Turbo Tuned with HFC's...Going Catless - Retune Required? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Shake & Bake · 08-18-2015, 10:15 PM

I have a Turbonetics stage 2 kit pushing around 550rwhp and I've damaged the Solo HFC's. Not sure how much is melted but both sides are rattling around. I also had a recent experience where I couldn't get the rpms above 2300 without the engine bogging down - felt sluggish getting to that point.

I limped the car over to my tuner who could not duplicate the sluggishness but I want the cats removed anyway - can't stand the rattling and I'm worried about something getting ingested into the turbo.

My other concern is having to spend as much as $900 for a retune and I don't yet have a wideband sensor to support a more affordable remote tune.

I have plenty of margin on the pump and injectors and the AFR was relatively rich/conservative, but I don't have the numbers handy.

Am I running on borrowed time without a retune (just going from hfc to catless)?

CamaroSS sleeper · 08-19-2015, 01:49 PM

Need to know a bit more about the tune.
but in general you will be ok with the current tune.
removing restrictions is OK. adding restrictions is a NO without a retune.

assuming the tune was done properly & you have a nice accurate MAF Curve, more air in = more fuel in. (bunch of variables in how the ECU calculates this) but one big one is MAF curve. even better is a hybrid MAF + density

but for this you would need the ZR1 Map sensor.. sorry getting side track here...

so why would you need a re-tune than?
key word "Spark Timing"
since your timing was done with restrictions i.e. CATs
removing restrictions means less chance of predetonation. thats good!

but it also means you are now leaving power on the table.

you can see why going the other way is a no go.
if you tuned timing without restrictions and you latter decide to add them.
the ECU will assume it can get away with it when in reality it cant.

with that said, knock retard will kick in and save your engine, but its not recommended to rely on the KR to adjust your timing like that.

Conclusion: you'll be ok...
but the urge of extra power will take you back to the dark side and re-tune lol

camarosspower · 08-19-2015, 04:00 PM

Just curious wouldn't it just be a update on the tune? That is a lot of money for a tune to go catless

beavisr1 · 08-19-2015, 04:13 PM

Are you see an increase in boost without the cats? If so you need to have it retuned. At a minimum I would throwing it in on a dyno and have the air to fuel ratio check, cheap insurance.

Unreal · 08-19-2015, 04:25 PM

Have it datalogged and see. Could need a tune, could be fine. Without seeing a log, we can only guess.

Shake & Bake · 08-19-2015, 07:17 PM

Thanks for the feedback...expected a mixed response and I've absolutely asked my tuner to slap it on the dyno to check AFR before charging me a ridiculous amount of money to retune. I've been waiting several days for a recommendation and no joy so I'm looking at alternate shops.

Unreal · 08-20-2015, 11:33 AM

No need for dyno per say, just hook up a computer and drive it around.

1KillerSS · 08-20-2015, 12:26 PM

Its all in the Data logs, 5 min on the street can tell you that. I wouldn't pay 900 for a "retune" to ditch the cats. If AFR and KR are all good then no need.

Shake & Bake · 08-20-2015, 03:53 PM

Yep, need to add a wideband. Can I temporarily replace one of the existing post-cat sensors and live with the code or do I have to add a new bung?

1KillerSS · 08-20-2015, 03:54 PM

Yes, the code will not effect anything. However I would disable it in HPT

Shake & Bake · 09-06-2015, 10:45 PM

CamaroSS Sleeper called it...pulled the cats and the car was running much richer than before. Retuned and gained about 30 hp from baseline with new hfc's.

BTW, found that the driver side cat was severely damaged and shrapnel was found in a waste gate. Turbo appears to have survived, but this is a warning to those debating whether to go hfc or catless. I'm running about 580rwhp and 600rwtq on a very safe tune but with 11lbs of boost and the cats lasted maybe 1k miles.

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08-18-2015, 10:15 PM	#1
Shake & Bake Drives: 2011 Black 2SS/RS Convertible Join Date: Jan 2014 Location: Cary, IL Posts: 28	Turbo Tuned with HFC's...Going Catless - Retune Required? I have a Turbonetics stage 2 kit pushing around 550rwhp and I've damaged the Solo HFC's. Not sure how much is melted but both sides are rattling around. I also had a recent experience where I couldn't get the rpms above 2300 without the engine bogging down - felt sluggish getting to that point. I limped the car over to my tuner who could not duplicate the sluggishness but I want the cats removed anyway - can't stand the rattling and I'm worried about something getting ingested into the turbo. My other concern is having to spend as much as $900 for a retune and I don't yet have a wideband sensor to support a more affordable remote tune. I have plenty of margin on the pump and injectors and the AFR was relatively rich/conservative, but I don't have the numbers handy. Am I running on borrowed time without a retune (just going from hfc to catless)?

08-19-2015, 04:25 PM	#5
Unreal Drives: 2006 Z06 Join Date: Oct 2010 Location: Gilbert, AZ Posts: 5,712	Have it datalogged and see. Could need a tune, could be fine. Without seeing a log, we can only guess. __________________ Nick Corvette Z06 -1200ish rwhp

08-20-2015, 11:33 AM	#7
Unreal Drives: 2006 Z06 Join Date: Oct 2010 Location: Gilbert, AZ Posts: 5,712	No need for dyno per say, just hook up a computer and drive it around. __________________ Nick Corvette Z06 -1200ish rwhp

08-20-2015, 12:26 PM	#8
1KillerSS Too much is never enough! Drives: AGP TT SS [COTW] 4/20/15 Join Date: Feb 2014 Location: Toledo,OH Posts: 4,149 View My Garage	Its all in the Data logs, 5 min on the street can tell you that. I wouldn't pay 900 for a "retune" to ditch the cats. If AFR and KR are all good then no need. __________________ AGP TT kit, 54/57 Forged rotating assembly, Custom grind cam... Dual nozzle meth, ID850's, Livernois dual fuel pumps, ECS BAP, 25% UDP, 3 inch Magnaflow catback with X pipe, Mantic 9000 clutch, DSS 1000hp axles, DSS aluminum driveshaft, ZL1 rear end, solid subframe bushings, HE differential offset bushings, BMR Trailing arm, BMR toe rods, Lingenfelter LNC-2000,SJM Line Lock. 747 whp 714wtq *Build thread* http://www.camaro5.com/forums/showth...55#post8107855

08-20-2015, 03:54 PM	#10
1KillerSS Too much is never enough! Drives: AGP TT SS [COTW] 4/20/15 Join Date: Feb 2014 Location: Toledo,OH Posts: 4,149 View My Garage	Yes, the code will not effect anything. However I would disable it in HPT __________________ AGP TT kit, 54/57 Forged rotating assembly, Custom grind cam... Dual nozzle meth, ID850's, Livernois dual fuel pumps, ECS BAP, 25% UDP, 3 inch Magnaflow catback with X pipe, Mantic 9000 clutch, DSS 1000hp axles, DSS aluminum driveshaft, ZL1 rear end, solid subframe bushings, HE differential offset bushings, BMR Trailing arm, BMR toe rods, Lingenfelter LNC-2000,SJM Line Lock. 747 whp 714wtq *Build thread* http://www.camaro5.com/forums/showth...55#post8107855

08-19-2015, 01:49 PM	#2
CamaroSS sleeper Drives: Sleeper_NOT Join Date: Feb 2014 Location: Ventura Posts: 184 View My Garage	Need to know a bit more about the tune. but in general you will be ok with the current tune. removing restrictions is OK. adding restrictions is a NO without a retune. assuming the tune was done properly & you have a nice accurate MAF Curve, more air in = more fuel in. (bunch of variables in how the ECU calculates this) but one big one is MAF curve. even better is a hybrid MAF + density but for this you would need the ZR1 Map sensor.. sorry getting side track here... so why would you need a re-tune than? key word "Spark Timing" since your timing was done with restrictions i.e. CATs removing restrictions means less chance of predetonation. thats good! but it also means you are now leaving power on the table. you can see why going the other way is a no go. if you tuned timing without restrictions and you latter decide to add them. the ECU will assume it can get away with it when in reality it cant. with that said, knock retard will kick in and save your engine, but its not recommended to rely on the KR to adjust your timing like that. Conclusion: you'll be ok... but the urge of extra power will take you back to the dark side and re-tune lol

08-19-2015, 04:00 PM	#3
camarosspower Drives: 2010 camaro ss Join Date: Jun 2010 Location: Port Arthur, Tx Posts: 2,383	Just curious wouldn't it just be a update on the tune? That is a lot of money for a tune to go catless

08-19-2015, 04:13 PM	#4
beavisr1 Drives: 2010 SS 2SS Join Date: Jun 2015 Location: Woodbridge, Virginia Posts: 25	Are you see an increase in boost without the cats? If so you need to have it retuned. At a minimum I would throwing it in on a dyno and have the air to fuel ratio check, cheap insurance.

08-19-2015, 07:17 PM	#6
Shake & Bake Drives: 2011 Black 2SS/RS Convertible Join Date: Jan 2014 Location: Cary, IL Posts: 28	Thanks for the feedback...expected a mixed response and I've absolutely asked my tuner to slap it on the dyno to check AFR before charging me a ridiculous amount of money to retune. I've been waiting several days for a recommendation and no joy so I'm looking at alternate shops.

08-20-2015, 03:53 PM	#9
Shake & Bake Drives: 2011 Black 2SS/RS Convertible Join Date: Jan 2014 Location: Cary, IL Posts: 28	Yep, need to add a wideband. Can I temporarily replace one of the existing post-cat sensors and live with the code or do I have to add a new bung?

09-06-2015, 10:45 PM	#11
Shake & Bake Drives: 2011 Black 2SS/RS Convertible Join Date: Jan 2014 Location: Cary, IL Posts: 28	CamaroSS Sleeper called it...pulled the cats and the car was running much richer than before. Retuned and gained about 30 hp from baseline with new hfc's. BTW, found that the driver side cat was severely damaged and shrapnel was found in a waste gate. Turbo appears to have survived, but this is a warning to those debating whether to go hfc or catless. I'm running about 580rwhp and 600rwtq on a very safe tune but with 11lbs of boost and the cats lasted maybe 1k miles. Sent from my A500 using Tapatalk