where can i find a 4" downpipe for my rx?
#1
Bimmer *****
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where can i find a 4" downpipe for my rx?
i swear i've seen one somewhere, i can't remember where, any ideas? its gonna be a part of my big build soon...
#2
SOLD THE RX-7!
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nowhere...
1. the stock turbo outlet is only 2.5"...
2. 3" will handle 500hp without problems
3. if you want more then 300-400. you need a full turbo kit. which requires a custom downpipe anyways.
1. the stock turbo outlet is only 2.5"...
2. 3" will handle 500hp without problems
3. if you want more then 300-400. you need a full turbo kit. which requires a custom downpipe anyways.
#3
I'm a boost creep...
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I'm assuming "big build" means big turbo.
While several Japanese companies make 90mm (3.5") systems for later model cars, I've never seen anything that big off-the-shelf for FC's. You'll almost definitely be going custom for anything over 3", particularly for non-standard turbos.
Scott, while a 3" system will handle 500hp, bigger is always better behind a turbo. The less restrictions an engine has to overcome (both intake and exhaust), the less boost you need to make the same power, and that's always a good thing.
While several Japanese companies make 90mm (3.5") systems for later model cars, I've never seen anything that big off-the-shelf for FC's. You'll almost definitely be going custom for anything over 3", particularly for non-standard turbos.
Scott, while a 3" system will handle 500hp, bigger is always better behind a turbo. The less restrictions an engine has to overcome (both intake and exhaust), the less boost you need to make the same power, and that's always a good thing.
#5
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Originally posted by NZConvertible
I'm assuming "big build" means big turbo.
While several Japanese companies make 90mm (3.5") systems for later model cars, I've never seen anything that big off-the-shelf for FC's. You'll almost definitely be going custom for anything over 3", particularly for non-standard turbos.
Scott, while a 3" system will handle 500hp, bigger is always better behind a turbo. The less restrictions an engine has to overcome (both intake and exhaust), the less boost you need to make the same power, and that's always a good thing.
I'm assuming "big build" means big turbo.
While several Japanese companies make 90mm (3.5") systems for later model cars, I've never seen anything that big off-the-shelf for FC's. You'll almost definitely be going custom for anything over 3", particularly for non-standard turbos.
Scott, while a 3" system will handle 500hp, bigger is always better behind a turbo. The less restrictions an engine has to overcome (both intake and exhaust), the less boost you need to make the same power, and that's always a good thing.
Also, have some thought into how large the pipes will be under the car. I have 3" and it rubs when I go over speed bumps so I always need to take it in an angle.
#6
Rotary Motoring
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I have the JIC Magic stainless Spec 90 3.5" turbo back exhaust.
You can buy the 3.5" front pipe seperately, but it is a bit longer than the stock cat forward as there is a bolt off adapter for the Spec 90 catback so it can be a full 3.5" turbo back w/ no neck downs OR a 3.5" catback that bolts to the small 2.5" stock catylitic flange.
Rishie (ARD T2 on this forum) can get you a great price on this system.
The Spec 90 turbo flange is stock sized to a reverse "velocity stack" to match 80mm pipe that makes up the 1st ~6" (the firewall bend) and them 90mm pipe all the way to the 1 muffler.
VERY LOUD
No turbo exhaust is too large for maximum performance, but you better have a large exhaust side on the turbo and a high flowing wastegate.
I have T4 "O" trim exhaust wheel clipped 15 degrees in a bored out '89 housing, ported/ relieved wastegates utylizing full 15mm of WG actuator travel (stock is 7mm travel) w/ wastegate flow divided and open air vented.
on a 60-1 Hi Fi compressor upgrade stock hybrid
Boost creeps to over 20 psi.
I will yank the turbo (again...) take out the WG flappers, hog the WG passages HUGE and put a 45mm or larger external WG on the turbo backplate.
Yes, it spools fast!
If you have an aftemarket turbo in the "standard" more forward position it is easier to go w/ 4" (or larger)downpipe as you can make the firewall bend earlier.
You can buy the 3.5" front pipe seperately, but it is a bit longer than the stock cat forward as there is a bolt off adapter for the Spec 90 catback so it can be a full 3.5" turbo back w/ no neck downs OR a 3.5" catback that bolts to the small 2.5" stock catylitic flange.
Rishie (ARD T2 on this forum) can get you a great price on this system.
The Spec 90 turbo flange is stock sized to a reverse "velocity stack" to match 80mm pipe that makes up the 1st ~6" (the firewall bend) and them 90mm pipe all the way to the 1 muffler.
VERY LOUD
No turbo exhaust is too large for maximum performance, but you better have a large exhaust side on the turbo and a high flowing wastegate.
I have T4 "O" trim exhaust wheel clipped 15 degrees in a bored out '89 housing, ported/ relieved wastegates utylizing full 15mm of WG actuator travel (stock is 7mm travel) w/ wastegate flow divided and open air vented.
on a 60-1 Hi Fi compressor upgrade stock hybrid
Boost creeps to over 20 psi.
I will yank the turbo (again...) take out the WG flappers, hog the WG passages HUGE and put a 45mm or larger external WG on the turbo backplate.
Yes, it spools fast!
If you have an aftemarket turbo in the "standard" more forward position it is easier to go w/ 4" (or larger)downpipe as you can make the firewall bend earlier.
#7
Rotary Motoring
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Also, have some thought into how large the pipes will be under the car. I have 3" and it rubs when I go over speed bumps so I always need to take it in an angle.
The JIC Magic 3.5" front pipe is tucked up so the "frame rails" are lower than it, BUT the catback has a section going past the rear axle that is lower than stock- but does not scrape (though a large square flange is lowest point- so there would be plenty of material to grind away anyways).
My car is lowered and only the exhaust cannister right before the tip drags going up very steep driveways.
Spec 90 is made so even a lowered race car can ride over the curbs of a racetrack w/ no scrapping. Race lowered, not show lowered, that is.
The JIC Magic 3.5" front pipe is tucked up so the "frame rails" are lower than it, BUT the catback has a section going past the rear axle that is lower than stock- but does not scrape (though a large square flange is lowest point- so there would be plenty of material to grind away anyways).
My car is lowered and only the exhaust cannister right before the tip drags going up very steep driveways.
Spec 90 is made so even a lowered race car can ride over the curbs of a racetrack w/ no scrapping. Race lowered, not show lowered, that is.
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#8
Bimmer *****
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i already have a 3" downpipe... and 3" straight pipe exhaust... no cats, no mufflers, just pure 3" all the way back.... but i'd like to go bigger... as for stock exhaust manifold... yeah i can't use that with the turbo i'm going with.... way too big a turbo(either greddy t78 or t88)... we've got the whole build basically planned out, and i'm doing as much research as possible before we begin. yes i believe dan's last name was burkett... its the black TII that has Rotary Motorsport stickers all over instead of TII logos... i blew the motor 400 miles after i bought it from mike(the guy who bought it from dan and put a JDM S4 motor in it)... he didn't rebuild that motor, so it was a used motor, and he was thinking pushing 17+ pounds of boost wouldn't hurt it at all.... i paid 3500 for this car, worth 6000 if it were running still... now i'm going to drop somewhere between 10 and 12 grand into it.... and if you guys got a link to the 3.5" downpipe itd be greatly appreciated... i'll go ahead and message ART T2 about it
#9
SOLD THE RX-7!
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since you are going with an aftermarket turbo. as I posted above. you need a custom made downpipe. in which case you can make any size you can fit.
that is why nobody makes anything bigger. there is no point with the stock turbo.
that is why nobody makes anything bigger. there is no point with the stock turbo.
#13
Rotary Motoring
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Check scrap yards
Our local srapyard has thousands of pounds of stainless steel 4", 5" and larger stainless pipe w/ V band flanges and clamps already on it AND clamshell style contant volume/radius bends.
I presume it is from the old chlorice pulp mill that they had to retrofit.
Check around...
Our local srapyard has thousands of pounds of stainless steel 4", 5" and larger stainless pipe w/ V band flanges and clamps already on it AND clamshell style contant volume/radius bends.
I presume it is from the old chlorice pulp mill that they had to retrofit.
Check around...
#14
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im probably gonna have to go with a custom downpipe because of my 3 inch exhaust (i plan on getting a 2.5-3 inch adapter). what degree bends so i need to match up to the turbo to the exhaust?
#15
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Originally posted by Black13B
speak to any heavy truck exhaust place. they make big exhaust.
speak to any heavy truck exhaust place. they make big exhaust.
#16
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you guys can go too large with the exhuast you know
the idea is stil the same with a piston motor as with a rotary
velocity of the exhuast helps gives power
too large of an exhuast equals no velocity
the idea is stil the same with a piston motor as with a rotary
velocity of the exhuast helps gives power
too large of an exhuast equals no velocity
#18
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even with a turbo the exhuast should still have pulses as far as I know
wouldn't those pulses work better if the exhuast had a higher velocity causing a lower net pressure at the exit of the turbo?
wouldn't those pulses work better if the exhuast had a higher velocity causing a lower net pressure at the exit of the turbo?
#20
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think about scavenging though
when the exhuast pulse leaves it creates a low pressure zone
the low pressure zone helps pull the next pulse
there is limits either way though
too large and you have no velocity and so no scavenging
go to small you might haev high velocity but it is overcome by the pumping losses
if we just follow your simple idea there NZConvertible
then N/A owners would even have 4" exhuast
sure you have less velocity but less velocity equals less restriction
when the exhuast pulse leaves it creates a low pressure zone
the low pressure zone helps pull the next pulse
there is limits either way though
too large and you have no velocity and so no scavenging
go to small you might haev high velocity but it is overcome by the pumping losses
if we just follow your simple idea there NZConvertible
then N/A owners would even have 4" exhuast
sure you have less velocity but less velocity equals less restriction
#22
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Originally posted by Digi7ech
I believe Carx7 has/had 4inch on his beast
I believe Carx7 has/had 4inch on his beast
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