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Running a Stage 2 with a Cat

4K views 21 replies 11 participants last post by  nomoreammo 
#1 ·
Hey guys,

To start things off, I made this thread in hopes to learn about how different mods affect the way our cars run. I do not endorse deviating from any vendor-suggested setups if you are running their kits.

That said, I'm wondering if anyone has ever run a primary cat with a stage 2. BR's stage 2 tune calls for bolt ons (FMIC, intake, full TBE, 550 injectors). Since the cats are restrictive, it only makes sense that a cat delete will fully open up the gains.

I've done a bit of reading regarding the stage 2. The consensus seems to be that catless is going to be smelly and that's not something I want to deal with. I'm running a stage 3 right now and I get headaches when I idle. I could go down to a stage 1, but I already have my FMIC, intake, and catback, so I feel like I'm stuck between stages.

What are the dangers of running a stage 2 with a cat?
 
#2 ·
I've thought about this as well, because as long as I DD my car, I won't be deleting the Primary CAT. So I would like to go a full Stage 2 as well, but while retaining the Primary CAT

I don't think it's a question of "danger"... it will just result in lower performance gains compared to someone with a "full" Stage 2 including Primary CAT delete.

Just like in threads discussing Stage 1.5/2's , people often ask the vendor "but what if I don't have aftermarket I/C" or other things... in the end, the vendor may say that "it's possible" to run without certain supporting mods... but that the gains would not be as great.

While this might seem logical/obvious.. I think that some people believe that they can cut out some supporting mods, but expect that they should hit the advertised gains... and then when they don't, they come running back and start bashing on the vendor.

Just as you say though, I do not encourage anyone to limit their supporting mod's when moving up to Higher Staged tunes
 
#3 ·
100% agreed. I'm approaching it in that I'm wanting to get a bit more out of the automatic. I'm not going to go apesh1t if I don't hit expected gains either.

As you said, running a stage 2 with a cat will probably make the car less responsive, but I'm also wondering about richness, etc. Since the car is supposed to have more air flow, I wonder if putting a cat in would create surge from the back pressure.
 
#5 ·
your afr will most likely be off and temps would be higher i assume, i wouldn't get the stage2 without getting rid of the primary cat. as it's not "tuned" for that, and you can potentially do harm.
 
#7 ·
If anything, adding a primary cat will slightly richen the mixture as you're reducing flow efficiency and allowing a bit less air into the engine. Running lean is something you wouldn't need to worry about. I'm not certain on the severity of the effects on EGT's but my guess would be that the car will run fine unless you're basically beating on it full boost for extended periods of time and even then it may be fine.
 
#9 · (Edited)
Early this year I was talking to Tim from BR, I was also considering doing a stage 2 setup while keeping the primary cat for my automatic. I wanted to keep the primary cat because we have emission testing once a year here, and my car is DD so I didn't want the hassle of putting in a cat every year.

Tim was all for it. We discussed what the possible results would be and we agreed the car would just have less Hp and torque with the restrictive cat in place. I was thinking about 225ft lbs wtq and maybe 210-215whp.

Ultimately, I decided that it wasn't worth the money and the trouble. But it would have worked, just mention to the tuner (probably br) and maybe they will change the tune, or maybe they don't need to. I'm not sure how that would work.

In conclusion, it can be done.

BTW, im curious - you said you are stage 3 now, did you mean stage 1.5?
 
#13 · (Edited)
Interesting. The fumes are my biggest concern. Making power is a distant second.

I didn't get a clear answer from Tim but it sounded like it could work, just not as well as the actual catless stage 2 was intended to be for obvious reasons.

I'm running a BR Stage 3 right now. It is very rich so the cabin fumes fill up instantly when idling.

I have two choices: go down to a Stage 1 or Stage 2. Since I have an intake, FMIC and a catback already, a Stage 1 wouldn't make use of the FMIC/Catback as it only calls for an intake and an axelback.

However, catless is a requirement for the Stage 2. I can't stand the fumes so I am quite adamant about putting a cat back on. I wouldn't even bother with a hi-flow as I'd really like to avoid having any fumes whatsoever.

I was thinking of going Stage 1 and just letting the tune compensate over time for the FMIC and catback but I'm not sure if that's a better alternative than going Stage 2 and leaving the primary cat in. Secondary cat will remain removed since I have a CP-E exhaust. Furthermore, as itslikeanegg said, the presence of a cat in Stage 2 means less air flow mixed and if the car runs rich because of that, then I'm right back where I started anyway.
 
#10 ·
Back in the day... I ran a PRW Stage II tune with my primary cats on. I deleted my secondary cat because it really doesn't do much anyway. It will affect your spool time and it will have an effect on your top end power... but it's not as dramatic as that sounds. The primary cat in the 2.0T was designed as a high flow cat... if you are running it with the stock turbo it will work. To get the most out of a tune, a cat delete is definitely in order; however, if you live somewhere where you cannot remove your cats or you simply don't want to deal with the fumes and black smoke... leaving your cats in is always an option as long as you don't plan on doing a turbo swap.
 
#14 · (Edited)
I agree fumes from the car in the cabin is unacceptable to me as well. However, I have read many threads about the possible smells, and they all conclude that it only smells when you are really getting on the gas, and usually from behind the car. If your experiencing fumes as bad as you say,in the cabin, at idle, I would suspect an exhaust leak.

I apologize if this seems condescending, but I think you have your stages mixed up. Check out the "return of project falcon" thread - it explains there what they all are.

Stage 3 auto at least in canned tune form, from br currently doesn't exist. They may be able to do customs set ups, but I've only read about one, mira2blue's or mira2white, not sure what he's calling himself now. But he eventually traded for a manual. Anyhow, stage 3 requires a turbo swap, and all bolt ons.

Right now it sounds like you have stage 1 with fmic. With maybe a bit more aggressive tune then stage 1, but I'm not sure about the tune.

If that is the case, stage 2 would be your only option, so that at least narrows your choices. And it would work with primary cat, just not as well as without primary cat. I say go for it.

Also since year 2010 to 2012 don't have wideband Afr sensors, I'm pretty sure the tune can't learn to compensate during open loop. Br sets open loop values, and they stay like that until you get a new tune. Im like 95% on that. I may be wrong and I hope someone tells me if I am.

Again I don't mean to sound condescending, just trying to help. In fact I wish someone spelled it out for me when I was learning, but it seems that the guys here (and everywhere) like it when everyone learns for themselves, which is understandable.

Good luck, and definetly make sure you don't have an exhaust leak. A catback's fumes shouldn't be as bad as you describe - at least that's my understanding.

Edit: I looked over some of my past correspondence with Tim and found that if I had gotten an fmic as I was considering at one point, BR would have updated my tune with more timing. More timing is more power, so you most likely do have a stage 1 with a more aggressive tune.
 
#15 · (Edited)
Hey Nord, you are mistaken. I am running a Stage 3 with a 19t turbo and all my bolt ons + DW550 injectors. I'm not sure why you think I am running on a different stage.

The reason BR's Stage 3 "doesn't exist" was because it was not put it on the market for autos as they were running into issues with limp mode and partial throttle boost spikes. The reason I'm running the tune is because I have been working with BR to find a way around those issues. Given the obstacles that autos have, I've decided to refocus my efforts in a different direction with the car while retaining some power.

That said, I've spoken to multiple forum members who have run catless. Almost all of them say that the fumes are unavoidable when running a full TBE. I don't want to exaggerate the fumes, but I have to admit that my tolerance level for them is very low as well.

I'll have to find a time to call Tim and talk about adjusting the timing. I know that they have their dedicated canned tune for each of the stages and even some minor tweaks (hi flow cat vs completely catless) for some of them; just didn't think to ask them about Stage 1 + FMIC and catback.

Thanks for mentioning that.
 
#16 ·
The fumes are getting sucked into the car somehow. I seldom smell any thing, Do you have the heater fan off? It should force fresh air in and air out the trunk to stop any outside air from the rear from coming in.

Unless you mean at idle with the windows down.
 
#18 ·
Any news from Tim?
 
#19 ·
Nope, work has been crazy so I haven't gotten the chance to call him.

Will try to do that either today or Monday.
 
#20 ·
So I've been back on the stock tune for a little while now thinking about which direction I want to take.

Stage 2 is out. The less parts I have to deal with the better. I'm going with a Stage 1 and call it a day. That said, unfortunately BR does not have any tunes that compensate for an upgraded intercooler on stock injectors.

I'm thinking of using my Mishimoto FMIC anyway. Thoughts?

I have read other semi-related threads where people have asked if it's okay to upgrade their intercooler without a tune.
 
#22 ·
That's what I was thinking as well. The other threads said that the FMIC shouldn't have a huge effect on the tunes. Furthermore, the tune should compensate over time albeit not as optimal as a dedicated tune.

However, I've also read that depending on if the tune is closed or open loop (which I know nothing about), tunes may or may not be able to compensate and adjust.

I ran this Mishimoto Race Intercooler while I had the BR basic reflash and am currently running it with a stock tune as well and it SEEMS okay. I don't have any AFR gauges so I can't say for sure.
 
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