Stock Exhaust Capabilities Question??

[CHAOS]

So here I am talking to a rocket scientist about exhausts and he tells me that Dodge has probably specked out the Viper exhaust to pass the engine capability and that changing the headers, cats and mufflers would be a waste unless there were some other serious performance upgrades. For example, he drove a Mustang GT and said his exhaust, stock, would be good for up to 600HP in upgrades...

I want to change the sound to Borla, should I just go with the pipes (2.5") right now and save the money for reckless driving and speeding tickets???

 

[mjorgensen Woodhouse]

Dynos don't lie scientists do!

 

[ViperGeorge]

Interesting thought. I have an 06 with a Paxton. It had a stock exhaust and was putting down 646 rwhp on a Dynojet. I did change to Random Tech high flow cats and Corsa exhaust primarily to lower the heat in the side sills. The OEM cats got way too hot with the richer tune the blower requires. However, Dan at DC performance as well as the folks at Paxton told me not to put headers on as I would lose power. Apparently the blower needs back pressure to create optimal power. Too little and the boosted charge ends up going out the exhaust or something like that.

I would say exhaust mods will add power depending on the mods that you do. On the other hand my stock exhaust was able to handle 646 rwhp without issue although it did so with a lot of heat. The new exhaust is way cooler but it is louder as well.

 

[dragon rider]

Changing the exhaust and using high flow cats helps out with the side sill temps and it also helps the Viper sound like a Viper. I does free up a few ponies, but on the Gen 3 it's nothing earth shattering, 10-15 hp gains can be expected.

 

[Martin]

So here I am talking to a rocket scientist about exhausts and he tells me that Dodge has probably specked out the Viper exhaust to pass the engine capability and that changing the headers, cats and mufflers would be a waste unless there were some other serious performance upgrades. For example, he drove a Mustang GT and said his exhaust, stock, would be good for up to 600HP in upgrades...

I want to change the sound to Borla, should I just go with the pipes (2.5") right now and save the money for reckless driving and speeding tickets???

Well, I am a rocket scientist (at least I was earlier in my career), and I have a different opinion on how Dodge designed the exhaust. They worked hard to get every bit of power out of the engine by minimizing losses through the exhaust, but they also had to meet EPA and ARB emissions and noise guidelines. So, there is a tradeoff - and they did have to do some things to pass emissions and those things did affect the efficiency of the exhaust system.

Note that, for a non-street Viper ACR-X (they don't need to meet emissions requirements), they installed a different exhaust that freed up 40 extra HP. If they could have done that for the street car, they would have

 

[SquadX]

Underground racing uses the stock exhaust on some of there 800-900rwhp Paxton builds. Good backpressure as stated above

 

[KenricGTS]

Any engine is just an air pump. The more air in and out the more power! Simple as that. Get better heads so they flow better the more power. Add a blower and force more air in the more power. The only reason Paxton would say to leave the stock exhaust is because they don't want you to have the engine goe lean. On a stock bottom end that a lean condition would be bad for stock cast piston. On a fully built bottom end you want headers with high flow exhaust. Like on my DLM car I used to have 900rwhp on pump. Like I said more air in more air out more power!

 

[TrackAire]

What is the exact exhaust system used on the new ARC-X? Also, that is not a standard Gen IV motor...I think is has a different cam, pcm and a modified lower intake IIRC.

The Devon GTX is listed at 650 hp. I heard that the 50 hp increase was the lower intake and exhaust upgrades. I can't find what the exact exhaust upgrades are, does anybody here know?

Thanks,
George

 

[Tom F&L GoR]

It's not really the backpressure, so don't go thinking you need a certain size cork in the exhaust. It has to do with the pressure waves that (at high frequency) push and pull on both the fresh air and exhaust. Timed properly, the system expels more of the exhaust without sucking too much of the intake charge through. I think F1 engines are, at their torque peak, about 115% efficient, so there is a lot of tuning that can be done. I suspect that Paxton doesn't want a higher flow exhaust because fresh air+fuel will end up in the catalyst, too... The better question for the Paxton folks is what cam to use (which will change the resonance) when going to a new exhaust system.

 

[TrackAire]

Regarding the Gen IV's, has anybody done dyno runs showing the difference between a full header system (like Belangers) and Corsa track type exhaust versus just a Corsa type exhaust with stock headers?

How good or bad are the stock Gen IV headers from a construction and flow point?

I'm not adverse to doing headers, but if the gain is only 15 to 20 crank hp over the stock setup with hi-po exhaust, it just doesn't pan out in my book.

Are the aftermarket headers significantly lighter than the stock setup?....if it's taking 20 to 30 lbs off the front of the car, that means something.

Thanks,
George