Hey Guys....what Kind Of Diffrence Would It Make If One Set Of Headers Had 1 1/2 Primary's.....and The Other Set Had 1 5/8 Primary's? Would There Be A Significant Diffrence Between The 2 On Say A 2003 1500 5.3 V8?

 

very significant, smaller tubes have a higher exhaust velocity, creating a better scavenging effect (good down low) but you run out of space for the exhaust at the top end. So basically if you have a blower or a stall, get the big tubes, if not and don’t have plans to go bigger then get the little tubes.

 

go with at least 1 5/8 pri. i'm running 1 3/4 pri. and i have plenty of down low power although i have the mods to support it. all depends how heavily you want to mod your truck.

 

Smaller the primes better the torque down low. Bigger the primes more up top power but less down low. Just like they said.

 

The smaller pipes will make the engine more responsive to throttle inputs during nprmal driving, haveing too large of headrer primaries will take that away.

I have seen some low 11 second Vttes with 1 5/8" primaries. I run 1 5/8" primaries. Both these engines are 346+ CID engines.

I would use no larger that 1 5/8 on a 325cid engine unless using a blower or nitrous, then I would step up to the 1 3/4".

peace
Hog

 

325ci here, cam only, 1 3/4 pri.
sometimes i think i have too much low end...

 

If you are gonna spend he money why not go ahead and get the big tubes... b/c we all know that once you start modding your truck, that it usually doesnt stop!!!

 

Yeah me too, but at the drags, there is no such thing as too much low end, only not enough traction esp. in trucks.
Low ET's are dependant on hard launches. TC's with higher stall ratings can make up for any lack of low rpm torque pretty easily. The 3.06 1st gear on our trucks help the 60 ft.
Heck if you want too go big, go 1 7/8's then. But this is all talking about WOT drag race action, street behaviour is another matter.

How does your truck behave at low rpm with only about 1/8th throttle input, is the throttle response snappy? Will it spin the tires with only a small throttle input?? I am curious.

peace
Hog

 

put it this way, poking the trottle maybe a 1/4 of the way = tire spin for me. like i said before it all depends on what he wants to do with the truck down the road.

 

Very nice, thats the way an engine should respond IMO. I love the throttlke response of the 96 and up trucks, my tBI trucks never responded like the 96 and up trucks do. It is hard for me to not spin the tires.

I agree, it all depends on what he want to do with his truck.

peace
hog