parish8

iTrader: (6)

just got done putting twin 60mm turbos on my g8. base spring pressure is 5psi.

timing is set at 11.5deg at peek tq and 15deg at 6000rpm. a/f ratio in the mid 11's. iat's at 120max. coolant temp at 180. fuel is 91octane from bp

we were seeing knock retard from it mid 2nd gear on.

we tried more fuel, put the wideband into the high 10's and that didn't help. put the fuel at 12/1 and it got much worse.

last thing we tried was to put timing at a flat 10deg at wot. car showed no knock retard at all but it lost power.

is 11.5deg-15deg too much timing for the motor at 5psi? i wouldn't think so but maybe.

thinking about a meth kit.

tomz28

iTrader: (20)

its the fuel my car on 91 sucks it wants to knock all the time but when i use my meth no knock at all and thats on 17degs for hp and 22degs for tq

but i have not tryed race gas yet to see if that helps any

or its a bullshit knock sensor thats bad, and thats picking up nosie from something else just some ideas. but you guys look pretty smart so i dont know LOL

98Z28CobraKiller

iTrader: (17)

You running an intercooler? What kind of charge temps are you seeing? Have you tried running race gas to see if it goes away? Is it knocking everywhere on wot or always in one spot? Screen shot of knock retard histo log of a pass? You sure it's kr and not just pulling timing?

stock48

iTrader: (17)

Does that thing have VVT? Can you actually hear it ping? I would try mixing in a little E85, Keep the AFR tuned in the high 10's and let the E85 take it to mid 11's.

parish8

iTrader: (6)

99% sure it is real knock retard since it completely goes away if i pull timing back to 10deg. never have heard it. but it looks real on the scan tool. always come in sometime mid to top 2nd gear and gets worse in 3rd.

cant post up pic of scan, right now my hptuners box it out for repairs so i was using a buddys box and laptop.

it is intercooled. iat's varried but when i tried to not let the car heat soak they started at 120deg and actualy fell to 118 during the run. only 5psi.

injectors have no head room so i cant mess with e85 right now.

no vvt but it does have dod.

i feel like we tried a lot of things and we are probably at the limit of the fuel we were using. might be crap gas or just all that 91 is good for.

parish8

iTrader: (6)

oh yeah, stock exhaust, stock cam, stock converter, stock injectors.

of those items i wonder if the stock exhaust could be making the knock worse? duel 2.25" with 5 mufflers.

hellbents10

iTrader: (10)

Those cars have a lot of false knock, you will have to try race gas to verify. Just tuned a procharged one at 7psi the other day. It had headers and exhaust, it made 499whp through the auto. This was with about 15-17 degrees of timing, AFR was 11.5:1 and IAT's of about 125.

parish8

iTrader: (6)

wouldn't the test i did taking the timing back to 10deg and then showing no knock be a good indication that it was real knock?

1320

iTrader: (6)

I agree, but 120 iat seems really high to me for 5psi. Yesterday we did the meth kit on the turbo van, and ambient was 113....iats were 113 -115 without meth, heat soak to 125 then come right. With meth, 79-80 degrees......with 10+ psi boost. Its set at 10, but the meth seems to add alittle boost.

Timing seems real good too, I wonder if its vvt related?

parish8

iTrader: (6)

i dont have vvt.

iats are 120 at idle sitting in the staging lanes. not much i can do about that and it is cooler than it was stock. then they drop during the run.

1320

iTrader: (6)

one thing I just thought of....when I was fixing cranks....there was up to 5 degrees of error on the reluctors when installed on the cranks. It could be really more timing then your seeing......I doubt it too....but might belong on the lis of consideration.

A cold air, and meth...might fix it. Hey are you a dealer for meth? I just got a new dealer relationship....and tried a kit on the van...and for the money it works pretty good.

frcefed98

iTrader: (16)

Disable the dod by shifthing manually and see if the kr still pops up. If you already havent tried this

98Z28CobraKiller

iTrader: (17)

Restrictive exhaust will cause detonation. My old setup was an LS2 408 with true dual 3". I used to daily drive the car and the true duals with the Borla XR1's were a bit loud. I had a friend that works at an exhaust shop make some removable baffles for it that quieted the car way down. Unfortunately, due to the restriction, I had to keep the RPM's under 5K or I would get horrible knock with the baffles on.

1320

iTrader: (6)

Could be a plug, or a problem with a plug.....try a copper tip plug,like autolites 103's....14$ to try.

stevieturbo

Why not just listen for knock instead of relying on the knock sensors, which can pick up all sorts of noises ??

The human ear is very good at filtering. Hook up a set of cheapy "det cans" and listen to see if there is any detonation.

cracker

iTrader: (1)

Plugs - NGK BR7EF (Stock 3346)

Octane - 91 is terrible anyway you look at it. If thats all you have available, stick with the blue gas stations. (Chevron, Fina)

With an efficient engine, I run 14 degrees on pump, c16, torco, whatever.

I would be willing to bet that the octane is the source of your problem.

-W

Slowhawk

iTrader: (12)

We did an APS kit and it ran 14-16 degree's of timing. Alot of the E-38 cars pull false KR.

GS Racing

Without a shadow of a doubt. Huge backpressure I bet even at 5lb, so det starts way sooner.

It certainly worth quickly removing the whole system and running open pipes just to check.

91 isnt great for boost, but what you describe sounds pretty extreme.

parish8

iTrader: (6)

it does not look like false knock. i wish it was on my laptop and i would just post up a pic. an uneven sawtooth all the way threw 3rd and half of 2nd. jump tp 4deg fall to 1, jump to 3deg fall to 2, jump to 5deg fall to 3, jump...

that is at 11.5deg at 4800 and 15deg at 6000rpm.

then with 10deg it is completely clean.

doesn't that seem real?

parish8

iTrader: (6)

if this were a $450 5.3 i wouldn't care but i dont want to break a piston in this thing. it is brand new.