Hi all

I've been collecting parts for some time to build a track focused NA Miata. A reasonably serious build plan including NB subframes, high comp ITB'd 1.8, motons, and a real focus on light weight.

In the meantime, I scored an unmissable deal on an S2000 that I'll daily for a while. I've since learnt some about them, and am starting to wonder...

Given equal power (let's say an F20 and gearbox in both chassis) , what do you think would be quickest on track with similar level of preparation?

Earlysport

 

Probably an s2k. It fits 245's from the factory, so a 255 or bigger is probably an easy mod. That alone means that it will have almost 4 more inches of rubber on the road, compared to an NA with 225's.
Figuring that they both have the same engine and transmission, and then calling them "similar in prep" isn't quite fair. You just doubled the NA power and spent a few thousand (4k?) dollars to do it. Dropping that into a miata is not a swap you do in a couple hours.
"Learnt" is not a word. Learned is what you were looking for, I think.

 

Ditch the NA idea and just get an NB and the NB subframes come for free. The NB body can fit 15x10's with just a fender roll. Emilio has photographic proof on this forum.

 

It also has 700 more pounds to haul around.

Both cars can be quick and it really just depends on how far you want to take them. I consider the Miata better for a track car because of weight, cost of consumables, and aftermarket support... but the s2000 is quicker out of the box and you can certainly do a lot worse.

 

I agree. I don't see how a similar power similarly prepped S2000 can hang with a Miata, just based on weight alone.

 

Equal power, the Miata. But what would be the point of an F20 Miata? It's a PITA swap. K24 much simpler, same power and probably cost less. Mod for Mod, the S2000 will be faster, but it will cost more and have more expensive consumables.

Figure out what your budget it , all in and let us know. Ultimately, that is always the deciding factor in any project.

 

Anyone know what the S2000 geometry does as far as roll centers and their migration? From descriptions I've heard of S2000s at speed, I wonder if Honda did something kinda weird there.

 

AP1 = Tries to kill you
AP2 = Succeeds in merely scaring you

 

OK, looking it up, I'm seeing AP1 with around 2" front roll center height and 7.5" rear at stock ride height, and the AP2 around a quarter inch lower roll center in the rear... front roll center dropping 75% faster than the body, rear dropping about as fast. If that's right, that seems like a lot of anti-roll through geometry in the rear, which is probably related to why they break away like they do.

 

Look at the rear bump steer curves for the two chassis. That will tell you more

 

Wait, what? How did Honda screw *that* up?

 

This is why the K series swap exists for the Miata, plus the big weight savings and lower consumable costs. I've had S2000 owners drive my Miata and they say its so much easier to control and very easy to correct if the back end steps out a bit.

 

Mazda did something similar with the ND. Really aggressive roll steer. Works fine if you are a smooth driver on low grip tires. Not so well with high grip tires or if you are less than smooth. Rear toe curve for the ND looks distressingly like the AP1. I had rear bump steer correction (one pick up point) on my AP1, massive front bar, tiniest rear bar, 17x10" wheels with 275's and it was finally very close to, but still not quite as good as a bone stock NA. ND requires fair bit of roll stiffness and specific rear damping rates to deal with the toe steer.

Essentially, the car toes the rear close to zero and mid bump then adds a wee bit of toe out at full bump. AP1 and ND share this design trait. The intent is to help the car rotate into a turn as it rolls over. This is fine when the front is sliding at .9g. Add high grip tires (RE71R) that don't slide at 1.2g, increase roll via the higher roll moment and the car becomes impossible to drive at the limit. Crazy loose and unpredictable as it cycles up and down with insufficient damping for the tires being used. Adding a bunch of damping and roll stiffness dialed the bad behavior out on our ND. It's a 5 link rear with 4 of the links sharing the toe geometry. That means there is no single pick up point that can be moved to correct it. You would have to either cast a new knuckle or change four arms.

So yeah, not a big fan of the S2000 here. I enjoyed mine but have much happier with the C6 Z06 that has 2.5x the power and handles like a big NA

 

With equal power and rubber the Miata has the potential to be much faster. You just don't see that often because there are far fewer 250hp Miatas set up well to go fast around a track than there are S2000's with a few bolt ons. Regardless, I'd take a Miata over S2K any day for the better suspension geometry and lighter weight, despite knowing that the Miata needs a lot more surgery than the S2K. If getting deep into a project to achieve performance that could be had with fewer mods with a different chassis isn't your thing, the S2K might be the better choice.

 

Ugh. I guess this just goes back to my suspicion that anything where someone tries to be more fancy than "basically dual wishbones" is a bad idea.

 

You really need to be asking the dollar for dollar question..... In which case the Miata wins right up until the c5 or c6 vett wins.

Pretty much the only place the s2k wins is STR with a big budget.

 

Great feedback all, and confirming my thoughts that the miata is still the platform to proceed with. I'm heavily biased toward light weight and I it seems getting an S2K under 2300 lbs is really tough, where I;'m aiming for under 1800lb Miata. The geo as Emilio poiints out is also something I've read a lot about, and I've already put bump steer correcting toe arms on the rear of the S2000. I haven't run it on track yet, but honestly now it will stay as a fun street car.

The F20 engine is a peach though. I've got an NB2 1.8, 12.5:1 pistons, cams, Maxim header, ITB's etc all sitting around, but yes a K swap is starting to look really appealing...

What I was ultimately wondering Ryan has confirmed above. If you can make similar power, and fit similar rubber, the Miata will be faster :-)

Cheers,

Earlysport

 

This, NB is a better chassis to racecar. Most of the weight you can strip out when becoming racecar, and the rest of it is from stuff you want like bracing, the bigger brakes, the torsen, and the 1.8.

 

There's a very good reason my AP2 is a street car and my NB is a track car There's just no comparison in terms of running costs + mod costs for the speed you get.

 

Also, if you think that the surgery on the NA/NB tubs are bad, the surgery required on the S2000 is all sorts of sad panda.

Not to mention for all of the bitching that we've done about $600 hardtops now costing $1200, S2K hardtops have always been $Texas; nevermind Toyota MR-S hardtops.