New to the turbo world
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Teching In
Joined: Mar 2016
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New to the turbo world Morning guys! I have some questions about my stock 1999 4.8! I currently have 55# inj. 320lph pump. 76mm turbo. Running 7# of boost with a great tune. I want to know what this girl will take for boost without making any mods to it?? How far can I go with boost and b ok! Thanks in advance
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Joined: Mar 2014
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From: Ohio
All of it. It should take all of it.
You'll top those fuel injectors out before that 4.8 has any problems. Just keep the timing low, these engines love low timing. I run 12 degrees above 14 PSI. I didn't gain any power when I added timing.
You'll top those fuel injectors out before that 4.8 has any problems. Just keep the timing low, these engines love low timing. I run 12 degrees above 14 PSI. I didn't gain any power when I added timing.
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My 6.0 was running 115% duty cycle on 60 lb injectors and around 13-15 lbs of boost-the 4.8 might not be as hungry, but I would keep an eye on the duty cycle, depending on base pressure
Thread Starter
Teching In
Joined: Mar 2016
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my tuner told me that at 90-100% there pretty much peaked! I have to log some more data and check it out. I raised it to 14psi last nite but didn't get a huge hit on it as to my tranny isn't likin life at the moment!! lol thatll be next!
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Joined: Mar 2014
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From: Ohio
If your fuel pressure regulator is boost referenced, you can still be adding fuel and running fine even at 100% duty cycle, or above. If your duty cycle is climbing because your fuel pump is maxed out and pressure is dropping, switching to a large pump or adding a second pump to hold constant pressure can also bring duty cycle down. So duty cycle is more of an indicator than an actual measurement of how far you can push your injectors.
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Joined: Mar 2014
Posts: 7,192
Likes: 109
From: Ohio
62 PSI Base, I'm pushing my 80s into the mid 90% at 20 PSI. I've had them over 100% on several occasions, and one overboost occasion where they were at 170%.
I can run 24-26 PSI and have them at 110-120% or so before they actually start to lean out. Turns out, my regulator isn't raising pressure at a 1:1 ratio so if I fix that, I should be able to keep them down near 100% at the same boost level.
I can run 24-26 PSI and have them at 110-120% or so before they actually start to lean out. Turns out, my regulator isn't raising pressure at a 1:1 ratio so if I fix that, I should be able to keep them down near 100% at the same boost level.