Are K miatas the Ultimate Naturally Aspirated miata?

NickD said:

Carbon (Forum Supporter) said:

Tommy f-yeah's (built a/f, ohlins, no heat, etc.) was almost exactly as fast as my 1zz turbo zzw30 with an open diff and a five speed. They're not that impressive imho. Dont get me wrpng, it's a great motor, I just dont like em in these cars.  Id do an lfx or an ls. Lfx sounds awesome, has good weight dist., and a ls is just bad ass. K24 swap was grunty but didn't really feel special to me. Felt real s2k ish to me, if you want one of them, it's probably a better investment to just buy one. Gm drivelines that I discussed are arguably tougher too. 
 

The thing I remember was how badly that thing shook itself to pieces through the day too. He was griping that KMiata went too stiff on the motor mounts, envisioning them for hardcore race usage, and didn't offer softer bushings for street usage. The oil cap rattled off, the one bolt kept rattling free of the intake manifold and causing a vacuum leak and all the header collector bolts for the 2-piece header came out at the end of the day. It also kept popping the transmission out of gear.

The Honda J-series V6 is the one that calls to me, if/when I yank the Rotrex-blown BP out. It makes insane sounds, still uses the stock driveline to keep costs down (compared to the LS and LFX), and I'm sure the low-end grunt makes it a blast. 

The flip side to that is that you're still running into the same gearbox strength limitations. Using the stock driveline is both a blessing and a curse.

Keith Tanner said:

NickD said:

Carbon (Forum Supporter) said:

Tommy f-yeah's (built a/f, ohlins, no heat, etc.) was almost exactly as fast as my 1zz turbo zzw30 with an open diff and a five speed. They're not that impressive imho. Dont get me wrpng, it's a great motor, I just dont like em in these cars.  Id do an lfx or an ls. Lfx sounds awesome, has good weight dist., and a ls is just bad ass. K24 swap was grunty but didn't really feel special to me. Felt real s2k ish to me, if you want one of them, it's probably a better investment to just buy one. Gm drivelines that I discussed are arguably tougher too. 
 

The thing I remember was how badly that thing shook itself to pieces through the day too. He was griping that KMiata went too stiff on the motor mounts, envisioning them for hardcore race usage, and didn't offer softer bushings for street usage. The oil cap rattled off, the one bolt kept rattling free of the intake manifold and causing a vacuum leak and all the header collector bolts for the 2-piece header came out at the end of the day. It also kept popping the transmission out of gear.

The Honda J-series V6 is the one that calls to me, if/when I yank the Rotrex-blown BP out. It makes insane sounds, still uses the stock driveline to keep costs down (compared to the LS and LFX), and I'm sure the low-end grunt makes it a blast. 

The flip side to that is that you're still running into the same gearbox strength limitations. Using the stock driveline is both a blessing and a curse.

"That is true" says the guy who blew up a 5-speed 2 years ago while 900 miles from home. Actually that wasn't the fault of the Rotrex-blown BP-4W, I had a freak occurrence where the lowest input shaft plate bolt came loose (all the others were still tight) and dumped all the oil out of the gearbox into my bellhousing and also wiped out my clutch. That sent me down the path of new clutch, flyhweel, 6-speed and 3.63:1 gears. I have that single $3000 bolt sitting on my workbench to remind me.

AnthonyGS (Forum Supporter) said:

In reply to NickD :

Dallas.  I will let you drive one of my cars.

Ooof, I'm in NY. And Keith isn't much better in terms of proximity to me.

jwagner (Forum Supporter) said:

I hate turbo lag and think that the turbo motor takes away from the immediacy of the car even if it does get you to about the same power as a K.

A turbo doesn't just get you to the same power as a K -- if you do it right then it gets you to significantly more. :)

Yes, a turbo car doesn't drive the same way as a naturally aspirated one.  You need to think ahead a bit more, learn to judge how fast the turbo is spinning, anticipate how much torque you're going to want, and get on the gas a little sooner than you would otherwise.  Maybe you get on the gas harder than you would otherwise, then lift a bit as the boost comes up.  It's a skill you learn from driving them, just like anything else.

AnthonyGS (Forum Supporter) said:

Can someone round up a Rotrex Miata, FM turbo Miata, K Miata and LS powered Miata and drop them off at my house?  I'd like to conduct some research before modifying my Miata...... 

 

I'll take you for a spin in my turbo Miata next time you're in Austin.

In reply to Keith Tanner :

I will likely be up that way this summer.

In reply to calteg :

Deal.  I will buy lunch at a minimum.

Having owned a NA BP, Turbo, MSM, LS, and driven a rotrex a lot, I think there is one missing from this conversation....The LFX miata. It keeps the light weight of a BP miata, turns 300ish HP with a transmission that can handle it, and is not a heat management issue on long runs at the track. I just wish the process was a lot less expensive. 

I loved Betty and she was so much fun but I'm still amazed Wilco didn't lock me up and burn my license. Great car but really needed room to roam. The Turbos were alway fun but I don't have a lot of time to keep up with the little things that always came up after hard track sessions. The Rotrex are great compromise and I'd go that way next possibly at some point if I stayed with the BP platform.  

In reply to bmw88rider (Forum Supporter) :

I want to go LFX eventually. I have a rotrex car and it is a lot of fun - very little fiddling and no heat issues that I've run into to get a very potent little power plant (makes good noises too!). LFX is a beast though - redline and all matches the miata super well from what I've been told. Should be really under-stressed (and fairly cheap to replace) as noted, and typical GM reliable power plant. Nothing particularly interesting about tuning it or getting it to be happy RWD, etc (a good thing). 

codrus (Forum Supporter) said:

jwagner (Forum Supporter) said:

I hate turbo lag and think that the turbo motor takes away from the immediacy of the car even if it does get you to about the same power as a K.

A turbo doesn't just get you to the same power as a K -- if you do it right then it gets you to significantly more. :)

Yes, a turbo car doesn't drive the same way as a naturally aspirated one.  You need to think ahead a bit more, learn to judge how fast the turbo is spinning, anticipate how much torque you're going to want, and get on the gas a little sooner than you would otherwise.  Maybe you get on the gas harder than you would otherwise, then lift a bit as the boost comes up.  It's a skill you learn from driving them, just like anything else.

The K gave me about as much power as I'm comfortable running in a stock Miata drivetrain.  Mine did 240+ at the wheels.  Yes, you can get more if you turn up the psi on a big turbo system, but I question the long term reliability unless you start doing some serious upgrades.

I've owned and driven a bunch of turbo cars, and the last one being my 94R Miata on which I swapped the turbo engine out for a fresh NA motor with some bolt-ons.  Don't miss the turbo.  YMMV.