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Stock cats

Old 11-06-2018, 12:29 PM
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Tennispro1986
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Default Stock cats

Looking to do some upgrades soon. Currently I have an x pipe and axle back, but now I want to start modding for more power. I'm leaning towards the Magnuson 2300, but I don't want to get too deep into it like doing headers, meth, and what not. Ideally I would like to strap the 2300 on, get it tuned, and make a solid 650-700 whp and call it a day. I have also been thinking about doing a lower pulley and intake, as I think that would get me around the 650 mark. I have spoke to a few shops and some say you have to upgrade the headers because there is a high risk of melting the cats when you increase boost. I don't buy that. I know there are tons of people on here making more power with more boost and haven't touched the manifolds/cats. So what is the general consensus? Can you raise boost and make good power without doing headers as well?
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Old 11-06-2018, 12:56 PM
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The car has a detection for cat temperature. If they are too hot (which they already become too hot on stock cars, fairly often) then the car pulls timing and/or runs rich as this allows the cats to cool back down to a safer temp.

If the car runs rich to protect the cats, and pulls timing, it is no longer making full power. The lack of power is how people found out about the cat protection. It was a mystery at first why cars were making less power at times.

Anyway, the point is, you can put as big of blower on the car as you want, it will produce more exhaust heat, and the cats will be too hot more often than not, and you will end up with less HP than stock cars have.

And if you don't pull timing and run rich (take the precautions out of the tune), then yes, you will melt the cats, even with the stock blower.

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Old 11-06-2018, 07:51 PM
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I guess I don't understand what you're writing. You've talked to professional shops, I presume but what do they work on----other brands, other motors only? If not, if they actually work on modern Z's and have put on bigger blowers, why wouldn't you take their word for it? I'm sure you've read/know the Z's sometimes run hot depending on how and where you use the car. As posted above, you are adding both more power and more heat. Do you expect it to run fine with the additions on the Schuykill Expwy., or Roosevelt Blvd. in traffic? Maybe.

In the Philly area you've got at least a few "name", good shops who work on Corvettes and LS/LT engines---at least a couple/few of which are vendors on here---I'd hope these are who you're talking with, and why you'd disagree with them is a mystery to me.
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Old 11-07-2018, 08:42 AM
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I had a 2015 C7Z that was stock and was tracked extensively. I cracked two catalytic converters. I now have a stock C7 ZR1 and just broke my first cat after less than 6 months of tracking.
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Old 11-07-2018, 12:45 PM
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I run the American racing headers COATED with cats. Don't skip the coating well worth it. I gained about the same amount from the headers install and tune as I did from the 2300. They work in concert with the intake
all allow more air flow.
The cats longevity is no worry with the headers. The cats are further back than the stock placement. I put a set of headers on a Supercharged C6 for about 25,000 then moved the same set to a Supercharged C6 Z06 for another 35,000. Now the car is stock w/ headers doing great.
You will not get as good of result without the headers which are far and away SUPERIOR exhaust to the junk GM hangs on the car and calls it EXHAUST.

The power you gain then the weight of 35 pounds the car drops and the better exhaust are reason I always do headers if I keep the car vey long
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Old 11-07-2018, 02:59 PM
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another option is the Norcall SS downpipes, and catless X pipe combo.

I believe AFE makes the catless downpipes as well. These downpipes are less expensive, and are much easier to install.
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Old 11-07-2018, 08:27 PM
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Is there a way to tell if your CATs are plugged or burnt out?
v/r
THEYAV

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Old 11-07-2018, 09:12 PM
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Originally Posted by HessViper View Post
another option is the Norcall SS downpipes, and catless X pipe combo.

I believe AFE makes the catless downpipes as well. These downpipes are less expensive, and are much easier to install.
Isn't that going to require a tune though?
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Old 11-07-2018, 10:15 PM
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Headers require the tune more than the catless downpipes do.

Big daddy 02 Sims keep the stock tune happy with norcal or afe downpipes and catless x pipe.

I think the OP plans to tune if he is going to a larger blower.

if he removes the cats, then he can remove the COT protections from the tune. Good tuners should know how, no problem.

if you are asking for your zr1 poorsha and wish to maintain the stock tune (as if zr1 owners currently have a choice)... then we can continue to talk

norcals are less expensive than afe hess... but I think you meant both are less expensive and easier to install than headers... which is true

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Old 11-08-2018, 10:37 AM
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Originally Posted by Poor-sha View Post
Isn't that going to require a tune though?
I would say so Jmho
time you buy the catless midpipe and a borla xpipe
You may as well do headers they are the better option better base for other mods
produce more hp than the other choice
which retains the heavycast manifolds
That really add heat underhood
headers are king for exhaust flow and sound
Plus some weight loss

Last edited by 3 Z06ZR1; 11-08-2018 at 10:43 AM.
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Old 11-08-2018, 01:58 PM
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when I was warned about a certain someone on this forum, I never dreamed it would be this bad.
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Old 11-08-2018, 10:43 PM
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a norcal cat delete kit or equivalent with your x pipe will stop your burning up cats situation. also if same as zo6s it wont throw codes or need a tune. plus side it will lower under hood temps. its a fairly easy to reverse if there are any war issues. side note,,, tube headers on our cars will raise under hood temps compared to stock manifolds that retain the heat better and they are not far behind in the power dept from good headers!
Charlie,,,
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Old 11-08-2018, 11:13 PM
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I would try a cat delete but I would also have it coated before installation (could do exhaust manifolds too) with a well known product like 'Jet Hot'. I believe they offer a number of colors and temp ranges. You will also need two screw in simulators/adapters for the 'rear' oxygen sensors to prevent any codes. I have used these down stream after converter 02 sims (home made cheap from plug anti-foulers sold in the auto stores) on an LS3 with headers (no cats) and never got a code. I would also wait to install the Borla cat-less X-pipe at the same time of the cat delete kit install if your going that route and remember that the odor out the tail pipes will change.

PS: Just to give it the best chance of success I would drive the car around 'normal' for a while before tracking it so the ecm has some time to make adjustments. Oh, and from what I have read the stock exhaust manifolds flow 'VERY WELL'. On F.I. having a 'tuned' exhaust is not that important. One company on here has found that headers made very little to no difference over the stock exhaust manifolds on their 9 second Z06 package so they don't recommend headers unless you really want them in their package.

Last edited by C7/Z06 Man; 11-09-2018 at 12:48 AM.
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Old 11-08-2018, 11:33 PM
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Originally Posted by Poor-sha View Post
Thanks. As you know you can't tune the ZR1 and I really don't want to throw away the warranty. I also don't really care about more power. I'm all about reliability and right now I've had a primary cat fail at less than 24 hours of track time. If this is a trend I'm going to have to replace cats twice a year. I already have a Borla catless x-pipe sitting in the garage that I haven't put on.
you'll be fine with the norcal or afe... and the big daddy 90 degree sims.

you'll wish you'd done it sooner.

they bring the engine temps down as well, the cats heat the oil cooler... the catless downpipes dont.

The stuff about LT headers bringing temps down more than the norcal is not true. Downpipes bring the temps down a lot more.

coat or wrap them like c7/z06 man said. I would probably wrap them, but that is all personal preference

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Old 11-09-2018, 12:36 AM
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Originally Posted by Poor-sha View Post
Thanks. As you know you can't tune the ZR1 and I really don't want to throw away the warranty. I also don't really care about more power. I'm all about reliability and right now I've had a primary cat fail at less than 24 hours of track time. If this is a trend I'm going to have to replace cats twice a year. I already have a Borla catless x-pipe sitting in the garage that I haven't put on.
Vendor Weapon X has installed headers on the ZR1 and they are doing great. The thing I like about the headers is the 35 pound weight loss on a Z06 which I feel would be even more weight reduction on the ZR1.
The weight reduction is just as welcome as the power increase. Plus it removes weight from the engine something that doesn't hurt with the ZR1.

No doubt about cooler under hood temps as well. Since you are removing the cast iron mainifolds (heat radiators) and the attached cats that are close to the engine by design, Replacing them with ceramic coated tubes that cool to the touch it minutes where the stock manifolds don't Then the hot cats are way down stream past the x pipe.NO effect on under the hood temps like the stock ones.
ARH headers make 40 rwhp on the Z06 and also reduce weight and run coolers all great benefits.

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Old 11-09-2018, 01:10 AM
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Originally Posted by 3 Z06ZR1 View Post
Vendor Weapon X has installed headers on the ZR1 and they are doing great. The thing I like about the headers is the 35 pound weight loss on a Z06 which I feel would be even more weight reduction on the ZR1.
The weight reduction is just as welcome as the power increase. Plus it removes weight from the engine something that doesn't hurt with the ZR1.

No doubt about cooler under hood temps as well. Since you are removing the cast iron mainifolds (heat radiators) and the attached cats that are close to the engine by design, Replacing them with ceramic coated tubes that cool to the touch it minutes where the stock manifolds don't Then the hot cats are way down stream past the x pipe.NO effect on under the hood temps like the stock ones.
ARH headers make 40 rwhp on the Z06 and also reduce weight and run coolers all great benefits.
The exhaust manifolds are 'not' cast iron (they are stainless steel) on the Z06 or ZR1 from what I have read. They 'are' cast iron on the base model non-supercharged corvette.

Last edited by C7/Z06 Man; 11-09-2018 at 01:13 AM.
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Old 11-09-2018, 01:21 AM
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Originally Posted by C7/Z06 Man View Post
The exhaust manifolds are 'not' cast iron (they are stainless steel) on the Z06 or ZR1 from what I have read. They 'are' cast iron on the base model non-supercharged corvette.
WRONG!
That's a problem people read which some is bad info that comes on here and theyrepeat it.
I pulled two sets of CAST IRON MANIFOLDS off my 2 Z06's which now sport coated headers!
They are not stainless period!

Last edited by 3 Z06ZR1; 11-09-2018 at 01:25 AM.
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Old 11-09-2018, 01:34 AM
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Originally Posted by 3 Z06ZR1 View Post
WRONG!
That's a problem people read which some is bad info that comes on here and theyrepeat it.
I pulled two sets of CAST IRON MANIFOLDS off my 2 Z06's which now sport coated headers!
They are not stainless period!
You know some stainless steel is magnetic, Right? like 400 series. Well I have read this more than once, it maybe in GM's specs. I could be wrong because I personally have not checked. Hopefully we will see what others think.

Last edited by C7/Z06 Man; 11-09-2018 at 01:37 AM.
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Old 11-09-2018, 01:43 AM
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Originally Posted by Tennispro1986 View Post
Looking to do some upgrades soon. Currently I have an x pipe and axle back, but now I want to start modding for more power. I'm leaning towards the Magnuson 2300, but I don't want to get too deep into it like doing headers, meth, and what not. Ideally I would like to strap the 2300 on, get it tuned, and make a solid 650-700 whp and call it a day. I have also been thinking about doing a lower pulley and intake, as I think that would get me around the 650 mark. I have spoke to a few shops and some say you have to upgrade the headers because there is a high risk of melting the cats when you increase boost. I don't buy that. I know there are tons of people on here making more power with more boost and haven't touched the manifolds/cats. So what is the general consensus? Can you raise boost and make good power without doing headers as well?
Less output from the 2300 without headers again it is about the combo of mods. The shops are right the stock set up is not good for adding more boost. You could ruin the cats. If you run the car hard.
Porsha is a good example. You may even need catless headers if you really run it hard full time.
The ARH headers make 40 rwhp over the stock exhaust. I stick with them they are they Cadillac of headers
The 2300 will perform much better with headers vs the stock exhaust. My headers gave me about the same gain as the 2300.
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Old 11-09-2018, 01:45 AM
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Originally Posted by C7/Z06 Man View Post
You know some stainless steel is magnetic, Right? like 400 series. Well I have read this more than once, it maybe in GM's specs. I could be wrong because I personally have not checked. Hopefully we will see what others think.
It is not what others think at all. I had them in my hand I know the answer. Very heavy CAST iron!
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