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Is there any need for a high-quality HJS Sport Cats option, or is everyone happy with the recent change most have made to the GESI cats?
We've not made any in years, since the price tripled and many manufacturers went to the GESI units to control cost. We have recently been getting inquiries and I was looking to get some feedback from the RL community.
@VektorPerformance At your leisure, perhaps you could bullet point key differences between the two different sources? I personally love my Vektor headers and think I've found the perfect balance between sound and power with the OE Sports exhaust on my T. With that said, I've always wondered what hi-flow cats would do to the formula.
When you say “recent change most have made”, who are you referring to? Soul and Fabspeed, two of the most popular aftermarket exhaust brands in Porsche world, use HJS. The real question is, can the catalyst withstand the temperatures of the high HP powertrain exhaust?
When you say “recent change most have made”, who are you referring to? Soul and Fabspeed, two of the most popular aftermarket exhaust brands in Porsche world, use HJS. The real question is, can the catalyst withstand the temperatures of the high HP powertrain exhaust?
Basically every other platform. BMW/Supra, WRX/STI, Honda, Nissan GTRs, Mustangs, VWs, etc. Basically every aftermarket company out there making a sport cat option is using GESI as they have EPA-approved variants.
Basically every other platform. BMW/Supra, WRX/STI, Honda, Nissan GTRs, Mustangs, VWs, etc. Basically every aftermarket company out there making a sport cat option is using GESI as they have EPA-approved variants.
If the cores don't melt at the track, I am all for it. Especially given the fact GESI is a Canadian company!
When you say “recent change most have made”, who are you referring to? Soul and Fabspeed, two of the most popular aftermarket exhaust brands in Porsche world, use HJS. The real question is, can the catalyst withstand the temperatures of the high HP powertrain exhaust?
After melting the AKRA (300 cell) cats from too much tracking, I will never run cats again. They had the top of the line HJS cats. So the best cat is NO CAT!
Picked up 52hp at the wheels after going with Tubi Catless pipes. The car is perfect with valves closed. When they open it turns heads.
After melting the AKRA (300 cell) cats from too much tracking, I will never run cats again. They had the top of the line HJS cats. So the best cat is NO CAT!
Picked up 52hp at the wheels after going with Tubi Catless pipes. The car is perfect with valves closed. When they open it turns heads.
300 cell might be just little bit more prone to clogging than say 200 cell cats. I say this because I have the Vektor 200 cells and I’m hoping they stay strong.
Catless will always be best for power especially on turbochargers.
After melting the AKRA (300 cell) cats from too much tracking, I will never run cats again. They had the top of the line HJS cats. So the best cat is NO CAT!
Picked up 52hp at the wheels after going with Tubi Catless pipes. The car is perfect with valves closed. When they open it turns heads.
After melting the AKRA (300 cell) cats from too much tracking, I will never run cats again. They had the top of the line HJS cats. So the best cat is NO CAT!
Thet's interesting that they use 300 sell vs the more common 200 cell more commonly seen in higher power applications. If you still have them kicking around, can you DM me the HJS number, I'm curious what version they are using.
Also, something else to note here, there are MANY different sizes and models of HJS cats. If you are shopping around, pay attention to cell density, diameter and length. The lower the cell density the higher the flow, the larger the diameter the higher the flow, and the longer they are the better for substrate exposure to exhaust gasses for improved emissions. There's a lot more to it, but these are some generalizations to consider when researching products.
After melting the AKRA (300 cell) cats from too much tracking, I will never run cats again. They had the top of the line HJS cats. So the best cat is NO CAT!
Picked up 52hp at the wheels after going with Tubi Catless pipes. The car is perfect with valves closed. When they open it turns heads.
How do WEC/IMSA race cars do 24 hour races with cats? It seems that if they’re racing Le Mans they must have something figured out.
How do WEC/IMSA race cars do 24 hour races with cats? It seems that if they’re racing Le Mans they must have something figured out.
They only have to last just long enough. Back when F1 cars first went hybrid, they got new battery packs every race. Going a little further back, they got a new engine every race too. In WRC, they used to get new turbos every event. Bang bang anti-lag is hard on turbos. And cats too. I hear all these pop crackle tunes and how the cat is getting killed a bit every time.
They only have to last just long enough. Back when F1 cars first went hybrid, they got new battery packs every race. Going a little further back, they got a new engine every race too. In WRC, they used to get new turbos every event. Bang bang anti-lag is hard on turbos. And cats too. I hear all these pop crackle tunes and how the cat is getting killed a bit every time.
Yea, but 24 hours of flat out racing is a pretty long time. F1 and WRC are both sprint races by comparison to Le Mans. The cats used in WEC (Le Mans) races, same used in IMSA, I never hear of them failing, or seen one fail during a race. I think they really just got something figured out with how they size the cat and how they tune the car. Those cars make anywhere between 500-900hp, all run cats, race up to 24hr, and aren’t having problems with cat failures. It’s not the cat that is a problem.
Yea, but 24 hours of flat out racing is a pretty long time. F1 and WRC are both sprint races by comparison to Le Mans. The cats used in WEC (Le Mans) races, same used in IMSA, I never hear of them failing, or seen one fail during a race. I think they really just got something figured out with how they size the cat and how they tune the car. Those cars make anywhere between 500-900hp, all run cats, race up to 24hr, and aren’t having problems with cat failures. It’s not the cat that is a problem.
Managing exhaust gas temps is critical. Often times, street car tuners like to lean out the air fuel a bit too much for sustained power output. Good for short pulls, but will roast the cat in sustained use on a road course.
03-18-2023, 11:58 AM
HJS High Flow Cat Pipes 991.2
