an immediate bottleneck from a 3.5" testpipe to a 3" exhaust is a bottleneck

 

I will make it even simpler. gatti man insults people rather than discussing forced induction issues. And he provides personal attacks and no information. Your post is meaningless. You give all new meaning to if the facts are with you, then argue the facts. if the facts are not in your favor, then argue like the devil. Weak and lame.

You are just POed because APS customers expose your posts for what they are. Childish personal attacks.

I have always said the turbo kit setup you argued with me about can be made safe with the addition of the right parts. I have never said the turbo kit you argued with me about is crap. I have always said it is a good kit if upgraded with the right parts. You post is not only childish, but untrue. What are you, about 14 years old or is that just the maturity level of your posts?

 

Yeah, I figured somone would say something like this. Nice try, but I was talking about the forced induction aspect and not the engine build. Obviously one cannot go all APS with the forced induction AND the engine build parts, but my route still holds the number of manufacturers to a minimum in the total setup. And that has merit in my experience.

 

Interesting post. I will look into this. Do you know this is a bottleneck for a fact or do you just suspect it is a bottleneck in the exhaust flow that affects performance? This could potentially be tapered from the 3.5" to the 3" in such a way that there is no bottleneck. I don't know if it is or not, but I would like to see real evidence of actual exhaust flow restriction problems at say.... 600 wheel hp and below to support your claims before I accept them.

 

soo a PE oil pan wont work with a greddy TT kit either? and im currently running a APS fuel return on my procharger thanks to failsafe but if i had the $ i bet aam or CJ is a better unit why limit yourself?

 

test pipes into straight 3" is a bottle neck. even tapering is still restrictive to flow.

 

could be tapering , theoratically it is more restrictive, but probably in this case the effect is so minimal that it won't make any difference. I think the designer knew what he was doing.

 

how much power are you guys running if a dual 3" exhaust is holding you back? That's bigger than the single 4" exhaust the crazy high hp supras are using

 

Re read my posts. I never said things couldn't be mixed and matched successfully. I said something altogether different. There are several valid approaches. Yours is one, mine is another. Both have their merits and disadvantages. As I said.

For instance many have posted that they bought a Borla or other exhaust and some brand of test pipes and then an APS twin turbo system. Some of these people had to fabricate their own adapters and the like. Sometimes all this worked pretty good together. Often not. Yes like the Borla exhaust with the APS kits, they WILL work together, but WILL NOT work as good performance wise as the APS TTs with APS 2.5" test pipes and APS 2.5" exhaust. Many many posts of these people with problems of getting and maintaining desired boost and the like. Many of the eventual solutions to these problems turned out to be the parts of differing manufacturers did not work well together. Whereas the APS turbo kits, test pipes, plenum, and exhausts have been designed, tuned, and tested to work well together. Just because things can be thrown together and will work does not mean that is the best way to go. And it gets trickier with engine managment systems, fuel injectors and such. I have heard many many many more posts of people that mixed and matched parts that did not work as well as the APS TTs with the other parts being APS as well, than vice versa. Same thing has happened for other FI kits as well. Not saying it can't be done though. Many have done quite well. But they are also on their own if things go wrong in many cases. I have seen the success of how the APS parts have been designed, tested, and work together and better than most mixed and matched setups and prefer that route. And that route also has advantages as far as product support if there are problems. If you like your way better, so be it. It is just not for everybody.

 

In theory yes, but does this small amount of ?potential backpressure adversely affect performance at 650 wheel hp (which is where I eventually want to go)? In other words at 650 hp with an APS TT (or similar forced induction system), hi flow plenum, and APS 3.5 inch test pipes and APS 3" dual exhaust, would having the dual exhaust enlarged to 3.5" help performance, hurt performance, or be about the same? Just because you think it might hurt performance "on paper', does not mean it will. APS tested the system in actual practice. Do you have any actual evidence that making the dual exhausts 3.5 inches would help? How would the 3.5" dual exhausts affect low to midrange RPM power and torque? Bigger is not always better. Best to have actual tests on something like this before we say for certain it has deficiencies and what those deficiencies are, IMO. That it true regardless of the exhaust manufacturer, IMO.

 

it's not that having 3" isn't big enough, its the simple fact of an exhaust bottleneck. 3" turbo back is fine, and going to a 3.5" test pipe is good and nice but going back to 3" exhaust defeats the purpose. Ask any decent hp car if running bigger into smaller is good and they'll tell you the same thing.

if the APS is normally 3" from the turbo to exhaust (whatever exhaust you use) then that's fine, especially if you run the APS 3" true dual setup.

any kind of bottleneck is bad. I don't care what hp numbers we're talking about, a bottleneck is a bottleneck. It just becomes more pronounced at higher figures.

 

going from 3.5 to 3" is indeed a bottleneck, so better to have 3" all the way it gives a smoother flow, with the bottleneck, the flow becomes turbulent and might increase back pressure. But in this case the effect is minimal since even though you are going from 3.5 to 3 it is still free enough for your application, let us say for the sake of approximation it is as if you are running 2.8 " straight all the way which is in dual pipes more than enough.

 

I would like to first say I really have no idea but I was under the impression that going from a 3 1/2 down pipe to a 3 inch exhaust causes the air to move faster out of the pipe. Assuming that a 3 inch exhaust is appropriately for the engine. So 3 1/2 to 2 1/2 bad because 2 1/2 isn't enough anyways. Again I have no idea just what I thought.

 

i dont disagree aps has done a great job in all they have done and adressing as many aspects of the motor to make their kit work or perform best my main point is dont limit yourself when there are much better parts out there but maby you just enjoy the car finished and not have to worry about the parts mesh i respect that but if there is a plenum/exhaust that flows better then / makes more power than aps i would use it just because the parts were tested together dont mean they will be the best in the end imo or maby you prefer the exhaust note of another brand or true return fuel system etc.. any who happy modding

 

there's no scavenging effect in exhaust post turbo. The turbo is basically forcing the air out as fast as it can and any bottleneck slows down that flow.

 

OK makes sense. So in a NA car my statement may be valid?

 

Regarding a possible bottleneck in the APS 3.5" test pipes into APS 3" dual exhausts: I remembered APS and others discussing several times back in the past that the part of the exhaust immediately after the turbo needs to be larger and that this is the most important portion of the exhaust.

Anyway, I contacted APS to verify my and some of you guys thinking on this and they definitely agree. I think they know of what they speak.

In short the exhaust gas temps are hottest right after the turbocharger (gases still expanding) so this is the reason why APS designed the larger test pipes. The test pipes taper back to 3 inch just before the connection flange to ensure a smooth transition of gas flow into the intermediate pipes which are 3 inch pipes.

In theory and practise the size of the exhaust system needs to be largest
when closer to the turbo charger and can then reduce in diameter/size (as
the gases cool off) over the rest of the exhaust system, EG, the exhaust
system could easily have 3.5 inch test pipes connecting to 3 inch
intermediate pipes connecting to possibly 2.5 inch tail pipes. This
ensures high gas flow and helps to reduce/eliminate exhaust drone. In
reality the size of the tubing required simply depends on the intended HP
level. Larger engine pipes or down pipes (which ever you chose to call them)
are critical on turbocharged engines as the gases are very hot right after
the turbocharger, the first 20 inches or so are the most critical part of
the exhaust system on a turbo engine.

It is better to have a high flowing exhaust system with larger test pipes (3.5 to 4 inch test pipes) mated to a twin 3 inch exhaust than a 3 inch twin exhaust system with smaller 3 inch test pipes. Simply put the larger test pipes will handle the higher gas temps and flow more quickly and help to reduce the total exhaust back pressure.

The 3.5 inch test pipes taper back to 3 inch to ensure a smooth transition between the test pipes and the 3 inch intermediate pipes.