28th March 2002, 03:27 PM
can you guys enlighten me?
most engines, saabs included, seem to breath by sucking from the side of a swiftly passing airstream - the standard snorkel on my T16S conforms to this model.
is there any reason why this doesn't face into the airstream? i would have thought that with the forced induction that the turbo provides, any extra help would have been appreciated....
i also notice that you can now get aftermarket induction kits which do precisely this - such as JR's D-CAF system - see http://www.filterpower.com/
am i missing something?
silver 1985 900 turbo16S - 200K+ miles & counting...mild mods for sustainable pleasure!
<font size=-1>[ This Message was edited by: rich on Mar 28, 2002 7:31pm ]</font>
28th March 2002, 04:23 PM
Early 8v turbo's had a front facing inlet which drew air from between the bonnet and grille. The side mount is in still air as it's in the inner wing - an induction system that is perpendicular to an airflow will actualy produce movement of the air in the opposite direction if the air flow is fast enough - theoreticaly. In practice the turbo generates so much suction as to make the position in relation to airflow irrelevent. The relevent factor is how restrictive the induction system is when subjected to high amounts of airflow - the stock snorkel, airbox and filter can get to be a restriction when you are pushing high above stock levels of power. Many cars intakes are not designed with maximum airflow as the only criteria - induction noise is supressed with airboxes - just like exhaust boxes. Aftermarket 'induction kit's' are as much about producing a roar of induction noise as they are about performance - infact have you seen any HP claims with these things? One final point - air mass meters are very sensitive about how the air enters them - their output i.e how much air they think is going into the engine can vary with changes in airflow direction and all sorts of other complicated airflow characteristics. The fuel map in the ECU may well have been computed with the stock intake setup and therefore the AMM signal this produces - change it and you could theoreticaly get worse performance!
28th March 2002, 04:42 PM
wow johann - thanks for your very comprehensive response!!
my set up is just a free flow filter element in the standard air box - from what you're saying it sounds like this is about as far as you can safely push the envelope without causing unforeseen consequences
the only bit where i would disagree with you is your statement about still air in the inner wing - i thought there was a rush of air here by design from the gap under the bonnet..
29th March 2002, 01:55 AM
On a similar theme.
I want a real no dreamers opinion from those of you who have put a performance filter in the stock t16 airbox.
Does it make any real performance gain or does it just sound louder?
Also has anybody altered the snorkel sucessfully for better induction???
Where did you re-route it?
What did u use?
Was there any real gains?
(sorry I don't really regard any of you as dreamers, thats why we drive Saabs and not WRX's isn't it?)
OOP'S Did i say that???
<font size=-1>[ This Message was edited by: Fan-TC on Mar 29, 2002 6:00am ]</font>
29th March 2002, 03:29 AM
Check out this link to jouko's site...
29th March 2002, 03:33 AM
There's not a lot to be gained through a modified induction system - but, as you force more boost and do other performance modifications, the induction suddenly becomes very relevant. The stock system will only work well with slight increases of power. Especially if you are running high boost (in excess of 1 bar or so) the stock air box will rob you several hp compared to a good induction kit.
Everyone, tell you opinions about custom inlet systems causing the air mass meter to operate inefficiently! I have a design my own for a custom inlet system for my T8 with CIS, and would like to know if there be any potential problems!
29th March 2002, 06:48 AM
The inner wing is pretty much sheltered from the outside air as there is only a very narrow bonnet to wing gap and the bottom is closed - if there was any significant airflow from the outside you would expect the area to become very dirty with road grime etc - mine is pretty clean in this area compared with the engine bay where there is airflow from the radiator and underneath.
I put a drop in filter in an old 8vT and can't remember anything spectacular about the improvement. On both my T16's I replaced the whole airbox with a cone that goes directly on the AMM -more noise, slightly better throttle response and a bit more free reving at high rpm. Not as significant as removing the CAT, doing the Red Box APC mod or fitting a RRFPR but It's just nice to know it's there I guess!
Other benefits of removing the whole airbox and snorkel is that you now get better airflow through the IC - an obstruction behind is just as significant as one in front! It also gives you better access when changing the oil filter. With the airbox removed you now have enough space to mount a small car rad fan on the back of the IC to pull air through at low speeds when th eIC is at it's least efficient. The downside of an airfilter in the engine compartment is that on hot days the engine will suck in very hot air when you have been standing at the lights -my early T16 used to have a bit of a flat spot on very hot days. Once you are moving outside air quickly fills the engine compartment and there is no problem.To cure this you can make a cowl around the filter to sheild it from the engine side - I made one out of a plastic plant pot! or do 'Jouko's mod' .
3rd April 2002, 05:45 AM
when i modified mine, i noticed that there was more airflow and more power, but on the downside my ecu could not compensate for the higher air intake and i got higher idle speeds and it killed my gas mileage. with a turbo it might help by giving it more air, but forced air induction, you will not see bennifits. forced induction for all practical purposes will not work for you unless you always drive over 70 miles per hour. and your intake will have to be 11 inches over your car (the hood).
with my n/a 900 i found it best to keep the standard snorkle and intake setup.
3rd April 2002, 11:51 AM
I completly removed the factory air intake system from my '84 900 turbo, mounted the AMM/fuel distributer assembly to the fender, and placed a K&N cone filter directly to the bottom of the AMM. This set up gave me very impressive gains in all ranges of power. I did this in two stages, first I removed the snorkel and hose that goes to the exaust, leaving the factory air box with a cone filter in it. This make the biggest imporvement, letting the car suck air without having to run it through all those hoses helped a lot. Later I removed the factory air box, this made another noticable improvement (as well as an increase in engine noise). I plan to add something to help get cooler air to the filter later, but for now the increase in air flow seems to work great (I had no problems with my AMM or ECU).
I have also removed my cat, added dual-stage water injection, and tweaked my boost up as high as it will go without changing the wastegate actuator arm. I now run boost that very quickly runs up to the red and stays there no matter how long I hold the throttle down. The car runs great, but after the removal of the cat I noticed that the engine spools down more slowly and I have to wait longer between shifts if I want them to be smooth.
3rd April 2002, 04:07 PM
I was not pleased with the K-N fitted to my car. It robbed low end torque. An kn will have more effect on a N/A car than it will on a turbo. If you are looking for some extra power and are foolish enough to run 20+psi, an air kit will help. saab engineers spent months drawing and get paid well to design an induction system which will work better than some amateurs like us trying to think of a way to get 5hp or something. If you want better throttle response clean your throttle cables and intercooler.
3rd April 2002, 07:02 PM
Sorry Viktor i have to disagree, Saab compromised there design like other manufacturers do with air inlet to provide a adequate air intake that isnt noisy under hard throttle and is easy and cheap to maintain, service and assemble.
If you look at the air filter in the box you will notice that the filter gets dirty in only one place (where the snorkel enters the airbox)- obviously the engineers didnt try to hard on the Saab design then.
This design may work when running standard power output but can restrict flow when power levels are increased.
10th April 2002, 10:13 AM
I know i have already posted this under another subject, but seeing as this is the topic of conversation....i've just fitted a clamp on K&N, and removed the whole of the old airbox system. Right from the word go i noticed a crisper response from the engine, whether from HP gain or just a livlier throttle response i don't know. As has been stated the only problem i can see is the positioning of the cone, firstly the weight of the AAM and the cone mean that some sort of suspension system will have to be found, and secondly the cone will be taking air in from around the engine itself, rather than the free airflow. I'm sure the second point can be altered, although thinking about it the air is heated by the turbo and cooled by the IC anyway, so what does it matter if the intake air is a slightly higher temp?
Anyway i'm pleased with the addition and am working on a reliable system of supporting the AAM and providing clean cold air.
11th April 2002, 02:17 PM
I put a small bracket on the inner wing which bolts to the end of the cone - holds it quite firmly. I was doing a lot of city driving today and I noticed that I was getting quite a few flat spots when I was pulling away from a stop - sucking in hot engine air. I turned on my fan which i mounted on the back of the IC and the problem disappeared! - it's obviously pulling enough outside air into the engine compartment to overcome this problem.
12th April 2002, 08:27 AM
Great, now can you enlighten me as to where i get a suitable fan from for the IC, and how easy is it to fit?
12th April 2002, 11:38 AM
Got mine off an abandoned Mini Metro down my street - fits perfectly! I'm sure you could get a new one from a motor factors very cheaply as well. I just screwed it to the plastic parts of the IC with some self tapping screws. Got a small relay from Maplins and wired it all up via a spare push switch next to the lighter socket. There are others who have activated it by various other methods - throtttle position, IC temp etc but I reckon manual is simple and effective! When the weather starts to hot up a bit it should really be usefull and pemenantly on.