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How Much Power Will Hooker Headers Make on A 5.7L Hemi?

Author: Richard Holdener | 12/07/2020 < Back to Motor Life Home
hemi_header_test__6_.jpg

There's plenty of love for the 5.7L LS, but why should they get all of the love when the 5.7L Hemi is also a killer platform? While there are plenty of LS loyalists who will argue the against the latter, the reality is that the Gen-3 Hemi platform has plenty going for it, and has a lot in common with the current darling of the industry. Like the LS, the Gen-3 Hemi was blessed with just about everything it needs to make good power. The factory intake manifolds (truck, SRT8 and Magnum) work well, and the motors have ample displacement and plenty of head flow. It is the head-flow that allows the Hemi (like the LS) to respond so well to performance mods, including things such as long-tube headers. Big gains are available from other mods, but for this test, we decided to take a look at the effect of long-tube headers on a Gen-3 Hemi. There was just one problem...we only had part of a test motor!


5.7L truck block starting point

Our test motor was an early 5.7L Hemi pulled from a 2006 Ram truck. Unfortunately, it had a few missing pieces, like the factory lifters. We installed new (non MDS) lifters with the non-MDS plugs. While it was apart, we also added some ring gap for later turbo testing.


The 5.7L Hemi was originally pulled from a 2006 Ram 1500 but had sat in a torn-down state for some time. To ready the Hemi for dyno testing, it was reassembled and a Comp Cams HRT camshaft (Comp Cams P/N 112-303-11), a Meziere electric water pump, and the factory Ram exhaust manifolds were installed. In previous tests, the factory, cast-iron exhaust manifolds left a lot to be desired, so we expected big things from the header swap. The stock manifolds were designed with longevity and fitment in mind rather than outright power. All of the testing on this Hemi utilized a Holley HP Management system and Hemi harness. After dialing in the air/fuel ratio and timing with the stock manifolds, the 5.7L Hemi produced 407 horsepower at 6,000 rpm and 418 lb-ft at 4,400 rpm.


5.7L car intake

One of the other components missing on our test motor was the factory Ram truck intake. We chose to install a Magnum/300 5.7L Hemi intake instead. Make sure to check your Hemi intake if you buy one on eBay - ours came full of broken piston components from the previous demise. Note drive-by-wire throttle body converted to a conventional manual throttle body.

Chrysler 5.7L Hemi Valve Covers with MSD coil packs

Other missing components on the Hemi included the valve covers and coil packs. We found a set of used (slightly damaged) covers and combined them with these MSD coil packs, part number 82258 .

Holley HP EFI in use

Dialing in the air/fuel ratio and timing was this Holley HP EFI management system.

5.7L header test stock manifold

First up, we installed the factory, cast-iron exhaust manifolds from a Ram truck. The manifolds were run into a set of 3.0-inch diameter exhaust extensions. On the dyno the 5.7L Hemi produced 407 horsepower at 6,000 rpm and 418 lb-ft at 4,400 rpm.

5.7L Hemi comparison test headers

Now it was time for some Hooker long tubes. We tried both 1 5/8-inch and 1 3/4-inch primary sizes to see how the 5.7L would respond.

5.L Hemi header test, 1 5/8 primary tubes

With the Hooker Super Comp 1 5/8-inch headers (p/n 5020HKR) feeding 24-inch collector extensions, the power output of the 5.7L jumped to 434 horsepower at 6,100 rpm and 439 lb-ft of torque at 4,500 rpm.

5.7L Hemi header test: 1 7/8 primary tubes

Run with the larger 1 3/4" Hooker BlackHeart headers (p/n 70102303-RHKR), the “cam'd” 5.7L Hemi produced 442 horsepower at 6,100 rpm and 437 lb-ft of torque at 4,500 rpm. That equals a nice 35 horsepower gain from the larger, long-tube headers over the stock manifolds.


Dyno Sheet, 5.7L Hemi with Hooker 1 5/8 Headers

The only thing better than making extra peak power is making more power everywhere! The long-tube headers improved the peak power output from 407 horsepower to 434 horsepower, and the peak torque jumped up too, from 418 lb-ft to 439 lb-ft. We also liked the torque gains offered by the headers down low. The Hooker headers provided a solid increase in power and torque from 3,000 rpm past 6,000 rpm.

Dyno Chart, 5.7L Hemi, Header 1 vs Header 2

If we take a look at the graphs produced by the two different headers run on the 5.7L Hemi, we see something interesting. Common sense would tell us that the smaller header should make more low-speed torque, while the bigger header might make more peak power. In this test, only one of those came to pass. The bigger 1 3/4-inch headers did indeed make more peak power, but so too did they make more low-speed torque. From 4,000-5,100 rpm, the two headers were all but identical, but above and below that, the bigger header seemed to shine on this combination. Both were miles better than the stock manifolds, but the 5.7L Hemi combo responded to the bigger headers.


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