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CATEGORY LISTINGS > DETROIT > Adding a turbo to a 4-71 N engine [ REFRESH ]
Thread Title:

Adding a turbo to a 4-71 N engine


Created On Friday August 25, 2006 04:30 Diesel Talk
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DieselMech
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Joined: Jan 2006

Note Friday August 25, 2006 04:30 View thread in raw text format
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I'm working on a 4-71N Detroit Diesel trying to get some more power out of it and thinking about adding a turbo to it without replacing the pistons. The Compression ratio of the n/a engine is 18.7:1 and the normal compression ratio of the turbo engines is 17:1. I'm only spinning this one 1600 since it turns a generator and needs to be at that rpm to supply the correct voltage. So what is boils down to is... The turbo engine has a minimum airbox pressure of 27psi at 2300 rpm and 17 psi at 1800 with 17:1 compression. My engine would only see 1600 rpm so it would develop less than 17 psi but with my static compression being 18.7:1 I would have higher cylinder pressure than the normal turbo engine at that same boost level but would it be more than the turbo motor sees at 27 psi of boost and 17:1 compression????



Doug
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crossthreaded
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Joined: Aug 2006

Note Sunday August 27, 2006 01:07 View thread in raw text format
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yes, the turbo engine is seeing a compression ratio of 17:1, where as if the cylinder is at 1psi bdc at tdc the engine is at 17 psi, plus the 27 psi of boost, so it is actually at 34psi at tdc and 28psi at bdc.

so at tdc your 4-71 would be seeing cylinder pressure at 18.7:1 compression ratio plus the 17 psi of turbo boost pressure.
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