BlackMagic14
Needs a job
Posts: 2058
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posted June 19, 2011 01:24 PM
Turbo Questions.
Bike should be ready in the next week or so. I am just sitting here daydreaming about it and have some questions. First. At 6psi on pump gas with Carpenter Valve springs am I going to be completely safe without pulling timing? Second my understanding is that by using a smaller turbo Garret Gt25 or GT28? THat it will spool up quicker. I thought about requesting a bigger turbo but essentially 6psi is 6psi correct? and the smaller turbo will build boost quicker correct? Also About how much HP and TQ will she make on pump gas at 6psi?
  
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dubious
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Needs more time to ride!
Posts: 8442
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posted June 19, 2011 02:02 PM
 Edited By: dubious on 19 Jun 2011 22:04
250 hp and 140 ft lbs with a GT28 or GT30
the problem with a smaller turbo is that the higher cfm and pressures creates excessive inlet temps, which correlates to excessive combustion temps when you crank up the boost
My understand is that the small turbo's that are so reasponsive make the bike more violent, wheras a bigger turbo will be smoother, and have reduced temps, and more room to grow or increase boost pressures.
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Oz Booster
Expert Class
Posts: 230
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posted June 19, 2011 02:40 PM
How safe it is depends on your fuel tuneup , seen too many bikes hurt at 6 psi at std compression , not to be cautious , pulling a couple of dgrees out around peak torque may increase the safety margine . better still if your tuner can moniter knock or detonation and adjust accordingly
Gt2860?? , will spool fast , was making positive pressure on my gen 1 busa from 2800rpm
comes on like a light switch and more wheelie prone than a bigger turbo , great fun for street use but if your using the top end much you will be choking it some with the small exhaust housing and wheel , if you found the 28 too small its easily replaced with a gt3071 that can opt in the same physical shape and size as the 2860
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Oz Booster
Expert Class
Posts: 230
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posted June 19, 2011 03:14 PM
And watch the boost levels carefully, if your gt25/28 has an internal wastegate they can be prone to boost creep, 6 psi becomes 9 psi and a dead motor...
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BlackMagic14
Needs a job
Posts: 2058
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posted June 19, 2011 08:12 PM
This turbo I think has an external wastegate. If i pull 4* timing between 8000-11000 rpm what will be the benefits of this and how will it affect power?
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Oz Booster
Expert Class
Posts: 230
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posted June 19, 2011 09:46 PM
External gate is good
how it effects power realy best answered by your tuner
if you pull 4 deg and the power levels remain mostly unchanged then it was the right move, if you pull 4 deg and the power drops off it was not needed
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01smokes
Needs a job
Posts: 2243
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posted June 19, 2011 10:22 PM
i have no idea how someone can break one of these motors on pump gas with AFRs in the mid 11s and on 6psi
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