383 LT1 Emissions Tuning - Passed with flying colors
#1
383 LT1 Emissions Tuning - Passed with flying colors
Thought I'd post up my tuning experience... as I had some good results and I know some of you are a little hesitant to try emissions testing with a larger cammed car.
Car specs:
383 Stroked
AFR 210 Heads
Cam - 226/234 @ .050 (Lloyd Elliot Custom Grind)
2 Bullet cats
Car is somewhat lumpy but not too crazy (between a cc305 and cc306). I wasn't sure if it would pass.
I filled up with 91 Octane gas with no other additives and took a nice little drive before getting to the testing station.
4 simple things in the tune:
- increase idle to 50rpm below the maximum allowed
- dropped idle timing 6-7 degrees
- lowered the overall timing tables 4 degrees (it was easier than doing one by one)
- increased fan temp back to stock values
My results were as good as a stock Camaro, and far off what I was expecting.
Here are the results:
.......Idle...........2500rpm drive
.......Limit/Result...Limit/Result
HC......300/22.........242/12
CO%...1.50/0.06......1.92/0.41
NO........N/A...........2520/89
Car specs:
383 Stroked
AFR 210 Heads
Cam - 226/234 @ .050 (Lloyd Elliot Custom Grind)
2 Bullet cats
Car is somewhat lumpy but not too crazy (between a cc305 and cc306). I wasn't sure if it would pass.
I filled up with 91 Octane gas with no other additives and took a nice little drive before getting to the testing station.
4 simple things in the tune:
- increase idle to 50rpm below the maximum allowed
- dropped idle timing 6-7 degrees
- lowered the overall timing tables 4 degrees (it was easier than doing one by one)
- increased fan temp back to stock values
My results were as good as a stock Camaro, and far off what I was expecting.
Here are the results:
.......Idle...........2500rpm drive
.......Limit/Result...Limit/Result
HC......300/22.........242/12
CO%...1.50/0.06......1.92/0.41
NO........N/A...........2520/89
#5
#6
I'm guessing for low rpm, igniting the mixture closer to TDC (when it's more compressed and volatile) the more complete the burn, as opposed to alot of idle spark advance.
I had my car hooked to an emissions machine at school once and also noticed Much better idle emissions at like 5 degrees spark advance when compared to 15-20 or whatever stock is.
I had my car hooked to an emissions machine at school once and also noticed Much better idle emissions at like 5 degrees spark advance when compared to 15-20 or whatever stock is.
#7
Could you please provide a bit more details on your setup. I have a smaller LE cam and all the emission connected and not getting anywhere your numbers.
What injectors?
Compression?
Type of cats? metal or ceramic substrate?
What "is" your timing at idle to pass emissions?
Thanks!!
What injectors?
Compression?
Type of cats? metal or ceramic substrate?
What "is" your timing at idle to pass emissions?
Thanks!!
#8
Could you please provide a bit more details on your setup. I have a smaller LE cam and all the emission connected and not getting anywhere your numbers.
What injectors?
Compression?
Type of cats? metal or ceramic substrate?
What "is" your timing at idle to pass emissions?
Thanks!!
What injectors?
Compression?
Type of cats? metal or ceramic substrate?
What "is" your timing at idle to pass emissions?
Thanks!!
Compression: 11.5/1
Cats: Bullet style... pretty sure they are ceramic. But if they are working, either would do. If your numbers are crazy high and the car is running right... may be something to look in to.
Idle Timing: 17-19 degress on the computer. A few higher on the scanner (the computer adds a few degrees)
Thread
Thread Starter
Forum
Replies
Last Post
F'n1996Z28SS
Cars For Sale
8
08-23-2023 11:19 PM