: Anyone have problems w/ Exhaust Manifolds??



coach123
06-12-10, 07:56 PM
Has anyone ever experienced issues with the exhaust manifolds on our cars such as cracks, broken parts, etc? I'm not concerned with the welded in catalytic converters but just the manifold itself.

Since no one has produced headers & cats for our cars I was thinking about taking the exhaust manifolds off the car using a chop saw to cut off the catalytic converter and welding in a 200 cell catalytic converter in it's place. The converter is the most restrictive point in the exhaust system so this may very well free up some good hp on my new snakebite setup. Does anyone know how many cell catalytic converter is used on our stock setup? I know the Mercedes use anywhere between 400-600 cell cats but they usually have 4 or more cats on their exhaust systems.

Just in case anyone was wondering I would only replace the stock catalytic converter if there was an issue with it :). Comments are welcome. Just brainstorming to try and unlock some restriction. I will be contacting Kooks headers on Monday to see what the cost for possibly doing a group buy. If it is cheap enough and we have people interested in it, I will drive to their shop in N.C. and have them made.

Psycho-albanian
06-12-10, 08:36 PM
Doesn't d3 make headers for the sts-v, i could swear i saw them on their website.:confused::confused:

coach123
06-12-10, 10:12 PM
They advertise but never have them in stock. I think they are not going to produce them unless there is a group wanting them. I can't speak for them but I had heard that they didn't produce the hp they thought they would which is one of the reasons they don't have someone produce them now.

Dr. Design do you have any comments on your headers?

I highly doubt I go with headers but I was going to contact Kooks anyone to get a rough price for everyone and to see what they thought the gains might be for our application. I think replacing the cats will yield the best benefit as the exhaust manifolds are already extruded honed. If someone was to do LT's you might see more benefit. I'm not an expert on exhausts so I would gladly here what others have to say about it.

TimmyC
06-13-10, 01:10 PM
I'm considering building LT headers for my as-yet-unpurchased STS-V. I have a set of manifolds from an STS I could use to make a jig. I think they are the same but they have different part numbers. Can anyone shed some light on that? I could do high-flow catted or uncatted (for off-road use, of course). I am a fabricator by trade and have built headers and exhaust systems many times.

If there is some interest here I can see about having primary tubes bent up and flanges water-jetted out.

coach123
06-13-10, 11:33 PM
Count me in :thumbsup:. Let me know if there is anything I can do to help. I'm not sure if the exhaust manifold are the same for STS and STS-V.

coach123
06-13-10, 11:34 PM
Come on guys.... I'm assuming that since no one has said anything no one as had issues with the manifolds/

Psycho-albanian
06-14-10, 12:05 AM
I would do headers but,i had bad luck with headers when i had my 02 ws6.

TimmyC
06-14-10, 12:11 AM
You can turn the SES light for the secondary O2 sensors off with HP tuners. Problem solved.

People haven't been talking about headers because they are expensive and no one has them. I'm betting that headers with high flow cats or none at all will provide significant gains. Which way do you want to go coach?

Psycho-albanian
06-14-10, 12:20 AM
No headers for me :tisk: i'm just gonna get the snakebite and a intercooler upgrade.:thumbsup:

TimmyC
06-14-10, 12:31 AM
No headers for me :tisk: i'm just gonna get the snakebite and a intercooler upgrade.:thumbsup:

What about a cold air kit and the piping from there to the back of the blower? I'm definitely building those pipes for my car.

Psycho-albanian
06-14-10, 12:34 AM
I already have the d3 1.5 intake.

coach123
06-14-10, 12:56 AM
I need both... haha In the end it all depends on cost but if I got headers I would go catless for the extra power. If its too loud then you can always weld some high flow cats in later in the exhaust run. I do want to get some dyno runs for everyone without and with headers along with CAI so everyone knows what the differences are. People can make the decision for themselves what mod they want. I really love that more people are coming forward finding inventive ways to get power out of our cars. TimmyC you have PM

550HP STSV
06-15-10, 09:53 AM
Coach,

Ive got some pictures of the underside of my car. Im fairly positive the only cats are right off the manifold. Then there is a resonator, then mufflers, to my knowledge. I had a custom muffler shop leave the 2 precats on, remove the resonator and install a H-pipe, then I welded on two magnaflow mufflers and corsa tips.

I also feel the cats are the most restrictive part of the exhaust, and have always wanted to install 2 high flow cats to replace the factory ones. The problem is that they are literally RIGHT off the manifold, and I think it would be extremely hard to weld two high flow cats while removing the stock ones.

Under heavy acceleration, you get the higher pitched pinging sound, a characteristic of exhaust gas not being able to flow freely. Under lower RPMS it sounds great. When my car was on the dyno, the exhaust flow towards the upper end was so great it blew a metal gate over.

Any ideas?

bobs-sts-v
06-15-10, 09:58 AM
Forgive me for being naive, but if you are going the custom route and are planning on installing hi-flow cats, can't you move them back so they aren't so close to the manifold? Or is there no room for something like that?

Bob

BlownV
06-15-10, 10:58 AM
Any good exhaust shop should have no problem running a custom 2.5 or 3 inch exhaust with whatever mufflers, tips, cats (or test pipes) you want. May require pulling the exhaust manifolds to cut off the cats and weld on some pipes but I am sure it is all feasible. Last exhaust system I ran was full 3 inch, no cats, all mandrel bent, no resonators, turbo back...but you probably wouldn't want that on a caddy lol.

coach123
06-15-10, 11:13 AM
If you were to cut the stock cats off it would require removing the exhaust manifolds which most mufflers shops do not want to do. You could definitely move the cats further back in the exhaust system but would need O2 extensions. I have been told that closed couple catalytic converters like we have are not good for backpressure or cylinder temps. GM likes to use them because they have extremely quick preheating which allows them to pass the rigors of emissions testing. Most cars will fail emissions during the first 30 seconds of starting the engine. It is a lot easier to get emissions numbers once a car is warmed up fully.

What I don't understand is the regular V8 STS has the exact same exhaust manifold and cats. GM must have known that with us being supercharged we would need a higher flowing design. Either they over engineered the V8 STS or severely under-engineered our exhaust manifolds.:cookoo:

BlownV
06-15-10, 11:32 AM
I would guess the latter of those two options.

Do any of the tuners out there allow the user to bypass or 'fake' the O2 sensor readings? This may be an opportunity to run some 'high flow' cats :)

TimmyC
06-15-10, 07:19 PM
Forgive me for being naive, but if you are going the custom route and are planning on installing hi-flow cats, can't you move them back so they aren't so close to the manifold? Or is there no room for something like that?

Bob

The proximity of the cat to the manifold is not really the problem. As long as the new cat is not much wider than the stock one it could be welded on in place of it. The stock manifolds, especially the left side unit, are too small. The left side manifold necks down to just over 2" where it passes by the steering shaft. There are definitely gains to be had in replacing the whole manifold. I like complete replacement because you can go back to stock if you need to.

Muffler shops won't replace your catted manifolds with non-catted headers and they won't cut your cats off either, so this is going to have to be a DIY project.


I would guess the latter of those two options.

Do any of the tuners out there allow the user to bypass or 'fake' the O2 sensor readings? This may be an opportunity to run some 'high flow' cats :)

HP Tuner and EFI Live allow the user to change the effect of each different code. All you have to do is set the secondary 02 and cat efficiency codes to "No error reported"

BlownV
06-16-10, 01:33 AM
Well if that is the case then by all means yank the cats if you live in a state without inspection...that includes all you FL guys!!! And I can tell you personally that an exhaust shop will cut the cats off if you request it...I have had it done...when I lived in FL. Sounds like a good opportunity to run 2.5 inch straight pipe all the way.

550HP STSV
06-16-10, 10:01 AM
I dont like the sound of uncatted exhausts. This isnt a 70's camaro guys, the STS-V should have a nice, low, deep rumble. No unrestricted, smelly, ratty, cammed exhaust noise.

My entire reason to replace the cats would be to get less restricting ones to make the exhaust note smoother at higher RPMs.

coach123
06-16-10, 10:28 AM
The best flowing cats are going to be either 100 or 200 cell cats. Usually with the 100 cell cats you throw CEL codes but these can be bypassed by tune. The 200 cell cats are the best option I think for the most performance while not throwing codes. FYI.. most magnaflow high flow cats are either 300-400 cell. Sound level is relative to the number of cells so the lower the cell number the louder the sound.

550HP STSV
06-16-10, 10:55 AM
I see. I'd be interested in getting a magnaflow high flow cat then, as I'm not interested in making my V any louder than it is right now. I had no mufflers for a while, which was insane. Right now with the magnaflow set up, it is still very loud.

BlownV
06-16-10, 10:58 AM
The right muffler/possibly resonator combination will provide a wide variety of sounds...you don't need cats to keep a low deep note.

BPatterson
06-16-10, 06:35 PM
Some people want louder. When I was looking at getting a V last year, I researched everything you guys are doing right now. I contacted other companies about building cold airs, headers, pullies, etc, and noone was really interested, so I decided to start designing my own stuff. I build CAI's for Grand Prix GTP's, as well as TrailBlazer SS, so building one is not a problem, and looked at what would take to build a set of longtubes for these cars. These cars are hindered sooooo much right from the factory by the poorly designed intakes, and complete exhausts. Blower cars need larger exhausts moreso than NA cars to help expel all those hot exhaust gases. I'd be willing to bet that a set of longtubes, and a full 3" exhaust with an x-pipe would pick up close to 40 rwhp.

550HP STSV
06-16-10, 09:05 PM
removing the resinator, factory exhausts, and running a custom H pipe with magnaflow performance mufflers, removing the 'baffle" on the intake, and changing to the custom made torquemaster plugs from D3, I gained 0 rwhp on the dyno.

STS_Chiller
06-16-10, 09:54 PM
removing the resonator, factory exhausts, and running a custom H pipe with magnaflow performance mufflers, removing the 'baffle" on the intake, and changing to the custom made torque master plugs from D3, I gained 0 rwhp on the dyno.
:arghh:

Some people gut the inside of Cats so they are empty cans. I would not recommend anything illegal but its OK off road. Turn off rear O2s and good to go. It looks stock but wont pass emissions and will show up in scanner.

coach123
06-16-10, 10:34 PM
550HP STSV - did you at least get the sound you were going for? I went with the magnaflow mufflers. Removed the stock resonator and installed a magnaflow x-pipe. Did you replace the stock exhaust pipe along with the mufflers?

550HP STSV
06-17-10, 01:07 PM
The sound is 100x better than factory, and very unique. Passengers in my car and drivers in others agree that under 50% throttle, it sounds amazing. I am 1000% happy I went with H-pipe over X. Its just when you open it up fully, you can hear a pinging type sound from the exhaust not being able to escape.

I kept the stock exhaust pipe, I never even though about replacing it. Maybe thats where I screwed up. If you want some videos/sounds of my exhaust, PM me your email address. Also, do you have any videos or sound clips of your X pipe coach? And did you keep the factory exhaust piping, or did you go to a larger size?

coach123
06-17-10, 02:29 PM
I kept the factory piping as well.. I have an area of piping right before the mufflers that I need to replace with mandrel piping. The exhaust shop crimped the pipe to make the turns into the muffler. From the looks of it the pipe may be 2-2.25" ID in that section. Might gain a few hp when I get it fixed. I don't have any video's of mine right now. I might try and get one this weekend and post. PM sent

PGA2B
06-17-10, 05:33 PM
I kept the factory piping as well.. I have an area of piping right before the mufflers that I need to replace with mandrel piping. The exhaust shop crimped the pipe to make the turns into the muffler. From the looks of it the pipe may be 2-2.25" ID in that section. Might gain a few hp when I get it fixed. I don't have any video's of mine right now. I might try and get one this weekend and post. PM sent

Use Vibrant part number 13070 (T304SS 60 DEG MANDRELBEND) :thumbsup:

coach123
06-17-10, 05:36 PM
Thanks for info.. I will be ordering it this week. Will this be the only bend I need?

PGA2B
06-17-10, 05:45 PM
Thanks for info.. I will be ordering it this week. Will this be the only bend I need?

Yes, and they come per each. They will get you from the factory pipe to the muffler with out having to bend anything.

TimmyC
06-18-10, 09:19 PM
I'm going to do a 3" stainless mandrel-bent system on my car when I get it. Which Magnaflow mufflers are you guys using specifically. The shop I work at is a Magnaflow dealer so I should be able to get a good deal.

coach123
06-18-10, 10:20 PM
Tim... Here is the part number for the magnaflow muffler (14326) and x-pipe (10791) I used. These are all 2.5inlet/outlet exhaust parts.

coach123
06-22-10, 02:35 PM
bump ttt

TimmyC
06-22-10, 08:01 PM
Did you guys get to the dyno yesterday? I assume not.

coach123
06-22-10, 10:39 PM
We did but the results were less than optimal. First the D3 intake is less than 4" ID and my MAF sensor was tuned for a 4" ID tube which resulted in some funky results. My DIY CAI is only the first section but it is a full 4" ID tube. The one run we did after reinstalling my intake resulted in lower numbers than the previous week.

I started a thread called boost control logic which explains what I thought happened. Basically our ECM's require several boost limiters adjusted and I don't think Vengeance Racing changed these because they didn't know about them. Based on the results the ECM seemed to reduce boost by the boost solenoid during the final dyno pull. Unfortunately, I completely forgot to hook up a mechanical boost gauge to verify:alchi:. (Littlevlisdan) recorded all data during the pulls with his HPtuners. I sent an email to Jesse explaining what happened and I'm anxiously waiting for him to send me a revised tune.

In short I think it was a waste of money besides getting some data with the HPtuners. If anyone has HPtuners or EFIlive please look for the following variables to confirm that we have these overboost limits on our STSV's.

In EFILive it is the following locations:
B7006 Overboost Upper Limit
B7007 Overboost Lower Limit

In EFILive the variable is:
Description: Supercharger Boost Solenoid Duty Cycle
Caption: SCBDC
System: Conditions
Parameter: GM.SCBDC

If you are using HPTuners then you need to change the variables in the following area:
Engine
- Torque Management
- - Supercharger

Then go to the following section of the "Supercharger" tab:
- Boost Disable

In the "Boost Disable" section you will have the following stock data:
MAP Disable: 192 kPa
MAP Enable: 172 kPa

550HP STSV
06-23-10, 12:24 AM
wow.