Anyone running catalytic converter on a turbo setup?

[Noobz347]

A couple of things come to mind:

Those catalytic converter images above look small. Very small. It's hard to imagine an exhaust system that you've calculated is right around the size it needs to be for the power we want to produce then putting a perforated plug into the mix. It seems to me that surface area of the catalyst need to be quite a bit larger in order to accommodate the same mass of air as the rest of the exhaust. In the words: It should be much larger.

The other thing that comes to mind about cats before turbos is the time that it spends cold and filling up those little holes with muck before it perfectly hot.


If I had nothing but time and money, I'd try installing two of those little cats in parallel on each side and see if it blew them out over time --or-- plumb a 4-inch cat inline with a 3-inch exhaust and see if that helped.

 

[Noobz347]

This is exactly the problem.

If you go back to that BMW engine I posted the picture of, it has a total of four catalytic converters, two of which are bolted directly to the turbos on top of the engine. They're big, damned big, bigger than the single Mike posted a pic of, and this is for a 4.4L engine making approximately 500 horsepower at the flywheel.

When I put the turbo behind the 4V in the Mustang II, it'll be a large, 3" in/out unit of a size for a 6.2L or larger N/A engine.

Do they also have any type of bellows or surge tube between the turbo and converter?

 

[a91what]

My f150 has two huge converters right after the turbo. Easily twice the diameter of the pipe

 

[7991LXnSHO]

My f150 has two huge converters right after the turbo. Easily twice the diameter of the pipe

theorizing here -
Besides on OEM turbo engines, a Hellcat has to have big and durable Cats. 700 Hp of airflow should not be much different between NA and turbo, except the turbo could take some of the heat out.

 

[Mstng93SSP]

Now that my car is up and running with the turbo I don't seem to have any horrible exhaust smell like I remember before with no cats and stock ECU. I'm sure the tune has a lot to do with it.

 

[Monkeybutt2000]

Now that my car is up and running with the turbo I don't seem to have any horrible exhaust smell like I remember before with no cats and stock ECU. I'm sure the tune has a lot to do with it.

Mine was the same way, whatever voodoo Steve used worked very well.

 

[Mstng93SSP]

Yeah, but I just got back from driving the car, I reverse into the garage and the queen of the house says "your car stinks!" Hmmm........

 

[jozsefsz]

I run a 3" 3-way cat on my downpipe. I passed tail-pipe emissions here in Ohio up until last year (I had to retard timing a bit for NOx because I deleted EGR) when it was no longer required. It's had no noticeable negative effect on a street-driven (since 2009) turbo 5.0's performance (though I only ran with it off briefly before I decided I wanted to pass emissions). Sure the VE is probably reduced a little, but the beauty of a turbo is you can bump up the boost controller a notch and more than compensate. Guess it depends on your area, your desire to remain legal (especially if you ever want to sell the car), and how much you care about the hydrocarbons huffing out of it. With that said my wastegate uses a dump-pipe so take that for what you will.

One thing of note, at boost you're probably running 10.5-11:1 AFR. It's gonna get smelly or you're gonna burn pistons, one or the other.

 

[Mstng93SSP]

We don't do any smog testing here.

 

[jozsefsz]

We don't do any smog testing here.

You can get hit with one of those RECON fines though and have to deal with it. HI laws specifically state if your car had a converter, it needs one (hi-flow spun converters are cool with them). Whether or not you'd like to gamble is up to you. I figure $100 for a MagnaFlow spun converter is worth the peace of mind, and while I'm not an environmentalist by any stretch, I don't care for the stench of raw fuel while I'm driving (nor do I imagine the people behind me in their convertibles do) and I do like to breathe when I can.

 

[Mstng93SSP]

I'm not getting hit with any kind of fines or citations,....trust me on that.

 

[7991LXnSHO]

We don't do any smog testing here.

For now. I can see the feds wanting the flowers and pineapple to have clean air there after the cattle here have to fill Whoopee Cushions. How do they know if your spun cat is blown out?

I’m not surprised the newer computers can be tuned to run clean and well at the same time by someone with knowledge of cars and the software.

 

[jozsefsz]

That's cool, to each their own. If you ever want to add one, it's easy and cheap enough to do and won't hurt anything. Only thing @7991LXnSHO no matter how good the tuner, the minimum AFR at boost to keep things cool enough not to blow a gasket, piston, or valve is around 12:1. That's pig-rich if naturally aspirated, and without a cat the whole neighborhood's going to smell it - especially the guy in the driver's seat on a nice warm day. If it's not that rich, you've got a time-bomb on your hands which is a function of the physics more than the tune.

 

[Mstng93SSP]

My intention is to put a catalytic converter on the car. That was the purpose of me asking the question. My point was that there is no one, and I mean no one checking cars here to see if they have catalytic converters. Recon is a joke and they are working on legislation to get rid of it as it is only a money grab by the state.

 

[7991LXnSHO]

That's cool, to each their own. If you ever want to add one, it's easy and cheap enough to do and won't hurt anything. Only thing @7991LXnSHO no matter how good the tuner, the minimum AFR at boost to keep things cool enough not to blow a gasket, piston, or valve is around 12:1. That's pig-rich if naturally aspirated, and without a cat the whole neighborhood's going to smell it - especially the guy in the driver's seat on a nice warm day. If it's not that rich, you've got a time-bomb on your hands which is a function of the physics more than the tune.

I was thinking of clean running when not under boost. I picture the tables can adjust for cruise and boost much better than a carb ever could. Melting pistons is bad.

 

[a91what]

I run a 3" 3-way cat on my downpipe. I passed tail-pipe emissions here in Ohio up until last year (I had to retard timing a bit for NOx because I deleted EGR) when it was no longer required. It's had no noticeable negative effect on a street-driven (since 2009) turbo 5.0's performance (though I only ran with it off briefly before I decided I wanted to pass emissions). Sure the VE is probably reduced a little, but the beauty of a turbo is you can bump up the boost controller a notch and more than compensate. Guess it depends on your area, your desire to remain legal (especially if you ever want to sell the car), and how much you care about the hydrocarbons huffing out of it. With that said my wastegate uses a dump-pipe so take that for what you will.

One thing of note, at boost you're probably running 10.5-11:1 AFR. It's gonna get smelly or you're gonna burn pistons, one or the other.

If you have to run at 10.5-11:1 afr to keep from melting the engine down your doing it wrong. That's pig rich even in boost.

 

[bwest]

My intention is to put a catalytic converter on the car. That was the purpose of me asking the question. My point was that there is no one, and I mean no one checking cars here to see if they have catalytic converters. Recon is a joke and they are working on legislation to get rid of it as it is only a money grab by the state.

I used to run Random Tech cats on my turbo car way back when. Never had an issue, and I passed my tailpipe emissions no prob with it. Unfortunately, they aren't in business any longer. For cat's melting - I've seen that happen when a motor dumps excessive fuel and the cats meltdown from the heat during oxidation. Sized appropriately, tuned correctly, I highly highly doubt you'll have any issues.

 

[jozsefsz]

If you have to run at 10.5-11:1 afr to keep from melting the engine down your doing it wrong. That's pig rich even in boost.

You'll have to forgive my faulty memory as it's been a few years since I tuned mine, I run mine at 11.5 not 10.5. "Have to" and what's considered safe are two different things. What's considered 'safe' also varies according to how much boost you intend to run, I'm usually set to around 11psi -- for higher boost, 10.5 or even richer may be advisable. And as the SN95 doesn't have knock sensors, it's a guessing game if you're experiencing any knock so 'safe' timing is also a bit of a guessing game.

Been running this way on the same stock engine since 2009 without any failures and passing emissions, but you be you. Either way the point remains the same, at boost you're running significantly richer than 14.7 (unless you like replacing engines) so you're dumping some fuel and can benefit from a cat. Perhaps you can enlighten us on what 'doing it right' means rather than being pedantic?

 

[CarMichael Angelo]

 

[a91what]

You'll have to forgive my faulty memory as it's been a few years since I tuned mine, I run mine at 11.5 not 10.5. "Have to" and what's considered safe are two different things. What's considered 'safe' also varies according to how much boost you intend to run, I'm usually set to around 11psi -- for higher boost, 10.5 or even richer may be advisable. And as the SN95 doesn't have knock sensors, it's a guessing game if you're experiencing any knock so 'safe' timing is also a bit of a guessing game.

Been running this way on the same stock engine since 2009 without any failures and passing emissions, but you be you. Either way the point remains the same, at boost you're running significantly richer than 14.7 (unless you like replacing engines) so you're dumping some fuel and can benefit from a cat. Perhaps you can enlighten us on what 'doing it right' means rather than being pedantic?

I tune 3 to 4 cars a week. Anything below 12psi is 11.8-12.2 in boost depending on the engine design and fuel used.
11.5 is considered safe street afr above 12psi..

When I'm tuning a real engine making 4 digit numbers and 25+psi I may dip into the low 11 high 10 afr if I need to cool the piston crown, but this is done with special enrichment settings.
Most get the same 11.5 richest point at peak torque. I prefer to keep away from the lower flammable limit on the fuel used and simply not over time the engine.
If you need to over enrich the engine to eliminate or reduce knock chance then you have too much spark advance near peak torque (or in general). You can lift a ring land with an overly rich mixture when things go wrong or cause missfires and force a tighter than necessary plug gap.

If we are talking about low boost under 16psi... Then no reason to go below 11.5 unless you are making big power or trying to keep a hyper piston from exploding.

I rarely use or rely on a knock sensor, most of the time they are completely blind at wot anyway.

To summarize 11.5 is perfectly fine to target on a street tuned engine in boost for safety.