0Anthony @ LGMotorsports

Something I have been playing around with on my own car...and some good info for you guys. Some of you have already went to a TR6, but may not have known why it is a good idea...so I did a little test.

...THE TEST...
No big build, high compression, stupid timing table setup here....STOCK GM parts and tune.

Test car....2008 C6 Z06 Corvette LS7
Stock plugs
Stock timing table
93 octane pump Dallas fuel
40k street driven miles.

This car developed a bit of audible knock, so HP Tuners was used to log the car to see exactly where the knock was going on and to what degree.
LOG FILE

Make note that we have knock across the board, not just at the top of the RPM range and it is happening not only under WOT but also at throttle tip in (noted by now far down the cylinder fill it goes)

To make a quick test we mixed 5 gallons of 104 octane fuel in the mix to see if it was mechanical or possibly fuel/timing related (remember this car still has the stock timing table and spark plugs in it)
LOG FILE WITH RACE GAS MIX

Here you can see that the knock is still there but greatly reduced from stock. Again still throughout the board but not as much in the lower ranges.


STOCK GM PLUG BEING REMOVED

Notice the detonation marks (bits of black)


Back ground checks...
Air/Fuel ratio checks out and is similar to any other stock car, reaching almost 11.4:1 when the car goes into cat over temp. So it is not running lean.

All plugs look the same, injectors check out and the car has plenty of fuel pressure.

02 sensors check out, and are functioning properly.

So now the question....what to do?

1. You can modify the tune and remove timing, which is also going to pull HP as well. Those of you wanting a stock tune...big no no
2. Run race gas full time...sorry $7/gallon for a daily driver isn't fun and it still has knock
3. Run a colder plug to reduce spark knock.


In this case I am going slightly colder on the spark plug to a NGK TR6iX plug to hopefully reduce the amount of knock.


At this point the car has no audible knock, and feels much stronger in the mid range, which is probably due to the lack of 4-6 degrees of timing being removed.


Tomorrow I will follow up with a plug removed for inspection, and also a data log of the same drive conditions to see if we have in fact removed all of the knock from the car with no fuel or tune changes.

Log results tomorrow with a plug pull for inspection

DaOtherOne

Very interesting .. subscribed!

Too-Fast

J.J.D.O.

Jawnathin

NHRA95

also subscribed

bass mechanic

Turbooo2u

Is this plug swap advised for a bolt-on Z with a tune?

Random84

He posted that this is on an essentially all-stock Z, so yes this should be applicable for a "bolt on" car also. the only thing is depending on your tune, the timing might already have been pulled to prevent knock on the dyno.

Perhaps a re-tune to take advantage of the colder plug (if it works) would be beneficial.

EX1

very interesting. Could be a factor in some short lived and stock LS7s that have been ran hard?

LS9Drew

Been running TR6s in every LSx I have owned and in my families LSx's. My tuner says you can also get more timing out of them, so I'll take that which means more opportunity for HP. Had mine in my Z06 since about 2weeks after I bought the car even before I tuned it

Plus $16 for plugs you spend 3 times that on a fill up

H82BFST

08VRZ06

mistermog

z51vett

I'm in want to know the out come 2012 z06 here 14000 miles.
z51vett

Olddudesrule

Agree also. This is what my tuner recommended. Running the Torquer 110 with HP Tuners software.

gatti-man

isnt that a lot of knock on a stock tune? This is on 93 octane I'd imagine it's even worse for the 91ers.

briancb1

Are you saying you can get more timing before a knock... or get more timing which equals more power?

My Last L92 6.0L build would take 27* no problem w/o knocking, but didn't make any more power than when it had 24* advanced. This was done on TR55s (stock heat range). Swapping to new wires and TR6's yielded 0 gain on the dyno, but I left them in anyway.

LS9Drew

Typically with a colder plug you can get away with more timing on a car from my understanding before getting knock, same with a lower reading T-stat. And with only 91 I'll take all I can get lol

But I'm not a tuner you would have to wait for Anthony to respond

y2kvette

I have a '08 zo6 22k miles and I thought i could hear knock. Just last week i was on a on ramp, not accelerating hard, easy slow (50%), shifting long and easy in 3rd and 4th, in 3500-4500rpm range. I heard knock the whole time ( I was thinking " can't be". ??? Was in some traffic (a/c on) about 85 deg. out, just before getting on on ramp, so maybe i was a little warm??

Wonder if GM has a new tune for my car? Did GM ever change the tune from '06 to current '12 z06 ( 6 year span ) ????

Maybe I'll buy those plugs. I'm definitely going to follow this thread.

thanks for the info.