Cold Air Intake (based on HOLDEN VL Turbo)

[Sweeper]

Ha. Here we go. Once I was browsing the net and I've found interesting article (in Russian) about how cold air intake can be custom fabricated on HOLDEN VL Turbo car.
The engine bay looks quite familiar so I will post some pics with the comments translated from Russian. Then we can discuss if it can be accomplished on S'es

INTRODUCTION :

HOLDEN VL turbo have 6 cylinders , 3 liter turbocharged engine. The author of the article didn't intended to spend a lot of money on intake system , so in place of just spending his money on new K&N filter he decided to search for any weak point in intake system in order to receive more power.

To do this he constructed quite simple manometer to get required data.

Here it is :


As we all know there are 2 main ideas how to get more power :
less backpressure and colder air.

Here how the airbox and air receiver looks like:


Looks quite familiar

TEST :

So he tested the system to find data about backpressure. And it look like this (at 5600RPMS) :

intake tube ------------ 3.5
lower part of airbox -- 4
filter --------------------- 1
higher part of airbox - 2
MAF ---------------------- 14.5
air tube(ribbed one) - 4.5

Total - 29.5 (water inch)

of course backpressure it's only a half of work , then goes the air temp. So it's 30 C in lower part of the airbox with the 15 C temp outside. Then it's quite fast temp went to 50 when car goes slowly or it's stops.

So in standard we have :
Backpressure - 29.6 inch
Temperature - 50 C
0-100km/h - 8.0 sec

[Sweeper]

MODIFICATION - STAGE 1 :



He removed 2 protective net's that used to protect intake from alien flying objects . What he received ? In only 5 mins he lower 9.5 inch of backpressure (32% of total backpressure). And in cost nothing ! So it was no use to nerve about filter because it produce only 3% of total backpressure.

Backpressure - 20 inch
0-100km/h - 7.7 sec
Cost - 0$.

MODIFICATION - STAGE 2 :

We still have 7 inch of backpressure in airbox.



In this case it's no use to modificate higher part of the airbox because it's not so important. So he found a 100mm tube and cuted needed hole in the lower part of the airbox.


The he made a turn(tube) in 45(percent). He didn't want to use front bumper for the air intake because he already removed protective net's.



Then he decided to make air intake tube more widely on the end. So he heated it for some time.


Then repainted black.


After research we got 1 inch of backpressure in case of 4 earlier. And Air Temp dropped from 50C to 20C.

Backpressure - 17 inch
Temperature - 20C
0-100km/h - 7.6 sec
Cost - 15$.

[Sweeper]

MODIFICATION - STAGE 3 :

Now it's time for a ribbed peace of pipe that goes from MAF to TURBO. In this case it have 4.5 inch of backpressure because it's ribbed. (26% of total backpressure). He discovered that most of backpressure is on 90 (degrees) turn.


So he found appropriate tube for 15$.


So oh my god 4 inches of backpressure gone.

Backpressure - 13 inch.
Temperature - 20C
0-100km/h - 7.45
Cost - 30$

CONCLUSION :

So only for 30$ he constructed a well working system. Power gain is 0.5sec in 0-100km/h. Ah not good ??


Cheers.
Sorry for english .

[S2central.net]

This sounds like the same sort of trick that another wonderful Australian webzine covered for such a mod on a 100-UrS4.

I'd like to try this on the S2 to see what gains can be had without having to tweak the ECU.

If the only thing it does is to reduce intake air temps then it would be a great mod as it could reduce heat soak if done properly ...

Paul

[Pisobiker]

As much as I can see I think it's also supposed to lower pressure losses in the intake duct before turbo cold side.
If numbers are correct, the article talks about reducing internal vacuum from 29,5 to 13 inch of water, which means reducing vacuum of ~0,02 bar.
Compression ratio delivered by turbocharger cold side is P2/P1 where P1=pressure at inlet of cold side and P2=pressure at outlet of cold side. So if max P2/P1 at a given rpm (lets say 2.6 bar absolute for a K24 @ 2800 rpm), if you have only 0,920 bar at inlet of cold side, you get only 2,39 bar at outlet (1,39 bar boost).
Instead, having 0,940 bar at inlet of cold side, you get 2,45 bar (1,45 bar boost) with the turbocharger working the same way.

Of course, cars like S2, that have ECU controlled boost, need to have the boost map changed to take advantage of this. Otherwise ECU will just reduce boost (via WGFV) to meet its setted values, meaning you drive same boost as before with turbine working a little less than before.


.....
may be worth some more in-depth research...


Marco

[Zeus]

Of course, cars like S2, that have ECU controlled boost, need to have the boost map changed to take advantage of this. Otherwise ECU will just reduce boost (via WGFV) to meet its setted values, meaning you drive same boost as before with turbine working a little less than before.

Wouldn't lowering the backpressure reduce turbo lag? As the turbine would have to make less rpm (and a lower rpm is reached faster). So instead of getting 300Nm at 2000 rpm you would already have max boost at 1900 rpm, thus decreasing your 0-100 time

Also, the drop in intake temperature is allways usefull isn't it? You would be getting more airmass in the engine... This should give the same kind of performance difference on an s2 as between driving in the winter or in the summer shouldn't it?

So even without remapping the ecu, it should make the cars slightly faster or not?

[Bowlerwell]

Wow... I think that's the oldest thread resurrection i've ever seen! over 7.5 years!