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how much boost on close to stock 2jzgte engine

20K views 33 replies 12 participants last post by  KevinB6876 
#1 ·
i have a 2jzgte jap spec engine. it is almost stock. the thing i have done on it is.

fmic
cat back system (still have the 1 kat closest to the engine)
run ttc

how much boost should i reach on the engine 0.75 bar or 0.9 bar
 
#6 ·
Its not the engine that you need to worry about. Worry about those ceramic jdm turbos. Correct me if im wrong but isnt the consensus that running anything more than 14psi(~.9bar) is detrimental to the turbos life span.
 
#11 ·
yes but I've talked to some people. who says the changes I've made on the car, it should have 0.9 bar without any kind of boost controller on the engine. while others say that as long as I have mounted the cat mountet, it leaves the only standerat boost setup at the 0.75 bar. so just wanted to hear who was right?
 
#14 ·
I would keep it below 40-50 psi on a stock longblock

Stock jdm turbos I would keep 16-18psi
 
#15 ·
So glad I found this post before I started a new one...

I have a JDM 2jzgte swap in my Supra

Mods are
-Megan Racing Downpipe 3"
-Greddy Power extreme Exhaust 3.75"
-No Catalytic Converters
-FMIC

And I'm seeing 18-19psi (1.3-1.39 bar)

Is there a malfunction.... I've checked all vacuum hoses they look fine..
I know the stock twins can't handle this amount of boost. And I'm getting boost/fuel cut in 3rd gear..
 
#17 ·
Ok sorry to ask, but what is a the restrictor ring and where do I get one..I don't want to invest a lot of time in the twins but I need them to last until I get all the minor details handled...
 
#18 ·
I don't know if you can buy one but they're easy to make. The restirctor ring goes into the exhaust pipe or downpipe; easiest to install one at one of the joints in the exhaust system. It's just a stainless steel plate with a hole in it, say 2" hole. The overboost is caused by exhaust that is too free flowing and wastegate too small.
 
#29 ·
I put an RMM downpipe, HKS Super Drager exhaust, and an intake on my Supra years back. Boost rose from the OEM 10.8psi to 15psi after the modifications. Why? Because the OEM wastegate gets choked from the increased mass of exhaust, which overspeeds the turbine, resulting in a boost increase from the OEM 10.8psi to 15psi.
 
#20 ·
Ok I'll try that hopefully this works...I have a greedy Profec B spec II, I'm assuming that installing it won't help to lower the boost since it over boosting due to the exhaust..
 
#21 ·
yes but I've talked to some people. who says the changes I've made on the car, it should have 0.9 bar without any kind of boost controller on the engine. while others say that as long as I have mounted the cat mountet, it leaves the only standerat boost setup at the 0.75 bar. so just wanted to hear who was right?

who is right?????
 
#24 ·
To Jza86: dont be sorry for asking, we're all learning something new everyday. So why would having an exhaust cause you to over boost? What does over boost mean? How do you know you are "over boosting"?

A restrictor ring is a term only used in Europe/Australia due to sea level/altitude that played a factor during certain seasonal weather conditions. If anyone was to make a restrictor ring, how come the Japanese has never made one yet alone heard of one?

Electrnic boost control is a good thing, but I'm starting to think you guys are posting questions here without even reading mkiv.com tech articles..
 
#28 ·
Restrictor ring works ...I basically installed two metal multilayer exhaust gaskets with a 2" diameter between my catback and my down pipe and the car is now at 1.0 - 1.1 bar so thats works for me ....no more 1.4bar...thanks
 
#30 ·
Like I said, I had full decat, catback, intake, upgraded ecu, cam gears tuned, big intercooler and my boost stayed at 11-12 psi all day, all night. I thought I had a boost leak but the vacuum system was perfect.

Oh ya and at 11.5 psi my car dyno'd 379rwhp.

My car never over boosted once even without a restrictor ring was my point.
 
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