We're keeping it polite so far. This would be a record on some other sites, but this site is probably the most mature. Hopefully we can all keep it calm, and just advance this topic.

 

The topic is over. You all are arguing the same point at this point. Yes the collector is a restriction, yes long tubes are better than short tubes, yes the scavenging effect is important. All of this has been documented previously. @adriver You are not wrong in what you are saying but there is more than to exhaust than a restriction.

Also stock NBS exhaust is 2.75" after the y-pipe if I remember correctly.

 

I said what my exhaust setup is in post #15, and I think that you need to read up on what exhaust scavenging is. To change the subject even again, exhaust scavenging is the effect of the exhaust pulses pulling exhaust out of adjacent cylinders at the right time, which is determined by the tube length. Just going by memory, because this isn't college and I will not look up and provide my sources, the length is the neighborhood of 31 inches. The longer the tube, the lower the rpm is that the primary pulse occurs. I think that I read that this length only varies a few inches to correspond to the rpm band of a low rpm V8 engine. So for 7000 rpm, the tuned length is only going to be an inch or two shorter than for 5000 rpm. That is precisely why shorty headers don't scavenge, because there is no RPM high enough for their length to be tuned for. And the inconsistentcy in the length of long tubes vs equal length is less than critical because it is such a small difference. If shorties actually scavenged, then an inch or two would miss the RPM goal by a significant amount.
Check the videos on YouTube of F1 engines revving to 20,000 rpm and notice that their primary tubes are quite a bit longer than shorty headers.

 

adriver was asking about the difference between a 1500 and a 2500, the 2500 came with dual 3" pipes all the way to the muffler, after a short piece of 2-1/2" off the manifolds. They didn't have a Y pipe.

 

It seemed like he was referencing his 1500 a few posts up.

 

Hey now. I'm the only one who can make my post off topic LOL

So last question, pretty well regarded a TOON make a big difference on these trucks. What are people seeing for real world results on a legit local dyno or street tune (not a canned bullshit deal)??? Assuming that is well worth the roughly $500 most seem to charge for that?

 

I would suggest just getting a mail order tune if you are not getting too radical. $300 and is going to get you pretty similar results. I have no idea what the gains are to be had on a stock engine though.

I have a mail order tune that has been running strong for 2 years now for my H/C 6.0

 

Don't you have to have a computer interface handheld though that is a few hundred dollars? I've seen some of them on the BBT website and it all works out to what a local dyno tune would cost after you factor in the cost of the hand held, then tune.

 

You can take your PCM out and physically mail it to them.

Also personally I would be investing in HPTuners or EFI Live anyway as it is a fantastic diagnostic tool. HPTuners and a mail order tune is only about $100 more than a dyno.

 

I can email you my tune if you want. I use EFI Live 99% of the time but i do have HPTooners. Which ever one you were to get, there are plenty of guys on here that would help you out. Ive had my 2500HD for about 3 years now and just yesterday i got to tinkering with how it cranks so RPMs dont flare up to 2000 and then fall to 600. And i mess with shift points and TCC Lockup a little trying to get it just right.
My Tow/Haul locks TCC at 24mph in 2nd and stays locked thru 4th so it doesnt build heat on the back roads towing heavy and pulls a little better.