Knock Levels On A Garrett Gt3076 Wg

[tridentt150v]

What boost level are you running and what knock/ping level do you have?

I've got spikes of 130 if I hammer it [foot all the way down] in say fourth gear and 3-3500 rpm, 80 to 130km/h overtaking maneouvre, doesn't happen in 3rd, I'm running at 1.2 bar. I've seen it twice now, so it's definitely out there.

I was wondering if anyone else has this problem?

If I drive it normal and ease the power on a bit more progressively, I'm lucky to see a knock level of 10 to 15.

Std 2.5 motor, fmic, power fc, hks cast low mount extrude honed, hks 40mm wastegate 18psi spring, 550 injectors, split dump, tomei 256/8.5 cams, hks hyper exhaust, pod, sard fpr, z32, boss cat, nismo pump etc etc. 275rwkw.

I was wondering if its tune, too high boost level, or because of a fuel starvation [need a surge tank, long shot this one].

I would prefer not to have to touch the motor [thick head gasket, forgies etc].

[Devils_Advocate21]

what sort of afr's is it running, surely a safe one i hope, it wouldnt hurt to get it checked out at a tuner would it and just explain what is happening, they just might be able to tweak the tune retard the timing slightly so its a more of a safe area of play. Id say its in the tune in a short shot

[fEkuaR]

Id say you just need to get the tune touched up in that area. Have a look on the tracer where its doing it and drop a couple degrees timing from that area. The extra load in 4th could be highlighting the issue.

[The Mafia]

thats really bad.

I have a GT3076 with 550cc injectors, powerfc, Standard manifold, 0.63 rear housing, etc and this morning I went for a blat at 6am, and at 22psi, and 300rwkw+, it got to 30 on the knock meter.

Your tune is shagged, get it checked properly.

Dynos don't load cars up enough.

[fEkuaR]

Normal drive you say its 10-15. Whats your knock levels like full throttle in say 1st to 2nd up to 100kh/h?

[STATUS]

yeah some tuners forget to compensate for one important force acting on a car on the road........ wind resistance.... gaurantee that in 4th and 5th flt out there is too much timing on the ramp.

[Dale FZ1]

It's not only wind resistance, but the terrain being travelled too. Loading an engine up a long, long climb is way different to what can be achieved on a dyno.

Any tuner worth their salt would (should) be running Datalogit, with wide band input. Really takes the guess work out of things. At that power level, your fuel system shouldn't be under strain, but why run with a non-standard FPR? Provided the fuel delivery and mapping is working as needed, it should be a matter of tweaking the ignition map.

Off thread, but can you post up some pics of your engine bay?

[The Mafia]

Dale is right.

And when doing my ignition maps, I like for nice steep hills to hammer it up.

[tridentt150v]

FPR cos my std one was supposedly leaning out, I don't need the rising rate, just a good qual fpr, and SARD are OK.

And thanks to all that responded, I didn't want to say what I thought cos I was after an unbiased opinion. But I agree with you, I'll have to have a look at the map and knock some timing out in the range where it is pinging.

I intend to get it on a dyno at another shop as well, and get a second opinion/tune.

As an aside - the first time I got high knock levels I thought it was maybe triggered by a random thing eg bad fuel, injector, other stuff...........but the next time was different fuel, and I couldn't feel anything wrong with the car, no miss or stutter, so I agree with everyone, its in the tune.

And Mafia - you run with MI, I don't, I might one day soon, but not yet, one step at a time for me, I'll get this setup sorted first.

Dale, I can do that, but there is nothing remarkable about my engine bay, its got some decent stuff in there, but its not a show car, its not polish and chrome, you'd see nothing unusual.

[tridentt150v]

Normal drive you say its 10-15. Whats your knock levels like full throttle in say 1st to 2nd up to 100kh/h?

Haven't done it in 1ts or 2nd, but it doesn't do it in 3rd, and as I say if I ease it on and build up slower like floor it over say 10-20 seconds then it doesn't do it in 4th either, only when I floor it instantly.

But I reckon its the tune!!

[Dale FZ1]

Dale, I can do that, but there is nothing remarkable about my engine bay, its got some decent stuff in there, but its not a show car, its not polish and chrome, you'd see nothing unusual.

Come on, don't be shy... Actually I'm just interested in how you've gone about doing the inlet trunking, and any heat shielding.

Haven't done it in 1ts or 2nd, but it doesn't do it in 3rd, and as I say if I ease it on and build up slower like floor it over say 10-20 seconds then it doesn't do it in 4th either, only when I floor it instantly.

But I reckon its the tune!!

I'd say with certainty it's in the tune. And going by own experiences and the above comments, would it be reasonable to suggest this happens at relatively low rpm and WOT? I struck this situation with mine on a test hill known to Mafia. Basically hit the hill around 2000rpm in 4th gear, steady throttle, and feed the throttle heavily into it. The hill is about 500 metres long and top rpm is about 4500. In that 2000-3000 bracket, the engine is loaded much heavier than can be achieved on a dyno. Basically you access cells in the map not normally hit, and if the ignition is too far advanced, it will knock. What makes it more noticeable is that the steepness of the hill keeps the engine operating within those cells for seconds at a time, rather than just flashing straight past them. On more level ground, the rpm picks up too fast for that load area to count for anything significant.

Mine was sorted with adjustments to about 5 cells in total.