Smog questions for Gen 4's...Tuners what do you think?

[TrackAire]

Smogging a Viper was discussed in another thread...but here is a tech question for the tuners on the board. If you have to smog a Gen 4 that was mildly modified (exhaust, etc), what would allow it to pass smog easier, 91 octane or 87 octane? I was thinking the lower octane would burn easier and ignite the cats faster , but I might be wrong in my reasoning.

What do you guys think?

Smog test consists of car being sniffed at 15 mph and 25 mph on a smog dyno.

Thanks,
George

 

[Martin]

No difference at all with different octane ratings. As long as you have cats on the car, your Gen 4 will pass the sniff test without a problem. It's the visual that kills most of us here in CA. If you have headers, you have about a 95% chance of being screwed. There aren't any CARB certified headers for Gen III and Gen IV Vipers, and the smog tech will figure that out in thirty seconds when they go into their computer to look it up. If you have questions, feel free to ask away - I've been through the smog wringer enough times to know just about every nuance of it...

 

[TrackAire]

Assuming that the visual inspection is not the issue, if running one cat with both O2 sensors, will the lower octane help with a more complete burn?

Cheers,
George

 

[Martin]

Nah - you'll be fine. Even with one cat, the exhaust coming out of the car will probably be cleaner than what is going into your intake (if I remember Vacaville during the summer properly ). To play it safe, drive the car up and down I-80 in third gear for a few miles before doing the test. You'll get the cats nice and hot and clean, and you should be fine. Even with a new car, there is a pretty wide range of what's acceptable, and I've seen cars pass with no cats at all (albeit at the high end of acceptable). These engines run really clean.

 

[Viper X]

Hey George,

Gen IV should pass the sniffer easily with cats and OE computer. Very clean running engine. Octane rating doesn't matter, but I'd run 91.

Make sure the engine is fully warmed up with no codes.

Gen III, now that's another story .....

Dan

 

[TrackAire]

Hi Dan,

I'm wondering about headers and a single cat, both O2 sensors in place with stock computer. If I get a chance, I'm going to try to schedule a pre-test to see what she blows compare to stock.

Regarding headers and the visual inspection, most smog techs have never smogged a Viper...so unless they are very versed in Vipers they probably don't know what to look for unless the headers are super obvious (chrome finish, etc).

The side sills can be a pain in the butt at times, but they do hide the catalytic converter(s) nicely

Have a nice evening,

George

 

[Martin]

If you can get it to pass with headers, let me know where you went You might get lucky and they won't look too carefully, but I just got done having a long talk with a smog tech and they're under a lot of pressure right now to make sure they don't miss anything. CA is sending undercover agents to shops in high-performance cars, and they try to get their cars passed even though they have something 'obvious' that shouldn't pass. If the shop passes them, they get hit with a huge fine. The guy I talked to said that everyone in the industry is pretty leery of anyone that comes in with a car that doesn't sound stock... He said that when he heard my car coming, he immediately got ready to do a very thorough visual.

 

[TrackAire]

Martin,

Probably time to drive around and find an noob 18 year old smog tech that would be dazzled with the ACR and just happy that he got to drive it on the rollers to smog it

Cheers,
George

 

[Viper X]

Hey George,

Your car should pass the sniffer easily as long as the cats are working properly and you are running the OE computer. My Vipers always have passed and are set up the same way.

Even my 530 ci Paxton car making over 900 rwhp on 91 octane with the rear OE cats installed behind the headers in the side sill - one on each side, tuned by DC Performance with the factory computer, passed the sniffer easily.

Dan

 

[Martin]

A good way to go about it is to ask around in your local region to see who's had good experience with a smog shop. Some of the shops are better than others, and if a shop has just been hit with a fine for passing someone, you obviously want to stay away from that one. Also, if they've never seen a Viper before, they can just as likely go over it with a fine-tooth comb because it's unfamiliar to them as be overwhelmed and miss things. These cars are hard to get past the visual...

I posted a while back about a shop I went to where the guy went over my GTS with a fine tooth comb, and almost sent me to a referee station because he couldn't see the cats on my car. Duh. The cats are covered by the side sills... He told me that if he sees something suspicious, and can't verify it is OK, he is obligated to put my VIN into the computer and flag my car. I flipped out and wanted to choke the guy... One thing you don't want is to have your car flagged and sent to a referee. Once your VIN is in their system, it will haunt you until you bring it in, get it inspected, and have them release it - and those guys KNOW what headers look like...

If you have other cars, I've found that the best way to get a 'grey area' car passed is to bring your other cars in first. I have three that need to be smogged within a month of each other, and all three of them look/sound sketchy - but the first two are 100% CARB compliant. The third has some stuff that won't pass if caught. I bring the first two in, get to know the tech, and by the time I bring the third car in, he just connects the tailpipe sensor, plugs into the OBD port and I'm done in five minutes.

 

[Viper X]

Martin,

Good advice.

Getting to know local service providers, like smog guys and tuners, can be very helpful.

Sometimes other club members can refer you to good, local service providers.

Dan