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Performance Modifications for the NG900 / Old 9-3 This forum contains PERFORMANCE related Q&A's for the NG900 and 9-3. This may also include suspension.

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Topic Review (Newest First)
11-18-2009 06:58 AM
JZW
Quote:
Originally Posted by stevehayes01 View Post
I totally understand what you are saying Dave and I get it... what I am saying is that the WGA on a T25 from the factory is good for about 19PSI max steady and thats what it was designed for. The TD04 WGA seems to do better than that.

The issue of raising boost levels to meet the optimal flow of the turbo is fine and if needed then so be it. But my pointis that through software control you should be able to modulate the WGA and set your sticking point to what you need rather than set it to overshoot and settle as most tunes are written for these days.


Look at the Dyno plot for Drew's car... this is a great reference point. It hits peak boost that he set and stays there all the way to redline on a stock WGA because it is controlled properly. Even though his turbo is a 19T it is still possible to do on a stock 15T 5CM2 which is what I do in mine on a daily basis.


Tune for the HW you have and if you have a weak point in a WGA then replace the WGA.. dont bandaid it... Thats really my point.
When the actuator is good, tdo4 one is much stronger than the t25 one, so its not a good example using Drew's car, then you have the choice, buy an expensive actuator or you can use a cheap helper spring.

It is a cheap easy way to solve some issues and many people don't have the money to put new actuators on the car. If I had a stock of good actuators, would not recommend the helper spring.

Its a real world practical solution in my opinion. Is it the best one? No, does it work, yes...

John
11-18-2009 06:54 AM
JZW I have tried many combinations of pid mapping and it does help things, but if the actuator is weak and there is a lot of back pressure, no amount of sw tuning is going to fix it, that was my main point.

I have found I get in the ballpark much quicker by adjusting reg kon, then fine tune with pid.

John
11-15-2009 12:54 PM
comtrang
Quote:
Originally Posted by JZW View Post
Drew, I have tried doing everything, turning up the reg kon as far as it will go, when you can hear the flapper going pst, pst pst under boost at high rpm, no sw is going to fix that.

In the first dyno I posted, the wast-gate was blowing completely open at 4500rpm. 5 bucks later and maybe 15 minutes, it was a whole new car

John
John in this case, wouldn't it be more related to the PID rather than the reg kon?
11-15-2009 07:33 AM
mike9000aero i thought the point that john was trying to make was to rais base boost with helper spring if you have a weak actuator? and that he had an even larger gain when uping it to 9psi? i still dont completly understand all this but thats what i got from what he said
06-01-2009 05:10 AM
David in Tallahassee
Quote:
Originally Posted by stevehayes01 View Post
Tune for the HW you have and if you have a weak point in a WGA then replace the WGA.. dont bandaid it... Thats really my point.

Agreed my good man!

David
06-01-2009 04:45 AM
stevehayes01 I totally understand what you are saying Dave and I get it... what I am saying is that the WGA on a T25 from the factory is good for about 19PSI max steady and thats what it was designed for. The TD04 WGA seems to do better than that.

The issue of raising boost levels to meet the optimal flow of the turbo is fine and if needed then so be it. But my pointis that through software control you should be able to modulate the WGA and set your sticking point to what you need rather than set it to overshoot and settle as most tunes are written for these days.


Look at the Dyno plot for Drew's car... this is a great reference point. It hits peak boost that he set and stays there all the way to redline on a stock WGA because it is controlled properly. Even though his turbo is a 19T it is still possible to do on a stock 15T 5CM2 which is what I do in mine on a daily basis.


Tune for the HW you have and if you have a weak point in a WGA then replace the WGA.. dont bandaid it... Thats really my point.
06-01-2009 03:39 AM
David in Tallahassee
Quote:
Originally Posted by stevehayes01 View Post
I am not trying to oversimplify but the wastegate and turbo are sized for each. But the fact is to run a stage 3 at 17-20psi you should not have to change base boost if your actuator is in good shape.

The other issue is that in the software it is controlable to maintain boost and hold it at the levels you set it to. I think Drew's tune is case in point for that... stock wastegate running 4.5PSI base boost and peak and holding 24PSI at full boost.

So instead of raising base boost to meet 8psi to get a max 18PSI and only get an increase 11psi.....when if you set your software up right you can get the same gains to 18psi with a 5.5psi base boost and have a solid gain of 13-13.5psi and no need for a helper spring or an increased base boost setting.

just my opinion..
Sorry Steve I wasn't actually targeting you on the over simplification comment it's an issue I have overall. My bad.

I hear what you are saying but you don't seem to be catching me. Boost level is largely irrelevant. It's the volume of air that is more relevant. Drew's car may hold 24 PSI to redline with 4.5PSI base but at redline it's still only moving enough air to produce around 300 whp. What's more is his car has a 19T turbo which has a rated 550CFM compressor wheel along with a 6cm hot side with a clipped turbine. ALL of these bits contribute to the ability of the exhaust to exit without higher base boost.

The higher base boost is required where you are reaching the flow limits of the turbo.

All of that said, I tried the "helper spring" concept and found it to be simply too unpredictable for my liking. The FORGE WGA has been a great piece of HW for me.

When I was running the stock T25 I will tell you that the gate could be blown open from inside the exhaust even with the BPC disconnected. It would hold 23PSI until about 4500 RPMs then drop to 17 in one second and taper from there as the door opened. With the new WGA it held just over 20 past 5200RPMs and then slowly and steadily tapered to about 17 at 6K and then 16 at 6.5K.

David
06-01-2009 03:21 AM
g96nt It's also worth mentioning that he's got a t25 HOT.

my old t25 HOT was only good for a 19psi spike Around 3k rpm, and it would drop to 13psi by 4200.

A helper spring may have... helped this... but I ran an MBC, so there's no blaming the ECU

I'm guessing he's talking about his black car, which is a t25, no matter what transmission he has.
06-01-2009 02:41 AM
a12
Quote:
Originally Posted by stevehayes01 View Post
I am not trying to oversimplify but the wastegate and turbo are sized for each. But the fact is to run a stage 3 at 17-20psi you should not have to change base boost if your actuator is in good shape.

The other issue is that in the software it is controlable to maintain boost and hold it at the levels you set it to. I think Drew's tune is case in point for that... stock wastegate running 4.5PSI base boost and peak and holding 24PSI at full boost.

So instead of raising base boost to meet 8psi to get a max 18PSI and only get an increase 11psi.....when if you set your software up right you can get the same gains to 18psi with a 5.5psi base boost and have a solid gain of 13-13.5psi and no need for a helper spring or an increased base boost setting.

just my opinion..
Yeah, but this is only valid if the flapper is not being forced open before reaching 18psi. No amount of tuning can hold the flapper shut if the BPC is not routing any air pressure from the compressor to the wastegate actutator.
It really comes down to turbine housing restriction vs. wastegate actuator spring pressure.
05-31-2009 09:12 PM
stevehayes01
Quote:
Originally Posted by David in Tallahassee View Post
This issue of whether or not a base boost increase is required, or advisable, is another example of a topic oversimplified.


David

I am not trying to oversimplify but the wastegate and turbo are sized for each. But the fact is to run a stage 3 at 17-20psi you should not have to change base boost if your actuator is in good shape.

The other issue is that in the software it is controlable to maintain boost and hold it at the levels you set it to. I think Drew's tune is case in point for that... stock wastegate running 4.5PSI base boost and peak and holding 24PSI at full boost.

So instead of raising base boost to meet 8psi to get a max 18PSI and only get an increase 11psi.....when if you set your software up right you can get the same gains to 18psi with a 5.5psi base boost and have a solid gain of 13-13.5psi and no need for a helper spring or an increased base boost setting.

just my opinion..
05-31-2009 09:02 PM
stevehayes01
Quote:
Originally Posted by soccerrplyr View Post
What software? I have 3+hardware but only pushes to hold around 15 and by then I'm at 90sh, spikes to 17 at times when i first floor it atfirst, drops to around 11/12 and then rises to 15


I am using my own software that I tuned....... I spike to 20-21 and settle to 18-19psi on hot days and on cold days i peak and hold 20psi steady.


Your drop is due to limiters in the software for your gearing more than likley.
05-31-2009 07:26 PM
a12 Helper spring or higher pressure actuator is only required if wastegate actuator will not hold flapper shut under high boost.
You want just enough to keep the flapper closed, but not too much pressure that it interferes with boost regulation.
Watch your EGT's if you go with either stronger actuator or helper spring, as increased EGT's lead to higher risk of detonation (knock).
05-31-2009 06:00 PM
soccerrplyr
Quote:
Originally Posted by stevehayes01 View Post
You should not have needed the base boost adjustment to make the power though... thats the point of software..it handles the adjustments for you.


I am pushing 20PSI with no issues and no base boost adjustment on my 9-3 SE HOT Automagic. And no helper spring.
What software? I have 3+hardware but only pushes to hold around 15 and by then I'm at 90sh, spikes to 17 at times when i first floor it atfirst, drops to around 11/12 and then rises to 15
05-31-2009 03:04 PM
David in Tallahassee This issue of whether or not a base boost increase is required, or advisable, is another example of a topic oversimplified.

There are many variables in the exit of exhaust through the turbine housing and wastegate flapper and these variables are complicated and compounded by the variables associated with the wastegate actuator itself.

When flow is limited, pressure is created. As boost pressures are raised from SW or an MBC the WG remains closed more of the time allowing the exhaust gasses to "power" the turbo for the increased boost. At the same time, pressures inside the exhaust manifold begin to rise because the turbine flow (among other things) is not able to exit the, now much larger, volume of air being moved.

At some point the pressure inside the exhaust manifold will exert enough force on the wastegate flapper to open it from inside with absolutely no regard to the SW targets and BPC action. The point where this occurs is determined by the strength of the WGA itself, to some extent, but to an even greater extent it's determined by the actual volume of air being moved by the engine. The later cars, like SteveHayes and Drew in Houston own, are running T7 cams and TD04s. The T7 cams do not move as much air past 4500 RPMs, right where most "helper spring" activity is experienced on T5 cars. Also, both Steves and Drews cars run turbochargers with slightly higher flow compressors than a stock Garrett T25.

Even though the T25 has a decent hot side for a small unit, it will still create enough backpressure in the exhaust manifold to require an increase in base boost. It requires the base boost adjustment just to reach it's rated max flow rate from Garrett. By the same token, a later car with the T7 cams and a little higher flowing compressor wheel might not need as much base boost to keep the flapper closed and at the same time make similiar power. I believe that Vigge reported that one of the turbos that he used (maybe the GT2860RS) had exhaust manifold pressure that EXCEEDED his boost pressures up high in the revs. The reason many tuners use the FORGE WGA is so they can utilize the turbochargers full range of flow. The more CFM the engine moves the harder it gets to flow the exhaust out through the turbine nozzle. The harder it gets to flow the exhaust through the turbine nozzle, the higher the exhaust manifold pressures go. The higher the exhaust manifold pressures go the harder it is for the flapper to stay closed no matter what the BPC is doing. As a matter of fact, if you are going to push a smaller turbo (IE less than about 600CFM) to it's max with T5 cams and decent supporting HW you're very likely to need more base boost.

Another thing to remember is that the boost level is really not the key point in what necessitates the higher base boost. The key point is really the flow volume as relates to the turbine nozzle area.

I have mentioned some variables but others would include the actual size of the flapper, (which I've never actually measured.) the flow characteristics of the exhaust, the EGTs etc. A smaller flapper, for example, would require more pressure to open than a larger one with more surface area.

Just my $0.02

David
05-31-2009 11:15 AM
stevehayes01
Quote:
Originally Posted by dcr99vig View Post
my stage 3 software was only making about 12-14 psi, i uped the base boost to 8 and wow that made a huge differance. automotion reccomended this to me when i got my tune to check and make sure it was around 8
You should not have needed the base boost adjustment to make the power though... thats the point of software..it handles the adjustments for you.


I am pushing 20PSI with no issues and no base boost adjustment on my 9-3 SE HOT Automagic. And no helper spring.
05-31-2009 11:13 AM
dcr99vig my stage 3 software was only making about 12-14 psi, i uped the base boost to 8 and wow that made a huge differance. automotion reccomended this to me when i got my tune to check and make sure it was around 8
05-31-2009 10:46 AM
Legit Would the differences be this drastic on stock software?
05-31-2009 10:41 AM
lowbudgethero how do you install a helper spring?
05-31-2009 04:23 AM
stevehayes01
Quote:
Originally Posted by DeLorean View Post
Just commenting on this point, I agree with the rest, but you ever price a new W/G actuator for a saab? They are shockingly expensive.

But there are other options too.... I have seen one of these used where the rod was cut/threaded with a threaded piece to use for adjustment and it worked just fine.

http://www.cimotorsports.net/motor-s...n-sr20det.html
05-23-2009 07:04 AM
JZW Shortening the rod a hair is ok, but you also shorten the travel of the waste-gate and that is the whole point of running a helper spring, you can retain full travel of the waste-gate and get the base boost where you want it and its adjustable by simply increasing or decreasing the hooked end for a change in spring tension.

When you crank the rod all the way in to get say 10psi for a t28, you have almost no waste-gate travel left and that could be bad.

John
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