[maartenvandorst]

According to the guys at Hirsch Performance the Viggen T7 intake pipe connected to the TD04 turbo is the most restrictive part in the current set-up on my car. Most tuners use a bigger intake at comparable powerlevels. This can be either a big intake pipe like Hirsch, Maptun, Abbott, etc. offer, or a set-up like Abbott offers for their TD04 kit. The restrictive last bend before the air enters the turbo is replaced by a silicone hose.

After checking out the intake on the Belgian Maptun/Speedparts importer's 9-3, we came up with this idea. A 70mm silicone hose will fit the T5 airbox outlet and the T7 spec turbo inlet. The 90 degree bend silicone hoses are a smoother design than on the picture. I've never been good at drawing

I've been thinking about possible problems I might encounter and came up with this:

The silicone hose connecting to the turbo will be a tight fit. A coolant line is situated very closely.

Another problem might be the crankcase ventilation. It has to be welded/fitted to the intake somehow.

ERP ported and polished the intake on his TD04. I'll probably do this after the new intake proved to be working. A big T7 intake pipe won't fit anymore after porting the turbo intake, so it's irreversible.

The custom ECU I'm using was written for the Viggen intake pipe. Will Trionic be smart enough to compensate for the different airflow?


Any thoughts on how to improve the 70mm set-up before I start working on it?

 

[California Saab Tuner]

It's an interesting idea. I had always thought the intake was a little restrictive on the Viggens. Given you're at around the same power output (possibly even more), but with lower compression, a smaller engine, and more boost you can probably use all the intake flow you can get!

Here as some thoughts to keep in mind though before you go ripping anything apart. I'm not sure if they apply to you, but it's worth thinking about.

The efficiency of the TD04 compressor wheel is best for peak flow at about 22 psi of pressure difference between inlet and outlet pressures. (1.5 bar)

Because of intercooler backpressure (which raises the high pressure side) and intake restriction (which lowers the low pressure side) on a stock Viggen the ratio is just about perfect, or at least pretty good, in the stock setup, and I think that may have been part of the reason they chose the restrictive IC and intake pipe.

Your car on the other hand, is probably running TOO much pressure difference with your current setup so I give a big

to the mod. It should also allow you to get more boost at lower RPM because the turbocharger won't have to work so hard. But you might want to keep these sorts of thoughts in mind. The TD04 is still pretty efficient even at 24-26 psi of pressure difference, more-so than it is at below 15 psi. So think about what kind of pressure difference you're currently running before doing anything too drastic.

I'm behind you though. Really all that^ is more just for stock Viggen owners (such as myself) who might also consider the mod, and while I don't think it would hurt anything at all (it could give better gas mileage and quicker spool up, though I don't know from experience), I can't imagine it would be benificial to hp.

Just food for thought. Setup looks good! Just watch for sharp edges facing against the flow. Those are usually pretty restrictive.

Cheers,
Dubbya

 

[California Saab Tuner]

I hate to make two posts in a row, but I thought it would be good to note it's not a "pressure difference" as I said before, but rather a pressure "ratio".

To determine the pressure ratio between compressor inlet and outlet divide the outlet absolute pressure, by the inlet absolute pressure.

Here's an example of an approximation for something resembling a stock B235R:

Boost pressure at manifold = 15 psi

Manifold Absolute Pressure (MAP) = 14.7 + 15 = 29.7 psi

Intercooler Back-pressure (IB) = 2 psi

Intake Restriction (IR) = 2 psi

Ambient Pressure (AP) = 14.7 psi

(MAP + IB) = Outlet Absolute Pressure

(AP - IR) = Inlet Absolute Pressure


(MAP + IB)/(AP - IR) = 2.50

2.50 is just about ideal for the pressure ratio. Of course I haven't measured the intake restriction or IC backpressure, and each depends on the airflow. But this was just an example in case you wish to approximate.

Cheers,
Dubbya

 

[ERP]

Crankcase breather is no problem, just add one of these.

It's an easy solution and everything runs fine. Even Frank Stromqvist said it would be okay.

I have a few interesting points to note about my TD04. When I upgraded my turbo from the T25 to the TD04 and larger intake pipe I noticed that spoolup was a little better. Not much but about 300 rpm sooner with the TD04 than the T25. I was quite happy with this since bolting on a bigger turbo usually means more lag.

However, even with all my mods the spool up of my TD04 is still much slower than a stock Viggen. Take a look at my dyno. Torque is a direct indication of boost pressure. I hit my max boost of ~18 psi at 3000 rpm.

On a stock Viggen max boost, which is also around 18 psi if I remember correctly, is achieved by 2600 rpm. This is Adrian's recent dyno test.

http://groups.msn.com/_Secure/0QAAAABsSNCrIYlsQ8K*mUH07rW2o4VKh3NVmaWcj4k9is2X3*yqxmnuHxJVXahOVlEwlbY0KThG1I4q
49P6d5epuyholWjkAAAAAAAAAAA/206.JPG?dc=4675452395109166885

I never tested the stock Viggen intake on my NG900. I am curious what it would have been like. It is possible that stock Viggen intake is already good for spoolup despite its looks. It's hard to imagine hitting max boost much below 2600 rpm.

Eric

 

[California Saab Tuner]

Actually I believe the max boost for a stock Viggen is about ~15 psi. At least that's what it always was when I had the graduated boost gauge hooked up. The higher 9.3:1 compression makes it a little more efficient torque wise than the 2.0 though with 8.8:1, so it can do more on less boost pressure. Which is why the torque peaks so high.

Because in a turbo car there isn't a direct link between restriction and MAP, slight restrictions in intake ducting don't hurt the power as much because the MAP is controlled by the computer, and the turbo just compensates for it by spinning faster. The only real power loss is due to high exhaust load, turbo inertia, and turbocharcher inneficiency. None of which take away as much power as the lower MAP that the same restrictions would give a naturally aspirated car.

With enough load in 4th or 5th gear, I've seen close to full boost by ~2,000 rpm. And at least some boost by 1,600 rpm.

Given that the stock intake easily makes 213 whp with only about 13 psi @ 4,900 rpm I can't see the need for a better intake until well past that mark. Though if you need to manipulate the pressure ratio for more efficiency, it's cheaper to get a good intake than a higher flowing IC, which would just accomplish the same thing.

Anyway, just more food for though.

Cheers,
Dubbya

 

[Vigge]

For the record, viggen with an upgrade ECU will reach max boost at 2250. That is just with an ECU no filter nor exhaust mods.
Here is a part of a graph where this can be seen.
Here
If you want to look closer how boost correlates with rpm's, here is a vid from my dyno run.
Dyno run about 6Mb
1 bar of boost is reached around 2000rpm.
The video is with 3" DP, racekat and 3" exhaust.

 

[Vigge]

Sorry the link to the video was wrong.
It has now been corrected.