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February 24, 2006
Backpressure Pt2
So comparing after cat pressures at the same power output it starts to get interesting... With the 3" JT we had 4.4 psi max after the cat. With the Remus 3.2 psi max. This one is 60mm or almost 2-3/8" Both of these are the same configuration. One muffler in the rear. Straight through center pipe and a flex after the downpipe. The sound is so much nicer with the Remus. I still have to find time to test a factory exhaust with and without middle muffler and with and without the downpipe.
I have been double checking all this data just to be sure and get very repeatable results. Not exactly sure why My old cat flowed so poorly with no visible damage to the core. After cat measurements are my main point here. Just trying to compare different size apples... Also as a side note While playing all this exhaust I left the 6point subframe brace off. Thinking I would be going back to all 3", No way. So a few days of driving without the 6pt reminded me how much of a change it actually makes for steering feel and tramlining. Had to put it back on. this sort of power and plain old P6000 "winter" tires just won't play well together. I also posted some more photos in the the http://GenuineSaab.com/Gallery
Posted by nick at 9:56 AM | Comments (1)
February 20, 2006
Cool Video of my CNC
Made this video saturday. Thought it was prretty cool. Got bored after watching it run about 40 times and my iPod battery died.
Posted by nick at 3:05 PM | Comments (0)
February 9, 2006
Exhausting Tests
Since I am not one to just listen to the mainstream and I always wondered about the need of 3" exhaust on our 4 cyl engines I decided to do a little scientific research. The main measure of exhaust system effectiveness is Back-pressure. Too much back-pressure hurts turbine efficiency and affects the power output and Knock sensitivity. Noise is also a factor but not my main concern. Read on to find my suprising results...
My test setup was on my stage 4+ Viggen. I used a Fluke digital pressure gauge and my Fluke meter to record maximum pressure readings on the same test loop driven at full throttle both at peak toque and horsepower. I started backwards and tested the already installed JT3" complete system with JT racecat and 1 muffler. The maximum readings were very high in front of the cat 21.3psi or 1.5bar Way too high! Next to locate the restriction I moved the pressure pickup to behind the catalyst. The problem was immediately apparent, peak readings of 4.4psi or 0.3 bar. Now to find out why. First step to take the system off the car. Even off the car you cannot look in and see the catalyst core so I had to cut it apart. Here are a couple images.
Expecting it to be visibly damage. It appears fine! I plan to cut it further to inspect. Now with no exhaust system on the car it was time to dig into my collection and get the Original Saab accessory remus catback system with straight through center pipe. After adding a few extra sensor fittings to one of my off the shelf stainless downpipes with larger metal core catalyst. The downpipe is 3 inch tubing and reduces to stock 2-3/8 (or so) to mate to the original flex pipe. Knowing the books say this is fine for my ~340 hp but "they" say I need 3inch... In the same test conditions the peak pressure before the catalyst was now only 6.9 lbs or 0.47bar I added the wideband and pressure ports but forgot the pressure port after the cat.. The sound is nicer too.
This system stays on the car for now. The difference in the power and drivability is huge! So this is the extent for now. Off to the Dyno tomorrow. My plan is to collect more data from stock exhaust and a few other combinations as time permits. Hope this is as interesting to you as it is to me. Gallery of related Images
Posted by nick at 8:01 PM | Comments (0)
February 7, 2006
Bigger Injectors
Added the "Green Giant" injectors and the corresponding Nordic Stage? software. The change is not huge. The software is a bit more agressive but there is still the limit of the smallish turbo. The injectors plug right in but since they are a bit longer it requires spacers for the fuel rail mounting. I made some up out of aluminum. The Injectors also require more fuel pressure from a different regulator. These are probably a bit large for this power but ;) As always this power thing is addictive and room to grow is nice. I was certainly pushing myluck with stock injectors and fuel press at these power levels.
Posted by nick at 10:52 AM | Comments (0)
Been a while..
I have been really busy with the whole GenuineSaab.com business. Not even to mention my New Haas CNC machining center. May new projects are in the works or getting started in production right now. The steering rack braces are a big part I was able to bring in house for manufacturing and both improve the part and lower the sale price! 9-3 and 9-5 stainless downpipes are done.. Now on to Header and big brakes... Oh and to tell about the recent changes to the Viggen. It is stronger than ever and aiming for more. I will get some dyno time in hopefully soon.
Posted by nick at 9:08 AM | Comments (0)