how many pounds of boost on stock internals

Discuss the RB20, RB25 and RB26 series engines.
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how many pounds of boost on stock internals

Postby sonic30101 » Sat Sep 10, 2005 4:36 am

i have an rb25 in my s13, my stock turbo just fried and i am upgrading to a t3/t4. the local shop says that i can run 14 pounds all the time on stock internals and stock injectors. i was thinking about 10, but i wanted to know what you guys thought o how many pounds of boost i shoud push for a rb25 with: 12X24X4" fmic, 2 1/2 inch intercooler piping, 3" exhaust, walboro 255 fuel pump.

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Re: how many pounds of boost on stock internals (sonic30101)

Postby Joe » Sat Sep 10, 2005 5:13 am

id never go above 12 with stock injectors.

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Re: how many pounds of boost on stock internals (sonic30101)

Postby IowaRB240SX » Sat Sep 10, 2005 11:40 am

I've been told 14 psi several times from different sources, including MAC, on stock injectors. And up to 20 on stock internals with injector upgrade.

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Postby krayton » Sat Sep 10, 2005 12:13 pm

we talking about stock turbos too?

i ran 17psi under 3000rpm and my turbo pieced out.

does anyones turbo actually hold 10+ pounds all the way through? i put mine up to 12 and it would just fall off at top rpms.

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Re: (krayton)

Postby themadscientist » Sat Sep 10, 2005 1:19 pm

without a way to know what your mix is you shouldn't be messing with it. My standard setting for a bone stock RB20 is .9 BAR with a little bump up in fuel using a piggyback or an adjustable regulator. Beyond that the first shortcoming is the turbo then immediately afterward the injectors, the engine's guts are up to the task.

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Postby eh? » Sat Sep 10, 2005 1:39 pm

I ran 17psi with a t3/t4 50 trim with the stock injectors, duty cycle was up at 98%.

Someone on the forum posted something like 290rwhp with an RB20 that had stock injectors. Supposedly stock fuel pressure. RB20's have 270cc injectors and RB25's have 370cc inj's. Make what you will out of that.

here's the link

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Re: (krayton)

Postby IowaRB240SX » Sat Sep 10, 2005 2:30 pm

no, if you read his first post, he said he had a new t3/t4. Te ceramic wheels in the stock turb shouldn't go past 9.

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Re: (IowaRB240SX)

Postby sean8564 » Sat Sep 10, 2005 3:57 pm

Stock turbo is good for 10-12 PSI safely Now you can run 14 psi on the t3/t4 just dyno it and make sure your fuel maps are good and adjust accprdingly i personaly would only run 10psi.

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Postby sarver » Sun Sep 11, 2005 9:01 am

12 psi - 14psi

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Re: (sarver)

Postby Carl H » Sun Sep 11, 2005 12:05 pm

sarver wrote:12 psi - 14psi
um ok there buddy, dont thinkso.things limiting max boost depend on such things as fuel quality, injector sizes, turbo sizes and the general state of engine health.currently im boosting 17psi on high boost with supporting mods, however my fuel maps need major enrichment..........when i get my aquamist in the car i will crank the boost to 20psi and see what kind of power can be made.

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