Are high flow cats worth it?
1 - 20 of 21 Posts
i would say yes since the OEM catalytic converters are very restrictive. with aftermarket high flow cat, you will improve top end by a margin when comparing with the stock ones.
the most significant gains are usually noticed on Turbo cars, and as for NA car goes, i think it should also benifit some but not as much as the turbocharged ones.
the most significant gains are usually noticed on Turbo cars, and as for NA car goes, i think it should also benifit some but not as much as the turbocharged ones.
Shawn,ive got the random tech cat,right now without the headers but with the stromung midpipe back.The gains are there,my top end improved.Like blitkrieg said,,look at the stock unit compared to the high flow units,,1 cat instead of two and also less restrictive piping.
Random Techs cat from Cobb is the cheapest way to get one of those.If you order from Random Tech the price is higher
Hope this helps
Random Techs cat from Cobb is the cheapest way to get one of those.If you order from Random Tech the price is higher
Hope this helps
Info on cats
Just a little note about free flow cats. If the original cats are new or in good condition, they offer very little restriction so I don't think it would be worth the money to replace them. However, if you are going turbo go for it. If your current cats are plugged up or have a lot of mileage on them I'd go for the free flows also, they tend to be less expensive than the OEM cats. Guess what I'm saying is that ,unless you are planning on going turbo, if it aint broke don't fix it. :nuetron:
Just a little note about free flow cats. If the original cats are new or in good condition, they offer very little restriction so I don't think it would be worth the money to replace them. However, if you are going turbo go for it. If your current cats are plugged up or have a lot of mileage on them I'd go for the free flows also, they tend to be less expensive than the OEM cats. Guess what I'm saying is that ,unless you are planning on going turbo, if it aint broke don't fix it.
:nuetron:I installed a Randon Tec Cat last night. Here are the pics:
http://www.scoobymods.com/forums/showthread.php?s=&postid=347#post347
When I got the cat I didn't get the bolts I was supposed to get for the rear flange. I put some in there temporarly till I get the ones Cobb sent out today. I'm haveing a little leaking problem by the rear flange right now. I have the stock header and a stromung exhaust is all. I really think that my car pulls quicker to red line now that w/o the Hi-Flo. Later this week I'll put the G-Tec on there to remove the Butt Dyno factor.
http://www.scoobymods.com/forums/showthread.php?s=&postid=347#post347
When I got the cat I didn't get the bolts I was supposed to get for the rear flange. I put some in there temporarly till I get the ones Cobb sent out today. I'm haveing a little leaking problem by the rear flange right now. I have the stock header and a stromung exhaust is all. I really think that my car pulls quicker to red line now that w/o the Hi-Flo. Later this week I'll put the G-Tec on there to remove the Butt Dyno factor.
Attachments
FYI - CE light info
I got an e-mail from Random Technology today:
Quote:
The alleged problem with low converter efficiency that triggers a Check Engine light isn't real. The OBD II system uses exhaust gas oxygen content to gauge converter efficiency. That's like using fuel pressure to monitor fuel flow. The assumption is that a given pressure in a line of a given diameter will flow a specific volume. However, if there's a restriction in the line, volume will be severely limited, in spite of system pressure.
With the OBD II system, the assumption is that oxygen content behind the converter will be substantially more consistent than content in front of the converter. And that's true when you have a restrictive converter that causes exhaust gases to back up in front of it. But when you increase flow capacity, the residual oxygen content behind the converter is not as consistent, so the PCM erroneously thinks converter efficiency has deteriorated. In spite of the fact that the system "thinks" converter efficiency is below the acceptable threshold, the converter is doing its job and the vehicle will pass an emissions test.
As for a fix, we're experimenting with different chemistry. There is no official specification for an OBD II-compliant converter.) As for existing vehicles with Check Engine light problems, the easiest fix is a "spoof" which incorporates two resistors in the rear oxygen sensor wiring. I have a wiring diagram if anyone would like to experiment and if we can find connectors, we'll make up plug-in units.
End quote.
To reply to Dave, if you want to help out, go here:
http://www.randomtechnology.com/contact.html
and use the e-mail at the bottom to send a message.
Peaty
I got an e-mail from Random Technology today:
Quote:
The alleged problem with low converter efficiency that triggers a Check Engine light isn't real. The OBD II system uses exhaust gas oxygen content to gauge converter efficiency. That's like using fuel pressure to monitor fuel flow. The assumption is that a given pressure in a line of a given diameter will flow a specific volume. However, if there's a restriction in the line, volume will be severely limited, in spite of system pressure.
With the OBD II system, the assumption is that oxygen content behind the converter will be substantially more consistent than content in front of the converter. And that's true when you have a restrictive converter that causes exhaust gases to back up in front of it. But when you increase flow capacity, the residual oxygen content behind the converter is not as consistent, so the PCM erroneously thinks converter efficiency has deteriorated. In spite of the fact that the system "thinks" converter efficiency is below the acceptable threshold, the converter is doing its job and the vehicle will pass an emissions test.
As for a fix, we're experimenting with different chemistry. There is no official specification for an OBD II-compliant converter.) As for existing vehicles with Check Engine light problems, the easiest fix is a "spoof" which incorporates two resistors in the rear oxygen sensor wiring. I have a wiring diagram if anyone would like to experiment and if we can find connectors, we'll make up plug-in units.
End quote.
To reply to Dave, if you want to help out, go here:
http://www.randomtechnology.com/contact.html
and use the e-mail at the bottom to send a message.
Peaty
Joined
·
289 Posts
Hmmm, old cats clog...I have 71,000 miles on my stock cats, do you think they are hurting flow? I actually onlt have one in place, one major difference I noted is that the exhaust tone is louder...much louder. Anyways, back to the orginal question, how many miles can you have on a stock cat before its performance degrades?
-Andy
-Andy
The secret to CAT longevity is keeping out the things that cause it to clog in the first place. These include but are not limited to the following:
High sulphur fuels... cheap gas will kill your cat!
oil .... if you are burning oil your cat is going with it!
low silicon coolants....they may keep your engine cool but if you blow an intake gasket in the right place the coolant goes out through the exhaust....setting your cat up for a future catastophic failure!
fuel additives....BE CAREFULL some contain compounds that will shorten the life of older cats beware of methylated sulphur compounds claiming to reduce harmfull deposites and make your engine run smoother. Many a cat failure occurs with an 'older' engine just after a 'treatment'
Running too rich ....although this may not seem like a problem but an exposion in the cat due to unburned fuel buildup physically damages the structure of the cat sometimes leading to a catastophic failure.
Cats have been known to fail due to abuse in as little as 60k miles
Poor fuel failures ave about 80k miles
A well cared for cat can easily go 120k miles or more (My 86 fwd/4wd wagon died with 184k miles on the original cat!)
High sulphur fuels... cheap gas will kill your cat!
oil .... if you are burning oil your cat is going with it!
low silicon coolants....they may keep your engine cool but if you blow an intake gasket in the right place the coolant goes out through the exhaust....setting your cat up for a future catastophic failure!
fuel additives....BE CAREFULL some contain compounds that will shorten the life of older cats beware of methylated sulphur compounds claiming to reduce harmfull deposites and make your engine run smoother. Many a cat failure occurs with an 'older' engine just after a 'treatment'
Running too rich ....although this may not seem like a problem but an exposion in the cat due to unburned fuel buildup physically damages the structure of the cat sometimes leading to a catastophic failure.
Cats have been known to fail due to abuse in as little as 60k miles
Poor fuel failures ave about 80k miles
A well cared for cat can easily go 120k miles or more (My 86 fwd/4wd wagon died with 184k miles on the original cat!)
what abt when you start to smell rotten eggs when you go WOT and then theres the occasional loud POP! from the exhaust. sometimes people say they see black stuff coming out of my exhaust too. does that mean my cat is abt to go?
The 'rotten egg' smell is sulphur the 'pop' is unburned fuel detonating in the cat. How many miles you got on your RS? What octane and 'brand' of fuel do you use? When was tha last time you cleaned your fuel system? (It doesn't hurt to do this every time you change oil!) Do you still your original spark plugs?:sunny:
I have almost 30k now. I use 89 octane from chevron, i used to drink acro but it stank soooo bad so i switched to cheveron and it helped reduce the smell. last time i cleaned my fuel system?? I don't think i have. any suggestions on how to do this? what to use/do? and yes.. still original spark plugs and wires.Dave G said:
Don't fight change!!!
Probably time to change out those plugs bro!!
If they are the originals, 30K is about the time they really start to lose it. Go with the NGK's listed in the owners manual as a replacement. IMHO you get the most bang for the buck with those. Also be sure to run high quality petrol in the car and mix in a tank or 2 of 89 octane once and awhile. Running a bottle of good injector cleaner through the car once in awhile is a good idea too. Chevron with Techron works good.
Good luck and happy motoring!!!!:sunny: :sunny: :biggest:
Probably time to change out those plugs bro!!
If they are the originals, 30K is about the time they really start to lose it. Go with the NGK's listed in the owners manual as a replacement. IMHO you get the most bang for the buck with those. Also be sure to run high quality petrol in the car and mix in a tank or 2 of 89 octane once and awhile. Running a bottle of good injector cleaner through the car once in awhile is a good idea too. Chevron with Techron works good.
Good luck and happy motoring!!!!:sunny: :sunny: :biggest:
1 - 20 of 21 Posts
