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Discussion Starter #1
Why do you think that having exhaust AFTER the turbo is going to anything for it ? The faster you get rid of the exhaust after the turbo the better, less restriction pushing back onto the turbine wheel.
This is what soembody told me after i said something about someones homemade remote mount turbo setup. is this correct cuz the dude was a bit of prick about it, so if he is right i can stand corrected or otherwise.
 

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im gonna take this as... "having an exhaust after the turbo will not help performance."

which is basicly true. the less exhaust the more power. most high hp boosters run maybe 3ft of unrestriced exhaust.
 

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Discussion Starter #3
what about in a low boost remote mount turbo setup for a truck? the guy has the exhaust dumped right after the turbo and i suggested that he add a little to the exhaust, but i guess i was wrong, thanks for the quick reply :TU:
 

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the more research i did on options of having exhaust against having an open downpipe i did find alot of good arguements that HAVING an exhaust did help with back pressure which the valve need and blah blah blah im not a big motor guy so search it abit
 

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the concept does seem to make sense... i imagine if the valvetrain was strong enough it would be better with less exhaust on a turbo setup-less heat, backpressure on turbo. kinda comes down to " upgrade one thing, you better upgrade everything"
 

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you need al il back pressure to build up that energy faster to make the turbo spool.. just a small 1 ft 3 inch section with a turn down is going to make the turbo more efficient than having a open exhaust housing
 

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You'll want some piping to ensure that all of the exhaust gases are expelled away from the engine bay.

Back pressure is never desirable in a performance application, neither in a naturally aspirated application nor in a forced induction application.
 

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Back pressure is never desirable in a performance application, neither in a naturally aspirated application nor in a forced induction application.
your right and your wrong at the same time.

http://www.flowmastermufflers.com/backpressure.html
http://www.veryuseful.com/mustang/tech/engine/exhaustScavenging.pdf

at high rpm, back pressure is not needed and indeed hurts performance. while at the same time back pressure promotes exhaust scavenging when at low rpms. when it is the most important to pull all the exhaust gases out of the cylinders to promote efficientcy.
 

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your right and your wrong at the same time.

http://www.flowmastermufflers.com/backpressure.html
http://www.veryuseful.com/mustang/tech/engine/exhaustScavenging.pdf

at high rpm, back pressure is not needed and indeed hurts performance. while at the same time back pressure promotes exhaust scavenging when at low rpms. when it is the most important to pull all the exhaust gases out of the cylinders to promote efficientcy.

exactly..

lol ever take an exhaust off a dog slow 4 cylinder ford ranger and rive it .. it makes no tq and goes slower than a old man with a walker.. it need backpressure to gain its midrange back
 

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at high rpm, back pressure is not needed and indeed hurts performance. while at the same time back pressure promotes exhaust scavenging when at low rpms. when it is the most important to pull all the exhaust gases out of the cylinders to promote efficientcy.
Back pressure itself doesn't promote scavenging. The smaller piping diameter promotes scavenging at lower engine speeds, which inevitably increases back pressure at higher engine speeds.

It is (currently) impossible to design a system in which efficiency is maximal at all engine speeds. Therefore, engine builders must identify the region of the powerband at which they desire peak torque (and therefore minimal back pressure). If this region is lower in the powerband, back pressure will increase at higher engine speeds, and efficiency will decline. If this region is higher in the powerband, efficiency will suffer at lower engine speeds.

In any case, it is better to concentrate on maximizing fluid velocity than minimizing back pressure.

Also, I said that back pressure is never desired in a performance application because for a street driven car, it's more useful to have ample torque at lower engine speeds. Furthermore, back pressure aids in noise suppression.
 

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Discussion Starter #12
The theory is correct but the term back pressure isn't what helps the scavenging effect, it's exhaust gas velocity. but you guys are absolutely right with everything else and it's not really the term that's important.

I'm just a noob with F/I systems, so i wasn't sure if the same theories worked for them as they do for N/A setups. Keep the conversation going i am learning a lot, which is why i am here :TU:
 

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It is (currently) impossible to design a system in which efficiency is maximal at all engine speeds

umm no its not... its just not PRACTICAL

all you need is a valve that gets bigger as the rpms rise
 

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It is (currently) impossible to design a system in which efficiency is maximal at all engine speeds

umm no its not... its just not PRACTICAL

all you need is a valve that gets bigger as the rpms rise
Ok, you're right, my choice of words was wrong. It's definitely is not practical though.
 
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