Brand new MITA Motorsports NSX Exhaust. Using high grade stainless steel to help produce a low tone volume to compliment the NSX engine.
Weight: 27lbs (12.247kg)
Piping diameter: 51mm (2 inches)
Exit Pipe diameter: 10.16mm (4 inches)
304L Stainless steel
1. Material Used
All Steel have the same basic iron and carbon composition. However, stainless steel also contains chromium, the alloy that gives stainless steel its famous corrosion resistance. Remember, that stainless steel does not mean it is stain proof. It means it will "stain less."
Stainless steel must contain at least 10.5% chromium. But there are other multiple grades under the stainless steel umbrella, each with slightly different alloy composition, and therefore slightly different physical characteristics.
The most commonly used Stainless steel grades are 200 series and the 300 series. The 200 series is a class of austenitic (highly corrosion-resistant) stainless steels that are characterized by having low nickel content. However this is not ideal when purchasing for a new exhaust system as the lower nickel and chromium content makes it less resistant to corrosion. 304 "food grade" stainless steel on the other hand, which is comprised 18% chromium and 8% nickel (nicknamed 18/8). 304 proves to be resistant to oxidation, corrosion, and durability. We use 304 food grade for our exhaust system. Why don't all manufacturers use 304 then? Well, because these austenitic alloys are higher grade materials and harder to work with, they are therefore too expensive for the vehicle manufacturers to supply.
Not all 304 grade is considered the same. There is the standard 304 that we mentioned earlier and 304L grade, which to make explanation easier, is .03 max carbon and is good for welding whereas 304 has a mid range level of carbon. What does this mean then? The 304L plays a strong part in welding due to the .03 max carbon level. This means that the 304L variant was produced to overcome the risk of intercrystalline corrosion aka, weld decay, which was identified as a problem in early stages of the application of these steels. This can result if the steel is held in a temperature range 450 to 850°C for periods of several minutes, depending on the temperature and subsequently exposed to aggressive corrosive environments. Corrosion then takes place next to grain boundaries.
If the carbon level is below 0.03 then this intercrystalline corrosion does not take place following exposure to these temperatures, especially for the sort of times normally experienced in the heat affected zone of welds in thick sections of steel.
MITA NSX Exhaust uses 304L grade stainless steel.
How can you check your exhaust's grade?
While there is no easy way to check, there is the Moly drop test you can perform. By dropping a electrolytic potassium thicocyanite solution then taking 9v battery to the drop area, you can check the steel used. If the solution gives off a red color but disappears after a few seconds, then the steel used is of 304; however, if the test drop area turns black, then the steel used is of 200 grade.
Of course it is hard to obtain a chemical spotting test kit as they are expensive; therefore, the best test is to see how your exhaust is handling corrosion as the years pass by. If the steel is of extremely high grade, it can easily be buffed by using steel wool and a polish compound; while also remaining extremely shiny as years pass by. MITA NSX Exhaust will be able to be buffed out by using steel wool and a polish compound to keep that new look even throughout the years.
2. Welding Methods
MIG or TIG?
What? Okay, let's try to simplify things. MIG welding is a very simple and easy process to learn compared to learning how to TIG weld. The technical names for these are Metal Inert Gas (MIG), and Tungsten Inert Gas (TIG).
MIG welding works by continuously feeding spool of welding wire that burns, melts and fuses both the base and parent metals together. A variety of materials such as ild steel, stainless steel and aluminum can be welded using MIG
TIG welding is a more complex method. Commonly used for thinner gauge materials. Items that are made with this process can be kitchen sinks and tool boxes. A strong benefit is that you can get your power down really low and not blow through the metal. TIG welding is a more fine and delicate welding technique.
MITA's Welding Process
We discussed TIG welding earlier and how it is a more delicate method. Though MITA's method goes an extra step. For MITA's exhaust system, MITA introduce 100% Argon to be flown throughout the exhaust to act as a shielding gas. Meaning that MITA feeds gas into the exhaust system and weld it both on the exterior and interior of the 304L grade stainless steel. This allows for stronger welds than the traditional TIG welding.
How To Differentiate A Good Weld vs Bad Weld
The rule of thumb of welding is to check consistency. The welds need to be consisted and not all over the place and be extremely messy. Welds that show inconsistencies are considered bad welds. MITA's exhaust adds character by adding color to our welds to give a “flare” look but still structurally strong.
3. Dyno Performance
The tester NSX was a complete OEM NA1 NSX with original OEM headers, original OEM catalytic converters, and with 83,000 KM (51,000 miles). Tested on Dynojet 224x
Each exhaust was then tested, MITA NSX Exhaust , then OEM , then the SACLAM Silencer Spec A
This is the results. Each exhaust was run twice for consecutive testing while only taking in the top Max Power.
MITA Exhaust ran 237 MAX.
OEM Exhaust ran 233 MAX.
MUGEN Exhaust ran 230 MAX.
With the MITA prototype product, we found an issue with installing the upper flange where it was difficult to install and bolt onto the catalytic converters with the exhaust mounted first; though after alternating it, the installation process then became easier in which you mount the exhaust first then bolt onto the catalytic converters.