solution to jdm twins overboosting with 3" exhaust
09-20-12, 09:27 PM
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solution to jdm twins overboosting with 3" exhaust
i didnt like the idea of restricting my exhaust to keep the boost levels in check, so before i did my swap i pulled my front turbo off and made some modifications.....
this is the stock wastegate port on the front turbo, its tiny and the flow sucks.
this is what it looked like after i got done with the rotary carbide bit.
what i have done is enlarge the opening a few mm, but more importantly, i cleaned up the casting leading up to the port, and made everything as smooth as possible. I run a shop that specializes in subarus, and a common problem is boost creep on the stock wastegates of the 2.5L cars. this porting has worked time and time again on the subaru turbos, so i figured id try it on the 2jz....
my results were ideal, my car runs a rock solid 10psi on the stock boost control system, and with a MBC im able to run 16psi with no boost creep. im thinking about swapping out the JDM o2 housing for the usdm one which is bigger for less restriction, or throwing it away entirely and making a Y pipe after the ECV plate and running that into a 3" pipe, since the wastegate now seems capable of controlling boost.
i did this mod with my motor out, so getting the turbo off was pretty simple, it might not be feasible if your motor is in the car, since most people upgrade when they remove the stockers, but i figured id post anyways, maybe this will help someone before they install their motor and keep them from having boost creep issues!
this is the stock wastegate port on the front turbo, its tiny and the flow sucks.
this is what it looked like after i got done with the rotary carbide bit.
what i have done is enlarge the opening a few mm, but more importantly, i cleaned up the casting leading up to the port, and made everything as smooth as possible. I run a shop that specializes in subarus, and a common problem is boost creep on the stock wastegates of the 2.5L cars. this porting has worked time and time again on the subaru turbos, so i figured id try it on the 2jz....
my results were ideal, my car runs a rock solid 10psi on the stock boost control system, and with a MBC im able to run 16psi with no boost creep. im thinking about swapping out the JDM o2 housing for the usdm one which is bigger for less restriction, or throwing it away entirely and making a Y pipe after the ECV plate and running that into a 3" pipe, since the wastegate now seems capable of controlling boost.
i did this mod with my motor out, so getting the turbo off was pretty simple, it might not be feasible if your motor is in the car, since most people upgrade when they remove the stockers, but i figured id post anyways, maybe this will help someone before they install their motor and keep them from having boost creep issues!
09-20-12, 10:00 PM
#2
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i didnt like the idea of restricting my exhaust to keep the boost levels in check, so before i did my swap i pulled my front turbo off and made some modifications.....
this is the stock wastegate port on the front turbo, its tiny and the flow sucks.
this is what it looked like after i got done with the rotary carbide bit.
what i have done is enlarge the opening a few mm, but more importantly, i cleaned up the casting leading up to the port, and made everything as smooth as possible. I run a shop that specializes in subarus, and a common problem is boost creep on the stock wastegates of the 2.5L cars. this porting has worked time and time again on the subaru turbos, so i figured id try it on the 2jz....
my results were ideal, my car runs a rock solid 10psi on the stock boost control system, and with a MBC im able to run 16psi with no boost creep. im thinking about swapping out the JDM o2 housing for the usdm one which is bigger for less restriction, or throwing it away entirely and making a Y pipe after the ECV plate and running that into a 3" pipe, since the wastegate now seems capable of controlling boost.
i did this mod with my motor out, so getting the turbo off was pretty simple, it might not be feasible if your motor is in the car, since most people upgrade when they remove the stockers, but i figured id post anyways, maybe this will help someone before they install their motor and keep them from having boost creep issues!
this is the stock wastegate port on the front turbo, its tiny and the flow sucks.
this is what it looked like after i got done with the rotary carbide bit.
what i have done is enlarge the opening a few mm, but more importantly, i cleaned up the casting leading up to the port, and made everything as smooth as possible. I run a shop that specializes in subarus, and a common problem is boost creep on the stock wastegates of the 2.5L cars. this porting has worked time and time again on the subaru turbos, so i figured id try it on the 2jz....
my results were ideal, my car runs a rock solid 10psi on the stock boost control system, and with a MBC im able to run 16psi with no boost creep. im thinking about swapping out the JDM o2 housing for the usdm one which is bigger for less restriction, or throwing it away entirely and making a Y pipe after the ECV plate and running that into a 3" pipe, since the wastegate now seems capable of controlling boost.
i did this mod with my motor out, so getting the turbo off was pretty simple, it might not be feasible if your motor is in the car, since most people upgrade when they remove the stockers, but i figured id post anyways, maybe this will help someone before they install their motor and keep them from having boost creep issues!
09-20-12, 10:11 PM
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they are showing up in your quote, let me double check....
should be working, lmk if they are!
oh and gs300luv, thanks for a very helpful thread about your swap, helped me do mine in 12 hours!
should be working, lmk if they are!
oh and gs300luv, thanks for a very helpful thread about your swap, helped me do mine in 12 hours!
Last edited by Meyagi; 09-20-12 at 10:17 PM.
09-21-12, 04:37 PM
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Oh sweet! Im glad it helped someone out!!!!! Yea I finally can see the pictures today! I wish I would have done that before I installed my engine. My exhaust seems to keep my turbos in check though. I run 11 psi with a creep up to 14 psi sometimes. I had a restrictor in there but I didnt need it. As long as it stays under 16 psi im happy. I been thinking of trying to find a single turbo set up that I can just bolt on and use the exciting ecu and injectors. Im sure there is one I can use but Im not sure what to get. Congrats on your swap! Post a vid of how the exhaust sounds if you can!!!!
09-21-12, 04:58 PM
#5
Oh sweet! Im glad it helped someone out!!!!! Yea I finally can see the pictures today! I wish I would have done that before I installed my engine. My exhaust seems to keep my turbos in check though. I run 11 psi with a creep up to 14 psi sometimes. I had a restrictor in there but I didnt need it. As long as it stays under 16 psi im happy. I been thinking of trying to find a single turbo set up that I can just bolt on and use the exciting ecu and injectors. Im sure there is one I can use but Im not sure what to get. Congrats on your swap! Post a vid of how the exhaust sounds if you can!!!!
my idea was to use the BPU items that work on the Supra (boost controller, boost cut controller, downpipe and cat back) when i do the swap. is this feasible? does the vvt-i have the fuel cut that needs to be bypassed in order to run 16-18 psi, consistently?
thanx for any answers, fellas.
09-24-12, 05:58 PM
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ive read damn near every post about the aristo swap. i have a question...can you not use a boost controller to keep the boost in check?
my idea was to use the BPU items that work on the Supra (boost controller, boost cut controller, downpipe and cat back) when i do the swap. is this feasible? does the vvt-i have the fuel cut that needs to be bypassed in order to run 16-18 psi, consistently?
thanx for any answers, fellas.
my idea was to use the BPU items that work on the Supra (boost controller, boost cut controller, downpipe and cat back) when i do the swap. is this feasible? does the vvt-i have the fuel cut that needs to be bypassed in order to run 16-18 psi, consistently?
thanx for any answers, fellas.
If this doesn't make sense let me know, or if I'm just wrong. So the limiting factor is the wastegate. It isn't big enough to prevent boost with free-flowing exhaust.
BTW OP, good job investigating that, I know it plagues many JDM 2J's.
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02-17-13, 12:27 PM
#9
As an FYI - the VVTi JDM engine doesnt seem to overboost as badly or at all compared to the non VVTi JDM - I have a JZS161 Aristo with a 3" turbo back exhaust splitting out to dual 2.5", fully mandel bent with free flow mufflers and no restrictor, and my boost is rock solid at just under 18PSI - a lot of MK2 Aristo owners find this as well.
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04-08-13, 07:23 PM
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As an FYI - the VVTi JDM engine doesnt seem to overboost as badly or at all compared to the non VVTi JDM - I have a JZS161 Aristo with a 3" turbo back exhaust splitting out to dual 2.5", fully mandel bent with free flow mufflers and no restrictor, and my boost is rock solid at just under 18PSI - a lot of MK2 Aristo owners find this as well.
04-08-13, 07:48 PM
#15
