Polo Intake Thread

[Wand Weaver]

sure and they often change the intake too

Perhaps a larger K04 is able to shift enough air to take advantage of the larger intake.

I was saying that the K03 struggles to shift enough air above 5500RPM, even with the standard intake pipe. By fitting a larger turbocharger, that point becomes no longer relevant.

The question posed in this thread was whether changing an intake, WITHOUT changing the turbocharger, was likely to make a measurable difference in power or torque output. Like the OP, I'm not totally convinced that it would.

Let's put it this way - if a pump can only move X amount of fluid a minute, increasing the potential flow rate of the pipe feeding fluid to it won't make any difference, unless the pipe was restricting the flow of fluid to a figure less than X to begin with.

What I, and the OP would like to find out, is whether the standard intake pipe restricts the flow to a figure less than X. IF, and only if it does, will an intake mod make any difference.

[Timbo]

This is with the standard intake - giving the turbo even more air isn't likely to make it shift more air - it already can't shift the air coming through the standard intake pipe.

There, my friend, is the nail hit on the head!

[GT3]

Perhaps a larger K04 is able to shift enough air to take advantage of the larger intake.

I was saying that the K03 struggles to shift enough air above 5500RPM, even with the standard intake pipe. By fitting a larger turbocharger, that point becomes no longer relevant.

Unless you have engineering data that supports your claims re air intake capacity of the K03 (that's frequently conjectured but never verified), then you're simply making an assertion.

[Adam]

Unless you have engineering data that supports your claims re air intake capacity of the K03 (that's frequently conjectured but never verified), then you're simply making an assertion.

boys boys! let's settle this on the black top! end quote from F&F3

[DaveMack]

I think Guy's Vagcom idea is the best way of settling this. Other than that ... it's really just all hot air - pun intended.

Dave

[Wand Weaver]

Unless you have engineering data that supports your claims re air intake capacity of the K03 (that's frequently conjectured but never verified), then you're simply making an assertion.

You want some data?

Fine. Here's some flow rate vs "boost" pressure airflow maps, for both relevant turbochargers.

KKK K03

KKK K04

Note that the K03 Graph is sideways - the X axis should be the airflow, in cubic metres per second (one cubic metre being 1000L), the Y axis being the pressure, expressed in bar.

The K03 doesn't shift nearly as much air as the K04 - note how the choke lines drop dramatically as airflow hits around 0.1 and approaches 0.15 cubic metres per second, even at 2.2 bar boost.

The K04 exceeds that amount - and can handle more boost than the K03.

Now I've put up my data - would you like to put up data on the intakes? I'm interested in whether the intake really does choke the K03 - but to say that the K03 struggles to shift air regardless of the amount of boost you throw at it isn't speculation, as you just suggested but fact.

The compressor just isn't big enough.

[GT3]

You want some data?

The compressor just isn't big enough.

well good for you lol. in my view, there's many variables at play and its the interaction between all these things, such as intake, MAF, charge temp, compression ratio, turbo efficiency etc etc that work togther to bring about gains. when isolating separate components, that gets overlooked

[Spec83]

well good for you lol. in my view, there's many variables at play and its the interaction between all these things, such as intake, MAF, charge temp, compression ratio, turbo efficiency etc etc that work togther to bring about gains. when isolating separate components, that gets overlooked

You hit the nail on the head... The MAF is the biggest restriction in the system... say the MAF accounted for 40Pa and the filter for 10Pa (50Pa total intake resistance)... if we reduce the filter to 5Pa we have reduced that part of the intake by 50%... however we have only reduced the total intake restriction by 10%....

Taking informtation from Guy and WandWeavers posts lets look at the efficency curves attached where i have marked out a few major points... The K03 is 72% efficent at loads lower loads (less than 2/3 max power) hence low lag, lots of down low torque... As Guy mentioned a stock 1.8t in a polo flows 120g/s at max power.. From the attached graph you can see that the polo is already dropping off the back of the efficency curve. Adding more air flow is only going to loose efficency. This may also be the reason why the polo does not benefit from an upgraded exhaust as it simply can not do anything with the incresed air flow. This would be true for both chipped and non chipped cars...



On a chipped car note that efficency of the K03 is the same for that at stock boost... this is why the stock intercooling system still works fine with the car in a chipped state... it is no less efficent and produces no more heat Also, the efficency band is moved higher in the rev range... where previously boost is starting to fall off it stays strong - hence the increse midrange poke of a chipped polo everyone raves about!!! And of course we all know the more air we flow the more power we can make...

This is also where adding more fuel when adding more boost becomes important... If the maps are not compensated then it will add the same ammount of fuel for stock boost - but we are now flowing 25% more air at any given point. Too much air and not enough fuel will put the A/F above 14.7:1. Not enough fuel is added to make the mixture to make it more dense in the combusion chamber and pre-ignition of the mixture occures as it enters the chamber and not on the compression/spark stroke. This puts untold stress on the engine components as it is now opperating out of time... two cylinders are firing at once etc etc... this is when things tend to break big time

It is also intresting to note that a K04 is more efficent at stock boost levels than the K03... Just by replacing the turbo you should make a little more power

The only thing de-restricting the intake would do is let the engine rev a little more freely and make boost come on a fraction earlier... above 2/3 max power it will do nothing as the turbo is past it's best

Thoughts.....???!!#$%#$

[DaveMack]

Hmm ... guess I shouldn't have flunked maths, Mark.

BTW ... I still have a DVD that you'll be wanting to see sometime (purely VWW business ppl ... nothing rude )

Dave

[Spec83]

Hmm ... guess I shouldn't have flunked maths, Mark.

BTW ... I still have a DVD that you'll be wanting to see sometime (purely VWW business ppl ... nothing rude )

Dave

You have a PM dude....

I put so much into that explanation too hahahaha... Basically anything that increases the kg/s to the right of the max power dots is a waste of money because you will loose efficency and create more heat that you can't get rid of..... if you add a bigger intercooler then it may help to add an exhaust also.. but i doubt it


No dyno tests should be necessary after looking at the curves... its all in black and white

[Timbo]

... say the MAF accounted for 40Pa and the filter for 10Pa (50Pa total intake resistance)... if we reduce the filter to 5Pa we have reduced that part of the intake by 50%... however we have only reduced the total intake restriction by 10%....

...This may also be the reason why the polo does not benefit from an upgraded exhaust as it simply can not do anything with the incresed air flow. This would be true for both chipped and non chipped cars...
...
On a chipped car note that efficency of the K03 is the same for that at stock boost... this is why the stock intercooling system still works fine with the car in a chipped state... it is no less efficent and produces no more heat
....
The only thing de-restricting the intake would do is let the engine rev a little more freely and make boost come on a fraction earlier... above 2/3 max power it will do nothing as the turbo is past it's best

I doffs me hat! Good work that man! Great analysis, supporting why neither intake nor intercooler mods have a dramatic impact with the KO3 in place, even on a chipped car. I'd just add to this, that while I don't have the flow data to support, if you look at the stock Polo exhaust, the greatest restriction in terms of reduced diameter through bends is from the turbo outlet to the cat....which is why replacing this section with a wider pipe liberates a startling number of ponies

[shaneth]

Nice work Spec, BUt i have one question not related to you analysis but to the thread.

WHats the purpose of having a CAI system??
Answer - to increase the flow of COLD air into the system, which in turn contains more oxygen and results in cleaner combustion.

Now its all well and good to say that the Turbo cant handle more Air. But that doesnt ruleout the fact that you cant improve the temp of the air that gets fed to the turbo.

Now lets take the stock Turbo inlet pipe. Half of it is metal. Now from what i know metal is a great conductor of heat so lets say the turbo inlet pipe is replaced by a silicone one the fact that you dont have the metal surrounding it and heating the air up as it passes through it is of benefit imo. Now if you increase the flow of it so that it passes through the pipe quicker which means it isnt being heated up as much would also be a good thing.

Now with regards to the seat air intake it increases flow which should mean more air and colder air gets there quicker and more effiecently.

So in my opinion we could go on all day about the turbo not being able to handle more air when the fact is that with regards to me im trying to improve the QUALITY of the air (i.e tempurature etc)

edit - Spec

Adding more air flow is only going to loose efficency.

Can you PM me and let me know how this can be. For some reason i just cant get my head around how more air in the intake is going to affect efficency. (i must have had a big night last night. )

edit 2 - im trying to get my hands on vag-com

[GT3]

...supporting why neither intake nor intercooler mods have a dramatic impact with the KO3 in place, even on a chipped car.

ha ha ha you've got to kidding. you've selectively isolated sections out of context from the broader analysis in order to justify the decisions you've made. it's obvious that intake and intercooler upgrades enable the K03 to run even more efficiently AND produce more power (the K03 is ideally matched to the pog's compression ratio, a K04 isn't).

shane, there's little point raising the proven benefits of deceased air temp, charge air volume etc bc it doesn't suit their argument (that's why those benefits are selectively ignored).

[Spec83]

ha ha ha you've got to kidding. you guys are interpreting these things in a way to justify the decisions you make, and point blank refuse to acknowkledge that intake and intercooler upgrades enable the K03 to run even more efficiently (the K03 is ideally matched the pog's compression ratio, a K04 isn't - which is why it's need signficant additonal mods to work efficiently).

Ahhh you are now speaking of ecu tuning technique... If the intake charge is cooler (same boost and rpm) it is more dense... This enables you to advance the timing more as you are reducing the chance of detonation or lean out the mixes a little bit as you don't need as much fuel in the cylinder.. This may go part of the way to answering your question Shaneth I just think a CAI is going to do SFA on a stock turbo as the intake is already OPTIMISED to the turbo charistics... If you wacked a GT3040 on then sure the intake would liberate some extra hp as it would be a restriction as now the compressor efficency curve probaly has it's peak efficency around 4500-5000rpm. The trade off is shocking lag and proably not much spool before 3000rpm.

This is the point i would be switching to a cable throttle and a microtec!!!

All of these parameters are inter-related... thats why it is hard to tune a microtec from scratch as you have to account for these things... its easier if you can crack the stock code and use the factory maps as a base!!! High boost with stock intercooler really requires a different tune to stock boost with intercooler and visa versa.... the APR/Revo/Ottengier tunes all use around 1bar of boost while leving everything else stock. This is the most mods you would want to do on teh exhaust side to a K03 1.8T as the turbo cannot flow anymore air even with a bigger exhuast.. Intercooler would make the air charge more dense hence more timing with a little bit more power... the intake would do nothing as again it is hardly adding any heat to the system - stock intake or CAI

[Wand Weaver]

Thoughts.....???!!#$%#$

My only thought is that's one of the most brilliant technical posts I've read on VWWatercooled in a long time, if not ever. Great work

I'd just add to this, that while I don't have the flow data to support, if you look at the stock Polo exhaust, the greatest restriction in terms of reduced diameter through bends is from the turbo outlet to the cat....which is why replacing this section with a wider pipe liberates a startling number of ponies

Does it really? I've not taken a good look under there, but having read through the (Vortex) buildup thread of the APR Polo, Guy mentioned, regarding the APR Exhaust:

Anyway, after a dozen dyno runs & a couple of changes this morning, there are no quantifiable gains to be made with stock turbo & stock intake.

(Page 4)

Although, he did mention that he believed the exhaust would be useful with the K04 upgrade, further down in the post.

Unfortunately, I think the APR Polo had its whole intake changed the same time as it got its intercooler and K04 update, so it's a bit difficult to say how much gains were gained by the intake.

Shaneth - I think Spec83 is referring to the chart, which shows that at maximum power, the choke line is already starting to drop of dramatically. The choke line represents the maximum volumetric flow rate from the compressor - in this case, the K03.

I noticed that you mentioned increasing the airflow so that it passes through the intake pipe quicker - it's interesting to note that the actual flow rate of an incompressible fluid through a closed system like a pipe is essentially constant - basically, you can increase the speed of the fluid by reducing the diameter of the pipe it is flowing through - sticking your finger partially over the outlet of a tap or a garden hose will dramatically show you that this is the case. But sure, air is a lot more compressible than water.

Still, it's quite obvious when you look at various Turbo inlet pipes that it's smaller in diameter at one end to the other - this is, as you mentioned, to increase the speed at which the gas flows through the pipe (but not the flow rate), by reducing the diameter.

I'm not so convinced in the benefits of a silicone hose compared to a steel pipe - sure, there might be an advantage as far as heat transfer is concerned (although the air isn't sitting in the pipe getting heated up for a lengthy period of time), but a silicone pipe might be more prone to hose collapse than a metal one, just due to rigidity.

GT3 - I'm not ignoring your data (do you have any?) that says that the inlet trumpet mod (or an intercooler mod) would enhance K03 efficiency. In lieu of any hard data to back your argument (even after I provided some data to support my point when you requested it) - it's a little rich for you to continue to claim that the people questioning the gains to be made from an intake mod are just being obnoxious and trying to justify our own decisions.

Given the friendly nature of Watercooled, and my own personal desire to keep it that way, I'll end my participation in this discussion with this post. I don't want to get into a flame war here, and if you strongly believe that the intake mods really are giving your Polo a tangible increase in power, then you shouldn't need me, or anyone else to justify that for you.