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Stock RB25det max boost?


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I have searched here, and on the net, and can't get a definate answer to what the stock turbo on a RB25det can handle. I have read 10 PSI max, and others say you shouldn't run it past the stock 7 PSI, or the wheels will grenade. Anyone know for sure? Also would 10PSI get this motor to 300HP? The stock turbo looks kinda small and I believe I read it was a t28, and also read it was a t3. I have decided to go ahead and do the RB25 in my 260Z, and eventually I intend to upgrade the Turbo, etc. I will be aiming for 400-450 in the future with upgrades, but if I could hit 300 with the stock one, that would keep me happy for a little while.

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bro,

 

the answers are here.... the stock turbine on the rb25 can only take up to 0.9bar of boost... that something like 11-13psi of boost before the ceramic fins blow. On 0.9bar boost your rb25det will probably only be pushing 290 flywheel horse power.... thats something like 240-250whp.... thats what mine was doing one a fully stock engine.. nothing changed... and i'm running a series 1 rb25det .

 

hope this helps...

 

z-monster

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Yea, I was running 13.5 psi at the track. I did run it at 15 for a little while, then backed it down. My boost without a boost controller was 10psi. When I am messing around I run 13.5 psi (which is most of the time). I couldn't go lower than 10 psi if I wanted to. Also I know of another rb25 locally running 15psi all the time, for 2 years now. That car dyno'd at 305whp and 315wtq.

 

I think it really depends on how well your engine was maintained before you bought it. My engine only has 26,000 miles on it right now. I have heard that the turbine likes to come apart at 14psi though.

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Yea, I was running 13.5 psi at the track. I did run it at 15 for a little while, then backed it down. My boost without a boost controller was 10psi. When I am messing around I run 13.5 psi (which is most of the time). I couldn't go lower than 10 psi if I wanted to. Also I know of another rb25 locally running 15psi all the time, for 2 years now. That car dyno'd at 305whp and 315wtq.

 

I think it really depends on how well your engine was maintained before you bought it. My engine only has 26,000 miles on it right now. I have heard that the turbine likes to come apart at 14psi though.

 

Makes me so sad in the pants knowing I can only run like 12-14 max... Time to dish out the wallet after all said and done for a slightly bigger snail.

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From what I have heard, the problem as stated is the ceramic blades blowing up around 13 psi. The stock turbo is a fairly good piece and many people on skylines Australia have switched out the ceramic blades for steel ones. While this is cheaper than a new turbo you still have to ship the unit out to a turbo shop to get it balanced. The good thing is however that the new turbo still spools just as fast as the old unit, and handles more boost.

 

As a question, the guys who were running 10-13 psi, where the engines bone stock or did they have rising rate after market fuel regs or anything ? My engine is pretty close to firing up and I was wondering what the injectors and the stock fueling /electronics can handle. Anybody have any experience ? Also when breaking in a new engine what kind of boost should be run ? Little to none or does it matter ?

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From what I have heard, the problem as stated is the ceramic blades blowing up around 13 psi. The stock turbo is a fairly good piece and many people on skylines Australia have switched out the ceramic blades for steel ones. While this is cheaper than a new turbo you still have to ship the unit out to a turbo shop to get it balanced. The good thing is however that the new turbo still spools just as fast as the old unit, and handles more boost.

 

As a question, the guys who were running 10-13 psi, where the engines bone stock or did they have rising rate after market fuel regs or anything ? My engine is pretty close to firing up and I was wondering what the injectors and the stock fueling /electronics can handle. Anybody have any experience ? Also when breaking in a new engine what kind of boost should be run ? Little to none or does it matter ?

 

I think at that point you might as well just buy a nice small turbo... the cost of parts and labor to redo that blade would just not be worth it.

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From what I have heard, the problem as stated is the ceramic blades blowing up around 13 psi. The stock turbo is a fairly good piece and many people on skylines Australia have switched out the ceramic blades for steel ones. While this is cheaper than a new turbo you still have to ship the unit out to a turbo shop to get it balanced. The good thing is however that the new turbo still spools just as fast as the old unit, and handles more boost.

 

As a question, the guys who were running 10-13 psi, where the engines bone stock or did they have rising rate after market fuel regs or anything ? My engine is pretty close to firing up and I was wondering what the injectors and the stock fueling /electronics can handle. Anybody have any experience ? Also when breaking in a new engine what kind of boost should be run ? Little to none or does it matter ?

 

I run a adjustable fuel regulator from SARD.

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The stock turbo is good to about 12psi before risking the exhaust blades.

it is an T3 exhaust side with ceramic blades mated to a T28 compressor.

I used a HKS GT2540 on my friends car it is basically a stock size turbo with larger guts and a steel exhaust impellor. good for a very usable 18psi up to probably 20psi, it is VERY responsive, starts building boost at around 2k rpm and pulls very strong all the way to redline. It is a direct replacement turbo on the stock RB25 manifold and makes a fantastic street turbo. my friends car that is internally stock but with a greddy intake and a 3 inch exhaust makes 305 rwhp at ~12psi with it.

We got it off ebay japan it was just over a grand shipped and included a nice divorced wastegate upper down pipe. A good deal because just the turbo goes for a tick over 2k new and this one was in very good condition Under 10,000 klm on it.

Chris Rummel

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The stock turbo is good to about 12psi before risking the exhaust blades.

it is an T3 exhaust side with ceramic blades mated to a T28 compressor.

I used a HKS GT2540 on my friends car it is basically a stock size turbo with larger guts and a steel exhaust impellor. good for a very usable 18psi up to probably 20psi, it is VERY responsive, starts building boost at around 2k rpm and pulls very strong all the way to redline. It is a direct replacement turbo on the stock RB25 manifold and makes a fantastic street turbo. my friends car that is internally stock but with a greddy intake and a 3 inch exhaust makes 305 rwhp at ~12psi with it.

We got it off ebay japan it was just over a grand shipped and included a nice divorced wastegate upper down pipe. A good deal because just the turbo goes for a tick over 2k new and this one was in very good condition Under 10,000 klm on it.

Chris Rummel

 

I've seen this exact turbo IRL, and the dump elbow, it was sooo pretty, made me really consider switching back to my stock manifold and this particular turbo.

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This turbo, makes really good usable power, it is not the biggest turbo out there, but it works really good on the street, with lots of meat under the curve. The guy that tuned it, said it was much nicer on the RB then anouther one he had in the shop with a larger turbo on it. Much easier to tune, and a lot more Usable power then a larger turbo, so a good match for the Rb for street use.

You could probably get another 40hp or so out of it with larger injectors and more tuning. I believe this turbo is rated at about 350-370 max.

Chris Rummel

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