01 STS mods

[iowaboy77]

A friend of mine got an exhaust system from Corsa Permormance for his Pontiac. The website has some pretty cool looking pictures and sounds. Has anyone had experience with this system and an STS or DTS?

Also while i'm in the mod mood, are there any good sites with some examples or things for sale that might catch my eye for the STS?

Check out the Corsa Exhaust pics and sounds:

Corsa Exhaust Link

put your cursor over the numbers in the pic, turn your speakers up, and prepare to smile.

[danbuc]

Ive got the Corsa exhaust on my 1998 STS and I absolutely love it. Its quiet while cruising on the highway, but sounds really mean at WOT. As far as "Mods" go, I have a small list like many others. The only things that I've found that would actually be worth doing are as follows.

-Heavy-Duty 4T80E transmission with High Stall Torque converter and Posi-diff (diff and torque converter can be installed by themselves also)

www.domesticperformance.com

-Corsa exhaust.

-"The Supercharger"-(need to get into computer in order to use, My teacher and his friends at Delphi electronics are working on that for me)

-A local dealer might be able to reflash the computer with a different vin# to remover speed limiter.

-Some people have put NO2 on their cars with some good results.

Other than transmission work and high flow exhaust, there just isn't that much out there. I'm looking to put in the Posi-diff and High Stall Torque Converter in my car. It's all a matter of how much you are willing to spend. If you have the money, anything is possible. Good Luck.

[MARK 99STS]

I also have the Corsa exhaust on my 99 STS and absolutely love it.

Other Mods would be like "danbuc" said. In addition to those:

I would put on a K&N cone filter #ru2590 and heat shield and duct out for cooler air. This will greatly enhance the Corsa exhaust.

Extrude/hone the exhaust manifolds and intake manifold to increase flow.

For better handling performance go with Eibach lowering springs and lower profile tires.

DANBUC,

If you find anything out on the supercharger let me know as I desperately want one.

[eldoman95]

something i posted a while ago....

puddles are gonna be your fear, if you want to open intake a little, i would rig a "Ghetto" forced air induction by rigging a tube from the grille, which will also reduce the air temp being used, to a cone filter with a heat sheild around it. itll give you more air, a deeper sound, and cooler air if you have a proper heat sheild. a cheap way to do this is to custome cut cardboard to block the engine from the cone filter, wrap it with aluminum foil, because aluminum is not a conductor of heat, and put a rubber gassget around the "homemade heat sheild". itll block the engines heat fairly well. remove the tube that gives you air from behind the headlamp, and run your tube from the grille through the opening behind the headlamp, and you got yourself a FAKE RAM AIR / COLD AIR INTAKE, WITHOUT POSSIBLEITY OF HYDRO-LOCKING THE ENGINE. just something i havent tried but seems possible.

[bigfoo]

My intake tube comes off the mass air, and points straight down inside the fender well with a k&n cone on it. Water can't go straight up very easily so i'm not worried about it. To change the filter though its' a real *smurf* I have to take off the plastic stuff around the fender well heh

Oh any by the way, aluminum is an excellent conductor of heat and it also dissapates heat very quickly as well. I think what you meant to say is that cardboard isn't a very good conductor of heat :>

[Bob_Caddy]

Will the corsa system fit a 98 STS because the web page reads that it will fot from 99+

[MARK 99STS]

I think it will but you may have to make some modifications.

[iowaboy77]

I called Jim at Corsa Exhaust (800-486-0999).

They say the system would be identical for a 1998 STS except the tubing diameter coming off the Catalytic Converter is different. They dont list the 98 STS because their product wont fit it stock. He said some kind of home-made bracket and/or block would make it work, other than that, everything else is identical.

I'd call corsa if you had any more questions. I got right thru to a real person who seemed to know his stuff. The web site is very helpful too.

Good luck

[danbuc]

Yes it will fit a 1998 STS. It will fit any Seville from 1998-2004. I'm not sure why they don't list it on their site, but I have it on mine, and it fits perfectly. If you want to give them a call first, they are very nice, and will answer any questions you may have. The catalytic converter is either a tad bit bigger or smaller, I don't remember. I had the place where I got it installed weld it on, to prevent any leaks that I might have had if I used clamps. They did an excellent job, and it fits great. No excess metal or anything. Good Luck.

[sts man]

Mark how did you extrude hone the intake manifold when it is made of high temp plastic???????? caddy made it out off plastic because it does not get as hot as aluminum and it is alot smoother than a cast metal type it dont have all the slag and ect from the mold it was made in.But the only problem when you install the S/C I wander if it can handle the intake pressure.

[danbuc]

The main reason the Supercharger project failed on the OBDII cars, was the lack of ability, to modify the prgamming in the ECM, to adjust timing and fuel. Without it, the engine would run like crap. However, if you have an OBDI car (1995 or older) it will work, since an aftermarket EEPROM chip can be programmed , to work with the Supercharger.

It was developed by XMS racing, but I have no idea if they ever sold any. If you have an OBDI car, and you can manage to purchase one, it can be installed, and run properly, provided the replacement EEPROM chip, has properly tuned settings.

To be honest, I would not have trusted the Supercharger with a base 4T80E transmission. Luckily, there is a company who build up heavy duty transmissions. I belive that a Limited Slip Differential, would also have been required to properly distribute all that power to the ground.

The intake manifold can be extrude honed, but the gains are not really worth the effort. I've been thinking about buying a used set of exhaust manifolds, in addition to the crossover pipe, to see what can be done with them. The space for the crossover is very limited, but I do believe, that there may be a little bit of romm left, to squeeze some more flow out of the stock manifolds. Quite a while ago, I was speaking to someone over at Domestic Performance, about their project for a custom, high flow exhaust manifold, and crossover setup. They already had a a design in mind, and wre working on fabricating a jig, so that they could weld them more easily. The wer only going to do it, if there was enough interest, but there never was. Just like the Supercharger from XMS.

[MARK 99STS]

I have not extrude/honed my intake because as "danbuc" said there is not much to gain and after a conversation with the co. that does it, they said it would not work on plastic.

Danbuc,

I am also interested in getting headers or better flow from the manifolds and down pipe from the front bank. As you said it is tight but I think it can be improved. If you find someone, let me know and I will do the same. I am currently working on a winter project of doing the exhaust ports on the heads, getting a limited slip differential, and putting in a 3500/SS stall converter from YANK. I'll let everybody know how things go.

[danbuc]

darn, I thought I was the only one thinking about the Yank High Stall Torque Converter, and the LSD combo. As I said before, I'm looking into purchasing a set of exhaust manifolds off of ebay, and see what I can do with a Dremel. I say Dremel, since I don't have a die grinder laying around.

PLease let me know how your High Stall Torque Converter, and LSD workout, as I've been trying to save up for them in the spring. Just out of curiosity, are you going with the Engineered Performance LSD, sold through Domestic Performance, or did you happen to find another company.

Best of luck on your project, remember to report back when it's finished.

[MARK 99STS]

Yes I am getting the LSD from Engineered Performance.

[danbuc]

I notice that you have a 14.1 second time in the 1/4 mile listed. I'm just curious, as to how your car was setup during that run. Did you have the Corsa? What tires did you have? What was the temperature? You know, stuff like that. My goal with this car, is to get it to consistanlty run mid to high 13's in the 1/4. I know it's possible, all I need is the money. Let me know what happens, so I can buy the stuff, once I have the money.

[MAC]

I found the below information from http://www.cadillacforums.com/cadillac-tech.html. I thought I would post it because many like info. on how to maximize HP. I don't think I have seen a post about extrude-honed exhaust manifolds.

"One thing that will help free up a few horse power is to get the exhaust manifolds off and have them extrude-honed. There are a lot of sharp edges and corners in the fabricated manifolds that can be ground, smoothed and radiused. Not a huge gain here and a lot of work to pull the manifolds and such but if you want the most power, the manifold rework with the low backpressure system will provide the most. I would say that the ultimate exhaust on a transverse passenger car with extrude-honed manifolds, large pipes and Flowmaster style muffler would probably provide 20-25 HP at peak power."

[MARK 99STS]

Danbuc,

It was in November about 45 degrees, low humidity and high barometric pressure.(just what the Northstar loves)

I had the Corsa exhaust, K&N cone filter heat shielded and ducted out for cold air, 80mm TB(not that helped any),Mickey Thompson E/T drags on the front @25lbs, thin hard,worn Michelins on the back @45lbs. All 4 mounted on light weight aluminum wheels. I also had a 2600 stall torque converter in it.

My hope is with the heads, 3500 stall converter, limited slip dif, and rework the exhaust to be in the mid 13's.

[danbuc]

I bet most of that time was just from those drag tires up front. I was a little hesitant to port the heads, since many people (especially Guru) mentioned that you would gain top end HP, but loose low end torque. If you do, post your timeslips, and tell me if you still have substantial low end torque.

I think I was just gonna go with the torque converter, LSD, and maybe mess around with exhaust manifolds a little. I've heard some people have had good results from a 50-75 wet nitrous injection system. I beleive most were using the one for the 3800, but added to more jets.

[MARK 99STS]

Yea in talking with Guru he said I should be ok if I only work on the exhaust ports and not the intake because that is where the problems were. Based on the flow bench, the guy that did the heads said I had 20cfm increase and only minimal change on the low end. According to him that would equate to a 40 hp increase. I doubt I will see all of that due to the exhaust restriction , but time will tell. I plan on doing a chasis dyno when I get everything finished. Maybe one before the exhaust mods and one after. Unfortunately I didn't do one before the project started.

Getting some used manifolds is a good idea because the guy wanted to cut off the flanges and reweld them back about 1.5 inches where the pipes opened up more on the manifolds instead of grinding but then I would have to redo all the exhaust to the cat. I might do that after I get it running and go with a true dual system with an x pipe between the two sides so they can communicate per Guru.

My biggest frustration was and is to find someone who would work on the car to do all this. The guy that is doing it has the knowledge,but he is doing it on the side and it is taking him foever due to family and medical problems.

[danbuc]

MARK 99STS, I was just wondering how the drivability of your car was affected by the High Stall torque converter. In particular, did it have a big affect on light acceleration, like from a stop light, or was it alsmost the same. Also, what affect did it have on fuel consumption. I imagine it would have been a little worse, since it slips more than the stock one. Thanks.

[MARK 99STS]

I don't have the car back together yet so I can't answer that, but the 2800 stall currently in the car had no noticable drivability issues at all. I will let you know when I get it back together.