American Racing Headers Details C8 Corvette Designs & Power Gains

C8 Corvette gains 17 horsepower and 33 lb-ft of torque without a tune, and the headers look amazing.

One of the most popular early upgrades for the first C8 Corvette Stingray owners is exhaust headers. Tuning has not yet been unlocked for the LT2, so headers are one of the most impactful upgrades available right now. There has been some discussion as to what size headers are best and how much power can really be gained without a tune. Several companies offer headers for the new Corvette, but the folks at American Racing Headers shared a ton of information about the development of their long tube LT2 headers.

Of course, the AR Headers account also shared power gains of 17 rear wheel horsepower and 33 lb-ft of torque at peak. If all you care about, those are the key numbers, but this thread also explains why they went with their current design.

C8 Corvette Header Design

The OP began the post by explaining why they went with a 1 7/8 primary for their C8 Corvette headers.

We’d like to share our results after some very extensive and methodical testing on three different primary sizes, including 1-3/4”, 1-7/8” and 2”. All were done on the same day at JTM Motorsports. Before testing anything, our team first designed headers with the most optimal primary length this platform would allow. We were also able to get those lengths extremely close to equal. You will notice that our headers are considerably longer than that of our competitors. Testing proved quite convincingly that 1-7/8” was the optimal size for a 100% stock application. The 1-7/8” netted 10 additional RWHP at peak over 1-3/4” and was 6HP and 5TQ better than 2”.

Next, the OP talked about the fact that they are using factory catalytic convertors, transitioning into the power gains.

It’s important to note that all tests were first completed through the factory cats. The larger diameter 6” face of the factory cats gave our headers all the breathing space they needed to produce these outstanding results. Though peak was 17 RWHP and 33 TQ, we produced as much as 36HP at 5250. Please read the charts below very carefully. You can see the gains in torque and HP in RPM increments up to 6500. ALL THIS THRU FACTORY CATS! What’s more impressive is that after testing our high flow cats with our best performing 1-7/8” headers, we saw no appreciable gains warranting the added expense. It’s important to note that we tested high flow cats with a 4” diameter face. The smaller body negated the higher flowing capabilities in comparison to the larger diameter factory cats that are more restrictive. The comparison was truly a wash. Going to a larger diameter, higher flowing cat design may net better results. We will be testing that possibility soon.

Our headers are long tubes, not mid lengths. They feature merge collectors with scavenger spikes and 3” outlets. They’re fully tig welded and manufactured to last indefinitely.

Lastly, we are seeing no CEL issues after multiple heat cycles and approximately 250 miles of street and highway driving.

The ARH representative then shared a Mustang dyno chart and a list of the power readings at the various engine speeds. That list of numbers gives us a great look at the gains across the powerband beyond just peak gains. The OP also shared a picture of the headers in the C8 Stingray engine bay.

Later on in the thread, “Snowblind2.0” shared pictures of the headers installed, when we learned that it was his car in the initial post.

Here are a couple more pics of the install. The heat shielding on the fuel line and the evap line may not be the finish product but they are addressing any potential issues. Overall the exhaust is louder and the numbers speak for themselves. I have no baseline passes at Atco to go off of but I’m anxious to see what she does. As you can see, they utilized all the available space to get a long primary tube and also a full size merge collector. Great work ARH

Community Questions and Answers

The first member to ask some good questions about the ARH headers was “Racer X”.

Interesting and surprising results given that it comes from the factory with tubular headers. Congratulations!
What are the primary diameters of the stock exhaust?
Did you run AFR for all configurations?
How did they change and did they drift back to stock AFRs?
Did the gains stay after the trims had a chance to stabilize?

I understand the computer stays in control due to wide band sensors, so the AFRs should move back to stock targeted numbers over time, until tuning can be achieved to change the targeted AFRs.

AR Headers replied with this information:

It commanded 12.0 consistently. It was extremely consistent stock and throughout all the tests during the course of the entire day, going from 1-3/4” up to 2”. The factory headers are 1-3/4” but things get even more anemic after they merge together. The dyno graph above clearly spells out exactly what happens when you open things up. When tuning is finally available, there’s far more on tap.

Next, “Adrian B” asked about underhood heat.

Super interesting! What are you guys doing to address the heat as I don’t believe the stock heat shields would fit in this case? I’m super interested in these and would love to work with you to feature them on my YouTube channel if possible!

This was the OP’s reply.

We’re experiencing no under hood temp issues. Our prototype vehicle, belonging to Snowblind 2.0, (see above), has registered at least 350 miles since completion. Most of that mileage in 85 or greater outdoor temps, in horrible traffic and open road. We’ve had no evidence of any temp related problem.

Finally, “RDSC8” asked if coating the outside of the C8 Corvette headers is necessary.

Will they rust ?
Rain water will get to them!
I will order a set & get the ceramic heat coated or Jet Hot coating.

The OP had a humorous reply.

Unless you plan on parking your C8 in the Atlantic Ocean, there’s no possibility of seeing rust on our headers. You can choose to coat them if you like but thus far we’ve seen no evidence of a need too. We can arrange to send our headers to the coater of your choice once ready to ship. Thanks.

If you have questions about these C8 Corvette from American Racing Headers, click here to check out the whole thread.

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