Induction kits - good or bad?

[John Sims]

Things have been a little quiet on here of late so a new topic for you to get your heads around.

Following our recent JZ Machtech visit I have been pondering my induction. As some may know I have a K&N cylindrical fillter mounted behind/above the radiator in place of the Turbo air box.

This was first installed to tidy up the engine bay, the original air box was falling appart, and see what was happening under the box as I had a mysterious water leak. The K&N didn't give any noticable change in induction noise, which was a shame, but that is and aside.

Those who sell such kits sugest IRO 10 bhp increase for such modifications due to the increased air flow. Machtech, on the other hand sugest a 10 bhp loss due to the induction sucking in hot air from behind the radiator.

What thinkest you? [8|]

 

[944Turbo]

Well hot air is generally bad, I know Gareth on titanic put some ducting around his to stop the hot air from behind affecting it but you are still sucking air through the intercooler and rad.

You are in effect taking air in that has been heated by the intercooler, then compressed by the turbo which makes it hotter then goes back through the intercooler (the other way) to try and cool it down (at the same time heating your intake air) and then into the engine. So this means you intake temps will get hotter and hotter.
In addition you are getting some heat from the radiator.
However the standard system whilst taking cold air from outside then takes it through a pipe right at the top of the engine bay (over all the hot bits) into a black box that sits above the radiator and coolant pipes, so warming it.

A map 2 with ducting is probably the best option for cold air.

However, just wondering could the J boot be inverted putting your filter down behind the headlight?

There are IIRC 3 pipes near the turbo inlet, 1 for the CV, 1 for oil breather, and one for the FVPS. I think the cv and fvps ones are opposite each other and about the same size. The oil breather one will be come redundant if you fit your catch tank, but probablly could also be extended.

The Dump valve would be an issue but you could dump to atmosphere and bung the hole.

Once you have done all that you can report back and answer your question! [][][]

Tony

 

[Fen]

John,

I was surprised to see your filter there when we were at Jam Sport. Most cone filters end up behind the headlight. That's where my MAF puts it and I now also have a Lindsey ducted headlight cover and a "MAF Trap" waiting to go on.

 

[John Sims]

However, just wondering could the J boot be inverted

Spookily I was thinking the same thing but because of the way the boot backs up on its self it gets in the way of the turbo cooling pipes for a start. Also it kinks/peaks too soon (oh how I know that problem []) so the filter would hit the expansion tank.

Working with MAP dumping to atmosphere is no longer the issue it was with the AFM as it doesn't effect the metering where it dumps. Danno has a theory that by dumping into the inlet infront and at an angle to the turbo this helps spool up but I'm not conviced that this would make much/any difference.

Cooling air that has previously been heated by the air you are trying to cool obviously isn't a good thing, and the cooler the air is the better. However, does it realy make that much difference?

Gareth did have a thermocouple at Snetterton, and we were going to compare inlet temperatures but his head gasket gave way before we could get down to some serious scrutiny. []

What we are all missing perhaps is that, when stationary the inlet is enjoying nice warm, pre-heated air. When the car is moving, however, the air is moving through the rad/intercooler at a rate of knotts and so may not increase in temperature that much. This is just speculation but hence the original posting.

Whilst, obviously, the air behind the headlamp is cooler, and can be further enhanced with a MAF trap and vented headlamp cover, it also looks tidier. As a man who thrives on KISS (Keep It Simple Stupid!) this alone would be a good enough reason to change but I am intrigued if there is any real world advantage.

 

[Diver944]

Methinks it's time to get a thermocouple plugged into a laptop and do some data capture on the move with it located behind the headlamp and also above the radiator. This is the only way we will really know.

What we need is someone with a healthy interest in gadgets [] Anyone know anyone.......[]

Funnily enough I've been following quite a few threads on Rennlist this week that discuss all the electronic monitoring tools that can be connected to our cars. I do like The Mo-Monitor sold by http://www.vitesseracing.com that can be connected to all sorts of inputs (boost, o2sensor, rpm, water temp, inlet temp etc). I am also keen on these PLX and Zeitronix wideband AFR sensors.

http://www.plxdevices.com/index.htm
http://www.zeitronix.com/gb/rennlist.htm

Both of these can do data capture and provide you with boost versus AFR over an RPM range. If I ever do go for even MORE power, I definitely want one of these to do it safely (especially after reading Tonys recent link to Dannos Head Gasket Tutorial)

 

[paulf968]

One quick bit of info from me -- with a question.

I went back to Jamsport a couple of weeks ago and proved the mid-range improvements from the PROMAX chip I have just put in -- that was satisfying.

Just for fun I took the air filter completely out for a second run to see what happened. (just an empty air box, fed by cool air from the front grill)

I was really surprised to find that mid-range performance took a big step backwards, max power was unchanged.

Now what is going on? is it a mapping problem with all that extra air going in -- I am at a loss to explain this. Thoughts?


For now the moral of the story for me is -- ' if you change the standard air filter beware! '

paul f

 

[944Turbo]

How about ducting some air up to the filter similar to the original system? The 'max power' section of the demon tweeks catalogue might be able to help [], you could then hide that filter inside a tube for an even tidier engine bay []
Tony

 

[John Sims]

How about ducting some air up to the filter similar to the original system?

Again, spookily, I had thought of that - great minds ...etc.

The down side, with reference to the original filter box, is the space above the intercooler outlet pipe and the underside of the bonnet is very limited. If you look at the Turbo fillter box neck it is little more than 1/2" deep. I concluded that to fabricate anything which worked and looked better than the original would be difficult and I don't want to loose my dump valve "woosh" either - "boy racer" I know, but at least I'm honest.

SFR do an induction pipe, similar to Rick's but, I hope, slightly smaller. This is now on order - at least I hope it is, it is a little difficult to tell with SFR. This should help things along as, obviously, the air should be cooler and the flow less turbulant.

With regard to real world performance, BKE is a little sod when left for half an hour after a good run and then re-started. No doubt all of the induction system has had plenty of time to absorb as much heat from the engine bay as is possible and is nice and hot. To say BKE lacks performance after a hot start is an understatement, so temperature does make a big difference.

 

[nfearn]

Can't add anything practical to the discussion, I'm afraid, but my recollection of A-level physics would indicate the following:

Air pressure is proportional to its temperature, and hence unbder constant pressure its weight per unit volume is inversely proportional to its temperature. Since temperature is an absolute when measured from Absolute Zero (-273. degrees Centigrade or 0 Kelvin) a change of intake air temperature from 0 degC to 30 degC would result in the density of intake air dropping by 10%. Air pressure also makes a difference, but the changes in absolute air pressure are relatively smaller so make less of a difference in practice.

I presume the lambda system on the 944 is closed loop, so this should result in a 10% drop in the power output of the engine straight away. This may or may not be compounded if the pumping efficiency of the engine and the turbo varies with air density - I don't know enough about fluid dynamics to comment on this.

So it would be worthwhile trying to get a figure for the temperature of the air being drawn into the engine, or at least the air temp near the filter. I did wonder if a sealed container containing a suitable thermometer could be used to get a rough figure if you leave it under the bonnet while driving around for half an hour, say. Not as good as a directly reading remote thermometer but a cheap way of getting some sort of feel.

Just a thought, but if the S2 draws it's air from the front and this then goes backwards via the filter under the nose panel, would it be possible to modify an S2 airbox to suit a turbo or build a custom setup to sit in the same position?

Nick

 

[Diver944]

ORIGINAL: nfearn

Just a thought, but if the S2 draws it's air from the front and this then goes backwards via the filter under the nose panel, would it be possible to modify an S2 airbox to suit a turbo or build a custom setup to sit in the same position?

Good idea Nick, but the S2 airbox occupies the position where the Turbo has it's intercooler, so there is no space under there (and you wouldn't want to restrict the intercooler)

We forgive you tho as you are a N/A guy []

but we may not be so forgiving if we all read some of your inquiring posts in another forum []

 

[John Sims]

but we may not be so forgiving if we all read some of your inquiring posts in another forum

I did but, as I understand, enquiries are relative to and additional Porsche not an alternative to the S2, so no excommunication in necessary at this moment. []

I like your cunning plan regarding engine temp analysis Nick. I must give that a try.

 

[nfearn]

Indeed chaps. the 3.2 is merely a subtle ruse to prove how good the S2 is. There is *no chance* of me selling that car short of something disastrous occurring.

I should have been clearer on the thermometer idea. I was thinking of a container filled with water (and said thermometer) to give it some thermal inertia.

I am still chuckling internally, btw, about Steve at JZ's comment on the 3.2. I had a "Swiss Toni" moment and it's kept me amused for a few days since.

cheers all
Nick

 

[John Sims]

I had a "Swiss Toni" moment and it's kept me amused for a few days since.

Would that be the "....a 944 is like driving a normal car where as driving a 3.2 is like making love to a beautiful woman." moment? I still smile myself.

Good idea, the water filled container. Initialy I was thinking the container should be matt black for the best reading but, in retrospect, perhaps gloss white would be better as we are more interested in air temperature and thus gain through convection not radiant gain.

 

[nfearn]

Yep, that was the one. The sincerity with which the remark was made just made me think of the character and that was it.

Not sure that the colour of the container will make any marked difference. Radiated heat is generally only signficant if the body is glowing visibly (try moving close to recently welded steel if you want to test this statement - it's bl**dy hot but gives off little radiated heat). Hence a clear plastic bottle and a 30 minute drive should be just fine.

regards
Nick

 

[John Sims]

Hence a clear plastic bottle and a 30 minute drive should be just fine.

I'm wondering if a plastic bottle will take the heat. Not that I've been able to do anything about it yet.

 

[nfearn]

If it doesn't, I think you will have your answer....