02sierraz71_5.3

iTrader: (2)

thorley thorley thorley

budhayes3

iTrader: (19)

I can tell you what I've learned from my personal experience with both shorties and lt's on the same set-up. I had the Gibson shorties on my truck for about 5 years, and didn't feel any noticeable gain. I recently installed StainlessWorks LT's with the catted y-pipe and difference is noticeable throughout the RPM range. At first I was concerned about the 1.75 primaries, but figured screw it since I have a 6.0 swap in my future anyway.

I literally can feel a performance increase in my SOTP meter from the moment I crack open the throttle...whether it be from a dead stop or cruising on the highway.

TravisH

iTrader: (1)

We need FACTS in this thread!!! LOL

Tell us why, dont just say the damn name!

seadoo

Yelo, get any news yet?? ?

Yelo

Some.....bear with me while I get the rest and put it together. I'll post up tomorrow.

I will tell you that we're BOTH right though.....I'll explain tomorrow

arv8100

Thanks to every one for your input...Looks like LT's with 1.75 primaries maybe the best option for my needs. When it happens I will let you know how the 8.1 responds...

BLACKND

iTrader: (5)

Oh and yes Lyndon does know how to tune. Although I have talked to other, more respected tuners, who will go nameless who think His tunes are a joke. Thats all I will say about it.

I don't have a lot of the technical knowledge like a lot of other on here, but I know what works, just can't explain it in technical terms. But a hell of a lot of it comes down to set-up and parts matching. You match parts and set them up correctly and you can acheive your goal. Long Tubes can serve several purposes, not just for all out drag racing, but you have to do your research, before you just go throw a set on that might not do what you want.

And if it were just me, I would just stick with the stock exhaust manifolds rather than throw the money away on Shorties. There is plenty other mods more deserving of the money spent on shorties that will help with the towing aspect.

Yelo

Your Welcome....and, sorry to have turned this into a minor pissing match, but I think we all have learned some things from it....and here's the last of it:

LT's vs. Shorties:

According to the R&D techs at Hooker and Dynatech (who were both really great guys and more than willing to help out with this debate) here's the story:

On your typical street car it doesn't matter how long the primary tubes are (some will debate this...I'll get into that in a minute), what matters is proper sizing and EQUAL primary tube length, the reason an LT typically outperforms a shorty is because LT's typically have equal length primary tubes which allows the exhaust pulses to enter the collectors at equally spaced times, due to venturi effect this creates a vacuum in the other primaries and increases chamber scavenging...therefor increasing torque at lower RPM's. Shorties typically do not have equal length tubing because of packaging and fitment issues (an exception to this is JBL who makes equal length shorty headers for quite a few applications....our trucks included), due to this inequality in tubing length scavenging is negatively affected and torque drops compared to a header with equal length tubes.

Tubing length CAN affect power output....but only in a very limited rpm range, most long-tube header manufactures tune their primary length for the best gains at mid-rpm and sacrifice a little at the top and bottom for better overall performance. Shorties are the same way, but due to their shorter primaries a shorty with equal length tubes will build torque lower than one with unequal length tubes (or even an LT due to the shorter primary length and exhaust pulse timing).

On top of all of this is tubing size: Too big and exhaust velocity slows (negatively affecting torque), Too small and you create a restriction in the exhaust (effecting horsepower more than torque).

Reccomendations for our engines are:

LSx engines (4.8/5.3/5.7/6.0):

Shorties: 1.5" - 1.625" equal-length primaries (13"-15" in length preferably), the 5.7/6.0 can run with 1.75" primaries without affecting torque negatively but do just as well with the smaller tubing sizes too

LT's: 1.625" - 1.75" equal-length primaries (30"-32" in length preferably), big cube engines can step up to 1.875" primaries but only if running WOT for long periods (road racing)

8.1 Liter:

Shorties: 1.625" - 1.75" equal length primaries (14"-16" in length preferably)

LT's: 1.75" - 2.0" equal length primaries (34"-40" lin length preferably)

These numbers are from the guys at both Dynatech and Hooker....I talked to the guy at hooker first and then gave the info he gave me to the guy at Dynatech and he confirmed the accuracy of it...unfortunately it didn't get the names of either of these guys (I was at work and in a hurry, they told me their names but I didn't write them down and forget them)


So...in short:

Shorties and LT's can both make good low end torque IF they have properly sized and equal-length primary tubing. When correctly sized shorties actually have a slight advantage due to thier shorter primaries, this however rarely happens due to fitment and packaging issues (JBL being the exception) so shorties on the whole have been given a bad name in the performance world and LT's have taken over as THE chioce of performance enthusiasts due to their correctly sized and equal-length primary tubing.

I told you guys we were both right......

Scott Mills

I couldnt find anything on the JBL, but I did find some Bassani shorty headers that appear to be equal length. There website does not offer a lot of info though.

shawn calvin

iTrader: (3)

i guess that i am not such a dumb *** after all !i hope that no one got to butt hurt over the hole deal.