Backpressure to damage car?

[tingboy]

Hi,

Been quite awhile since I've been here, and lo-and-behold, my login still works!

Background: I've had my 1997 MKIV NA for awhile and (10 years), and now want to upgrade to a turbo (not engine swap to GTE). So, i'm doing as much reading and researching as i can to mitigate any risk(s) involved etc. I want the build/upgrade to be as "seamless" as possible. Sort of a plug in play. Having said that, I'd like to keep everything intact - my catalytic converter to be specific. i know i know, not very smart if i want to go turbo since exhaust needs to be expelled quicker, however, i really don't want to deal with the hassle of taking everything apart every other year (smog check), or dealing with getting pulled over and getting a ticket for a failed visual inspection etc.

Question: Will the back pressure from keeping the cats in any way would harm the engine/turbo?

I looked around on several sites during research and could not find a clear answer. The subject seems to go off in a tangent with people stating what they should and should not do instead of whether or not it would actually cause damage. maybe because it won't? figured there are a few experts here and would try my luck.

Thanks in advance!

[pwpanas]

Originally Posted by tingboy

Hi,

Been quite awhile since I've been here, and lo-and-behold, my login still works!

Background: I've had my 1997 MKIV NA for awhile and (10 years), and now want to upgrade to a turbo (not engine swap to GTE). So, i'm doing as much reading and researching as i can to mitigate any risk(s) involved etc. I want the build/upgrade to be as "seamless" as possible. Sort of a plug in play. Having said that, I'd like to keep everything intact - my catalytic converter to be specific. i know i know, not very smart if i want to go turbo since exhaust needs to be expelled quicker, however, i really don't want to deal with the hassle of taking everything apart every other year (smog check), or dealing with getting pulled over and getting a ticket for a failed visual inspection etc.

Question: Will the back pressure from keeping the cats in any way would harm the engine/turbo?

I looked around on several sites during research and could not find a clear answer. The subject seems to go off in a tangent with people stating what they should and should not do instead of whether or not it would actually cause damage. maybe because it won't? figured there are a few experts here and would try my luck.

Thanks in advance!

No, it'll just slow the turbo spool-up, and reduce maximum boost. The oem twins on an Mkiv TT last just fine with cats, right?

[tingboy]

Originally Posted by pwpanas

No, it'll just slow the turbo spool-up, and reduce maximum boost. The oem twins on an Mkiv TT last just fine with cats, right?

woot. sounds good.

thank you for the reply.

and yes, i was thinking that the stock (any vehicle) turbo made in california with the dual cats would have tons of back pressure, but my logic was that most people would upgrade to aftermarket turbos giving higher boost. in turn needing more exit bandwidth. which in turn of course would cause more damage... well, i don't know how the fk i even came to that conclusion in the first place. was researching turbos and some wiki said it worked more effectively with an open outflow. so instead of thinking logically, like "oh, it just won't be as effective", i got a little paranoid and was like, "crap!".

in any case, that answers this one... and thank you much for that.


ting

[ianstaley]

Just a thought here, now I don't pretend to know about back pressure or Californian smog rules, but just a bit of logical thinking here, if a Lambo can have multiple turbs or a Ferrari same sort of set up then what should be the problem of getting a better flowing cat? You can't have been the first to ask this,so I would assume that a better flowing cat must be out there, just gota find it.

[pwpanas]

Originally Posted by ianstaley

Just a thought here, now I don't pretend to know about back pressure or Californian smog rules, but just a bit of logical thinking here, if a Lambo can have multiple turbs or a Ferrari same sort of set up then what should be the problem of getting a better flowing cat? You can't have been the first to ask this,so I would assume that a better flowing cat must be out there, just gota find it.

Yep there is. Too bad he doesn't have a TT:
http://www.randomtechnology.com/toyota.html

[tingboy]

Yes, i tried looking for that...
there was some new emission law that came out in 2008? i believe that made it almost completely illegal to get a hi-flow exhaust system.
The link provided above has this disclaimer "Note that aftermarket catalytic converters are not legal for use in California on OBD2 vehicles (some 1994 and 1995 and all 1996 and later vehicles)."

boooo... i also tried magna flow... and when i looked for california legal hi-flow cats, they listed "replacement" parts... -_-

but yes, after receiving the answer above, i went looking for one.

meh. will probably need to look harder. that would probably be a "Phase II" of the project if i decide to replace them though.
according to the gov website... only CARB approved hi-flow cat systems are legal.
that usually means $$$. we'll see i guess. :|

[ianstaley]

Me I am lucky over here in the UK, as mine is a 87.5 MK3 (one of the first) I don't need a cat they were only made compulsory after 95.

[pwpanas]

Originally Posted by tingboy

Yes, i tried looking for that...
there was some new emission law that came out in 2008? i believe that made it almost completely illegal to get a hi-flow exhaust system.
The link provided above has this disclaimer "Note that aftermarket catalytic converters are not legal for use in California on OBD2 vehicles (some 1994 and 1995 and all 1996 and later vehicles)."

boooo... i also tried magna flow... and when i looked for california legal hi-flow cats, they listed "replacement" parts... -_-

but yes, after receiving the answer above, i went looking for one.

meh. will probably need to look harder. that would probably be a "Phase II" of the project if i decide to replace them though.
according to the gov website... only CARB approved hi-flow cat systems are legal.
that usually means $$$. we'll see i guess. :|

Yep Cali sucks for upgrades. *shrug*