how many pounds of boost on stock internals

Discuss the RB20, RB25 and RB26 series engines.
sonic30101
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Joined: Sat Sep 10, 2005 4:35 am
Car: 93 s-13 fastback with an rb25 swap

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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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Joe
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Location: Phoenix, AZ

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id never go above 12 with stock injectors.

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IowaRB240SX
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Car: 1991 Nissan 240sx

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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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krayton
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Joined: Tue Jun 24, 2003 11:10 am

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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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themadscientist
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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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eh?
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Joined: Sat Jan 24, 2004 2:26 pm

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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 linkhttp://forums.nicoclub.com/zerothread?id=123090

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IowaRB240SX
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Car: 1991 Nissan 240sx

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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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sean8564
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Car: 1993 GTR Vspec, 1991 300zx TT Black , 1993 Nissan Silvia, 1990 Nissan 240sx Coupe RB25DET

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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.

sarver
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Joined: Sun Sep 11, 2005 8:50 am

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12 psi - 14psi

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Carl H
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Joined: Mon Aug 04, 2003 4:09 am
Car: 1995 240SX SE RB30DET

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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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