power gains on a budget?
02-26-12, 10:48 PM
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power gains on a budget?
what can i do to gain a lil bit of power on my na s4? for under 500? i was thinking exhaust but everyones telling me its useless on an na...remove cats?
02-26-12, 11:47 PM
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header helps alot along with the rest of the exhaust. cats are nice to keep for most (lots of unwanted attention if ya know what I mean), but I like the fire and noise/smell. so high flow cats are a nice way to avoid the issue of piggys. But if your up for the work. stand alone is the best bang for your buck. I think someone got 190ishwhp out of a header, ecu, intake, and flywheel (s4 I think maybe). wheels help too, but another contender for best bang for your buck is a 4.33 gear set or a 4.44,4.55 if you dont care about gas mileage much 
.
Oliver
.Oliver
Last edited by youngfc; 02-27-12 at 12:09 AM.
02-27-12, 01:21 PM
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i've done a bunch of FC NA's and here are my thoughts. most of this stuff can be done inexpensively. there are a few areas to look at and small gains in each one can result in a fairly large improvement.
the first thing is to make sure everything is working. is the engine healthy? tune up recent? good fuel filters? the ignition is critical too, on a budget test the plug wires, they should be under 16k Ohms, the lower the better. is the double throttle opening? all the valves in the intake unstuck? TPS good? cooling system? thermostat?
the exhaust is #2. since its very easy, i recommend putting a pressure/boost gauge into the 6 port hose, and read exhaust back pressure. plan B is to tap some fitting in some where, or take an old O2 sensor, and makes something. to make the 6 ports work you need 2.75-3psi of backpressure. the stock exhaust will give about 3.5 with the cats. 1psi is approximately 8hp. the stock exhaust is 50mm ID which seems fine, 55-60mm would be good, and bigger than that is probably too big.
a header will help, but the off the shelf stuff needs some work before its really an advantage over the stock manifold. the stock exhaust port is about 48mm and the stock manifold is 50mm, an RB header inlet is 43mm... so there is instantly a big bad port mismatch. the real problem is that the exhaust port is too big, 43mm is the right size for the header tubes but we can't fix that on a budget. the IS enough meat on the RB header to port match it. also the length of the RB piece is questionable, this is actually easier to change, they sell tubing, and bends, but cutting and pasting the header on a dyno isn't a budget option.
thirdly the tuning is important. on a budget S4's can use a little more timing (2-4 degrees), but the fuel is already pretty good. the S5's on the other hand run really rich, but don't seem to want more timing, so an SAFC works really well. being able to try a couple of different settings with timing and fuel is important, each engine is going to vary a little depending on its condition, and how the intake/exhaust is setup.
the next step would be something like an Rtek, which is still inexpensive.
fourth if you have the engine apart, find TDC on the pulley. then be really picky about housing condition and seal clearances, more sealing = more power.
fifth, change the oil! synthetic oil in the diff, and trans is good. lighter weight engine oil helps, you don't need to go nuts, but instead of 20-50, try 10-40 or 10-30. also put shorter tires on it, going from the stock 205-60-15's to 205-50-15's really woke the car up! its like going from the 4.1 to the 4.3 diff. also consider an alignment, stock uses a ton of toe in, and less toe in really does help the handling
examples. a couple years ago i was given a low mileage stock S4 NA. i pretty much went thru the car and gave it what they used to call a "power tune". first thing i did was hook up the back pressure gauge, second thing i did was hollow out the melted precat. then i put a SAFC into it, which didn't do much. then i played with timing. then it wanted better plug wires. the thing ended up much faster than my friends S4 NA, butt dyno says 10-15hp over how it was when i got it, cost of parts was $80 for the SAFC, and maybe another $80 for plugs and wires and fuel filters.
the first thing is to make sure everything is working. is the engine healthy? tune up recent? good fuel filters? the ignition is critical too, on a budget test the plug wires, they should be under 16k Ohms, the lower the better. is the double throttle opening? all the valves in the intake unstuck? TPS good? cooling system? thermostat?
the exhaust is #2. since its very easy, i recommend putting a pressure/boost gauge into the 6 port hose, and read exhaust back pressure. plan B is to tap some fitting in some where, or take an old O2 sensor, and makes something. to make the 6 ports work you need 2.75-3psi of backpressure. the stock exhaust will give about 3.5 with the cats. 1psi is approximately 8hp. the stock exhaust is 50mm ID which seems fine, 55-60mm would be good, and bigger than that is probably too big.
a header will help, but the off the shelf stuff needs some work before its really an advantage over the stock manifold. the stock exhaust port is about 48mm and the stock manifold is 50mm, an RB header inlet is 43mm... so there is instantly a big bad port mismatch. the real problem is that the exhaust port is too big, 43mm is the right size for the header tubes but we can't fix that on a budget. the IS enough meat on the RB header to port match it. also the length of the RB piece is questionable, this is actually easier to change, they sell tubing, and bends, but cutting and pasting the header on a dyno isn't a budget option.
thirdly the tuning is important. on a budget S4's can use a little more timing (2-4 degrees), but the fuel is already pretty good. the S5's on the other hand run really rich, but don't seem to want more timing, so an SAFC works really well. being able to try a couple of different settings with timing and fuel is important, each engine is going to vary a little depending on its condition, and how the intake/exhaust is setup.
the next step would be something like an Rtek, which is still inexpensive.
fourth if you have the engine apart, find TDC on the pulley. then be really picky about housing condition and seal clearances, more sealing = more power.
fifth, change the oil! synthetic oil in the diff, and trans is good. lighter weight engine oil helps, you don't need to go nuts, but instead of 20-50, try 10-40 or 10-30. also put shorter tires on it, going from the stock 205-60-15's to 205-50-15's really woke the car up! its like going from the 4.1 to the 4.3 diff. also consider an alignment, stock uses a ton of toe in, and less toe in really does help the handling
examples. a couple years ago i was given a low mileage stock S4 NA. i pretty much went thru the car and gave it what they used to call a "power tune". first thing i did was hook up the back pressure gauge, second thing i did was hollow out the melted precat. then i put a SAFC into it, which didn't do much. then i played with timing. then it wanted better plug wires. the thing ended up much faster than my friends S4 NA, butt dyno says 10-15hp over how it was when i got it, cost of parts was $80 for the SAFC, and maybe another $80 for plugs and wires and fuel filters.
02-27-12, 03:34 PM
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i've done a bunch of FC NA's and here are my thoughts. most of this stuff can be done inexpensively. there are a few areas to look at and small gains in each one can result in a fairly large improvement.
the first thing is to make sure everything is working. is the engine healthy? tune up recent? good fuel filters? the ignition is critical too, on a budget test the plug wires, they should be under 16k Ohms, the lower the better. is the double throttle opening? all the valves in the intake unstuck? TPS good? cooling system? thermostat?
the exhaust is #2. since its very easy, i recommend putting a pressure/boost gauge into the 6 port hose, and read exhaust back pressure. plan B is to tap some fitting in some where, or take an old O2 sensor, and makes something. to make the 6 ports work you need 2.75-3psi of backpressure. the stock exhaust will give about 3.5 with the cats. 1psi is approximately 8hp. the stock exhaust is 50mm ID which seems fine, 55-60mm would be good, and bigger than that is probably too big.
a header will help, but the off the shelf stuff needs some work before its really an advantage over the stock manifold. the stock exhaust port is about 48mm and the stock manifold is 50mm, an RB header inlet is 43mm... so there is instantly a big bad port mismatch. the real problem is that the exhaust port is too big, 43mm is the right size for the header tubes but we can't fix that on a budget. the IS enough meat on the RB header to port match it. also the length of the RB piece is questionable, this is actually easier to change, they sell tubing, and bends, but cutting and pasting the header on a dyno isn't a budget option.
thirdly the tuning is important. on a budget S4's can use a little more timing (2-4 degrees), but the fuel is already pretty good. the S5's on the other hand run really rich, but don't seem to want more timing, so an SAFC works really well. being able to try a couple of different settings with timing and fuel is important, each engine is going to vary a little depending on its condition, and how the intake/exhaust is setup.
the next step would be something like an Rtek, which is still inexpensive.
fourth if you have the engine apart, find TDC on the pulley. then be really picky about housing condition and seal clearances, more sealing = more power.
fifth, change the oil! synthetic oil in the diff, and trans is good. lighter weight engine oil helps, you don't need to go nuts, but instead of 20-50, try 10-40 or 10-30. also put shorter tires on it, going from the stock 205-60-15's to 205-50-15's really woke the car up! its like going from the 4.1 to the 4.3 diff. also consider an alignment, stock uses a ton of toe in, and less toe in really does help the handling
examples. a couple years ago i was given a low mileage stock S4 NA. i pretty much went thru the car and gave it what they used to call a "power tune". first thing i did was hook up the back pressure gauge, second thing i did was hollow out the melted precat. then i put a SAFC into it, which didn't do much. then i played with timing. then it wanted better plug wires. the thing ended up much faster than my friends S4 NA, butt dyno says 10-15hp over how it was when i got it, cost of parts was $80 for the SAFC, and maybe another $80 for plugs and wires and fuel filters.
the first thing is to make sure everything is working. is the engine healthy? tune up recent? good fuel filters? the ignition is critical too, on a budget test the plug wires, they should be under 16k Ohms, the lower the better. is the double throttle opening? all the valves in the intake unstuck? TPS good? cooling system? thermostat?
the exhaust is #2. since its very easy, i recommend putting a pressure/boost gauge into the 6 port hose, and read exhaust back pressure. plan B is to tap some fitting in some where, or take an old O2 sensor, and makes something. to make the 6 ports work you need 2.75-3psi of backpressure. the stock exhaust will give about 3.5 with the cats. 1psi is approximately 8hp. the stock exhaust is 50mm ID which seems fine, 55-60mm would be good, and bigger than that is probably too big.
a header will help, but the off the shelf stuff needs some work before its really an advantage over the stock manifold. the stock exhaust port is about 48mm and the stock manifold is 50mm, an RB header inlet is 43mm... so there is instantly a big bad port mismatch. the real problem is that the exhaust port is too big, 43mm is the right size for the header tubes but we can't fix that on a budget. the IS enough meat on the RB header to port match it. also the length of the RB piece is questionable, this is actually easier to change, they sell tubing, and bends, but cutting and pasting the header on a dyno isn't a budget option.
thirdly the tuning is important. on a budget S4's can use a little more timing (2-4 degrees), but the fuel is already pretty good. the S5's on the other hand run really rich, but don't seem to want more timing, so an SAFC works really well. being able to try a couple of different settings with timing and fuel is important, each engine is going to vary a little depending on its condition, and how the intake/exhaust is setup.
the next step would be something like an Rtek, which is still inexpensive.
fourth if you have the engine apart, find TDC on the pulley. then be really picky about housing condition and seal clearances, more sealing = more power.
fifth, change the oil! synthetic oil in the diff, and trans is good. lighter weight engine oil helps, you don't need to go nuts, but instead of 20-50, try 10-40 or 10-30. also put shorter tires on it, going from the stock 205-60-15's to 205-50-15's really woke the car up! its like going from the 4.1 to the 4.3 diff. also consider an alignment, stock uses a ton of toe in, and less toe in really does help the handling
examples. a couple years ago i was given a low mileage stock S4 NA. i pretty much went thru the car and gave it what they used to call a "power tune". first thing i did was hook up the back pressure gauge, second thing i did was hollow out the melted precat. then i put a SAFC into it, which didn't do much. then i played with timing. then it wanted better plug wires. the thing ended up much faster than my friends S4 NA, butt dyno says 10-15hp over how it was when i got it, cost of parts was $80 for the SAFC, and maybe another $80 for plugs and wires and fuel filters.
02-27-12, 04:41 PM
#6
i've done a bunch of FC NA's and here are my thoughts. most of this stuff can be done inexpensively. there are a few areas to look at and small gains in each one can result in a fairly large improvement.
the first thing is to make sure everything is working. is the engine healthy? tune up recent? good fuel filters? the ignition is critical too, on a budget test the plug wires, they should be under 16k Ohms, the lower the better. is the double throttle opening? all the valves in the intake unstuck? TPS good? cooling system? thermostat?
the exhaust is #2. since its very easy, i recommend putting a pressure/boost gauge into the 6 port hose, and read exhaust back pressure. plan B is to tap some fitting in some where, or take an old O2 sensor, and makes something. to make the 6 ports work you need 2.75-3psi of backpressure. the stock exhaust will give about 3.5 with the cats. 1psi is approximately 8hp. the stock exhaust is 50mm ID which seems fine, 55-60mm would be good, and bigger than that is probably too big.
a header will help, but the off the shelf stuff needs some work before its really an advantage over the stock manifold. the stock exhaust port is about 48mm and the stock manifold is 50mm, an RB header inlet is 43mm... so there is instantly a big bad port mismatch. the real problem is that the exhaust port is too big, 43mm is the right size for the header tubes but we can't fix that on a budget. the IS enough meat on the RB header to port match it. also the length of the RB piece is questionable, this is actually easier to change, they sell tubing, and bends, but cutting and pasting the header on a dyno isn't a budget option.
thirdly the tuning is important. on a budget S4's can use a little more timing (2-4 degrees), but the fuel is already pretty good. the S5's on the other hand run really rich, but don't seem to want more timing, so an SAFC works really well. being able to try a couple of different settings with timing and fuel is important, each engine is going to vary a little depending on its condition, and how the intake/exhaust is setup.
the next step would be something like an Rtek, which is still inexpensive.
fourth if you have the engine apart, find TDC on the pulley. then be really picky about housing condition and seal clearances, more sealing = more power.
fifth, change the oil! synthetic oil in the diff, and trans is good. lighter weight engine oil helps, you don't need to go nuts, but instead of 20-50, try 10-40 or 10-30. also put shorter tires on it, going from the stock 205-60-15's to 205-50-15's really woke the car up! its like going from the 4.1 to the 4.3 diff. also consider an alignment, stock uses a ton of toe in, and less toe in really does help the handling
examples. a couple years ago i was given a low mileage stock S4 NA. i pretty much went thru the car and gave it what they used to call a "power tune". first thing i did was hook up the back pressure gauge, second thing i did was hollow out the melted precat. then i put a SAFC into it, which didn't do much. then i played with timing. then it wanted better plug wires. the thing ended up much faster than my friends S4 NA, butt dyno says 10-15hp over how it was when i got it, cost of parts was $80 for the SAFC, and maybe another $80 for plugs and wires and fuel filters.
the first thing is to make sure everything is working. is the engine healthy? tune up recent? good fuel filters? the ignition is critical too, on a budget test the plug wires, they should be under 16k Ohms, the lower the better. is the double throttle opening? all the valves in the intake unstuck? TPS good? cooling system? thermostat?
the exhaust is #2. since its very easy, i recommend putting a pressure/boost gauge into the 6 port hose, and read exhaust back pressure. plan B is to tap some fitting in some where, or take an old O2 sensor, and makes something. to make the 6 ports work you need 2.75-3psi of backpressure. the stock exhaust will give about 3.5 with the cats. 1psi is approximately 8hp. the stock exhaust is 50mm ID which seems fine, 55-60mm would be good, and bigger than that is probably too big.
a header will help, but the off the shelf stuff needs some work before its really an advantage over the stock manifold. the stock exhaust port is about 48mm and the stock manifold is 50mm, an RB header inlet is 43mm... so there is instantly a big bad port mismatch. the real problem is that the exhaust port is too big, 43mm is the right size for the header tubes but we can't fix that on a budget. the IS enough meat on the RB header to port match it. also the length of the RB piece is questionable, this is actually easier to change, they sell tubing, and bends, but cutting and pasting the header on a dyno isn't a budget option.
thirdly the tuning is important. on a budget S4's can use a little more timing (2-4 degrees), but the fuel is already pretty good. the S5's on the other hand run really rich, but don't seem to want more timing, so an SAFC works really well. being able to try a couple of different settings with timing and fuel is important, each engine is going to vary a little depending on its condition, and how the intake/exhaust is setup.
the next step would be something like an Rtek, which is still inexpensive.
fourth if you have the engine apart, find TDC on the pulley. then be really picky about housing condition and seal clearances, more sealing = more power.
fifth, change the oil! synthetic oil in the diff, and trans is good. lighter weight engine oil helps, you don't need to go nuts, but instead of 20-50, try 10-40 or 10-30. also put shorter tires on it, going from the stock 205-60-15's to 205-50-15's really woke the car up! its like going from the 4.1 to the 4.3 diff. also consider an alignment, stock uses a ton of toe in, and less toe in really does help the handling
examples. a couple years ago i was given a low mileage stock S4 NA. i pretty much went thru the car and gave it what they used to call a "power tune". first thing i did was hook up the back pressure gauge, second thing i did was hollow out the melted precat. then i put a SAFC into it, which didn't do much. then i played with timing. then it wanted better plug wires. the thing ended up much faster than my friends S4 NA, butt dyno says 10-15hp over how it was when i got it, cost of parts was $80 for the SAFC, and maybe another $80 for plugs and wires and fuel filters.
I have a header back RB road race dual exhaust system and I can feel that I have more power. If I add a safc and a rtek, how much more power do you think I can get if I go get it dyno tuned?
02-27-12, 04:47 PM
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thanks for this valueable info!! i just bought the car it has a 70kmile motor that was gone through before swapping all new belts and plugs an wires oil in synthetic working on suspension already. trying to figure out an exhaust route i can fab a single side catback my self for relitivly cheap. but i was guna ask wich is better safc or rtek? how hard is it to install an tune with no prior experience?
the good thing is that both start with the stock tune, and you tweak from there. the SAFC is easier, just because its only adjusting fuel, and it doesn't need a palm device like the Rtek does.
single side catback is fine, just make it 50-60mm INSIDE diameter, and the straighter the better. muffler is up to you but it should flow more than 500cfm, and/or be straight thru
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02-29-12, 04:38 AM
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the Rtek is easier to install, its plug and play. the SAFC needs a little simple wiring.
the good thing is that both start with the stock tune, and you tweak from there. the SAFC is easier, just because its only adjusting fuel, and it doesn't need a palm device like the Rtek does.
single side catback is fine, just make it 50-60mm INSIDE diameter, and the straighter the better. muffler is up to you but it should flow more than 500cfm, and/or be straight thru
the good thing is that both start with the stock tune, and you tweak from there. the SAFC is easier, just because its only adjusting fuel, and it doesn't need a palm device like the Rtek does.
single side catback is fine, just make it 50-60mm INSIDE diameter, and the straighter the better. muffler is up to you but it should flow more than 500cfm, and/or be straight thru
04-06-12, 09:05 PM
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