VAST Stage 3 numbers

[updaboost]

Looking to get my new set-up dynoed next week. Just wondering what VAST Stage 3 guys are puttin down on the dyno...?

[Das General]

Blah blah dyno numbers...haven't you realized that one persons dyno number is useless to another.

[johnkent1212]

Blah blah dyno numbers...haven't you realized that one persons dyno number is useless to another.

I agree...from what I understand dynos can be all over the place. The only numbers that matter are the ones at the track, but I can understand you're interest in ball park numbers. Call them and ask. They have the best customer service I've dealt with and have been honest with all the questions I've asked.

[Das General]

ballpark 400whp

[The_Jerbel]

Depends on your altitude and on the other supporting mods your car has, but 400whp is a good start.

[SourDieselS4]

Not 400whp with piggies and stock intercoolers thats for sure

[AudiSportB5S4]

Piggies dont matter the stock IC's will.... you bastard you got the fueling before me! haha, I cant stand the 3- anymore its like a big strip tease! now that my FMIC is on and everything else is taken care of fueling is SO coming soon. cant wait

[The_Jerbel]

^^2nd.

[McKennaS4]

tree. i mean third. upgrade those shitty as stock sidemounts

[AudiSportB5S4]

i have some for sale, if you want you can try running FOUR stock IC's let us know how it is, logs of course lol

[sweed]

lol- ya i need to change my stockers out !

[Audi S4 Turbo]

Not 400whp with piggies and stock intercoolers thats for sure

Piggies have no influence, the stock ics do as they are restrictive.

[a4rings]

Piggies have no influence, the stock ics do as they are restrictive.

A larger diameter DP will definitely get you more hp, it just may not be worth it for the money for some people

[The_Jerbel]

^^That's debatable, depending how which turbos you're running and how much air you're flowing (what altitude you're at, etc)

[Paulyworld1432]

Hey where in Chicago are you located??

[updaboost]

Hey where in Chicago are you located??

Indian Head Park - West Burbs - Joliet & Wolf... And yes we all know that dynos and weather conditions affect dyno numbers.. I'm just looking for ballpark numbers for comparsion to see if my VAST set-up is a healthy tune.. and yes on stock ICs and piggies I'm not expecting anywhere near 400whp..probably closer to 360whp i'm guessing..we will see..

[joemomma]

^^That's debatable, depending how which turbos you're running and how much air you're flowing (what altitude you're at, etc)

How is that debatable? Its common car logic. More air in more air out the better. Put piggies up against ASP 3"dps or AWEs Dps either or with test pipes and you will see a good gain.

[The_Jerbel]

How is that debatable? Its common car logic. More air in more air out the better. Put piggies up against ASP 3"dps or AWEs Dps either or with test pipes and you will see a good gain.

Feel free to post up any experimental data you may have. To date, I've never seen any that supports that aftermarket dp's yield any more power than piggies. In fact, I've read people report just the opposite after experimenting with both setups....

It's debatable, like I said, depending on your fueling setup, what kind of airflow you're getting according to your MAF readings, which turbos you're running, and what altitude you're at. For K04's and smaller turbos applications, piggies are completely sufficient. Gains would be minimal by going with a larger exhaust setup. This is especially true if you're at high altitude and are flowing even less air than if you were at sea level. If your "common car logic" were sound, then everybody would be running 4" dp's and a 5" CB, in fact, the Audi engineers would have built the car with such a system for the little K03's and stock MAF. There is such a thing as overkill....
On non-turbo applications, back-pressure can be beneficial. So you see, there is no hard, fast rule for exhaust flow. Each engine design is a rule in and unto itself.

Also, if you want to compare dp's with test pipes, then you are not worried about running cats, and to be fair, would have to gut the main cats on the piggies as well as the pre-cats.

[Mwall]

A larger diameter DP will definitely get you more hp, it just may not be worth it for the money for some people

..............

Larger pipe=cooler exhaust=slower moving.

[The_Jerbel]

It's a compromise and a balancing act. To small restricts flow, too big and the exhaust flow speed is reduced.

[sCeRaXn]

..............

Larger pipe=cooler exhaust=slower moving.

Not only that, but the expansion of the gases is just wasted energy that would normally be used to keep velocity up. In 95% of turbod applications, volume will take priority over velocity...but there are limits to this rule. Typically, you dont want to go more than double the size of the turbine wheel or else you could actually cause backpressure. This happens when the expanding gas cools and slows down just outside of the "area of expansion" and starts backing up, which causes a high pressure zone from the faster moving gases slamming into the slower moving and cooler gases.

I have a hard time believing that a straight through 2.5" dp wont make more power than the 2" stockers, but its not entirely impossible. The "bulge" that used to contain the cat is probably the reason for piggies performance gains. This area will keep the turbulence(thats normally caused by gases from the turbine wheel and wg colliding) out of the primary piping, thus increasing velocity over a straight pipe.

Keep in mind that pressurized gases act much like fluid(which is why fluid dynamics is so important in exhaust design). So lets think of it in a way that will be easier to understand. Lets say you have a 2" pipe and you pour water from two glasses(representing the turbine wheel and wg) into it. The water thats exiting will be rough and slow because of the turbulence inside of the pipe. Now pour water from those glasses into a funnel that goes from 3" to 1.5" and the water exiting will be a straight stream and will have a much higher velocity than the water exiting the straight pipe. This same principal could be the reason that piggies give such good performance gains.

Sorry for the hijack...just thought id throw in my .2 cents on this whole exhaust theory discussion.

[BastardS4]

Dont upgrade those sidemounts, i hear larger intercoolers cause throttle cut and warranty problems at the dealer.

[s vier]

Feel free to post up any experimental data you may have. To date, I've never seen any that supports that aftermarket dp's yield any more power than piggies. In fact, I've read people report just the opposite after experimenting with both setups....

It's debatable, like I said, depending on your fueling setup, what kind of airflow you're getting according to your MAF readings, which turbos you're running, and what altitude you're at. For K04's and smaller turbos applications, piggies are completely sufficient. Gains would be minimal by going with a larger exhaust setup. This is especially true if you're at high altitude and are flowing even less air than if you were at sea level. If your "common car logic" were sound, then everybody would be running 4" dp's and a 5" CB, in fact, the Audi engineers would have built the car with such a system for the little K03's and stock MAF. There is such a thing as overkill....
On non-turbo applications, back-pressure can be beneficial. So you see, there is no hard, fast rule for exhaust flow. Each engine design is a rule in and unto itself.

Also, if you want to compare dp's with test pipes, then you are not worried about running cats, and to be fair, would have to gut the main cats on the piggies as well as the pre-cats.

I have ran both APR DP's and piggies after. I did notice a loss of power on the trusty Butt -Dyno in the mid and upper RPMs. Conversely, the car seems a bit snappier off the line.

[The_Jerbel]

Well, no offense, but the butt dino isn't very specific

Like I said, I have yet to see any actual data...