- 1 How do you choose a header size?
- 2 Is it illegal to put headers on a car?
- 3 What headers do for a car?
- 4 Can headers be too big?
- 5 How much horsepower do headers add to a 350?
- 6 How do I find the primary header size?
- 7 Do headers make the car louder?
- 8 Can you run headers without a tune?
- 9 Is it legal to run open headers?
- 10 Can headers damage engine?
- 11 Should you wrap headers?
- 12 Do headers improve gas mileage?
- 13 Are bigger headers better?
- 14 How do you calculate header pipe size?
- 15 What are tuned length headers?
How do you choose a header size?
To decide on the right primary tube diameter, there are numerous formulas used in the design of race headers, but for a street car, Don Lindfors of PerTronix (makers of Doug’s, Patriot, and JBA headers ) says the following is a great rule of thumb: 200-325 hp look for 1.50-inch diameter primaries, 275-425 hp use 1.625
Is it illegal to put headers on a car?
Headers aren’t always illegal, some vehicles come stock with them and most short tube headers are considered legal in most states. Not only will they make your vehicle louder, but it is also considered tampering with your vehicles emissions, which according to the EPA is illegal under federal law.
What headers do for a car?
They are constructed of individual tubes (one for each exhaust port) that meet in a larger tube called a collector. Headers are installed because they boost the rate of exhaust flow out of your engine compared to OEM stock exhaust manifolds, which are typically designed to take up as little space as possible.
Can headers be too big?
If the headers are too small for the application they will cause restriction and increase heat in the engine. Too large a header will reduce torque output of the engine and increase the possibility of exhaust gas reversion—again increasing heat.
How much horsepower do headers add to a 350?
The length of the primary tubing determines the effective rpm range, but headers can be worth 15-20 hp on the right application. Run on our restrictive two-barrel 350, the headers improved the power output to 248 hp and 365 lb-ft of torque, with consistent gains through the rev range.
How do I find the primary header size?
For performance engines, operating at higher rpm, you can use the formula below. Recommended Header Primary Tube Diameter.
|Horsepower Output||Primary Diameter|
|200-325 hp.||1 1/2 in.|
|275-425 hp.||1 5/8 in.|
|400-500 hp.||1 3/4 in. or 1 7/8 in.|
|500 hp. or more||2 in. or larger|
Do headers make the car louder?
Headers alone will not make it any louder. Midpipes and mufflers will give you louder exhaust.
Can you run headers without a tune?
Headers with the tune will net you around 25 hp, without the tune the engine will not run at peak performance, and may, please notice I say may, cause long term damage by running lean.
Is it legal to run open headers?
Emissions Laws If your car is newer than a 1971 model, you can’t run open headers on the street at any time for any reason. Federal emissions standards went into effect in 1972, so routing untreated exhaust gases past the catalytic converter on any car produced that year or later constitutes an illegal modification.
Can headers damage engine?
Headers will not hurt your engine.
Should you wrap headers?
Header Wrap keeps the heat in the pipes. This improves exhaust flow and The Scavenging Effect. It also lowers underhood temps. Wrapped headers will make a little more Torque and Horsepower than a bare metal set.
Do headers improve gas mileage?
While more involved from an installation standpoint, headers in combination with a cat-back system will give you a measurable boost in power. In most cases, fuel mileage will remain the same or improve a bit.
Are bigger headers better?
Header Size: Bigger Isn’t Always Better Although smaller-diameter primaries will flow less volume than bigger primaries, a smaller diameter pipe actually creates faster exhaust flow velocity with just enough resistance to foster good low- and midrange torque.
How do you calculate header pipe size?
Multiply your Volumetric Efficiency-adjust single cylinder displacement by 16.38; we’ll call this Figure C. Add 3 to your calculated length from Step 4, then multiply that by 25; this is Figure D. Divide Figure C by Figure D and you’ll have the header tubes’ inside diameter in inches.
What are tuned length headers?
A ” tuned header ” usually describes a header that has equal length (or nearly equal length ) primary tubes. We all know that primary tube diameter, tube length and collector design all go into the receipe for a tuned header.