Performance mufflers are a great addition to your automobile. Not only to do they give your car that sound you’ve always wanted, but they also relieve some back pressure created by the restrictive factory systems. Relieving back pressure not only increases engine efficiency (Horsepower and torque) but also allows you to obtain more gas mileage out of your vehicle. Performance mufflers come in all shapes and sizes as well as several different types of metals (aluminum, stainless, titanium, and coated). To name a few Flowmaster, Magnaflow, Hooker , Bassani, and Corsa, have all been thoroughly tested and gone through years of research and development.
The exhaust manifold is the component of an exhaust system which connects the exhaust ports on the engine block to the downpipe. Some problems you may have with a manifold are cracks, warping, broken studs and bad gaskets. Unfortunately most of these problems require a replacement of the manifold.
Exhaust manifolds are generally simple cast iron or stainless steel units which collect engine exhaust from multiple cylinders and deliver it to the exhaust pipe. For many engines, after market high performance exhaust headers are available. These consist of individual exhaust headpipes for each cylinder, which then usually converge into one tube called a collector. Headers that do not have collectors are called zoomie headers, and are used exclusively on race cars.
The most common types of aftermarket headers are made of either ceramic, or stainless steel. Ceramic headers are lighter in weight than stainless steel, however, under extreme temperatures they can crack - something stainless steel is not prone to.
The goal of performance exhaust headers is mainly to decrease flow resistance (back pressure), and to increase the volumetric efficiency of an engine, resulting in a gain in power output. The processes occurring can be explained by the gas laws.
There are certain vehicles that are prone to developing manifold leaks. Also, due to many different types and configurations of motors in modern vehicles, the degree of difficulty in replacing an exhaust manifold can vary greatly. Unfortunately, this also means the cost of such a job can vary greatly too. Some vehicles exhaust manifolds many even have a catalytic converter integrated into it. This setup can significantly increase the cost also.
FLEX PIPES ARE A COMPONENT OF MANY MODERN EXHAUST SYSTEMS, ESPECIALLY IN FRONT WHEEL DRIVE VEHICLES. THEY ARE DESIGNED TO ALLOW FLEX IN THE EXHAUST SYSTEM TO PREVENT HARD COMPONENTS FROM CRACKING OR BREAKING. THIS IS IMPORTANT ESPECIALLY IN FRONT DRIVE VEHICLES BECAUSE OF INCREASED STRESS ON THE EXHAUST DUE TO THE ENGINE AND TRANSMISSION LOCATION. THEY ARE TYPICALLY 4-10 INCHES IN LENGTH AND CONSIST OF THIN STAINLESS STEEL FORMED INTO AN ACCORDIAN SHAPE AND SURROUNDED BY BRAIDS OF STAINLESS STEEL WIRE MESH. OFTEN TIMES THESE FLEX PIPES ARE LOCATED WITH OTHER COMPONENTS, SUCH AS CATALYTIC CONVERTERS OR Y-PIPES, THAT MAKE THESE WHOLE PIECES COSTLY TO REPLACE. AT LOU’S CUSTOM EXHAUST WE CAN CUT OUT YOUR BROKEN FLEX PIECE FROM ITS LARGER COMPONENT AND WELD IN A NEW FLEX PIPE, WITHOUT HAVING TO REPLACE OTHER, MORE COSTLY, PARTS THAT ARE STILL IN WORKING CONDITION.
ALSO COMMONLY REFERRED TO AS MANIFOLD STUDS, THESE ARE THE THREADED RODS THAT ARE INSERTED IN THE END OF THE EXHAUST MANIFOLD IN ORDER TO SECURE THE DOWNPIPE TO THE MANIFOLD. THERE ARE MANY TYPES AND SIZES OF STUDS USED IN THE AUTOMOTIVE INDUSTRY INCLUDING BOTH METRIC AND SAE SIZES. SOME CONNECTIONS INCORPORATE A SPRING TO ALLOW SOME MOVEMENT OF THE DOWNPIPE ON THE GASKET WITHOUT LOSING THE SEAL. MOST OFTEN IN MODERN VEHICLES THE MANIFOLD WILL HAVE TWO OR THREE STUDS ON THE MANIFOLD AND USE A ROUND OR HALF-ROUND GASKET WITH A CONED DOWNPIPE TO MAKE THE CONNECTION. THESE STUDS HAVE A TENDENCY TO RUST AND ROT QUICKER THAN OTHER PARTS OF THE EXHAUST DUE TO THE HIGH TEMPERATURES THEY ARE SUBJECTED TO ON THE MANIFOLD.
BECAUSE THESE STUDS ARE USUALLY VERY DETERIORATED BY THE TIME THEY LET GO, THEY CAN BE VERY DIFFICULT TO REMOVE FROM THE MANIFOLD. AT LOU’S CUSTOM EXHAUST WE HAVE DEVELOPED SEVERAL TECHNIQUES OVER THE YEARS TO ACCOMPLISH THIS JOB.
A RESONATOR IS AN EXTRA MUFFLING DEVICE FOUND IN MOST LATE MODEL VEHICLE EXHAUST SYSTEMS. THEY ARE DESIGNED TO WORK IN CONJUNCTION WITH THE MUFFLER TO ELIMINATE EXTRANEOUS NOISE AND QUIET INTERIOR RESONANCE IN THE VEHICLE. SOME RESONATORS WORK ON A SOUND DELFLECTION PRINCIPLE AND DO NOT CONTAIN ANY FIBERGLASS PACKING, WHILE OTHERS ARE VERY SIMILAR TO THE GLASSPACK TUBES. EITHER TYPE CAN WORK WELL IF USED PROPERLY.
Q. IF MY RESONATOR GOES BAD (I.E. RUSTS OUT OR DEVELOPS A LEAK, ETC.) DO I HAVE TO REPLACE IT?
A. ACTUALLY, IF YOU DON’T MIND A MINIMAL AMOUNT MORE SOUND FROM YOUR EXHAUST, IT IS PERFECTLY FINE TO REMOVE YOUR BAD RESONATOR AND REPLACE IT WITH SOLID TUBING.
SEVERAL MODELS FROM NISSAN ARE SUBJECT TO A BROKEN FLANGE SITUATION, WHICH WE AT LOU’S REFER TO AS A “NISSAN REPAIR”. OFTEN, A HANGER IN THE MIDDLE SECTION OF THE EXHAUST SYSTEM WILL BREAK, CAUSING INCREASED STRESS ON A FLANGE THAT IS LOCATED NEAR THE REAR OF THE VEHICLE RESULTING IN A LEAK. INSTEAD OF REPLACING THE ENTIRE EXHAUST, WHICH IS WHAT MOST SHOPS WOULD BE FORCED TO DO, LOU’S CAN SIMPLY CUT OUT THE DAMAGED FLANGE AND WELD IN A SOLID SECTION OF PIPING WHILE ADDING A NEW HANGER WHERE THE BROKEN ONE WAS. THIS FIX ALSO ELIMINATES ANY FUTURE WORRIES IF THE HANGER BREAKS AGAIN DOWN THE ROAD, AS THERE IS NO LONGER ANY FLANGE TO LEAK. ANOTHER BENEFIT IS ALSO BEING ABLE TO KEEP THE STAINLESS STEEL FACTORY EXHAUST SYSTEM, WHICH IS USUALLY IN GREAT SHAPE EXCEPT FOR THE FLANGE, RATHER THAN REPLACING IT WITH A MUCH LOWER QUALITY AFTERMARKET SYSTEM THAT WILL HAVE TO BE REPLACED AGAIN IN ONLY A COUPLE OF YEARS.
The importance of a well-designed and fully functioning braking system has never been more apparent to me than during my last drive to my father’s. I was driving my Subaru when the OEM brake line on the front driver-side caliper failed. The flexible rubber line that crimps into a banjo bolt fitting that connects to the caliper separated at the crimped joint, leaving me with virtually zero stopping power as I entered a high-speed braking situation. As a result, when I hit the slow pedal at my usual braking point, the pedal went to the floor and stayed there while the car and I continued at speed off the road and into the grass. Luckily for me (and the car), the trajectory of the run-off didn't carry me into any other cars or the guardrail.
To satisfy my curiosity, confusion and sense of horror over this unexpected brake hose failure, I've been doing a little research on the flexible hose portion of the brake line system. That includes taking a closer look at the durability and reliability of OE rubber lines versus aftermarket high-performance lines that use a PTFE (Polytetrafluoroethylene, commercially known as Teflon) inner hose core that's wrapped in a braided stainless steel outer layer. Here's what I've learned so far.
A modern hydraulic braking system uses fluid stored in the master cylinder to transfer the force you apply to the brake pedal to the caliper pistons, which squeeze the brake pads against the rotors to generate enough friction to slow the vehicle. Considering the fluid in the brake lines is what ultimately moves the caliper pistons and provides the clamping force on the rotors, it's obviously a critical part of the system and any interruption or severing of its ability to build and apply pressure within the caliper will drastically reduce stopping power.
Given the consequences of a punctured or severed flex line, the durability and reliability of this part of the brake line system is particularly important. All vehicles sold in North America must be equipped with flexible brake lines that meet or exceed NHTSA Federal Motor Vehicle Safety Standard No. 106 and SAE standard J1401 for volumetric expansion, burst pressure/working pressure and whip test (repeated flexing). These standards specify the performance tests and requirements for hydraulic brake hose assemblies used in the hydraulic braking system of a road vehicle, and they also specify the methods used to identify the manufacturer of the hose. These standards are specifically aimed at brake hose assemblies made of hose fabricated from yarn and natural or synthetic rubber and assembled with metal end fittings (like the aforementioned banjo bolt fittings) for use with non-synthetic DOT brake fluid. The SAE standards even specify that the hose must be either 3.5mm or less in internal diameter or between 4-5mm in internal diameter.
So if all cars come equipped with flexible brake lines that meet these standards, why would anyone upgrade to PTFE braided stainless steel brake lines? Goodridge, one of the world's leading manufacturers of flexible brake hoses, with customers that include Formula 1, IRL, NASCAR and WRC teams and supplier to Alcon, AP Racing and Brembo for their brake kits, did a recent study of OE rubber brake hoses versus its PTFE braided steel hoses and found a number of interesting differences.
When testing volumetric expansion, Goodridge found that standard OE-type rubber brake hose expanded by 0.136 cc/ft at 1,000 psi, 0.150 cc/ft at 1,500 psi, and 0.290 cc/ft at 2,900 psi, whereas the company's PTFE braided stainless hoses expanded by only 0.0002932 cc/ft at 4,000 psi. The close-to-zero expansion to the braided hose means the brake pedal will feel firmer and will respond more quickly to brake pedal inputs, and if you've done any racing then you'll know that even a split-second faster response from the braking system can mean the difference between slowing enough to make the corner and finding yourself parked backward in the weeds.
When conducting the burst/working pressure test as defined by the FMVSS106 and SAE J1401 standards, Goodridge's PTFE braided hoses burst at 12,750-13,500 psi, which is triple that of the 4,250 psi required by the standard for this type of hose. By comparison, the OE rubber lines tested burst at 8,000-9,000 psi, with a recommended safe working pressure of 3,600 psi. What this means is that the PTFE braided hose provides a safety factor of 3, whereas the rubber hose provides a safety factor of 2.36.
The whip test standards require that "a hydraulic brake hose assembly shall not rupture when run continuously on a flexing machine for 35 hours." When Goodridge conducted its testing, the company found that the OE rubber hoses from five different manufacturers failed in 15 to 27 hours, whereas six sets of tests carried out on PTFE braided hoses of various lengths resulted in 45 to 82 hours of flexing before rupturing. What this means is that even though the rubber hose manufacturers claim compliance with the FMVSS106 whip test standard, Goodridge's internal testing showed failure of these hoses long before meeting the minimum 35-hour requirement, while its PTFE braided hoses far exceeded this standard.
It's also a little-known fact that rubber brake hose is generally only guaranteed for three years or 60,000 miles because rubber loses its elasticity over time. I've never really thought of brake lines as a wear item that need regular replacement, but having discovered this limited life expectancy for rubber lines, anyone with a car more than three years old should take a very close look at the condition of their brake lines and replace them if they show any signs of wear and tear. And if you're going to replace them, upgrading to stainless braided PTFE hose makes a lot of sense in light of the firmer pedal feel and faster braking response they provide as well as the increased safety factor illustrated by Goodridge's internal testing. It's also worth noting that Goodridge offers a 150,000-mile guarantee on all their brake lines, made possible by the greater durability of the PTFE liner and stainless braided outer layer.
Having a brake line fail and losing virtually all stopping power as a result is a shocking and extremely dangerous experience. Whether the line failed due to a manufacturing defect or damage to the rubber hose sustained during servicing or from road debris, we'll never know. But given the higher safety factor and far greater durability of a PTFE stainless steel braided brake hose, there's no doubt in my mind that equipping the car with these is the best decision when its time to replace your lines. Take this advice to heart and consider a brake line upgrade on your vehicles or at least inspect and replace the factory rubber brake hoses regularly.