so if you change the timing overall trim it makes absolutely no difference to the detonation? what are you changing it buy percentage wise? is your O2 sensor new and a good 4 wire bosch?

Yeah, The detonation is there regardless of ignition timing. In the wolf software there is an ignition trim, regardless if it is +20 or -30 it makes no difference. A/F is new motec PLM. LOL, when i say the trim makes no difference i mean it does not change the ignition timing. Nothing majour, but just thought it interesting.

that's fecking weird. i propose: it's not pinging, it's somethign else that sounds just like it. your car is making 5hit power because all the timing has been pulled out till the noise stops, but that is merely because the engine's dynamics change with the retarded timing. otherwise i'm stumped.

Well thats what i thought, Its not making **** power, It has Heaps of power.... But has slight detonation, very slight... I could probably tune around it and it would probably last for ever. but id rather find out what it is. We detuned the car on the dyno to try and get rid of the detonation, and came up with less than 200rwkw and it was still there. Thats with toulene and everything. If the slight detonation is ignored and just tuned until it pings and then backed off until no audible "majour detonation" its a scary scary car even on straight pump.

i would get hold of a knock link and see if it's really detonation or some thing rattling or knocking

well you've got good manifolding, a big turbine rear (low backpressure) and an otherwise seemingly well-built engine. it should be making (at a guess) somewhere up around 300rwkw at 18-22 pounds. if it makes the power but pings badly, then you might have a problem on a single cylinder, not all over the engine (if you know what i mean). for instance if cylinder 6 is pinging lightly every now and again, but overall the engine is making good power, then you may have a localised problem in one cylinder. could be a hotspotting problem, i know some of the big power GTR engines have modded cooling systems because the rear cylinders have higher coolant temps (further from the water pump) and thus have a tendency to hotspot in the combustion chamber and cause pre-ignition. haven't heard of it in an RB30 though, and it's certainly not a common problem.

Thats what it sounds like. One cyliner is detonating every now and again on a power run. OK, I have done plug checks and cant seem to find a single or even two cyliners that have any sign of leat mixtures. How do i check a plug for detonation? Or how do i check indervidual cylinders?

I know you wanna fix the problem completely but as a test have you tried putting some octane boost or better fuel in it to see if that removes the detonation? As far as im aware you cant check plugs for detonation can only to a rough check to see if theyre lean/rich whatever the case may be...you'd need to remove pistons to check for any indication that its been detonating...even then if its only been minimal detonation its unlikely youre going to see anything.

car has been run with and without 30%toluene. Same reasults. Might hook scope up to indervidual ignition leads to see if i can pin point what cylinder it is. Should have voltage drop or spike when detonation occures.

Could it be that youre being paranoid? Lol....

something is restricting the car and causing it to detonate. what sort of exhaust do u have? my exhaust is a little to restrictive i have been told, and its a 3"

3" from turbo back. 3" cat with resonator at rear. Thats it. LOL, I wish I was parenoid.

using the chassis ears, see if it's louder towards the rear of the engine (cylinder 6) than at the front (cylinder 1). if it is, you may have a plenum problem (poor airflow distribution) or the cooling problem that i mentioned before. it wouldn't be the exhaust manifold as it's one of kyles so that's about all i can think of. BTW if it doesn't go away with 30% toluene, that says to me that it's nothing to do with the tune, more something to do with the engine's airflow distribution.

this might sound stupid and im really out of my depth on this convo, but just wondering on the dyno when you hear it pinging does it flatt'n your power curve out too ?? and when you check your plugs do they all look ok or is one or two a bit black then the rest ?

if you veiw the plugs with a proper plug veiwer or microscope, they will have aluminium partcles on them, you can tell from that what cylinder has been doing what, or run 6 EGT's RB30's will always have more troble with no's 1 & 6 no matter what manifold you use.

Do you have equal length inlet runners? It could very well be (as someone has already stated) inlet design, as an example, a friend's GTR with a greddy plenum kept frying number 6 because the airflow would always run straight to number 6 cylinder and lean it out. So he adjusted the MoTeC with individual cyl trim to up the duty cycle in number 6...band aid solution, but it still made over 500hp at the treads...

Yeah im 99.9% its not the tune. My inlet plenum is used by heaps of people making big power and they dont seem to have this problem. The power curve doesn't flatten out. It not a great enough ping to even show up on the dyno. Engine quite happily power through it without flintching. The fact that we can add heaps of fuel and pull heaps of timing proves that its not in the tune. Its something else like a hot spot somewhere. I am running a headertank, with new radiator/hoses/thermostat... Infa red temp gauge is on the way. Then i can read 6 cylinders exhausts under load on the dyno, or even engine block/head to see if the rear of the engine is a lot hotter than the front. LOL may even have to let some of you guys have a listen in person if i cant figure it out.

i'll just nod knowingly and tell you it's the flux capacitor.

ahh thats where the flat pepsi and old banana skins go.

Ok Guys, Just to let you know..... I found out why my engine was detonating. The engine started to get worse. wouldn't rev... past 6000 and wanted heaps of fuel. it was running 12's A/F at 15 psi at 100% duty. Wich was very un like this setup. I was about to raise the fuel pressure and then figured something was changing. The valve springs had gone soft. (One of thoes should have picked up on that earlier problems ) They are 3 years old and i pulled them out before rebuilding this engine thinking they would be ok. Today I changed them. It has gone from a lethargic lemon to it will rip a power skid in third on 'pump' at 15 psi. No other changes. Its crazy. Thanks guys for your help. Hopefull this may help some one else that may be having a similar problem. Sean