Supercharged Saab 9-7x Build

[AdsoYo]

I've always loved the look and especially the sound of roots superchargers but could never get one because there isn't enough room under the cowl on my 4th gen Trans Am. Now that I own this 9-7x, it's time to seize the opportunity.

Here it is, a 2007 9-7x 5.3i with 95,000 miles on it. I had it on ramps to remove the factory running boards.



Phase 1 of the build involved removing DOD and swapping the axle gears from 3.73 to 3.42. Now WAIT! I know what you're thinking, "that's anti-hot rod, it's gonna be a dog off the line" etc etc. It's ok, this is my wife's car and it will never race or tow. I removed DOD because I want to avoid lifter failure, and the 3.42 gears are for a wider stride on the highway. The supercharger? That's all for me when it's my turn to drive it, she literally doesn't care.






Top end is off, engine looked great! I still did a handful of "while you're in there" tasks. Along with a DOD delete, I installed a new LS2 timing chain and LS2 dampener, and a new oil pump. Doesn't changing all those mean dropping the pan? Yes, we'll get there.

I also swapped the camshaft as another "while you're in there". It wasn't really part of the plan but since everything's apart, might as well get something that better supports the supercharger.



With the A/C condenser swung out of the way, there was plenty of room.

I contacted Cam Motion about a custom cam and they recommended a 214/226, 0.553/0.553, 116+3 LSA. This is nearly identical to the Cam Motion cam I have in my LS3 Trans Am. I told them this would be a daily, no racing/towing, supercharged with 6 lbs of boost so was surprised at the duration. They said in no detailed terms that once the supercharger is installed, it would fit my use case so I trusted them and went with it. That would prove to be a mistake.

Block and cylinder head surfaces all cleaned and ready for reassembly.






Now for the dreaded oil pan. I'd read a lot about how miserable of a job it is because the front diff and axle shafts need to be removed. Luckily there's good information on the forums and YouTube that really break it down step by step. The most helpful resource by far was this video:

There was obviously some seepage on the pan and the front diff and I don't want to do this job again for a very long time so that gasket is 100% getting changed.




Car up on the Quick Jacks, pan and front diff out.






The new diff and the rear ring and pinion came from Randy's Worldwide. I've never bought anything from them before but now I can't recommend them enough! Super fast shipping, excellent customer service and pricing.

New diff bungee corded in place so the freshly cleaned pan can go back in.




Since this is a Pennsylvania car, I had to fight rust like never before. 3 exhaust manifold bolt heads broke off, I had to replace my passenger axle shaft and quick disconnect because they were seized together, and a dozen other bolts took up SO much time to break free. This is what it took to get one of the exhaust manifold to Y-pipe nuts off.



I also had to replace the water pump and fan clutch because they were seized together! Oh well, at 95,000 miles probably not a bad idea anyway.

 

[AdsoYo]

Speaking of the Y-pipe, the oxygen sensors were rusted in there pretty good. All but one came out whole, the 4th came out WITH THE Y-PIPE'S THREADS STUCK TO IT! I had to order a new Y-pipe and went with Magnaflow and their "OEM replacement" option which is middle of the road between "federal" and "California".




After everything was buttoned up, I used HP Tuners to dial in idle, cruising, coast, basically everything except WOT since I didn't have a wide band.



I pulled the transfer case fuse so it wouldn't try and engage AWD since at this point the rear gears are still 3.73. For the gear swap, I paid a local shop and used Yukon gears. After 500 miles I changed the fluid and checked the contact pattern.



Now that the axles match, it's time to head back to the dyno and see what this big blower cam can do N/A. This is where things get disappointing. I was planning on running the cam N/A for a couple months until spring but the car lost power everywhere. I don't have a dyno comparison graph of stock vs new cam but peak numbers were down 6hp/8tq.

After posting on forums, talking to Cam Motion, and researching on my own, it sounds like the most likely cause is the late intake valve closing event at 42 degrees is the culprit. Too much cylinder pressure is lost as the piston pushes the charge out of the exhaust valve.

Ok then, I'll just get to supercharging now and give the cam what it wants right? Here we go!



This is a Magnuson TVS1900. I bought the kit for a Trailblazer SS and had to buy a larger 3.8" pulley separately since the included 3.3" pulley would've given me 8lbs+ of boost and I only want 6. Magnuson said they couldn't simply swap parts or alter the kit in any way sure.

The bulk of this install involves mounting the heat exchanger, coolant pump, and routing the hoses. Otherwise it really just plops right on!



The pump mounts to the frame with self tappers.



This was pretty nerve wracking. You have to drill the crank and pulley so you can insert these pins to prevent the pulley from slipping.

After another round of adjusting idle and MAF tables, it was off to the dyno for a 3rd time. Magnuson advertises +120/+120 at 6psi on a bone stock vehicle whether it's a 6.0 Trailblazer or a 5.3 Silverado so I was expecting more with this blower cam. Alas, the disappointment continues.

The good news is the supercharger is working great and making 19hp per psi of boost. It was hitting 5 psi on the dyno and picked up +95/+75. The bad news is the cam still didn't wake up. The dyno owner said it reads 10% low. So if you multiply 295 x 1.10 you get 325.

325 seems more believable because if you use our logged MAF g/s to estimate the horsepower, it comes out to 330. I also did a 1/4 mile hit and trapped 98 mph with a race weight of 5350 lbs and depending on the calculator comes out to 315-380 whp.

The power actually feels perfect, we've already done 1,000 miles of highway driving and this thing passes semi trucks like they're standing still, I love it. The problem is, it would be making this power with the stock cam! Also peak hp is 5900 rpm, way too high. It most certainly would've been higher if we didn't stop the run.

So Cam Motion sold me a cam that needs more rpm and more boost. The intake valve still closes too late for this small amount of boost. I'm currently in the process of ordering a new cam that will provide more low end torque and lower peak hp. You know, the DD cam I wanted from the start. I will update this thread as the cam saga continues.

 

[Mooseman]

Still impressive that you got it all together and running well despite the power that's lower than expected.

 

[AdsoYo]

Thanks! Wrenching on these actually isn't so bad. Except the oil pan, that is very bad. I should've gone with my gut when Cam Motion sent the cam specs. The duration was just so long for this small displacement V8 but the sales person told me the supercharger would make all the difference. I just ordered the new cam today. It'll be 204/208, 0.553/0.553, 118+4. It won't take advantage of or enhance the supercharger at all, but it will be perfect for my wife and I'll still have a supercharged LS in my garage.

 

[TollKeeper]

I think you would have been much happier with the 3.73 GT4 axles over the 3.42 GU6 axles. The drivetrain loss is probably what you are feeling.

Still a super sick build. I wanted to do this to my Envoy and Saab... Just didnt have the balls to get it done. Saab is now gone, and my Envoy has a lot of miles!

 

[AdsoYo]

I think you would have been much happier with the 3.73 GT4 axles over the 3.42 GU6 axles. The drivetrain loss is probably what you are feeling.

Still a super sick build. I wanted to do this to my Envoy and Saab... Just didnt have the balls to get it done. Saab is now gone, and my Envoy has a lot of miles!

If your Envoy has high miles that sounds like a good excuse for a 6.2 swap

I'd been looking online for a mint 9-7x for a few months when this one finally popped up. Only problem was I'm in Oregon and this was in Philadelphia. We decided to fly there and drive it back.

I had the width of the USA to get familiar with it and what I ended up disliking the most was how high the rpm's were during highway cruise. In Utah where the speed limit is 80, rpm's were 2500!

Now with the 3.42's I've shaved off about 250 rpm at the same speed. Once the 4L60 goes tits up, I'm going to swap in a 6L80 with it's 0.67 6th and shave off even more.

The 3.73's had a solid cross country trial but it just wasn't meant to be.

 

[TollKeeper]

Regarding the 3.73, it wasnt the legs they give on the highway... It was how those legs respond to the Supercharger. The 3.73 I think are the perfect fit for a Turbo/SC.

Should have joined a couple years ago, would have sold you my 9-7x for cheap. But it was not meant to be! Mine was an identical twin to yours, but with higher miles.

 

[Mooseman]

If I were installing a supercharger, I definitely wouldn't be fretting over MPGs and highway RPMs.

 

[AdsoYo]

If I were installing a supercharger, I definitely wouldn't be fretting over MPGs and highway RPMs.

Think of it like a "his and hers". She gets stock driving manners when it's her turn. I get instant torque and blower whine when it's my turn. I'll admit installing a supercharger and then taking steps to maximize efficiency isn't common. Not sure anyone's done a build like this. Maybe you could say I'm a... trail blazer.

 

[AdsoYo]

While I'm in this holding pattern waiting for the new cam to arrive, I went ahead and installed a Magnaflow catback part number 16656.




I had a local shop weld in an O2 bung for a wideband.





In typical Magnaflow fashion it sounds very tame relative to other aftermarket options. What it does sound like is pure 100% bass. My phone couldn't even capture a fraction of how much low frequency bass this thing is putting out. Our biggest priority is keeping the interior quiet so we'll have to drive it for a bit to decide on that one. There is just barely enough drone to be noticeable but I mean, once the radio is turned up two notches you can't tell. I'm keeping the stock resonator in the garage just in case.

 

[Mooseman]

Awesome! I miss my 9-7x. I wanted to soup it up with a 6.0L to make a sleeper out of it but it wasn't meant to be.

My Caprice's mufflers (JBA Headers) are too loud and drony. I was thinking of swapping them to something else so maybe something like this one would work. My wife is always on my case that it's too loud.

 

[AdsoYo]

Made a video mash-up of drive-by clips so people can hear what a full Magnaflow exhaust sounds like.

 

[Mooseman]

The SC is louder . That may be too tame for me but then the mic may not be picking it up right.

 

[AdsoYo]

The magnaflow might actually be quieter than stock at idle and cruise! I was mostly interested in the increased flow/ decreased restriction so it's all good.

What I DON'T like is the drone. We set cruise at 55-60-65 and so on to see if it ever bothered us. 60 and below was whisper quiet in the cabin. 65, 70, 75 was annoying enough I'll be installing a j-pipe or a Vibrant Ultra Quiet at some point.

I did a WOT throttle log while driving home and something happened I didn't expect: the peak MAF g/s decreased from ~350 to ~340 indicating a loss of power while boost stayed the same. I thought the g/s would increase

 

[AdsoYo]

The new cam arrived and I got it installed over the weekend in 13.5 hours total. The supercharger really complicated things, especially on the passenger side. I only took a few pictures this time.



Here it is mostly stripped down. Everything went smoothly except for the harmonic balancer of all things. If you recall from my first post, I had to drill the crank and balancer and insert two pins for the supercharger. Well when I pulled the balancer, one of the pins stayed glued to the crank and burrowed a tunnel into the balancer as I pulled it out!



The answer is yes, this one went right back in . I hammered the ridge back to flat, rolled some dice and reinstalled.

Next big problem was the heat exchanger. I didn't want to drain the coolant for the supercharger loop so it took some experimenting to figure out where to put it and the condenser so I had enough room for the cam. I ended up laying both on top of the engine bay and doing the cam swap from underneath.



Here's the pile of parts that had to come out for this event.



Here's the proof that the timing gears were lined up dot to dot after the swap.



Since I don't have any way to hold the flex plate when reinstalling the balancer, this was my solution to hold it in place while torquing the bolt.

 

[AdsoYo]

I reloaded the stock idle and MAF data back in since the cam is so close to stock. It's a grind I made with the help of Gemini and Claude AI bots: 204/208, 0.553/0.553, 118+4. Dubbed the "Wife Cam", I wanted to maximize efficiency above all else although so far that's not what happened.

While fuel trims are +/- 3%, highway mpg was 18 on my test drive and I was hoping for better with the high vacuum this cam makes. I can still advance spark in the cruising cells and lean it out a tad to try and get MAP down. Currently it's about 55 kpa on flat ground.

Where this cam blew me away was the power. I thought it would match the 330 WHP of the old cam but it put down about 375! Right now it's an estimation based on MAF g/s. The old cam was moving 350 g/s and now it's moving 490! It's moving so much air it went into high airmass spark cells that I couldn't even see because they were off my screen so I'll have to go back and fix those.

So next tasks are do one or two more WOT pulls to hit those spark cells and then trial and error cruising spark cells and AFR to get the lowest cruising MAP possible.

 

[TollKeeper]

I want to get a LQ4, 4L70, and SS rear axle (already have the front) and do this to my XUV... I just dont have the physical ability to do it anymore....

Maybe I just need to find someone to do it

 

[AdsoYo]

You only live once, do it!

I redid the math on the HP estimate.

If HP = (MAF g/s × 3600 / 453.6) ÷ (BSFC × AFR)
then HP = (490 × 3600 / 453.6) ÷ (.6 × 11.5).
HP = 3888.9 ÷ 6.9.
CrankHP = 563.6.
WHP = 563.6 x 0.7.
WHP = 394.5.

My injector duty cycle with these 50 lb/hr injectors barely touched 81% during my WOT runs. I never thought I'd be knocking on the door of 400 whp with this thing. I need to make a dyno appointment so I can see this graph!

Tomorrow I'm going to dial in the cruising cells on the spark table and experiment with leaning out the AFR.

 

[AdsoYo]

I had the opportunity to show a brand new F-150 Raptor the difference between "built vs bought". It was so new it didn't even have plates yet. It was a 2 lane to 1 lane road and I didn't want to get stuck behind him because people regularly go under the speed limit on this stretch. Apparently he was thinking the same thing. Neither of us floored it off the line but we both accelerated quickly. Then once I heard him floor it I did the same. We were neck and neck until I hit my brakes. I looked over at him and saw in his face he wasn't going to lift. Not sure what his plan was... keep flooring it in the bike lane?

 

[marigoldquadrasteer]

Speaking of the Y-pipe, the oxygen sensors were rusted in there pretty good. All but one came out whole, the 4th came out WITH THE Y-PIPE'S THREADS STUCK TO IT! I had to order a new Y-pipe and went with Magnaflow and their "OEM replacement" option which is middle of the road between "federal" and "California".

View attachment 118532View attachment 118533View attachment 118534
View attachment 118535

After everything was buttoned up, I used HP Tuners to dial in idle, cruising, coast, basically everything except WOT since I didn't have a wide band.

View attachment 118536

I pulled the transfer case fuse so it wouldn't try and engage AWD since at this point the rear gears are still 3.73. For the gear swap, I paid a local shop and used Yukon gears. After 500 miles I changed the fluid and checked the contact pattern.

View attachment 118537View attachment 118538

Now that the axles match, it's time to head back to the dyno and see what this big blower cam can do N/A. This is where things get disappointing. I was planning on running the cam N/A for a couple months until spring but the car lost power everywhere. I don't have a dyno comparison graph of stock vs new cam but peak numbers were down 6hp/8tq.

After posting on forums, talking to Cam Motion, and researching on my own, it sounds like the most likely cause is the late intake valve closing event at 42 degrees is the culprit. Too much cylinder pressure is lost as the piston pushes the charge out of the exhaust valve.

Ok then, I'll just get to supercharging now and give the cam what it wants right? Here we go!

View attachment 118539

This is a Magnuson TVS1900. I bought the kit for a Trailblazer SS and had to buy a larger 3.8" pulley separately since the included 3.3" pulley would've given me 8lbs+ of boost and I only want 6. Magnuson said they couldn't simply swap parts or alter the kit in any way sure.

The bulk of this install involves mounting the heat exchanger, coolant pump, and routing the hoses. Otherwise it really just plops right on!

View attachment 118540

The pump mounts to the frame with self tappers.

View attachment 118541

This was pretty nerve wracking. You have to drill the crank and pulley so you can insert these pins to prevent the pulley from slipping.

View attachment 118542
View attachment 118543

After another round of adjusting idle and MAF tables, it was off to the dyno for a 3rd time. Magnuson advertises +120/+120 at 6psi on a bone stock vehicle whether it's a 6.0 Trailblazer or a 5.3 Silverado so I was expecting more with this blower cam. Alas, the disappointment continues.

View attachment 118544

The good news is the supercharger is working great and making 19hp per psi of boost. It was hitting 5 psi on the dyno and picked up +95/+75. The bad news is the cam still didn't wake up. The dyno owner said it reads 10% low. So if you multiply 295 x 1.10 you get 325.

325 seems more believable because if you use our logged MAF g/s to estimate the horsepower, it comes out to 330. I also did a 1/4 mile hit and trapped 98 mph with a race weight of 5350 lbs and depending on the calculator comes out to 315-380 whp.

The power actually feels perfect, we've already done 1,000 miles of highway driving and this thing passes semi trucks like they're standing still, I love it. The problem is, it would be making this power with the stock cam! Also peak hp is 5900 rpm, way too high. It most certainly would've been higher if we didn't stop the run.

So Cam Motion sold me a cam that needs more rpm and more boost. The intake valve still closes too late for this small amount of boost. I'm currently in the process of ordering a new cam that will provide more low end torque and lower peak hp. You know, the DD cam I wanted from the start. I will update this thread as the cam saga continues.

View attachment 118545
View attachment 118546

This is such a great, old school writeup. Thanks so much for doing the work of making this post.

 

[marigoldquadrasteer]

I had the opportunity to show a brand new F-150 Raptor the difference between "built vs bought". It was so new it didn't even have plates yet. It was a 2 lane to 1 lane road and I didn't want to get stuck behind him because people regularly go under the speed limit on this stretch. Apparently he was thinking the same thing. Neither of us floored it off the line but we both accelerated quickly. Then once I heard him floor it I did the same. We were neck and neck until I hit my brakes. I looked over at him and saw in his face he wasn't going to lift. Not sure what his plan was... keep flooring it in the bike lane?

Sounds great. I love putting new vehicle owners in their place. I think the full magnaflow is perfect volume and tone wise from the videos. It never computes to me to put violently loud exhausts on very common motors (like LS, Coyote, VQ, Honda B and K motors, etc.). I know exactly what a loud LS sounds like and I never crane my neck . A nicely muffled one where I can hear supercharger noise? BREAKIng my neck to see

 

[AdsoYo]

This is such a great, old school writeup. Thanks so much for doing the work of making this post.

My pleasure! I always love seeing long detailed posts on automotive forums so I figured I'd contribute as best as I can.

 

[AdsoYo]

Sounds great. I love putting new vehicle owners in their place. I think the full magnaflow is perfect volume and tone wise from the videos. It never computes to me to put violently loud exhausts on very common motors (like LS, Coyote, VQ, Honda B and K motors, etc.). I know exactly what a loud LS sounds like and I never crane my neck . A nicely muffled one where I can hear supercharger noise? BREAKIng my neck to see

Thanks! The main reason I bought the magnaflow was for the straight-through 3" pipes and mufflers. I wasn't sure exactly how it would sound but I'm so glad it ended it being quiet. I would've left the stock system on there because it was silent but being 2.75" with a restrictive muffler just felt wrong to choke the supercharger like that. I'll eventually add a j-pipe to completely eliminate the very minor drone at ~2000 rpm.