Supercharger Performance and Engine Performance Parts

Update:

The article below was written for an older version (version 3.1) of the header calculator. Since then, in version 3.3 and above, the power calculator is able to do all forms of header calculations, including:

• Primary and secondary pipe lengths and diameters
• Shorty, tri-y, and long tube header designs
• Targeting a specific rpm range for your long tube or tri-y design for maximum launch power or best street cruising

The first part of the video below is still informational because it goes through the concept and theory of a 4-2-1 header and why it is benifitial on street applications. Part 2 of the video which covers using the old version of the header calculator is now obselete I’m afraid.

Be sure to checkout the link at the bottom of this page to the free trial of the power calculator where you can calculate the dimensions for your intake, shorty header and exhaust for FREE

Watch the videos here:

Part 1 -- Theory

Part 2 -- Calculations

The procedure:

Steps for doing a 4-2-1 (using my 1.8 liter , 160 hp @ 5800, 6200 rpm redline, Mercedes) …

So i setup my target power and everything normally (230hp) and I run a normal calculation and I get:

13psi of boost
1.52″ primary diameter
15.03″ primary length
Collector 2.36″

(I happen to know that these are almost exactly the dimensions of the kleemann shorty header for my car which dynos +13whp untuned on the car)

Now I want to redo this calculation for a the 2-1 section

I go back to my inputs and i select ‘true dual’ exhaust and re-run the calculations

This gives me a cutout and midpipe diameter of 2X 1.67″

So that will be the diameter of my 2-1 section

So we go 1.52″ to 1.67″ to 2.36″ 4-2-1 … that’s the diameters.

To find the length of the secondaries … we have to redo the calculation for our second rpm peak… for example my car could really use a boost at 2500 rpms… as the automatic (when not in manual mode) keeps the rpms below 3000 for fuel economy and the car is a but sluggish unless you keep the rpms above 3200.

So with my target as 2500 rpms I go back and change my redline to 2500 rpms

I click calculate and get a huge figure 54psi of boost, but i know i’m really going to run 13psi (from the first calculation) so i need to reduce my target hp number till i get 13psi again

So i go back and reduce my target horsepower and calculate (it takes a couple of trials) till i get 13psi again… the target hp is around 95hp (with the redline set at 2500 rpms).

This gives me the following header numbers:

Header primary diameter = 0.84 inches << ignore this
Header primary length = 29.51 inches << This is what we’re looking for
Cutout & midpipe & collector diameter = 2 x 1.07 inches << ignore this
Cat-Back diameter = 2 x 1.0 inches << ignore this

So now we know the total length for a header tuned for 2500 rpms is 29.5″ and the total length for 6200 rpms is 15.03″ That means your 4-2-1 is 4X 1.52″ to 2X 1.67″ to 1X 2.36″ --> 2.25″ catback
primary=15″ long
secondary= total length -- primary = 29.5″-15″ = 14.5″

And that’s your 4-2-1

So you see if you already know your target power and your 2 target rpm peaks you can design your own header like this.
If you already have a header, you can work it backwards… it will just take some trial and error with the numbers till you figure out originally what the header was designed for.

Results

Technorati Tags: 4-2-1, header calculator, header design, Power Calculator, supercharger performance, tri-y

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