2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

How much boost is safe?

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Old Aug 10, 2012 | 01:20 PM
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How much boost is safe?

So i finally have my car setup pretty nicely. 3" strait exaust, cone filter, rtek 1.7, ported wastegate, and now i got a boost controller. I've read about people scattering their motors past 13lbs, and people running over 20 on a stock block. What actually is the boost limit for my motor? I know the stock turbo becomes inefficient after 12psi or so. Would my car be completely safe staying steady at 12? or say 11.5?

Its freshly rebuilt, but i have no idea who rebuilt it. I always hear about getting the 13b-re corner seal springs, should my motor have those?
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Old Aug 10, 2012 | 01:27 PM
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10psi on the stock fuel system. 12psi with upgrades to fuel, beyond that you should really consider a standalone. the REW corner seal springs are recommended but not a requirement, they help with eventual blowby and compression loss due to the flattened wire springs.
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Old Aug 10, 2012 | 11:07 PM
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Rtek 1.7 requires 720cc secondaries, so that'll mean a little more injector to use up top. The secondary transition is better than stock, so the primaries won't necessarily max out, but you also need a better fuel pump before going over stock boost levels. There's no guarantee AFRs will remain safe at 12 psi on the stock turbo with the above mentioned fuel system. You should have a wideband as well.

From experience, I can tell you exactly what won't work: 9:1 rotors, stock fuel, stock ECU, FCD and 10 psi = blown engine.
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Old Aug 11, 2012 | 12:15 PM
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i forgot to add that i have a walbro, along with a narrowband.
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Old Aug 11, 2012 | 01:20 PM
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From: https://www2.mazda.com/en/100th/
i would try to run about 8-10psi. with the walbro you should be able to run a little more, but the cars vary a little, so its better to start low and see what your car will like
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Old Aug 12, 2012 | 07:59 PM
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From: New Hampsha
Originally Posted by chunkamunka1
i forgot to add that i have a walbro, along with a narrowband.
might want to pic up a wideband if you plan on doing any tuning.
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Old Aug 13, 2012 | 12:10 AM
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Sometime in the future yes. My dad had a narrowband laying around. I mean, it's better than nothing, right?
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Old Aug 13, 2012 | 01:08 PM
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Originally Posted by chunkamunka1
Sometime in the future yes. My dad had a narrowband laying around. I mean, it's better than nothing, right?
for boosted applications no, it is worth exactly nothing. it may even be worth less than nothing, since motors aren't free.
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Old Aug 16, 2012 | 01:49 AM
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I have been building turbocharged rotary engines for the past 7 years. I personally would never make modifications past the factory intake pressure levels without a wideband. Monitoring AFRs is crucial.
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