Magnaflow Exhaust

Ivan "Ironman" Stewart

Ivan "Ironman" Stewart took his first step toward off-road racing legend status in one of those, "Put-me-in-da-game-coach!" movie moments. It was 1973 at the Ensenada 300. He was scheduled to co-drive with Bill Hrynko in a Class 2 buggy. Hrynko broke his leg so Stewart tagged his mechanic Earl Stah to co-drive and, in true win-one-for-the-Gipper style, took home the First place trophy. By the time he retired from racing in 1999, he"d conquered some of the meanest dirt in North America and recorded 84 wins and ten driver"s championships.
During phase two of his career, he started the Baja Protruck Series and went looking for the kinds of aftermarket products for the V-8 powered spec trucks that would hold up from Baja to the Mojave to Pikes Peak. And who did he peg for his exhaust system? MagnaFlow.
"They wanted something durable, something with performance capability," recalls Richard Waitas, MagnaFlow"s engineering director. "They didn"t want to restrict performance, just to even the playing field."
All MagnaFlow"s systems are stainless steel from end to end, so that answers the durability question. Waitas describes the system MagnaFlow engineers came up with as minimalist-a 5x8x6-inch muffler.
We might not have access to the Ironman"s MagnaFlow mufflers, but the company"s line of Universal mufflers, tubing, X and Y pipes and stainless tips offers off-road enthusiasts the opportunity to put together a system for their specific application and favorite terrain. What does MagnaFlow recommend? That depends a bit on your specific setup.
"With off-road rigs that have to be street legal, you"re generally looking for a three-inch system with a single exit near the OE exit point," Waitas notes. "The goal is to reduce mass and weight with the minimum amount of tubing. The trick, is to maintain ground clearance and not to interfere with the articulation of the suspension system."
MagnaFlow"s Universal line of mufflers are 100-percent stainless steel, lap-joint welded with a free-flowing, straight-through perforated core, stainless mesh wrap and acoustical fiber fill. With both oval and round mufflers ranging in size from 3.5x7- to 5x8-inches, fitting your specific application is a breeze.
Another hot pick for off-roading is a dual swept system that exits in front of the back tire, a configuration that works equally well for both lifted trucks and slammed street vehicles. With the exit point, the tubing doesn"t have to work its way around axles or suspension components and has a nicely "aggressive note."
The fact that exhaust engineers talk about the sound of their systems in musical terms isn"t just an interesting quirk. Like your favorite tunes, your exhaust speaks to you. The pitch and tone of the exhaust lets the driver know what the engine"s doing. "In a lot of off-road situations, the tach is bumping around and is basically useless," Waitas points out. "You still need to know where your engine is and a good exhaust system will accentuate the sound of the motor." (After all, manual transmissions have been shifted by ear since the Model T.)
MagnaFlow"s engineers use their ears in the sound-tuning process to create that pleasant note without ending up with an annoying drone in the vehicle"s interior. Once they identify the right pitch, out come the instruments to identify the frequency. Using velocity and other parameters, engineers identify the sound and tune the exhaust to maintain the right note.
According to Waitas, the goal of a stock exhaust system is silence - usually at the expense of horsepower. "If you"ve got a V-8 truck, you want to hear that baritone," he says. Contrary to the OE"s perception, performance exhaust buyers make their selection based on sound, aesthetics and increased horsepower - in that order.
MagnaFlow"s 10- to 20-percent increase in horsepower, along with 5- to 10-percent increase in fuel economy, is a result of a more efficient engine. With a less restricted exhaust flow, the engine works less hard to achieve performance levels. You reduce the back pressure, and the engine works more freely. Exhaust scavenging, using X-pipes, plays a big part in that quick, efficient operation.
The exhaust pulse goes to the section of the X-pipe with the least resistance.This creates negative pressure, a vacuum, behind the pulse. The next pulse comes along and is both pushed by the action of the piston and pulled into the vacuum, leaving no spent gasses in the combustion chamber.
In the process of putting together a custom exhaust system, the size of the pipe can make or break the final result. Increasing the pipe diameter beyond 1/2-inch from stock can actually decrease low-end torque.
"Exhaust gasses are super-heated - they"re basically excited, trying to get out of the tailpipe," Waitas adds. "With too large a diameter, the heat energy is evacuated and the gasses cool and move more slowly. That creates a barrier for the next exhaust pulse. You have to have a balance."
To help select the right diameter tubing, MagnaFlow includes a chart on its website. Modifications like non-stock camshafts or other aftermarket products that change the engine compression and generate a higher level of exhaust gasses justify larger diameter tubing.
Our skills and our wallets may not be up to the Ironman Stewart Protruck circuit, but at least we can bolt on a MagnaFlow exhaust system and get the same advantages of increased performance and gas mileage.