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if i upgrade my wrx for an sti, will i be able to put my uppipe into the sti? i know the sti is catless but i heard that it still helps becasue of the wider piping. Or is there no point to put it on? thanks
 

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you'd get mayyyyybe 5 ponies. Hell...you get 5 ponies everytime the temp drops 20 degrees. Wouldn't mess with it. Not worth the 4 hour install.
 

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Every pony counts. 5 HP may not be much but you gotta get em where you can. I have heard headers/upipe combo helps the high end. By looking at the stock power curve, the engine could use some power in the high rpm range...

I would say keep it.. You are not going to get any more money out of the WRX by having it on there. Hell, if you told them it was on there they would probably give you less for you car assuming you had raced it.

True it would be a pain to un-install it on the WRX, install the stock pipe, and install the pipe on the STi but hey... You probably spent at least 150$ on the pipe. Why let money go down the drain?
 

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slowmo said:
Every pony counts. 5 HP may not be much but you gotta get em where you can. I have heard headers/upipe combo helps the high end. By looking at the stock power curve, the engine could use some power in the high rpm range...

I would say keep it.. You are not going to get any more money out of the WRX by having it on there. Hell, if you told them it was on there they would probably give you less for you car assuming you had raced it.

True it would be a pain to un-install it on the WRX, install the stock pipe, and install the pipe on the STi but hey... You probably spent at least 150$ on the pipe. Why let money go down the drain?

Where he picks up 5 hp top end he's going to lose spool time. Opening up the up-pipe is going to make the exhaust velocity slower. This is why Header's also make slower spooling. The difference is the header opens it up closer to the engine creatinig more power where the up-pipe just doesn't do much at all.

If he's already got the pipe I would sell it rather than install it. He could prolly get at least 100 bucks outta it and that money could go towards something more useful on the car.
 

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scooby24 said:
you'd get mayyyyybe 5 ponies. Hell...you get 5 ponies everytime the temp drops 20 degrees. Wouldn't mess with it. Not worth the 4 hour install.
not worth the leaks of death!
 

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scooby24 said:
Where he picks up 5 hp top end he's going to lose spool time. Opening up the up-pipe is going to make the exhaust velocity slower. This is why Header's also make slower spooling. The difference is the header opens it up closer to the engine creatinig more power where the up-pipe just doesn't do much at all.

If he's already got the pipe I would sell it rather than install it. He could prolly get at least 100 bucks outta it and that money could go towards something more useful on the car.
As for the upipe slowing down the exhaust because it opens up. No. Same amount of exhaust travels through the hot side no matter what. The path to the hot side is less restrictive, so the engine breathes better and +hp.

Headers can slow down the exhaust as they tend to cool the exhaust gasses more than the stock manifolds. That is if you don't wrap, or ceramic coat the headers. If done right the engine breathes better and exhaust doesn't cool off enough to reduce spool time. ie less exhaust .. uhh.. contraction.

Up pipe is a pain though. Exhaust leaks are even worse. Lots of work for extra power.

-Eric-
 

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Tgui said:
As for the upipe slowing down the exhaust because it opens up. No. Same amount of exhaust travels through the hot side no matter what. The path to the hot side is less restrictive, so the engine breathes better and +hp.

Headers can slow down the exhaust as they tend to cool the exhaust gasses more than the stock manifolds. That is if you don't wrap, or ceramic coat the headers. If done right the engine breathes better and exhaust doesn't cool off enough to reduce spool time. ie less exhaust .. uhh.. contraction.

Up pipe is a pain though. Exhaust leaks are even worse. Lots of work for extra power.

-Eric-

I'm sorry but this post is absolutely false.

Opening up the up-pipe WILL slow down the velocity. Period. If you can't understand that please go back to high school and play with straws. Blow through a small straw with your hand over the end...air moves faster. Blow through a thick straw with your hand on the end. Air moves slower.


While the header does lose more heat, even a wrapped and coated header will lose spool time slightly. They have done tests on both coated and uncoated headers and found the difference in spool nearly identical showing the heat loss does not play the largest part in the increased lag. The larger overall pipe diameter plays a much larger role.

Regardless, the header increase horsepower and torque enough to make it worth it in my mind to install a header....the increase in hp from an up-pipe would not be worth it, due to the loss in spool time which is important between shifts. What you gain in hp you most likely lose in overall speed due to lag.
 

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I'm trying to get my head around the "discussion" above.

Here's my question. How does changing the size (opening up) the up pipe or the exhaust manifold (headers) affect the spool up time if the turbine inlet/outlet size doesn't change?

I get the argument about the straw size, although it should be said that for a given volume/flow of air, changing the straw diameter will affect the velocity. Obviously if you increased the air flow, the larger straw would flow more air, and at a higher ultimate velocity than the smaller straw. Since the amount of air isn't changing, I grant that the smaller straw will have the higher velocity. Again though, it seems to me that a better analogy would be comparing a small and large straw connected to the same size opening. Only so much can pass through the opening, regardless of the size of the straw. Isn't the opening the limiting factor, and not the size of the straw? Granted, exhaust is a compressible gas, so maybe this is the factor being overlooked? Compressing it in the smaller straw increases the discharge speed since it is at a higher pressure? Please fill me in.
 

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scooby24 said:
I'm sorry but this post is absolutely false.

Opening up the up-pipe WILL slow down the velocity. Period. If you can't understand that please go back to high school and play with straws. Blow through a small straw with your hand over the end...air moves faster. Blow through a thick straw with your hand on the end. Air moves slower.


While the header does lose more heat, even a wrapped and coated header will lose spool time slightly. They have done tests on both coated and uncoated headers and found the difference in spool nearly identical showing the heat loss does not play the largest part in the increased lag. The larger overall pipe diameter plays a much larger role.

Regardless, the header increase horsepower and torque enough to make it worth it in my mind to install a header....the increase in hp from an up-pipe would not be worth it, due to the loss in spool time which is important between shifts. What you gain in hp you most likely lose in overall speed due to lag.
Read up on some fluid mechanics some time. Well, here ya go! Its called the "Venturi Effect"

http://online.cctt.org/physicslab/content/PhyAPB/lessonnotes/fluids/dynamics.asp

And I do understand the principle, since mechanical engineering was one of my majors(degrees) back in the day. Maybe you should read up a little to further your post high school education.

Since the cross section area of the hot side 'input' (cross sectional area) of the turbo never changes no matter the size of the up pipe, the the velocity of the air reaching the blades/impeller whatever, is the same. You seem to understand straws, you just didn't remember the limiting factor in this case, the turbo hot side.

And who is 'they', as in the they that do these test on these headers? Have a link to 'they'? Back up your facts. Heat loss plays a major factor in exhaust gas entropy (heat in exhaust for you).

You might not understand the math, but the pretty picture will help.
http://www.grc.nasa.gov/WWW/K-12/airplane/entropy.html

Lower the temp of the gas, the effective volume that this exhaust gas fills is less. In the real world we could refer this by, say, volumetric flux. Or a given volume of air to pass through a cross sectional area (pipe diameter). Lower the entropy, you then lower the volumetric flux of air. Lower the volumetric flux of the air, you effectively lower the amount of exhaust to spin the turbine.

Read this.
http://www.peoplephysics.com/physics-laws6.htm
..and I quote
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"the speed of the liquid,according to the definition of the volumetric flux( Q = SV in m3/s ), varies with the inverse proportionality law in relation to the section of the pipe (S1d1 = r S2 d2; S1V1Dt = S2 V2Dt ,we deduce that if, in particular, the pipe is horizontal, the speed increases where the section diminishes and that therefore,because the sum of the 3 pressures must be constant,in a narrowing pipe the pressure diminishes."
--------------

Don't get your panties in a bunch with the above quote by letting your mind wander back to the false statement that the bigger up - pipe will hurt spool because of cross sectional area enlargement BECAUSE, the hot side turbine 'input', never changes.

Possible other effects that I don't have time to find links for.

-New up pipe & Headers. Possible more direct and smooth flow of gases. Read some 'Heat Transfer', (think of fluid mechanics + thermodynamics), and you'll find laminar (smooth) flow of a gas will transfer less heat to its surrounding medium. Once again, more volumetric flux efficiency. Also the velocity of the exhaust gases will be faster, ie better spool. Faster exhaust in the sense that matters. Ignoring pipe cross section area, a smoother less kinked up path will enable better spool in the end as the gas spends less time getting tangled up in turbulent flow.

Short version.... wrap or coat the headers and up pipe, and you'll be cool. Keep the heat in. Pipe diameter really doesn't matter (within reason). The hot side input of the turbine stays the same. Maximize heat retention and a smooth path for gases.

-And... I have to get back to my real job.


Don't spread mis-information. Pick up a book. Understand the end cases of the particular model you're trying to argue.
-Eric-
 

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YBNormal07 said:
I'm trying to get my head around the "discussion" above.

Here's my question. How does changing the size (opening up) the up pipe or the exhaust manifold (headers) affect the spool up time if the turbine inlet/outlet size doesn't change?

I get the argument about the straw size, although it should be said that for a given volume/flow of air, changing the straw diameter will affect the velocity. Obviously if you increased the air flow, the larger straw would flow more air, and at a higher ultimate velocity than the smaller straw. Since the amount of air isn't changing, I grant that the smaller straw will have the higher velocity. Again though, it seems to me that a better analogy would be comparing a small and large straw connected to the same size opening. Only so much can pass through the opening, regardless of the size of the straw. Isn't the opening the limiting factor, and not the size of the straw? Granted, exhaust is a compressible gas, so maybe this is the factor being overlooked? Compressing it in the smaller straw increases the discharge speed since it is at a higher pressure? Please fill me in.
Yup, you got it! For the most part ;)

I just saw your last sentence.

A smaller exhaust will increase back pressure. Not good for getting exhaust out of the engine efficiently, bad for power. Velocity will increase, but once again will be limited by the hotside. Give the exhaust an easy path to the hotside. Keep heat in.


-Eric-
 

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In a smooth flowing system your arguement would apply. The larger pipe tapering down to the smaller inlet of the exhaust housing would mean an increase in velocity as the volumetric space decreases in size.

However when you have a large pipe going ubuptly into a smaller inlet your velocity decreases due to the venturi effect being disrupted at the abrubt change in direction of the air flow at the outside of the larger up-pipe. The air flows along the pipe walls smoothly until they hit the "wall" of the inlet pipe. The "wall" would consist of the lip that is now formed due to the ID of the inlet pipe being smaller than the ID of the Up-pipe. That airflow now takes an abrupt 90* turn towards the center of the pipe and must merge with the smooth flowing air towards the center of the pipe. This abrupt merge slows down the exhaust as the swirling is now completely abnormalized.

It would work well if you were to taper the inlet pipe of the exhaust housing to the exhaust flow had a smooth transition from large pipe to small pipe.

I, too, have taken engineering classes. This is a basic principle of flow. Smooth transitions from large to small increase velocity and normalize swirling.

The insulting is not necessary. I was not directly insulting you with my previous post. The high school comment was directed by those who do not understand the basic principle of diameter vs velocity and since you obviously do then the insult does not apply to you.

I would expect more positive criticism from a college graduate. Proof that maturity does not come with education.
 

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One issue that was heavily discussed leading up to the header test was wrapping the headers. Conventional turbo-tuning wisdom dictates that you want to keep the exhaust gasses hot on their way to the turbo. Most headers are constructed of steel and loose heat much more quickly than the stock manifolds that are made of cast iron. The headers tested here were wrapped and each car/header combination was given three full runs on the dyno to make sure the header was fully up to temperature.

Surprisingly, most of the headers showed little difference between the runs and some of them even made less power with each run.
This is not the thread I was speaking of about the header comparison but it does show a little bit of what I was speaking on. I searched Nasioc for the thread I had seen previously but do not have the time to dedicate searching through countless matches to find it.

Regardless the header loss in temperature of EGT's is not debatable...an uncoated will lose more heat but I don't think that would account for as much loss in spool time as enlargening the manifold does.
 

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scooby24 said:
In a smooth flowing system your arguement would apply. The larger pipe tapering down to the smaller inlet of the exhaust housing would mean an increase in velocity as the volumetric space decreases in size.

However when you have a large pipe going ubuptly into a smaller inlet your velocity decreases due to the venturi effect being disrupted at the abrubt change in direction of the air flow at the outside of the larger up-pipe. The air flows along the pipe walls smoothly until they hit the "wall" of the inlet pipe. The "wall" would consist of the lip that is now formed due to the ID of the inlet pipe being smaller than the ID of the Up-pipe. That airflow now takes an abrupt 90* turn towards the center of the pipe and must merge with the smooth flowing air towards the center of the pipe. This abrupt merge slows down the exhaust as the swirling is now completely abnormalized.

It would work well if you were to taper the inlet pipe of the exhaust housing to the exhaust flow had a smooth transition from large pipe to small pipe.

I, too, have taken engineering classes. This is a basic principle of flow. Smooth transitions from large to small increase velocity and normalize swirling.

The insulting is not necessary. I was not directly insulting you with my previous post. The high school comment was directed by those who do not understand the basic principle of diameter vs velocity and since you obviously do then the insult does not apply to you.

I would expect more positive criticism from a college graduate. Proof that maturity does not come with education.
lol, keep digging a hole. Watch your snide comments in general. You directed your insults to everyone in the thread. Everone is to take offense, including me. Back peddle more?

Maturity with education. Thats cute. Yet another insult from you. I guess I can thus conclude maturity doesn't come with those lacking an education? You're just mad because you acted like a jerk, spread false information to inflate your ego, and someone who didn't appreciate your comments and who knows more than you, put you in your place while setting the facts straight.

You try to change the argument now by stating my statements are false becuase because I'm ovbiously talking about installing an up pipe with an inner diameter greater than that of the inner diameter of the exhaust housing input of the turbo. Yeah, turbulent flow would disrupt the exhaust gas path in this case. Its too bad I've never seen an up pipe with such a 'cool' design feature. You've never installed an up pipe have you?


Being a 'graduate' doesn't mean I'll sit idly by while someone makes offensive incorrect comments.

I'm done here.
-Eric-
 

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Tgui said:
lol, keep digging a hole. Watch your snide comments in general. You directed your insults to everyone in the thread. Everone is to take offense, including me. Back peddle more?

Maturity with education. Thats cute. Yet another insult from you. I guess I can thus conclude maturity doesn't come with those lacking an education? You're just mad because you acted like a jerk, spread false information to inflate your ego, and someone who didn't appreciate your comments and who knows more than you, put you in your place while setting the facts straight.

You try to change the argument now by stating my statements are false becuase because I'm ovbiously talking about installing an up pipe with an inner diameter greater than that of the inner diameter of the exhaust housing input of the turbo. Yeah, turbulent flow would disrupt the exhaust gas path in this case. Its too bad I've never seen an up pipe with such a 'cool' design feature. You've never installed an up pipe have you?


Being a 'graduate' doesn't mean I'll sit idly by while someone makes offensive incorrect comments.

I'm done here.
-Eric-
Alright Eric,

If you want to get into education and lack thereof we can do so. I graduated from a well respected college with excellent grades.

Please explain what "misinformation" I've posted. Prove anything I've said wrong.

And what on earth are you talking about here:
You try to change the argument now by stating my statements are false becuase because I'm ovbiously talking about installing an up pipe with an inner diameter greater than that of the inner diameter of the exhaust housing input of the turbo. Yeah, turbulent flow would disrupt the exhaust gas path in this case. Its too bad I've never seen an up pipe with such a 'cool' design feature. You've never installed an up pipe have you?

Where are you going to find an up-pipe with an ID the same size as the ID of the exhaust inlet? What "cool" design feature are you talking about? Tapering the size down? Take a look at the APS up-pipe. Yes I have installed several up-pipes before. I've installed a helix, erz (basically the same as helix), and an HKS. All were 2" which is a lot bigger than the inlet which I believe is 1.25"

On a WRX this would be acceptable because you are getting rid of the cat and that is a dramatic increase in spool. However the STi, which we are talking about, will not benefit from cat removal since it doesn't have one. Therefore the increase horsepower due to the larger size (which is very small and prolly couldn't even be felt) would be offset at the decrease velocity and slightly increase turbo lag.
 

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scooby24 said:
Alright Eric,

If you want to get into education and lack thereof we can do so. I graduated from a well respected college with excellent grades.

Please explain what "misinformation" I've posted. Prove anything I've said wrong.

And what on earth are you talking about here:
You try to change the argument now by stating my statements are false becuase because I'm ovbiously talking about installing an up pipe with an inner diameter greater than that of the inner diameter of the exhaust housing input of the turbo. Yeah, turbulent flow would disrupt the exhaust gas path in this case. Its too bad I've never seen an up pipe with such a 'cool' design feature. You've never installed an up pipe have you?

Where are you going to find an up-pipe with an ID the same size as the ID of the exhaust inlet? What "cool" design feature are you talking about? Tapering the size down? Take a look at the APS up-pipe. Yes I have installed several up-pipes before. I've installed a helix, erz (basically the same as helix), and an HKS. All were 2" which is a lot bigger than the inlet which I believe is 1.25"

On a WRX this would be acceptable because you are getting rid of the cat and that is a dramatic increase in spool. However the STi, which we are talking about, will not benefit from cat removal since it doesn't have one. Therefore the increase horsepower due to the larger size (which is very small and prolly couldn't even be felt) would be offset at the decrease velocity and slightly increase turbo lag.

Sigh. I'm really tired of this all. Bench 'physics' etc is no better than bench racing. I'm done with this (for the 2nd time ;) ) I'd like to stop this argument before this thread loses all value. We can keep refining 'what I was talking about' forever. You gave some knowledge and so did I. The nature of it all is that neither of us will fully understand what the other means do to the basic limitations of written(typed) word.

I reacted harshly because you came off really abrasive. Sorry about that. Perpetuating anger does not make buddha happy.

I'll see you around this board quite a bit, given this is my 2nd home. Peace?

BTW, what was your major? If it was computer related I might have a project you might be interested in. In the realm of (STi + UTEC).

-Eric-
 

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Thank you for a more level headed attitude. Sorry I came off as abrasive. I'm like you I don't like to see 'mis-information'. Obviously we both spoke truth but were not understanding each other and thus the spiraling downfall.

Yes I graduated with a Major in information systems. I was originally going to go for engineering but after taking every class in high school we had available I just didn't find it that interesting. Too many nit picky details on numbers and tolerances and all that junk. blah.
 

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scooby24 said:
Thank you for a more level headed attitude. Sorry I came off as abrasive. I'm like you I don't like to see 'mis-information'. Obviously we both spoke truth but were not understanding each other and thus the spiraling downfall.

Yes I graduated with a Major in information systems. I was originally going to go for engineering but after taking every class in high school we had available I just didn't find it that interesting. Too many nit picky details on numbers and tolerances and all that junk. blah.
Thank you for a more level headed attitude.

Watch for a cross platform UTEC utility.
 

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Cross platform how? Combining GUI with Utec's basic programming functions? Or adding Wideband logging with Utec logging?

I want to create a graph tool that will graph at throttle and RPM the boost, AFR, Timing, and EGT.

I think seeing all those points out on a graph would make a very useful tool for fine tuning the car with ease. I would also like to add in fuctionality that would allow the user to edit the logged map and move things around like timing, egt, etc on the graph itself and have that be dynamic enough to change map values in an attempt to get the tuning so easy to do my 14 year old sister wouldn't break a sweat.

I don't know how feasible that is though...would have to get a Tuning God to assist in the build would also probably have to recruit other programmers. Imagine the posibilities though. ;)
 
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