mobius

ok got a friend who dynoed 390 with a slipping trans. He had the tranny rebuilt, took it to the track and ran 109mph... question one what mph should he be at approx, say with the 390 and two the tuner stated that the 93 octane he got wasnt really 93 and knock retard is responsible for hte low mph... thanks for any answers. his mods as best as i can tell you are
3400 stall
forged 347
afr 205 heads
231/237 cam on a 115 lsa
ls6 intake
long tubes

transAm-98

iTrader: (1)

i'm an M6 and with 365 RWHP my best trap speed was 114. i was getting 108 with just headers untuned. that's realy low for 390 hp if you ask me

mobius

yeah i know it is way low i ran 106 wit a stock auto and a stall... is it possible knock retard could slow it up that much? he ran a 12.6 with a 1.72 60 on et streets 15 psi in them and heated them up spun off the line some... seems like it had the power out of the hole but flattened out up top...

mobius

bumps

mobius

nobody knows this??? how much power can u lose from knock retard???

Mazzenger

iTrader: (5)

I believe if the computer reads knock then it pulls out timing and that costs power.
Dont' know how much you would lose.

109 seems low for 390in an Automatic - I trapped 114 with 386 and teasing the throttle with an easy idle launch due to my crappy burnout. But with differences in weather, weight and elevation I cant really say.

Bombguy99z28

It isn't always how much knock you get, but he could be running on the low octane timing table due to the knock retard. That would probably be a considerable power loss, depending on how his tuner set it up. Or his tuner could just suck real bad.