|12-10-2011 05:56 PM|
|Legit||Does anybody have any updated information about this??|
|10-22-2004 07:38 PM|
It is a restriction, but you have to keep in mind now, with this new data, that the throttle being only 50% open at full boost is a bigger restriction ... and if you remove the strainer ... to obtain the normal air-mass/combustion value T7 will just close the throttle more.
Once the car is heavily modified ... that concept may change.
On a heavily modified car that might change quite a bit. It will depend on the software/hardware you are using and whether it regulates boost in the same way the stock T7 software does.
That being said, removing the strainer probably would increase throttle response, but that's almost impossible to measure with a data-logger because the refesh rate is too low.
If I DO get any data on this (best time to test will be when I have the race fuel next week), then I'll be sure to post it. Until then for summary ...
Removing the strainer:
Pros: Less flow restriction after the throttle. When the throttle is fully open, air will flow quicker. Throttle is fully open during spool up
Cons: T7 isn't at full throttle when it's at full power, so you will have some un-equal air distribution. That means different cyllinders will run at different A/F ratios under full power. How big is the difference? No idea, you'd need a 4 channel EGT setup to really know for sure.
Make sense? Either way, strainer or not, T7 should make the same power. It will do whatever it takes to get the air-mass/combustion it wants ... and that more or less determines horsepower (more specifically torque, but they are directly related) ... so removing it has some advantages keeping it has some advantages.
|10-22-2004 07:13 AM|
No, my friend no argument at all here. A difference in understanding perhaps. But still envious of you that own Viggens.
I agree, that Adrian should try it out on his own car, and test the results scientifically?
But, something tells me, California Emission standards, the temperature, time to do it, or something will prevent actual tested results.
It would be interesting though...
|10-22-2004 06:02 AM|
OK, so you guys have differing opinions, but there is no reason to argue.
SaabTuner has brought to our attention a free mod that might increase power. There might be other effects, we won't know until tests have been run.
SaabTuner now that you have that cool data logger why don't you run some tests? That thing does dyno/airflow/1/4 times right? Let's see what happens.
Run some comparisons for us so that we can come to some conclusions about this mod.
I've been running without the strainer for about a week now and my car hasn't blown up yet. So I've already taken the chance as the guinea pig. I seriously doubt that removing this will significantly reduce engine/piston life.
Free cheap mods do add up. If I had a data logger I would run some tests.
I have a laptop, anyone want to let me borrow their Data Logger?
|10-22-2004 05:13 AM|
I'm not sure what problems your referring to...probably another tactic...because I'm not having any problems....in fact looking to do the next upgrade.
If you truly believe or stand behind your theory, why don't you just pull off your strainer and make me a believer... with all of your scientific equipment ..., you could easily test the results on your car.
Your boost gauge might possibly show a direct relationship to changes relative to pulling the strainer. Oops you don't have one... sorry.
How about an EGT gauge....? That's got to be a way of measuring how much leaner you might run....but perhaps the ECU would compensate to some degree. No, I don't think you have one of those either....I don't have one to loan you..., but I know where you could research some gauges to substantiate what your saying though.
Give it a try Adrian....besides your emission test are done every other year in California. You could always reinstall it after you've conducted your testing.
I'm really curious, and this would be the first mod you could do on your car to validate your claim.
I just hate to see a beautiful 2001 Viggen go to waste but somebody has to be the first.
|10-22-2004 04:12 AM|
As for overall compression of the motor, if you increase the VE, you'll require less boost pressure to attain the same air-mass/combustion, however this does not decrease the overall compression of the engine from turbo intake to TDC.
A higher VE just means that more of the compression is done internally in the engine instead of externally by the turbocharger. If the MAP remains the same it would increase the overall compression of the engine.
You can read more about Mr Yankton's 9000 Aero here: http://www.kyankton.net/9000index.htm
In the dyno runs section it shows pretty clearly the additional torque generated by the long pulse-wave tuned inlet manifold.
|10-22-2004 02:15 AM|
I thought we were talking about Viggen T7's with the strainer in the manifold, (am I in the right forum?) Does Kevin's 9000 really compare to the Viggen you were discussing? Okay, maybe it does, and I think we are saying the same thing. But I'm also curious about what do we do agree on:
1) Would you agree then that the naturily aspirated (your words) manifold on the 9000 Aero of Mr. Yankton, is a different discussion matter?
2) I'm not familiar with Yankton's car, but would you also agree that whenever you increase runners on an intake manifold you increase the volumetric air capacity and therefore decrease compression pressure of the overall motor?
3) Does a Viggen T7 run higher compression ratios than a ng900 turbo t5?
4) Will you have problems running a larger turbo on a car with higher compression numbers, given the same fuel, manifold, and timing...?
5) If you've answered at least 30 percent of these questions with yes, then your right, "we do disagree".
I read your last post, I'm just not sure that it relates to the Viggen t7 strainer issue you were talking about originally. I'm sure the Viggen and the Aero, have much in common, but you introduced Mr Yankton's Aero, and we'd have to explore that to understand further.
Hence the nature of why its hard to follow you sometimes, other variables tend to get to faulty conconclusions and convilute the point.
I could be wrong, but who cares >...
|10-21-2004 04:03 PM|
I'd dis-agree. See my other thread.
Even at "full throttle" the throttle angle on the Viggen was only sometimes at 50%,or in some cases even lower.
At that throttle angle, you'd need a strainer for exactly the reason shown in the image above. I just didn't think T7 would use the throttle THAT much to control boost!
And DC, I'm not sure which compression you're refering to. But in either case the change in compression is nearly completely moot on a T7 system ... here's why I think that:
There's an important summary at the bottom if anyone wants to skip over the heavy reading in the middle.
(Apologies for the long explanation)
Dynamic compression is often used to determine how much air an engine will take in for each revolution, because the intake valve is still open as the piston moves upwards, so therefore at low engine speeds, an intake valve which stays open well after bottom dead center (low dynamic compression) will allow a lot of air to go back out the intake valve. However, this only really applies when the engine is stationary. Once the engine is rotating, the dynamic compression becomes less and less important as the engine rotates faster.
What happens as engine speed increases is that things get a lot more complex. As the piston begins to move up the air does not start going back out the intake port even if it is still open. There are a couple reasons for this:
1. The air at the top of the combustion chamber does not "know" that the piston is moving upwards until the pressure wave formed on top of the piston reaches the intake valve. This pressure wave travels at roughly the relative speed of sound in the cyllinder, and so at higher RPM takes more crankshaft degrees to reach the top of the cyllinder.
This is why later intake valve closing timing is desirable for high RPM performance, despite significantly lowering the dynamic compression ratio.
2. Residual intake port velocity fights against the pressure wave that moves upward as described earlier. As the air moves into the cyllinder through the inlet ports it carries some momentum in the form of velocity pressure, which has a directional vector pointing into the cyllinder against the rising pressure wave from the top of the piston. So smaller ports tend to do this better ... but the smaller ports often don't fill the cyllinder up well in the first place (hence the residual port velocity as air is still trying to get into the cyllinder), so making the ports too small does not help things. The point to be made is that making ports too big doesn't help anything either.
3. Pulsewave tuning can also negate the dynamic compression ratio by generating a pressure pulse moving into the cyllinder as the wave moving upward from the piston reaches the intake valves. When the intake valve first opens it generates a negative pressure pulse that moves away from the inlet valve until it reaches the manifold's plenum. Then when the negative pressure pulse exits the intake runner a positive pressure pulsewave is reflected back. Both waves travel at the speed of sound, and if timed correctly the positive pressure pulse will reach the engine before the valve closes so that it can push some extra air into the cyllinder.
Remember Kevin Yankton's 9000 Aero and that naturally aspirated intake manifold with it's long intake runners? That manifold was a pulse tuned manifold, designed to generate a pulse doing exactly what I described at roughly 3,000 RPM, and this was shown by the drastic increase in torque Kevin saw when fitted.
Intake pulse tuning is usually relatively simple, the only difficult variable is when the wave is formed. It won't form the instant the valve moves off its seat necessarily, but soon thereafter. Usually knowing the intake valve opening crank angle at .050" lift is desirable because that is roughly when the pulse wave usually forms. (Hence most camshaft manufacturers using that as their cam data.)
In reality the reason we brought up all this talk of all this pulsewave tuning, and talk of compression ratio was to accomplish this ONE thing: To figure out the mass of air in the cyllinder, and how small a space it will be pushed into.
On T7, the air-mass/combustion is controlled by the ECU, right? And the combustion chamber volume is constant. So the rest is all just thermodynamics and pumping losses.
On T7, the same air-mass will always be pushed into the same combustion chamber volume if the ECU says so, thus the ratio is a moot argument.
Again ... sorry for the long post ... just pointing out that the strainer probably has almost no effect on any of that ... and rather is just used for the reasons mentioned above involving throttle angle being rather shallow even at full boost. Therefore to avoid unequal air-distribution a "band-aid" fix was used.
T7 would probably benefit highly from a good intake manifold which distributed air evenly WITHOUT a strainer.
|10-21-2004 02:52 PM|
I don't want to contradict anyone's theories or "pontification" of theories.., but I seriously think its to do with the higher piston compression ratios of the t7 cars compared to the t5s. When you add higher boost levels to a car., you are affecting the compression of that motor....higher volumetric pressure..
Consider the larger more capable turbos with more boost on those t7 cars with higher compression ratios ....compared to the t5 with smaller turbos and lower compression ratios... The t7 would be more prone to lean conditions or detonation, (also using the wrong fuel) more likely to have piston problems with more boost. That strainer is there not only to stabilize this pressure, but to decrease overall cr of the motor.
During the gas crunch in the late 70's, the older v8 cars had the same problem with higher compression ....runing 11-1 cr pistons in some cases, so they used similar devices to control cr of the motor preventing detonation problems on low octane pump fuel and more stable combustion.
My "theory" is that this strainer your seeing has the same affect on the higher compression t7 running higher boost.....to eliminate premature detonation (hmm, women really hate when that happens).
If you were able to check the volumetric air being compressed...or perform a test to confirm overall compression ratios of the t5 vice the t7...I believe you would find close to the same. Because a turboed car needs cr relative to perfect 8-1 ...any higher than something like 9.5 your going to run into detonation problems without the proper fuel, timing and having a method to control it.
its all about the pressure....
|10-21-2004 07:31 AM|
At any rate, I'd like to take a look at one of those stainers off the car to see how restrictive they really are....my thought is that its far enough down the manifold that the air has enough time to recover from the turbulance in the intake runners. Another thought is maybe this strainer is the reason for the 5 additional hp as well....well distributed air to all cylanders has to have some HP benifit....look at an extreme case in which you have an equal length runners intake manifold, that alone is worth handful of HP.
BUT maybe it is just an ECU change and none of this means sh*t!
|10-21-2004 01:16 AM|
Subsection: Technical Description
Sub-sub-section: Air Duct With Strainer (LEV)
If manifold gaskets were responsible for 5 hp, I wonder what that strainer is responsible for. Just kidding. I think the ECU was just revised for the reinforced pistons the 2000+ cars got.
Also, T7 does not open the throttle fully even at "full throttle" ... so there might be some reason right there to leave it in until very very non-stock.
|10-20-2004 09:55 PM|
Where did you find the reference to the air distributor in WIS? I see it in EPC, but not in the WIS...I have WIS version 18.104.22.168.
In addtion, it is only the 1999 Viggens that have the two piece manifold. I checked my 2000 Viggen, sure enough a one piece. I then check EPC....2000 Viggen intake manifold model number is 91-92-592, which is the same manifold listed in the B20x section. Primary manifold in 1999 for the viggen was 91-86-107 (ie the primary of the 2 piece manifold). The '01-'02 Viggens use 93-99-528 which is essentially the same as the '00, except is drilled for the different pressure sensor used begining 2001.
With all this I got to thinking that maybe the reason the 1999 viggens have only 225 hp compare to the 230 hp on the '00 and up is due to the different intake manifold design....this wouldn't suprise me as I know mind flow improvements to intake manifold can yield 5hp easily. That two piece I bet disrupts the air flow due to the additional gasket...gaskets normally aren't a perfect cut.
|10-18-2004 10:24 PM|
I think that, because T7 will still put the same amount of air into each cyllinder, regardless of relatively small intake restrictions, that it's not something worth removing when stock.
However, I found further justification for my idea that it's more a "part-throttle" issue from Philip H. Smith's book on Exhaust and Intake systems.
Notice that the intake shown is fairly similar to the T7 stock style unit (some differences being siamesed ports, but the principle is the same), and that during part throttle the flow is erratic and less-stable; the air-flow into each cyllinder varies more with each revolution, so fueling is uneven. That would mean the strainer probably makes each combustion more even during part throttle, which again is more of a fuel consumption and emmissions issue than outright power issue.
Then again, if it's not hurting anything on a stock car, why remove it? I just think that once you've upgraded intercoolers, turbo, ECU, exhaust, etc ... then you might want to think of removing it for some extra flow. The reduction in flow resistance will keep the turbo from working so hard.
|10-18-2004 07:13 PM|
|10-18-2004 06:58 PM|
I second that. When you start seeing things that may have been tampered with on a newer vehicle that you didn't know about, that definately is something to be concerned with.
Getting back to the topic however, if you consider the characteristics of this "strainer" if basically leads me to believe that its simply used to disperse the air that flows in. With this in mind, and concidering that it wasn't used previously on any other Saab model, that further leads me to assume that it wasn't impleted to "reduce noise" or for any other reason similar.
I personally believe that its a device similar to the "Tornado" that alters the airflow in this case possibly dispersing air evenly to every chamber, thus not necessarily showing a large gain in power, but to increase gas mileage and emissions as stated previously.
Although I of course don't have a T7, I would agree that since it doesn't seem to show gains by removing it, perhaps it should be left in because it was implement later on by Saab, who could've saved money and just left it out. Just a thought
|10-18-2004 03:26 PM|
|The Vigg||OK..here's something that's got me spooked. I was snooping around My IM, and noticed It is not a 2 peice design. It's the standard one peice from the b205. Problem here is my car is a 2000. Meaning either my IM was swapped, or my motor is from a 2001(IM didn't look like it was seperated from head). Another thing I noticed is that the oilpan has been off the car. There was a bead of gasket goop around it. The motor is strong , silent and pulls like a freight train, but it is cause for some concern. I think I should see if I can get the service history.|
|10-18-2004 05:39 AM|
|saabvos||mind you that saab is still considered a luxury car with power....remember that we here are an elite few who are concerned with the power of the car over the comfortable nature of the car hence when designing the car saab probably made it with comfort in mind as well as the life of the motor thus....you lose a few extra ponies for a quieter ride and longer lasting stock car|
|10-15-2004 11:11 AM|
|10-15-2004 10:40 AM|
You do also have to consider that Saab have also used such items as turbo silencers in the old style intercoolers. The silencer had a purpose, to quiet down the turbo noise, but it hampered performance.
my guess is that the strainer has a purpose, but that they weren't thinking of performance when they designed/installed it.
Is there soemone at Saab that we can contact asking what this thing is supposed to do and why it's there?
|10-15-2004 10:11 AM|
All I am saying is that Adrian has not tested this out. He does not do any mods himself, just theorize about them. in most experiments, it is rarely or never that results are EXACTLY like theory. otherwise you could skip the experiement/testing stage, right?
I would think that it is there for a good reason, why would saab spend extra money for producing and installing this part for nothing. the part would not be in older models because as the model gets older, they make more and more IMPROVMENTS as they see things not working right or breaking prematurely. So again, they must have ADDED it for a reason. and if this was a good idea, someone who does mods and tests the before and after results like Nick T or one of the tuners like Maptun or SQR would do this type of mod. I have never heard of this before, so until someone PROVES it is safe and increases performance, I , personally, am not wiling to risk it. Certainly give it a try if you would like, but I am skeptical.
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