Let's Play "How Much Power?"| Grassroots Motorsports forum |

NickD UberDork
5/19/18 2:23 p.m.

Finally got around to getting my Miata dyno-tuned today. The engine specs as it sits:

2000 1.8L

-Bored 0.010" over, with stock-compression pistons and opened ring gap

-ARP head and main studs

-Stock rods, crank, cams, head

-Racing Beat header, test pipe and Good-Win cat-back

-BP-5A "squaretop" intake manifold with MiataRoadster phenolic spacer and 1.6L throttle body

-Track Dog Racing c30-84 Rotrex supercharger kit

-MegaSquirt PNP9093

https://www.facebook.com/plugins/video.php?href=https%3A%2F%2Fwww.facebook.com%2Ffacebook%2Fvideos%2F1789201107812809%2F&width=500&show_text=false&height=281

So, how much power and torque did it make to the tires? Bonus points for RPM guesses. Winner gets a crisp high-five

MrChaos GRM+ Memberand Dork
5/19/18 2:28 p.m.

What size pully?

MrChaos GRM+ Memberand Dork
5/19/18 2:30 p.m.

75mm pulley i am guessing 250hp/195ftlbs

80mm pulley i am guessing 240hp/185ftlbs

NickD UberDork
5/19/18 2:31 p.m.

MrChaos said:
What size pully?

Whatever one comes with the kit normally, 80mm I believe. Gauge reads about 12psi of boost

NickD UberDork
5/19/18 2:33 p.m.

Also, it was high-40s, low-50s and rainy today And I was on a Mustang Powerdyne eddy-current dyno

MrChaos GRM+ Memberand Dork
5/19/18 2:38 p.m.

oh a mustang dyno so 225/150

NickD UberDork
5/20/18 6:48 a.m.

Well, right now Mr. Chaos is winning by default. Any other contestants?

mazdeuce - Seth Mod Squad
5/20/18 7:03 a.m.

235 165. You're posting because you're very happy with that.

Stampie GRM+ Memberand UltraDork
5/20/18 8:00 a.m.

236 (didn't see Seth) 200

kazoospec SuperDork
5/20/18 8:13 a.m.

Closest without going over? 1hp/1ftlbs

Serious guess: 225/185

dculberson UltimaDork
5/20/18 8:16 a.m.

Hmm. 280/200!!

secretariata GRM+ Memberand SuperDork
5/20/18 9:07 a.m.

I'll guess 215/190 at the wheels.

Zeitgeist Reader
5/20/18 9:20 a.m.

212 HP 186 TQ

Rodan HalfDork
5/20/18 10:14 a.m.

218/160

Antihero GRM+ Memberand HalfDork
5/20/18 3:04 p.m.

210/175

Dusterbd13 MegaDork
5/20/18 3:08 p.m.

200/200

Thats what i want in my supercharged miata......

EvanB GRM+ Memberand MegaDork
5/20/18 5:19 p.m.

180/180

84FSP SuperDork
5/20/18 5:24 p.m.

230/185- anticipation of real dyno chart...

Duke MegaDork
5/20/18 5:25 p.m.

12 psi? 10 psi nets me about 235/185 at the wheels.

I’m going with 245 hp / 198 tq. Peak HP at about 6500.

buzzboy Reader
5/20/18 5:52 p.m.

235WHP and 220 Ft•lbs

KyAllroad (Jeremy) PowerDork
5/21/18 4:30 a.m.

240 hp/215 tq

when will you let us know?

NickD UberDork
5/21/18 5:18 a.m.

So, it made a number of pulls in the 225-230hp/178-179tq, but the blower belt would start slipping at around 6800rpm. You could tell because the line on the dyno graph would just flat line. But when the belt did cooperate though, it made an uncorrected 245hp @6900rpm and 185 lb-ft @ 6400rpm (281/181 corrected). Trying to get a 250hp pull, the tuner tried bumping rev limit from 7000rpm to 7300rpm, but apparently 7000rpm is where the stock BP-4W camshafts run out of breath, because it dramatically nosed over after that.

Dusterbd13 MegaDork
5/21/18 6:30 a.m.

That is absolutely berkeleying amazing!!!

Rodan HalfDork
5/21/18 7:47 a.m.

Nice!

Most Rotrex results have seemed a little disappointing, but that's very impressive. Congratulations!