Scientifically - is there any good explanation why you're loosing a little bit of low torque when you're upgrading to filter/extractors/exhaust ?

And if there is ..... which component is guilty ?

I'll put it down to tuning. Or maybe it just feels like it because you are gaining high up torque. In any case, I'm sure you could iron out any flat spots with the fitment of a nice engine management chip.

A larger diameter allows more flow high in the rev range which helps scavaging of the cylinders. At low revs, the exhaust exiting slows down as it's got a larger area it can use so doesn't scavage as well.

That's what was explained to me.

Oh :shock: looks like I totally missed the question! :lol:

You mean larger pipe, smaller air speed. Hence smaller pipe, larger air speed. Regardless whether it is forced (exhaust) or inducted by air pressure (intake). Note, the total mass remains the same.

But - why does it happen then? Air needs to flow nicely like water - trust me - at 6000 RPM there is a helluva mass of air moving.
If the pipe is large, the flow is not very "organised". It just "bubbles along" until the mass becomes large enough to start to "fill up" the pipe. Then the air starts to circle/swirl/spiral etc along the inner surface. Makes it travel faster. Just one of those physical facts. Unless, of course one goes and uses un-even surfaces in these pipes, which prevents the air to commence the circulating movement. We have discussed this to detail in some CAI threads.
But, still, this doesn't explain the loss of torque? Well, once there is less spiralling air movement, it - well - moves less rapidly. Hence intake or exhaust is not as good. On the intake side this is very relevant when one has carburettors. With injector models, the Mass Air Sensor (MAS) detects the air mass (derr...) and adds the gasoline accordingly. If the flow is less, then there is less air and less gas - less bang etc.
But again - if one drives at 2000 RPM the displacement for mixture is always the same isn't it? So why does a mod like CAI then allegedly rob the low end torque? Because the larger pipe just does not get the air moving that well to provide the maximum mixture. Fortunately MAS senses all this and keeps the air/fuel ration correct. In carbi version one would need to play with jets and stuff. Not to forget the throttle sizes etc - but that's another story.
But of course on high revs, the larger pipes allow plenty of movement and improves breathing (power). How ever, this doesn't mean, the bigger the better. Remember the "bubbling air"....
On the exhaust side similar things apply. One can go and make the pipes too large and stuff everything. It's pretty fine science after all.
Next question is - how come dragsters have huge, straight 1 meter long pipes coming out and they produce enormous power?. Heh - bit different category there....
I tried to make this brief to stop ppl falling asleep. Hope it makes sense.
I have headache now for too much thinking......





A larger diameter allows more flow high in the rev range which helps scavaging of the cylinders. At low revs, the exhaust exiting slows down as it's got a larger area it can use so doesn't scavage as well.

That's what was explained to me.

wow, good stuff killer, oh, on stupid question, whats cai?

wow, good stuff killer, oh, on stupid question, whats cai?

This one I can answer - CAI is Cold Air Intake or Cold Air Induction - getting the coldest air possible into the engine.

And killer - good answer ;)

Manual

cheers, i know what it is, just didnt know what the abbreviation ment.

nurries mate ;)

:?

Does that mean what I said was close?

Yep, just that mine was bit more abbreviated.
:o

BTW - I kinda should have added that, say engine is running 2000 RPM on flat surface. There is certain amount of air travelling thru the MAS and TB (Throttle Body) etc. As in, there is a movement of air mass. Then u hammer it, gas pedal flat out. What happens to the airflow? There is momentary loss of flow, cos the TB BF (Butter Fly) opens suddenly and the previously mentioned massflow suddenly gets a large opening to go thru - instead of the small BF opening when going easy at 2K RPM.
If all timings and adjustments are not correct - the engine will splutter and perhaps die due to sudden loss of air movement. How ever - the pistons are still creating vacuum cos the crankshaft didn't really stop rotating, so the airflow will soon resume. Note - cylinder air is filled by ambient air pressure, not vacuum by pistons - the vacuum space has not enough power to overcome the airpressure. This is quite common "misbelief" - no big deal tho.
This kinda stuff is quite difficult to experiment, unless u have specific equipment. See, bit difficult to see the air....
But imagine a garden hose. Water travels in the hose as a steady flow, like a pillar if u wish. Once it exits the end of hose, it kinda goes everywhere and the flow it self lessens. Similar thing with air.

Ok, I shut up now. :)


:?

Does that mean what I said was close?

I noticed the same thing when I had the exhaust, air filter, throttle body
and fule pressure regulator done. Low down torque was reduced while top
end power was increased a lot. I also use Mobile Synergy 8000 ever since
they came out and only noticed slight improvement. Someone on this
forum or the US D forum mentioned about advancing timing and when I
went in for a service I got them to advance the timing. Big difference :D
Low down toque has increased noticably while top end power was still
there.

Now - help me with my ignorance :oops:
Can 3 L TE timing be adjusted manually? I thought it was all handled by ECU. Hate to admit - but haven't even checked if the dizzy can be turned to change timing. I know some guys have done so with the TRs etc "older" models - but mine?
But generally, advancing timing will improve the low rev bang, but reduce top end if done too much.


---advancing timing and when I went in for a service I got them to advance the timing. Big difference :D
Low down toque has increased noticably while top end power was still
there.

Now - help me with my ignorance :oops:
Can 3 L TE timing be adjusted manually? I thought it was all handled by ECU. Hate to admit - but haven't even checked if the dizzy can be turned to change timing. I know some guys have done so with the TRs etc "older" models - but mine?
But generally, advancing timing will improve the low rev bang, but reduce top end if done too much.

[quote:b0a7c2cabc="vlad"]---advancing timing and when I went in for a service I got them to advance the timing. Big difference :D
Low down toque has increased noticably while top end power was still
there.[/quote:b0a7c2cabc]

I believe that the TE/KE-TL/KL are still using distributor ignition rather than
distributor-less ignition (eg, Holden Commodore, where timing is controlled
by the ECU) so I guess that the timing can be changed by turning the cap.

Checked last night: the service manual states that this model's timing cannot be manually adjusted. I also checked the dizzy it self - no can do.
Pity - just when I got exited to do some testing....

I believe that the TE/KE-TL/KL are still using distributor ignition rather than
distributor-less ignition (eg, Holden Commodore, where timing is controlled
by the ECU) so I guess that the timing can be changed by turning the cap.

Checked last night: the service manual states that this model's timing cannot be manually adjusted. I also checked the dizzy it self - no can do.
Pity - just when I got exited to do some testing....

I believe that the TE/KE-TL/KL are still using distributor ignition rather than
distributor-less ignition (eg, Holden Commodore, where timing is controlled
by the ECU) so I guess that the timing can be changed by turning the cap.

Oh well, I do remember reading somewhere that the TE/KE onwards were
designed and tuned to run on normal unleaded (hence no knock sensor as
well).
It doesn't hurt to ask the service people whether they can advance the
timing or not when you go in for a service.

I also noticed that the fuel economy has improved and also that I'm using
less throttle.