[cmitchell17]

So after watching a youtube video of a guy that has a TSP Stage 3 cam with TSP headers and their "catted" x-pipe, I am seriously considering headers now.

I wasn't considering headers before mainly because I wanted the stock exhaust setup so I could maintain the factory cats and their location and the main reason being I hate the smell of exhaust. Even with E85 it still doesn't help the smell much. I have a 228/236 TSP cam right now and I have done a lot of tuning and tweaking but it appears though the unburnt exhaust smell will not go away since I put my cam in. I am assuming once you go with a cam with more overlap, the exhaust smell is just something you are going to have to deal with? With the stock exhaust setup and cam now the smell is so bad is smells like I am running no cats at all, so it could be a possibility I have damaged my cats somehow maybe with trying to tune the cam and negative timing at idle.

I have tried lowering fuel pressure (to increase pulsewidth time) to try to improve idle combustion but hasn't helped. I am also having a lot of trouble with low, negative timing at idle and timing bouncing and unstable, so hopefully I can get that worked out, however I still don't think it is going to help with the smell.

Go to the 7:00 min mark of this video and listen:


It completely baffles me how that car sounds so different and so much better than any other 6th gen Camaro LT1s. The sound is clean and almost exotic sounding. It sounds very similar to the Corvette LT1 with NPP (which I am pretty sure the Corvette NPP has sound deadening material in the muffler), which in my opinion sounds way better than the Camaro LT1 with NPP. He does say he has the "catted" x-pipe, not really sure how they make a cat in a x-pipe.

I am starting to think that basically all exhausts are the same and the difference I am hearing probably just comes from where the camera/microphone is mounted at and weather or not you are outside or inside the car.

Anyone else have a similar setup? At this point I guess I might as well get headers since it look like now with the cam I am going to have to live with the exhaust smell.

[oldman]

catted x pipe probably is LT with LT based cats clamped on to the factory x pipe, pretty much that standard LT with cat configuration. I'd not get lost in the weeds. I ran LT with cats for a while, did not notice too much smell. I have 3 of the factory cats in the car right now with a healthy cam and don't notice any smell, I also tune the car with healthy cam and LT with LT base cats and did not notice any smell. So really I think you are OK as long as you keep at least one set of cats in the car. CA front cat deletes move the 02 to behind the second cats should also work as a baby step (see if yo like it).

[s346k]

so...what did the car run

[Umbriel]

I don't understand the smell with E85 unless it is shitty quality with only about 50% ethanol. My car on E85 smells like corn from the exhaust.

[cmitchell17]

Originally Posted by s346k

so...what did the car run

I don't know he never said.

[cmitchell17]

Originally Posted by Umbriel

I don't understand the smell with E85 unless it is shitty quality with only about 50% ethanol. My car on E85 smells like corn from the exhaust.

Yeah I don't understand it either because my ethanol percentage is at over 74% right now.

And yes oldman, I was thinking about doing just that, I wanted to basically find a way to hook that cats up directly to the secondary stock cats, but given the weird angles and stuff it doesn't look like that is possible.

[Umbriel]

Originally Posted by cmitchell17

Yeah I don't understand it either because my ethanol percentage is at over 74% right now.

And yes oldman, I was thinking about doing just that, I wanted to basically find a way to hook that cats up directly to the secondary stock cats, but given the weird angles and stuff it doesn't look like that is possible.

So you have 74% ethanol and it still smells like regular gas fumes? That doesn't make sense at all to me, especially if you still have cats.

[KingLT1]

Have you played with SOI and removed negative spark in the minimum timing tables?

[BlackbeastSS2]

Had my 2016 SS run on E85 and usually around 79%. No smell at all, E85 burns very clean.

[70chevelleSS]

Originally Posted by Umbriel

I don't understand the smell with E85 unless it is shitty quality with only about 50% ethanol. My car on E85 smells like corn from the exhaust.

Granted I don’t have a cam, but mine(no cats) literally smells like a mix of corn and vodka from the exhaust. It’s not strong

[Umbriel]

Originally Posted by 70chevelleSS

Granted I don’t have a cam, but mine(no cats) literally smells like a mix of corn and vodka from the exhaust. It’s not strong

Yeah that is what mine smells like so I am not sure why he would smell something like regular gas, even on my 1000 hp turbo 4th gen I had it smelled like corn.

[cmitchell17]

So there is maybe a slight alcohol smell, but it is still definitely overpowered by the usual no cats gasoline smell, the kind that sticks in your clothes like after you've been around a 2 stroke engine.

Right now I have 20 degrees of advance on the SOI at idle. I would think as far advanced as I can get SOI without running into the exhaust valve closing event the better.

The negative timing at idle is another story, I've been fighting trying to get it to idle with somewhat positive timing, I can reduce virtual torque enough to where it will get to around 10-15 degrees positive timing from -15 degrees, but unfortunately the smell is the same with +15 degrees of timing. However, I cannot get the timing stabilized, it will fluctuate sometimes go to 20-25 degrees then go back down to 5-0 degrees within fractions of a second. So it could be that I just need above say 15-20 degrees positive timing consistently. The problem is its just impossible to get becuase of the torque based system on GEN V's. No one has a complete and through understanding of the tables we have access in HP Tuners in order to lower the predicted torque source enough to where the immediate torque source (timing) will kick in with a higher torque (higher timing).

[MackSteelPrivateEye]

Originally Posted by cmitchell17

So after watching a youtube video of a guy that has a TSP Stage 3 cam with TSP headers and their "catted" x-pipe, I am seriously considering headers now.

I wasn't considering headers before mainly because I wanted the stock exhaust setup so I could maintain the factory cats and their location and the main reason being I hate the smell of exhaust. Even with E85 it still doesn't help the smell much. I have a 228/236 TSP cam right now and I have done a lot of tuning and tweaking but it appears though the unburnt exhaust smell will not go away since I put my cam in. I am assuming once you go with a cam with more overlap, the exhaust smell is just something you are going to have to deal with? With the stock exhaust setup and cam now the smell is so bad is smells like I am running no cats at all, so it could be a possibility I have damaged my cats somehow maybe with trying to tune the cam and negative timing at idle.

I have tried lowering fuel pressure (to increase pulsewidth time) to try to improve idle combustion but hasn't helped. I am also having a lot of trouble with low, negative timing at idle and timing bouncing and unstable, so hopefully I can get that worked out, however I still don't think it is going to help with the smell.

Go to the 7:00 min mark of this video and listen:


It completely baffles me how that car sounds so different and so much better than any other 6th gen Camaro LT1s. The sound is clean and almost exotic sounding. It sounds very similar to the Corvette LT1 with NPP (which I am pretty sure the Corvette NPP has sound deadening material in the muffler), which in my opinion sounds way better than the Camaro LT1 with NPP. He does say he has the "catted" x-pipe, not really sure how they make a cat in a x-pipe.

I am starting to think that basically all exhausts are the same and the difference I am hearing probably just comes from where the camera/microphone is mounted at and weather or not you are outside or inside the car.

Anyone else have a similar setup? At this point I guess I might as well get headers since it look like now with the cam I am going to have to live with the exhaust smell.

Gee that sounds awfully swell.

[cmitchell17]

I think the first thing I need to do like King said is get the idle timing straightened out. I thought I had the idle timing bumped up quite a bit but after just driving it tonight it still looks like its pretty negative with very short spikes up to normal positive range. Its enough to make small backfires at idle, I kept thinking someone was hitting my car in the back or shooting at me.

That's the most frustrating parts about trying to tune these GEN V's is that when you think you might have fixed something and it appears to be working, then next day it will stop working out of nowhere. Now I know I can try the workaround and increase the MIN spark tables, but unfortunately anymore than about -5 degrees it will destabilize the idle speed control and it will then rev up and down and hunt for idle until it dies.

Anyway going back to the exhaust sound, does anyone have a setup that sounds similar to that? I have seen the lethal camaro videos and I think he has a stainless works exhaust but in one video he has it sounds similar to the one above and sounds really good, but in all his other videos it sounds like the normal obnoxiously loud, no-cats exhaust.