Project A8 hotrod A8
While the Audi A8 is a great car, it’s not exactly regarded as a hotrod Audi. The A8 has a wide range of great motors. The S8 obviously has the V10 monster in the D3 body, but the A8 also has the W12 and then the standard V8 4.2. All of them have great potential, but the 4.2 V8 formula is already layed out with the success of the JHM 4.2 motor mods. At the center off all the modifications is always the exhaust and how much a properly built exhaust can unleash the full potential of the motor.
While the 4.2 in the S4 and the A8 are not the same, the A8 was able to hold onto the belt driven motors that put out similar hp until it went to FSI motor. Since the motors are not exactly the same one would assume there are going to be some differences in the exhaust.
You would be right.
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The cat back exhaust is not only restrictive its small. If you thought that was bad look at how they have the precat and the main cat all in one big clump
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If the exhaust wasn’t killing enough power the car had a hot air intake
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If having a hot air intake wasn’t enough the A8 has a intake silencer that isn’t exactly making hp.
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So one of the first things we did was to eliminate that.
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We then looked over and made sure to do the maintenance to the intake. As expected the intake flaps were not working.
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From there we did an inspection and compression test of the motor.
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After we inspected and fixed some of the little issues that would come from a higher mileage A8. We went out to check the cars performance. With all the little work done the car felt better, but it clearly was going to need more help to make serious power.
So the next part happened.
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We pulled the motor out and got to adding the big power adder to these cars.
HEADERS
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The A8 requires a different approach to making the headers. One because of the power curve and two because of the cars weight. While the motor is a 4.2 the standard JHM headers for the S4 won’t even come close to fitting. So, I did kinda chuckle when I heard that people were told china knock off headers would fit every 4.2. That was an LOLCOSTER.
If you guys that installed the S4 headers thought the tolerances were close, this car will make you think again. Once we got the headers built the decision was made to send them out to get coated.
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Jet hot did a great job even though they did take a while. They did look great.
We stuffed everything back in and took the car out. While the headers make any car sound good and perform even better the cat back just had to go.
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Due to the cars weight and power curve we made the proper X pipe and worked to get it into the best location
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The customer had mufflers already on the stock exhaust. That in itself was a project to get them to work properly, but it did turn out great.
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After the dust settled the car did gain a big gain in hp. You can read over and over how everyone that gets the JHM headers sees a night and day difference. This A8 was no exception to that. The acceleration was incredible for such a large car. Once we got the tune sorted out the car was able to pass all readiness and accelerate like a true sports car.
The one thing that I see or get asked a lot by people is, “how much louder will headers make my car?” The answer to that is, in truth properly made headers should quiet down the car and make the exhaust tone tighter. We went from the stock exhaust system with all the cats resonators and aftermarket mufflers to. No cats, no resonators full headers and the in car decibel reading dropped by 10 points.
I think I’m started to believe that an A8 can be a hotrod after all.