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Knock Level Worries Rb26/30

leeroy_25

By leeroy_25,
in Engines & Forced Induction

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leeroy_25 Community Regular

leeroy_25

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Just trying to get some view points and maybe piece of mind as it seems to vary who you speak to! I have an RB26/30 motor with a stock RB30 bottom end. I am running about 1.2 bar boost and limited to 7000rpm.. I have an Apexi ECU for info. When I am driving hard on full load, 3rd, 4th gear the knock levels hit around 38 most of the time which I am not too worried about. However every now and then I get a low 40/41 recorded and very rarely I get a mid to high 45-48 pop up? Should I be worried about this and looking to put a bit more fuel in or dial out some ignition somewhere? The fact it is not consistent implies maybe it is one or two slightly rogue cells which I may be able to find if I investigate the map? But just wanted some thoughts before I get all carried away!

Thank you

Lee

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The Mafia Grand Master

The Mafia

Posted
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For starters, have you ever done anything tuning wise before?

Don't e er touch your fuel without a wide and present.

If you're worried about timing, you can take some out across the board. But you need to know what you are doing.

leeroy_25 Community Regular

leeroy_25

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I had a look in the map and spoke to my tuner and decided to take a degree out of the high load/rpm end of the chart in my apexi commander.. They are around 21-23degs at that end which looking at the basemap is possibly a degree or two high anyway? I will monitor the result and if need be take another degree out. The weather has just cooled down here after getting it mapped so I expect the cool dense air is not helping in as much as I am getting to the point of maxxing the fuel system anyway as well! So to be sure I might kick back the boost ever so slightly too if need be, only 1psi! I think better safe than sorry!

leeroy_25 Community Regular

leeroy_25

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Assuming the CAS was set correctly by me! Then it is at about 20degs. Idle is a bit lumpy so not easy to get a definite reading! Engine warm, idle at 950rpm.. Strobe on the front pullie? I presume there is no way that reading can be wrong?

I don't imagine a degree or two is going to make a huge impact on power is it?

And yes that is through the top end range.

Thank you

Lee

blue_vl_t Rising Star

blue_vl_t

Posted
Posted

well, considering you have FCLOGIT, just datalog a bit of driving about, then you can check the knock in all individual cells, so you will be able to see if its in the top end or the bottom end etc.

Most of the range where you have 40+ deg of timing, you would be hard pressed to use any of that map, you would need to be driving around in a lower gear, with a few revs and light throttle.

blue_vl_t Rising Star

blue_vl_t

Posted
Posted

Fair enough, so if your concerned about it, pull 2-3 deg out of the are you have stated and blend the numbers so the timing graph is still smooth/progressive

you say your running 1.2 bar, what turbo is that?? makes a huge difference to intake temps and detonation, if its a t51r or a stock turbo, i'm going to assume you have a gt3076 or similar

leeroy_25 Community Regular

leeroy_25

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Thanks for the info/confirmation.

I am running a Holset turbo.. HX40.. The intake temps on the commander are generally fine.. Gets a bit warm under the bonnet in summer when you stop! but I am fitting a vented bonnet soon!

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