3" or 4" uppipe/downpipe
02-22-2014, 10:57 PM
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3" or 4" uppipe/downpipe
Hi guys! Wondering if u could give me some insight n help me with a decision that I need to make here soon. Im pretty sure I'm gonna end up going with an uppipe but I'm not sure yet cuz if I have enough space when I get everything in there I might run it out past the rad n out the pass side bumper. I'm just wondering if there will b any benefit by going with a 3.5" or even a 4" pipe when doing this? Mayb u guys can take a look at my setup n make some suggestions. My setup is 84.5x89 ~9.5-1 with pro1s, Afi top mount with t3 6265 .82 ar. Will b running e85 n power goal is around 700-750. Thanks mike
02-23-2014, 12:32 PM
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well I know it's gonna b loud but I also know that a 4" uppipe is louder than a 3" uppipe. There wasn't a question of whether it's gonna b loud or not, I know it will b loud either way that I may do it because I'm not gonna put a muffler on it either way. My question is whether or not it will be beneficial to make it larger than 3" because if not than I will just do 3".
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02-23-2014, 03:54 PM
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Re: 3" or 4" uppipe/downpipe
Here's mine...
3" V-band off the turbo to 3"-4" cone, then 4" down.
For a street car, hood exit is stupid. A race-only car, yes, hood exit is perfect.
3" V-band off the turbo to 3"-4" cone, then 4" down.
For a street car, hood exit is stupid. A race-only car, yes, hood exit is perfect.
02-23-2014, 04:43 PM
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Re: 3" or 4" uppipe/downpipe
hood exits are very loud.. and if you tune on the rich side you'll blow carbon soot all over the windshield and roof, it's even worse when it rains.
bumper exits are a bit quieter due to the fast air moving around the bumper slowing down the sound waves as they leave the exhaust, if you slash cut, radius, or turn down the exit it's even quieter. the same buffeting effect applies to the hood exits but the effect is much less due to the high or low pressure around the end of the pipe (depends on chassis, piping diameter, and exit design/placement)
also, if this is a purpose built drag car there is some consideration that needs to be made for the effect on aerodynamics each exhaust setup has. there's been a long debated theory that bumper exits cause the car to be pushed one way, opposite the exhaust exit side, due to the velocity of the exhaust gas, conversely some say that the hood exit assists downforce at high rpm due to the exhaust gasses at high rpm pushing the front end down
however without wind tunnel testing or extensive telemetry analysis this is all conjecture
do whatever you want, either setup won't have much effect on power and such, although a few people with short hood exits have had issues with wideband readouts as the reversion causes fresh air to be sucked into the exhaust, causing a skewed leaner than actual wideband reading.
bumper exits are a bit quieter due to the fast air moving around the bumper slowing down the sound waves as they leave the exhaust, if you slash cut, radius, or turn down the exit it's even quieter. the same buffeting effect applies to the hood exits but the effect is much less due to the high or low pressure around the end of the pipe (depends on chassis, piping diameter, and exit design/placement)
also, if this is a purpose built drag car there is some consideration that needs to be made for the effect on aerodynamics each exhaust setup has. there's been a long debated theory that bumper exits cause the car to be pushed one way, opposite the exhaust exit side, due to the velocity of the exhaust gas, conversely some say that the hood exit assists downforce at high rpm due to the exhaust gasses at high rpm pushing the front end down
however without wind tunnel testing or extensive telemetry analysis this is all conjecture
do whatever you want, either setup won't have much effect on power and such, although a few people with short hood exits have had issues with wideband readouts as the reversion causes fresh air to be sucked into the exhaust, causing a skewed leaner than actual wideband reading.
02-23-2014, 06:50 PM
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hood exits are very loud.. and if you tune on the rich side you'll blow carbon soot all over the windshield and roof, it's even worse when it rains. bumper exits are a bit quieter due to the fast air moving around the bumper slowing down the sound waves as they leave the exhaust, if you slash cut, radius, or turn down the exit it's even quieter. the same buffeting effect applies to the hood exits but the effect is much less due to the high or low pressure around the end of the pipe (depends on chassis, piping diameter, and exit design/placement) also, if this is a purpose built drag car there is some consideration that needs to be made for the effect on aerodynamics each exhaust setup has. there's been a long debated theory that bumper exits cause the car to be pushed one way, opposite the exhaust exit side, due to the velocity of the exhaust gas, conversely some say that the hood exit assists downforce at high rpm due to the exhaust gasses at high rpm pushing the front end down however without wind tunnel testing or extensive telemetry analysis this is all conjecture do whatever you want, either setup won't have much effect on power and such, although a few people with short hood exits have had issues with wideband readouts as the reversion causes fresh air to be sucked into the exhaust, causing a skewed leaner than actual wideband reading.
02-23-2014, 07:01 PM
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Re: 3" or 4" uppipe/downpipe
It is a full exhaust with the addition of a Quicktime Performance electric exhaust cut-out placed under the passengers feet area, with a switch on the dash to open/close on command.
Since my car is majority a street car, I can choose to keep the exhaust closed and quiet. When I need to open it up for full power/high flow, takes just 5-6 seconds to open it.
Best of both worlds.
Since my car is majority a street car, I can choose to keep the exhaust closed and quiet. When I need to open it up for full power/high flow, takes just 5-6 seconds to open it.
Best of both worlds.
02-23-2014, 07:11 PM
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Re: 3" or 4" uppipe/downpipe
No numbers on the new engine (in sig) yet.
Old engine is pictured. Just a basic stock sleeved piston/rod setup.
That setup made 420whp/280tq at 18-20psi on that little GT3076R @ 3500ft elevation
This new engine should make 450whp/300tq at the same boost pressure, same turbo, same elevation.
Keep in mind this is a street car and big power is not what I am looking for. Fat powerband is what I need/want. The top-mount and 4" DP is overkill but gives room for growth with this new engine. New engine is more than capable of pushing 800+ with a larger turbo and fuel system.
Old engine is pictured. Just a basic stock sleeved piston/rod setup.
That setup made 420whp/280tq at 18-20psi on that little GT3076R @ 3500ft elevation
This new engine should make 450whp/300tq at the same boost pressure, same turbo, same elevation.
Keep in mind this is a street car and big power is not what I am looking for. Fat powerband is what I need/want. The top-mount and 4" DP is overkill but gives room for growth with this new engine. New engine is more than capable of pushing 800+ with a larger turbo and fuel system.
02-23-2014, 08:13 PM
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Re: 3" or 4" uppipe/downpipe
Oh **** ha I was on the mobile app earlier n it don't show sigs. Nice setup tho, should deff make the power ur looking for.
02-23-2014, 09:38 PM
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Re: 3" or 4" uppipe/downpipe
I wouldnt consider a 3076 small, at least because I don't drag race lol
my 10.5:1-11:1 street/road course build is using a 2871 because I want lots of midrange torque since my main "home track" is Atlanta Motorsports Park which is a tight, technical course with a 200ft elevation change, I'll run Road Atlanta every so often but I think the back straight is too long for my turbo size, it's a good 4th gear run by the time you reach the braking zone.
that and on the street the 2871 is perfect IMO. I hate laggy turbos on the street, I got spoiled by the response and torque my 2860r Sr20 made
my 10.5:1-11:1 street/road course build is using a 2871 because I want lots of midrange torque since my main "home track" is Atlanta Motorsports Park which is a tight, technical course with a 200ft elevation change, I'll run Road Atlanta every so often but I think the back straight is too long for my turbo size, it's a good 4th gear run by the time you reach the braking zone.
that and on the street the 2871 is perfect IMO. I hate laggy turbos on the street, I got spoiled by the response and torque my 2860r Sr20 made
02-25-2014, 02:47 PM
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Re: 3" or 4" uppipe/downpipe
Here's an idle video.
Here's a shitty track pass on WG pressure.
Just cruising it really isn't bad. I do have all the sound detonating still in the car. But you can still listen to the radio and have a conversation with someone in there.
Here's a shitty track pass on WG pressure.
Just cruising it really isn't bad. I do have all the sound detonating still in the car. But you can still listen to the radio and have a conversation with someone in there.
02-25-2014, 05:05 PM
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Re: 3" or 4" uppipe/downpipe
You guys are pussies. I have a 3" up-pipe with a big *** cam. Sounds great. It might be annoying if I drove the car 1/2 hour to and from work everyday, but I drive it when I wanna tear a little rubber up.
I made the pipe exit further toward the passenger side, so no fumes either. I like the ridiculousness of the fire and brimstone/anti-lag noises that emanate from my car.
BTW: turbos make GREAT mufflers.
I made the pipe exit further toward the passenger side, so no fumes either. I like the ridiculousness of the fire and brimstone/anti-lag noises that emanate from my car.
BTW: turbos make GREAT mufflers.