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Discussion Starter #1
Ok so i just got off the phone with KB and roush Supercharger and they both told me not to get long tube headers if i was going to get a SC because it was going to decrease the psi and i was not going to see any gain in performance.
All they recommended was a mid pipe and go straight to the SC. What do u guys think???
 

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The Blue Dragon
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Long tubes will decrease your overall psi because there is less back pressure, all in all it is a good supporting mod to have, not sure at what point LT's become necessary but I know that if you plan on higher boost then LT's are a must.

I have no proof of this but my speculation would be that less back pressure also means less stress on the motor and will also allow you to run higher boost in the long run
 

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Discussion Starter #3
GrabberBlue5.0 said:
Long tubes will decrease your overall psi because there is less back pressure, all in all it is a good supporting mod to have, not sure at what point LT's become necessary but I know that if you plan on higher boost then LT's are a must.

I have no proof of this but my speculation would be that less back pressure also means less stress on the motor and will also allow you to run higher boost in the long run
I thought the same but i talked to this guys and one of them has a 2012 5.0 with a roush and he said that LT would not be worth the $$$ with a SC, he was making 700 hp to the crank and had this set up for almost 2 years.
 

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The Blue Dragon
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2 years but how many miles? I could put a s/c on a car and have it for 100 years with no issue if I don't drive it haha.

They are not essential, most s/c cars come with just regular manifolds from factory, but we've also seen that it is more efficient with LT's. More air out also means more air in
 

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Discussion Starter #5
GrabberBlue5.0 said:
2 years but how many miles? I could put a s/c on a car and have it for 100 years with no issue if I don't drive it haha.

They are not essential, most s/c cars come with just regular manifolds from factory, but we've also seen that it is more efficient with LT's. More air out also means more air in
It was his daily driver so i dont know,
 

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I agree with grabber. I'm not gonna argue roush or kb, they obviously know more than I but the way it was explained to me is you'll run less psi w/ lts cuz the engine is operating more efficiently. I run a 10 psi pulley with 1 7/8 lts. My car is also 700 crank with a conservative tune. And if you can run the same power on less boost I'd think that would be a good thing!
 

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It probably has more to do with their tunes. I had a 3" turbo back exhaust with my sti. 2.5 litre. Ana yours is twice that. Do the math. We are talking efficiency here. Back pressure is for motors who cant let air out as well as they take in. Just saying.
 

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The Blue Dragon
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Black5.0 said:
I agree with grabber. I'm not gonna argue roush or kb, they obviously know more than I but the way it was explained to me is you'll run less psi w/ lts cuz the engine is operating more efficiently. I run a 10 psi pulley with 1 7/8 lts. My car is also 700 crank with a conservative tune. And if you can run the same power on less boost I'd think that would be a good thing!
Thanks! Explained this better than I could! Think of it like trying to exhale through a coffee straw vs a regular straw, but still inhaling normally. You gotta blow harder through the coffee straw to move the same air out as the regular straw with less force. Not that one is more powerful, just easier, and you won't pop a blood vessel in your eye trying to do it lol.

This is very much an oversimplification, but used to help visualize my point
 

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Grove2504 said:
It probably has more to do with their tunes. I had a 3" turbo back exhaust with my sti. 2.5 litre. Ana yours is twice that. Do the math. We are talking efficiency here. Back pressure is for motors who cant let air out as well as they take in. Just saying.
I really should not post if I've been drinking.
 

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It all has to do with the dinamic compression ratio, u have ur effective compression ratio , and the dinamic which is when the engine is moving , thats really ahrd to explain but it changes depending on your piston heads, rods , etc and the main factor is the psi induced, now if you have long tube header, u DCR will be lower so you can add more psi but at the same time a guy with the same setup a lower psi will be making your numbers, at the end of the day , the less psi you run , the less the stress on the engine
 
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