Air inlet track XV ( though same prob applies to others

[gregjet]

I also pasted this on the facebook page , but they tend to let stuff get lost over time.

I am finally getting around to cleaning up the disaster of wiring loom supports that is at the back of the XV and gets in the way of changing the gearbox oil. That's all good now minimal steel, a new aluminium support for the pipe and the rear ziptied properly to supporting wires and pipes. However I had to take the inlet tract between the throttlebody and the air intake monitor at the filter off and had a good look at it. The thing is huge and has resonators left right and centre. Now I know why they put them on 2 strokes years ago but that can't be the reason here. Has anyone made a "straight" pipe to replace it and dynoed it? What , if any, was the result. I suspect peak HP was unaffected but maybe partial throttle torque point benefits? Or is it just a noise reducer?

 

[Ratbag]

Greg, resonators in the inlet manifold are like the tuning of a musical instrument. Their purpose is to provide the right amount of turbulence to maximise fuel/air mixing and flow into the cylinder, while removing the possibility of back flow.

This latter is particularly important when a MAF sensor is fitted, as the sensor interprets all flow both ways as if it is flow into the cylinder. Without the resonators, it is not only possible but likely that you will get both way flow.

Do not muck around with the resonators unless you know exactly what you are doing. It's not hard to ruin your motor ...

 

[gregjet]

Most resonators on inlet ( read not ALL) , are to dampen harmonic resonances that cause noise, not to improve flow. Your point about the sensor is well taken however. That problem with that is there will ALWAYS be pressure waves travelling up and down the whole inlet tract ( THE most ignored part of motor tuning on a motorcar). It doesn't "flow" both ways, but pressure waves do travel back and forward. This could be one of the reasons for the helmholtz resonators to dampen the strength of the waves. Those of us from a motorcycle background , and particularly a 2 stroke background are well familiar with it's importance.
No matter what you do to the inlet resonance it is unlikely to majorly effect a motor and almost impossible to ruin it. It can , however , decrease it's output. This is why I am cautious about simply making a simpler version. The total inlet tract on this car is ridiculously long and accounts a fair bit for it's slow throttle response in the NA motors. The manifold doesn't help at all but , at first glance, getting a single throttle body positioned so it is at a simple harmonic is VERY difficult without long runs.
Turbulence in the inlet , right up to the injectors will have little effect on fuel air mixing. It will dance around doing all sorts of things before it gets to the injectors. Anything before the throttle body will be screwed around by the butterfly anyway. The long narrower inlet manifold ( than the airbox to throttle body) will force stream the flow there anyway and reasonably dampen any such turbulence.

 

[Ratbag]

Greg, I am sure that you know more than I do about these things, and perhaps when I used the word "flow" I should have referred to standing waves and the like that jointly comprise resonances in such a system.

However, bear in mind that the major contributor to the huge improvements in both low and high end torque from the EJ-251 to EJ-253 motors appears to be down to huge improvements in the tuning of the (complex) inlet tract, including, but not limited to, replacing the MAP sensor with a MAF sensor, adding tumbler valves, adding variable valve lift technology (and probably changing other aspects of the cylinder head design). Probably changing the exhaust system as well.

There is little to no lag in my SG. SWMBO's SH has a slush box, so let's not talk about lag with it ... . I know that the 2.0L donks are different in this regard, and they also lack the basic grunt and tractability of particularly the later EJ-253 donk.

It is hard to make up for lack of engine capacity without having a turbo that cuts in at just above idle speed ...

I also work on the principle that engineers usually know their product better than I do, regardless of design restrictions to make the car/engine usable by the widest range of people/purposes.

My major thought was to be careful.

I have come across reports of damaged engines on forums that have arisen due to failure to understand how the MAF sensor impacts 'flow'. MAP sensors measure one way 'flow' (etc), a MAF sensor measures two way 'flow' (etc), and adjusts the mixture as if all that 'flow' is one way flow. It is easy to see how the engine can run rich or lean under such circumstances.

Standing waves can impact the measurements performed by a MAF sensor, and the ECU adjusts fuel/air mixture accordingly. Hence the need to prevent such waves and reverse flow. Hence the resonators etc.

All the best with your endeavours, mate.

 

[gregjet]

Yeah your point is well taken. That's why I wanted to see if anyone had done it before and dynoed it.
The only real problem I can see at first glance is if a standing wave node occurs at the sensor so the apparent temperature and the actual pressure at the sensor will appear to be high pressure and temperature with no flow. That should confuse the sensor nicely...
I have seen aftermarket replacements for the plastic flowmeter to throttle body and "claim" HP ridiculous increases , which I of course don't believe. I mainly want to improve the actual flow and declutter the engine bay AND reduce the temperature uptake of the air under the bonnet. How is still yet to be determined but I won't be doing anything without seeing dyno figures fore the resonator tube removal.

 

[duncanm]

googling "FB20 intake dyno" pops up a few results..

A snorkelectomy rarely produces any significant power gain.

 

[gregjet]

OK Finally managed to take pics of the wiring declutter to be able to get to the gearbox dipstick.








Now I can get to the gearbox dipstick and filler without shreading my wrist and hand and a funnel now fits for the refill.

"""" Sorry but photobucket started charging for posting so I have deleted my photobucket account. No way to post pictures on this forum any more.

 

[Ratbag]

Heavens to Murgatroyd!

 

[gregjet]

Is that a good or bad Murgatroyd?

 

[Ratbag]

Well done, Greg.

Mine's nearly as hard to get at! Bloody silly design ...

 

[gregjet]

It's a simple change for good results.
Loses weight ( I hate unnecessary weight . A product of racing bicycles and motorbikes) and does not require and rewiring, just unclipping and moving the cables over. They actually have less tension on them (?). The lifting plate can be cut with a angle grinder or a hacksaw easy enough and smothed with the grinder or even just a file.
The riser for the breather tube requires a small amount of fabrication but could be dispensed with by zip tieing it ( not my preferred method).
The difference in access has to be tried to be believed. This car is full of stuff that was obviously designed in isolation and offcar instead of integrating the whole design.
There is more being removed or modded under the bonnet.