built so many things by now I don't see why I can't build an auto too.

QUICK UPDATE

i have the auto back the converter has been changed and the auto has had some precautionary mods done by my auto builder who is an absolute legend its almost bolted up iam just checking clearance's then it will be getting driven straight to a dyno to see the results

Good luck! I could never get ahold of the guy that's doing yours. I just bought a built C4 ford trans and am going that route instead. I'm on my second miata auto now and it's slipping at 25 psi with a few basic mods done to it.

yeah that sounds like it will work well if you need a photo's of my drop box and or measurements to fit the B&M shifter just let me know

What stall converter are you aiming for? Does it have a lock-up clutch in the converter?

I'm wondering what stall I should aim for. I'm thinking one that will flash to about 5K, and then up as it builds boost to around 6K or so.