I think I will start by playing with the throttle, and see how that works (probably not very well. Then, when I have had enough of that, I will go the route of flares and much larger wheels and tires.

 

If I may contribute. This is not specifically miata related, but I'm running the same kind of power and build in my first gen rx-7. Typically 17's look awful on that car, but flares or widebodies can pull it off quite well. Those big arches tend to swallow the wheel and make it look less like wagon wheels. Just something to consider. I'm going 17x10 with 255-275-ish

 

...and with 250whp and 205 Nitto Neogens in 2nd gear I can maintain traction on concrete in 2nd gear. If I don't adjust the shocks after leaving the track though, 2nd gear will hit the club, light the bitch up.

 

I would not go 17s the lower profile tire will not hook aswell, for instance a 275 60 15 will hook up better then a 305 50 17. i would suggest trying out a set of the nitto drag radials for street use they really arent bad in the rain considering there a dr. prolly would go with something like 245 60 15. also idk what your tunning with kpro i assume? you can setup the boost by gear it works very very well for the honda guys just throw like a 5psi wastegate spring in there so u can have it at 5psi through first maybe second aswell then ramp it up through 3rd gear.

 

Tuning with an AEM boost by gear is an available feature, but how much boost is just the right amount. Could take a few thousand dollars of dyno and real street testing to get it right.

 

Explain that please? Boost target by gear to prevent wheelspin would be a street affair. Why do you say thousands of dollars of dyno time?

 

nope no dyno, the load is different + the wheels on the dyno are designed to promot traction you have to just figure out what gear it spins in, does it spin in first? then turn the boost down in first till it hooks or just barley spins. then assuming it spins second back the boost down till it dosnt then in 3rd gear if it dosnt spin really bad start the boost at whatever it was in second and ramp it up through 3rd. this is assuming it dosnt destroy tires all the way through 3rd which it prolly does.

 

The size of the tire has little to do with the traction, your tuner sounds like an idiot.
What is important is the tire compound.
A 225 and a 245 of the exact same tire compound will have nearly identical amount fo traction, the only difference being that the 245 tire will last longer.

 

^so you do not feel that a set of 225 60 15s would hook better then a set of 225 50 15s assuming there both lets say nitto nt01s or 555rs?

 

The added sidewall should help (for reasons I dont understand)
But the width is almost irrelevant.

 

Excuse my ignorance but if you turn down boost, you need to change your fuel map right? Or can you keep each map and the computer adjust to the boost being produced. Now that I think about it that does make sense. I am also concerned about drivability. I want to make sure the engine runs well at all loads. I am not building this car only for WOT application.

I don't plan on doing any self tuning. We have one of the best tuners in the country for f20c engines located in colorado springs. It was not the tuner telling me that I would need to spend that much time on a dyno, just a noob to the FI world making that leap and assumption.

I have come to this web site because I know there is a lot of knowledge here. I am learning as I go, but I don't plan on building a starter kit then advancing it. I plan on just building the way I want it out of the box


But there is something to be said for being able to spin the tires by hammering the throttle at 60.

My tuner has told me that at 15# I should be in the 450whp range on a less than aggressive tune 420hp on conservative tune. The fabricator that I am working with is making 600 to the wheels on 24#, with the exact set up that I am building . HP is nice but I really am trying to figure out a way to make it usable...to a point

 

How is my tuner an idiot? The biggest factor for traction is the chemical compound of the rubber. The softer the tire the greater the traction. but a 225 trying to hold 450 hp is going to get worked

All things being equal the taller the side wall on the same compound the greater the traction because the sidewall absorbs torque (this is straight line we are talking about not cornering.)

For cornering there comes a point where to short a sidewall will adversely effect handling.

 

tuning FUEL in boost is as easy as making your car run the AFR you want it to in the 0kpa cell... and then setting up boost comp in the AEM box.

14.4kpa (1 Bar) = 100% more fuel over your 0kpa.
you copy the fuel duty cycle number for your 0kpa all the way up this way and the computer adds duty cycle based on pressure... very simple and this way you just have to mess with timing.


Being map based, you can control the boost down to whatever you would like, whenever you would like and it SHOULD run very well assuming you had each cell tuned well.

 

Well that makes sense ^ but with a load bearing dyno you and your tuner should be able to hit all the cells in your map at the correct PSIs and setup your fueling in a few hours.

If you turn down boost, you should be tuned for those cells already. Otherwise if you have part throttle less-than-max boost your engine might kerploopie.

 

I get it, it seems like it is fairly straight forward but my plan it still to let the guy who has a million times more experience than me at tuning, actually do the tune. I don't want to make a mistake and cost myself an engine due to tune. F20C engines are much harder to come by than miata engines

 

OK well be aware that a lot of tuners really ******* suck and don't know what the hell they are doing. I recommend asking him some questions around how he tunes timing, detects knock (if at all-- some don't even bother), and protects your baby.

 

Boost by gear is the way to go. After I dropped in a built motor the car was annihilating the tires in first through third. Tweaking wastegate duty cycle and target boost in the lower gears let the car hook up a ton better. Granted it feels slower, but is actually much faster.

Now if you're hazing the tires above 40mph that's a different story.

 

Duly noted. I have done a bunch of research, This guy is traveled by other performance companies because of his abilities. I feel comfortable letting him dial the car in after it's built. Servion tuning in Colorado Springs.

Conservatively, I think I am at least another 2-3 months away from having the car completed.

 

agreed, unless of course its a massive difference in size possibly.

 

You seem like you dont wana have to redo things and your kinda just doin it how u want it right away. So why not throw some flares on it now and stick the 275s back there. The stock f20c motor is good for over 500whp so why not set things up to run at there maximum potential? seems like you will prolly end up doing it later anyway and the extra set of tires you would buy could offset a huge chunk from the cost of flares.