Cam - Emissions
Thread Starter
Le Mans Master
Joined: Apr 2001
Posts: 7,412
Likes: 259
From: Little Elm TX
Cam - Emissions
I'm trying to get a good idea what the biggest cam I could possibly run and still pass emissions is. Anyone with real world experience please respond. Right now I'm running the LT4 hot cam but when I replace the heads, I want MORE! 
Currently it has NO PROBLEM passing the sniffer test. It's just barely running more emissions than stock. Mods are listed on the link in my sig. Below are the flow numbers for the new heads!
.100...88
.200...146
.300...205!
.400...249!
.500...277!
.550...284!
.600...285!
Here are the suggested cams:
Hotcam specs:
218/228 .492 /.492 (w/ 1.6 ratio = .525/.525)
Recommendations:
224/230 .503/.510 (w/1.6 ratio = .553/.561)
230/244 .510/.540 (w/1.6 ratio = .561/.594)
Currently it has NO PROBLEM passing the sniffer test. It's just barely running more emissions than stock. Mods are listed on the link in my sig. Below are the flow numbers for the new heads!.100...88
.200...146
.300...205!
.400...249!
.500...277!
.550...284!
.600...285!
Here are the suggested cams:
Hotcam specs:
218/228 .492 /.492 (w/ 1.6 ratio = .525/.525)
Recommendations:
224/230 .503/.510 (w/1.6 ratio = .553/.561)
230/244 .510/.540 (w/1.6 ratio = .561/.594)
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Emissions, what is that?
With the 383 you will probably be able to get away with a slightly more aggressive cam than you could with a 350. The 224/230 one should pass easily. The 230/244 might as well but your tune is gonna have to be dead on.
With the 383 you will probably be able to get away with a slightly more aggressive cam than you could with a 350. The 224/230 one should pass easily. The 230/244 might as well but your tune is gonna have to be dead on.
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Originally Posted by Nathan Plemons
Emissions, what is that?
With the 383 you will probably be able to get away with a slightly more aggressive cam than you could with a 350. The 224/230 one should pass easily. The 230/244 might as well but your tune is gonna have to be dead on.
With the 383 you will probably be able to get away with a slightly more aggressive cam than you could with a 350. The 224/230 one should pass easily. The 230/244 might as well but your tune is gonna have to be dead on.
The 224/230 or a 224/236 should pass fairly easy with minor tweaking. I have the 224/236 and as long as I don't have to pass a treadmill test she passes with flying colors. Oregon has a test that is called the Bar 31 standard, it is an enhanced test that gives them a measurement in grams/mile for what comes out of the tail pipe. That test is very hard to pass if your car is cammed up, even if it passes a idle sniff, it may not pass the treadmill portion.
I had a friends car and I spent hours on it. The car was a 1991 ZR1 that was a LPE 368 car with small cams. It passed with flying colors on the idle portion as the car had CATs. But duing the treadmill portion it failed everytime. No matter what I did to the prom it wouldn't pass. Finally in the end he went to another city where they didn't use the enhanced test and passed easily.
The 230/244 will pass with a lot of tweaking and probably adding some denatured alcohol into your gas tank. But that cam is a very lumpy cam, and while some say it drives fine and has no cam surge. I have driven a few cars with it and there is some cam surge and drivability issues in the low end. On the freeway you never notice it, except for the gas milage
Thread Starter
Le Mans Master
Joined: Apr 2001
Posts: 7,412
Likes: 259
From: Little Elm TX
Originally Posted by tjwong
The 224/230 or a 224/236 should pass fairly easy with minor tweaking. I have the 224/236 and as long as I don't have to pass a treadmill test she passes with flying colors. Oregon has a test that is called the Bar 31 standard, it is an enhanced test that gives them a measurement in grams/mile for what comes out of the tail pipe. That test is very hard to pass if your car is cammed up, even if it passes a idle sniff, it may not pass the treadmill portion.
I had a friends car and I spent hours on it. The car was a 1991 ZR1 that was a LPE 368 car with small cams. It passed with flying colors on the idle portion as the car had CATs. But duing the treadmill portion it failed everytime. No matter what I did to the prom it wouldn't pass. Finally in the end he went to another city where they didn't use the enhanced test and passed easily.
The 230/244 will pass with a lot of tweaking and probably adding some denatured alcohol into your gas tank. But that cam is a very lumpy cam, and while some say it drives fine and has no cam surge. I have driven a few cars with it and there is some cam surge and drivability issues in the low end. On the freeway you never notice it, except for the gas milage
I had a friends car and I spent hours on it. The car was a 1991 ZR1 that was a LPE 368 car with small cams. It passed with flying colors on the idle portion as the car had CATs. But duing the treadmill portion it failed everytime. No matter what I did to the prom it wouldn't pass. Finally in the end he went to another city where they didn't use the enhanced test and passed easily.
The 230/244 will pass with a lot of tweaking and probably adding some denatured alcohol into your gas tank. But that cam is a very lumpy cam, and while some say it drives fine and has no cam surge. I have driven a few cars with it and there is some cam surge and drivability issues in the low end. On the freeway you never notice it, except for the gas milage
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Originally Posted by R94 LT 1
Thanks for the info. I just found out today that if I tell them it has traction control and they can't shut it off, all they'll do is the idle test. I think I could get either to pass then. Especially if I lean it out real good at idle just to pass the test and then change it back to a more normal tune.
Thats good that you can get away with an idle test. But just a warning. It is not just a matter of "leaning" it out. If you go too lean then you get a lean miss and incomplete combustion. Then the HC levels skyrockets and then you are in the same boat as you were before. If you have CATs it makes life much easier, and not to mention that having high flow bullet cats won't make much difference as far as loss of power goes.
Thread Starter
Le Mans Master
Joined: Apr 2001
Posts: 7,412
Likes: 259
From: Little Elm TX
Originally Posted by tjwong
Thats good that you can get away with an idle test. But just a warning. It is not just a matter of "leaning" it out. If you go too lean then you get a lean miss and incomplete combustion. Then the HC levels skyrockets and then you are in the same boat as you were before. If you have CATs it makes life much easier, and not to mention that having high flow bullet cats won't make much difference as far as loss of power goes.
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