Bamd?

 

Bay Area Miata Drivers if I'm not mistaken?

 

here is a video of mine with the cnc head. Detuned for a flat power band at 158hp

 

Got a build thread? I'd love to see a timing and dyno plot for the motor

...though I completely understand if you tell me to get stuffed.

 

Who?

 

Tomei cams in that one too. Get him to post a dyno here.

 

Circuitmstr74 might be running ITB's, he had them on a Miata that was tuned by a company out of Orlando, Florida.

 

Nope. OEM for sure, square top IIRC.

 

He sold the itb's, iirc.

 

Same engine, with and without the hair dryer.

 

Whats with the HP and TQ not crossing at 5252 RPM??

 

Power and torque are on different scales.

 

Ah brain fart. NVM

 

Dyno is australian.

 

Rescaled the plot so it's easier to get a visual reference. My bad.

 

whats going on between 3 and 4 grand on the n/a plot?

I assume its because of the cams coming into efficiency.
Have you tried a shorter runner intake manifold with setups like this to give it a bit more jam up top (flatter torque), with even more inefficiency in the <3000rpm street car range?


iirc, Falcon's 1.6L would be the only example of what im talking about and its chart was pretty similar, but with a 1.6L.

 

Umm yes they do?
-----------------
nvm i see Emilio edited it.

 

Shorter runners always kill midrange and usually top end too. BTDT. Some fundamental acoustics tuning for an engine of this bore/stroke/CFM requires runners about the same length as stock. It's a low enough revving engine that one could theoretically build a first order length manifold and get more power everywhere. Packaging trickery required for that. It wouldn't look anything like the B18 Honda aftermarket/BP hybrid manifolds we and other have made.

What every "grand plan" for any B series Miata engine has to take into account is the low rod ratio and poor head flow. An NB will never be a free flowing high RPM screamer. The same OEM forged crank that will tolerate nearly 500whp at 7500rpm will explode at 8700rpm @ 190whp. The stock manifold is pretty close to the correct dimension, just a tad larger cross section in runner and straighter paths needed. The TB mounting flange offset is the main issue you want to correct.

The OEM manifold is folded and scrunched to clear the hood, ABS pump, EGR and other bits. Just get rid of the obstructions to get good flow paths and you have a good manifold.

 

In car from last weekend with the Rotrex removed. Car details in the youtube notes. About 170whp on pump gas with this engine. Down on power from the 185whp or so it should make because the piston/rings used were not our standard ST/XX. Burning some oil where we usually get no oil consumption. Anyway, I wanted to do one last run N/A before we put the K20A2 in it. Another 50whp and vtak should be fun.

 

Lost 15whp to piston rings? That's surprising.