Passing smog test after mods?
05-05-08, 05:12 AM
#1
Lead Lap
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Passing smog test after mods?
Hey
I'm thinking about supercharging my 93 SC400 (M90, 6psi). In order for this to be street legal in my country, I need to pass a ton of tests, one being smog. Supercharging would mean to remove EGR, and I have no idea whether I'd by able to pass like that.
Smog tests in my country are done like this:
- Cold engine / cats
- "Federal Test Procedure", FTP 75 (this is an old US standard, calling for a 17.8km, 41min test cycle at 34kmh average speed, 91kmh top speed)
- Max. CO: 2.1grams/km
- Max. HC: 0.25grams/km
- Max. NOx: 0.62grams/km
I have no idea how this test procedure or limits relate to smog tests done in the US, or if they can be compared at all. I have found this thread and it appears that the measurements are completely different.
Anyway, I just would like to find out how likely it would be that I fail/pass smog testing after EGR delete and mods like supercharger and/or headers and/or cams etc. etc.
Any help appreciated.
I'm thinking about supercharging my 93 SC400 (M90, 6psi). In order for this to be street legal in my country, I need to pass a ton of tests, one being smog. Supercharging would mean to remove EGR, and I have no idea whether I'd by able to pass like that.
Smog tests in my country are done like this:
- Cold engine / cats
- "Federal Test Procedure", FTP 75 (this is an old US standard, calling for a 17.8km, 41min test cycle at 34kmh average speed, 91kmh top speed)
- Max. CO: 2.1grams/km
- Max. HC: 0.25grams/km
- Max. NOx: 0.62grams/km
I have no idea how this test procedure or limits relate to smog tests done in the US, or if they can be compared at all. I have found this thread and it appears that the measurements are completely different.
Anyway, I just would like to find out how likely it would be that I fail/pass smog testing after EGR delete and mods like supercharger and/or headers and/or cams etc. etc.
Any help appreciated.
05-05-08, 05:57 AM
#2
Super Moderator
Well, you would possible have yourself in a pickle as we say in the U.S.
If you remove the EGR, there can be an increase in NOx. I have seen guys at an exhaust shop I used to go back in Mexico put their vehicles on a gas analysis machine and seen this occur time and again, sometimes a bit more and sometimes a lot more, but more the latter. You might, depending on the gas, get some knocking in the engine.
Back in Mexico, we had brand new cars not even pass emissions because of HC or unburnt gas (hydrocarbons) and that was because the gas was bad, high sulfur, (and being in Mexico City), not the greatest thing for good combustion.
If you remove the EGR, there can be an increase in NOx. I have seen guys at an exhaust shop I used to go back in Mexico put their vehicles on a gas analysis machine and seen this occur time and again, sometimes a bit more and sometimes a lot more, but more the latter. You might, depending on the gas, get some knocking in the engine.
Back in Mexico, we had brand new cars not even pass emissions because of HC or unburnt gas (hydrocarbons) and that was because the gas was bad, high sulfur, (and being in Mexico City), not the greatest thing for good combustion.
05-05-08, 07:32 AM
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Lead Lap
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Sorry, meant to post the link to this thread in my previous post
https://www.clublexus.com/forums/sho...d.php?t=181378
Wonder if anyone knows if and how those numbers could be compared to the ones I posted.
Yes, I would expect NOx to go up with the EGR gone. What I don't know is how close to the limits the car is now without any mods.
Btw, we have 98octane fuel over here (Switzerland), although I'm not sure the rating system is the same.
https://www.clublexus.com/forums/sho...d.php?t=181378
Wonder if anyone knows if and how those numbers could be compared to the ones I posted.
Yes, I would expect NOx to go up with the EGR gone. What I don't know is how close to the limits the car is now without any mods.
Btw, we have 98octane fuel over here (Switzerland), although I'm not sure the rating system is the same.
Last edited by supercoupes; 05-05-08 at 07:36 AM.
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