Gtir plenum design

Never really gave it much thought before but after doing some tests on our Dyno the other day I found that the wedge design of the gtir plenum is pretty bad really in terms of how it can affect the afr's on individual cylinders

When various sensors are getting around 70% of their duty cycle it appears that no 1&2 cylinders are always running at a leaner state than 3&4 so are much more susceptible to det even though the general afr's from exhaust is well within limits. This would explain why many stock engines suffer damage on the intake side of these particular Pistons through higher cylinder temps

I've recently purchased a knock ears kit so I can now mount upto 6 sensors in varying positions throughout the engine, although monitoring cylinders 1&2 will be more beneficial which makes me think that the oe knock sensor should ideally be placed between cyl 1&2 rather than in the middle of block
This is all caused through the poor design of the inlet plenum as the boost intake pressure is greater in the wedge part of plenum so when fuel / air is put into those cylinders the afr will be leaner than the other two.

Makes me wonder if their is benefit afterall in having a box type plenum
Certainly food for thought

Il be looking into other ways of monitoring these cylinders in future or other ways to remedy the problem.
Maybe by running slightly larger injectors on those two would cure this but don't know until I've tried a few things out.
unless your running a lot of boost otr it should not be a prob but on racetrack it will definately be an issue
So would like to find a solution

Tbh i would try box type plenum first I might be wrong but using 2 bigger injectors would put different load on them cylinders and would throw lambda out on individual cylinders (i might be little drunk but i think you would need 2 o2 sensors to keep it right) so ideally box plenum with centre throttle body  something like rb25det

Yes centre position intake (maybe a Y type pipe coming in) would equalise pressure much better than it being at one end for sure.

I don't think the 02 sensor would be affected at all as it monitors afr from exhaust elbow so if those 2 are running leaner than the other 2 it would make little difference to lambda reading, plus the lambda only works in open closed loop anyway so is only reading under light load.

The only thing I'm not sure about at the moment is injector frequency and pulsewidth as it will differ to the stock 444s but will try a few things out to see what happens

Lambda i meant air to fuel ratio you don't wan't cylinders leaning out and detonation. I've read article about it by dave walker from emerald but it was ages ago... But tbh it was about n/a engine i never thought that would be a problem with turbo as pressure in plenum should be equal... you learn something everyday.