1-7/8 headers on 5.3?
Thread Starter
Joined: Jun 2014
Posts: 1,241
Likes: 47
From: Noblesville, IN
1-7/8 headers on 5.3? Hello all.
Been wanting to put some headers on the 5.3 in my trailblazer. Only problem is the only headers that are available now are meant for the 6.0, and are a 1-7/8" primary. Is this size of primary waaay too big for a 5.3 or can I get away with it?
Been wanting to put some headers on the 5.3 in my trailblazer. Only problem is the only headers that are available now are meant for the 6.0, and are a 1-7/8" primary. Is this size of primary waaay too big for a 5.3 or can I get away with it?
Thread Starter
Joined: Jun 2014
Posts: 1,241
Likes: 47
From: Noblesville, IN
I know backpressure is a myth, however there is no ignoring that velocity is a thing, and an oversized exhaust pipe/primary can kill velocity which means you lose the scavenging effect, especially at low RPMs (where this truck lives, as it's my DD). I don't mind if I lose a few hp/ft lbs down low, but I don't want it to become a dog just trying to drive around town.
TECH Enthusiast
Joined: Jul 2018
Posts: 635
Likes: 329
From: Missouri
itll be fine, i ran some tsp 1 7/8 on my 4.8 ly2 silverado with a true dual set up and x pipe, i had no issue at all. plus itll give you room too grow if you add more power later on. im glad i went that route cause later on i did a procharger p1x.
Trending Topics
I know backpressure is a myth, however there is no ignoring that velocity is a thing, and an oversized exhaust pipe/primary can kill velocity which means you lose the scavenging effect, especially at low RPMs (where this truck lives, as it's my DD). I don't mind if I lose a few hp/ft lbs down low, but I don't want it to become a dog just trying to drive around town.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Holdner tested it on a basic 5.3 and the 1 3/4 were actually a little better than the 1 7/8 on average. I believe something like + 8-10ft lbs more torque down low midrange and a 2-3 HP less up top. Either way it's nothing drastic.
TECH Resident
Joined: Oct 2006
Posts: 993
Likes: 173
From: Euless, TX
Where you will notice the loss of the oversize primaries the most will be at part-throttle not WOT thus the full torque loss of the larger primary will not be seen on a dyno but you will feel it every time you accelerate from a stop or try to maintain speed uphill on the highway.
11 Second Club
Joined: Mar 2012
Posts: 158
Likes: 15
From: fbg, tx
I lost low end torque going from 1 5/8 headers to 1 7/8 noticeably yes it made mor power but lost so much down low it felt slower. Every c6 guy with an ls3 at least when i looked it up said youll be faster overall with 1 3/4 on a daily unless your car lives at 7k rpm.
11 Second Club
Joined: Mar 2012
Posts: 158
Likes: 15
From: fbg, tx
You will lose low end torque, idk where this thing came where tuners are recommending 1 7/8 headers for a 5.3. I had a built ls3 in my camaro and when i found out i had 15/8 primaries went to 17/8 and it did pick up some power on the top end but i noticed how much weaker it was on the low end.
everyone on the corvette forums was saying to go 1 3/4 as i would gain a lot more low end. 17/8 only added like 7hp on someones build and it was at really high rpm but he lost like 30ft/lbs torque on the low end.
everyone on the corvette forums was saying to go 1 3/4 as i would gain a lot more low end. 17/8 only added like 7hp on someones build and it was at really high rpm but he lost like 30ft/lbs torque on the low end.
Thread Starter
Joined: Jun 2014
Posts: 1,241
Likes: 47
From: Noblesville, IN
Hmm, unfortunate. My main reason for looking at 1 7/8ths is that they're the only affordable option. 2.2k for SW headers is ****ing ridiculous. That's what a full Kooks dual setup for an F-body was a few years ago.
Just buy the speed engineering ones like just about everyone else does. I will say the fitment is OK and the install sucked compared to my ARH headers on the TBSS.
TECH Resident
Joined: Jun 2011
Posts: 936
Likes: 472
Thread Starter
Joined: Jun 2014
Posts: 1,241
Likes: 47
From: Noblesville, IN
Because one time an influencer tested it on a dyno with a built 5.3L (probably from 3000rpm+) and it showed only a small difference. Now they apply the logic regardless of the engine combo, vehicle combo, rpm, and let's completely ignore the fact that what happens at WOT doesn't necessarily translate at part throttle.