GMC Truck Forum banner
1 - 10 of 10 Posts

· Registered
Joined
·
582 Posts
Discussion Starter · #1 ·
Ok, I have an 04 sierra with a 5.3 with a custom grind comp cam. I am currently running open header. I noticed that with the cats and y pipe on you could not here the cam lope very good. With the cats off it sounds like a top fuel dragster!LOL!

My question is, If I run new exhaust with no cats will it run ok? I have a tuner from comp that I can use to adjust the fuel and timing. It seems a little sluggish and runs really rich.

Or, should I run cats and try to tune it better?

Thanks for the help!!
 

· Registered
Joined
·
1,682 Posts
If you don't need cats, do without them. IMO, on performance builds catalytic converters are just problems waiting to happen... like getting clogged after they see too much fuel. As long as you gave the means to write them out of the tune, not only turning off the DTC's but also turning off C.O.T (Cat over temp)
 

· Speed Holes
Joined
·
5,631 Posts
either way it should be tuned for optimum performance. No reason it shouldn't run good with a full exhaust with no cats. That's what I'm running right now.

just curious, what are your custom cam specs?
 

· Registered
Joined
·
23,771 Posts
That cam is too big, but w/e.

Have a real tune put on it, dont fuck around with the comp handheld tuner thing. Then have exhaust ran, just replace the cats with pipe, then single exhaust back and a magnaflow muffler, or if you want it loud just put a 12 inch bullet in it.
 

· Registered
Joined
·
582 Posts
Discussion Starter · #6 ·
Thanks for the input! I am going to go ahead and run new exhaust with no cats and have it tuned by Dreamchasers.

I dont see why you say the cam is too big? It may be for a stock setup but it is far from stock!! Its not just a big cam.
 

· Speed Holes
Joined
·
5,631 Posts
Thanks for the input! I am going to go ahead and run new exhaust with no cats and have it tuned by Dreamchasers.

I dont see why you say the cam is too big? It may be for a stock setup but it is far from stock!! Its not just a big cam.
what motor are you running and what do you have done to your motor? I'm intrigued by your set-up if you say that cam is not too big. Your idle has to be crazy.
 

· Registered
Joined
·
582 Posts
Discussion Starter · #8 ·
what motor are you running and what do you have done to your motor? I'm intrigued by your set-up if you say that cam is not too big. Your idle has to be crazy.
I'm tellin you, It sounds like a top fuel dragster without the cats choking it!!

Its a 5.3. To be honest with you I dont know exactly what has been done to the motor.:crazy: My brother is a mechanic and He did all the work to it. I just handed him some money and told him to make it run. I outran my sisters 05 mustang GT pretty easily.
 

· Registered
Joined
·
23,771 Posts
Its still a 5.3. If that cam has 283° of advertised duration I hope you have a manual trans or a converter that stalls at least to 4000.

With that and the 109 LSA your tuner is going to hate you.

And it doesnt take much to outrun a Mustang.
 

· Registered
Joined
·
582 Posts
Discussion Starter · #10 ·
Maybe I looked up the specs to the wrong cam.:think:

Because I have a stall but nothing that big and it runs great, so maybe I got the wrong specs.

Anyway thank for the help guys.


It may still be a 5.3, but I'm more for looks and sound!! And it sounds mean!
 
1 - 10 of 10 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top