04.5 Cummins 100% injectors and Stock Turbo Question

Foster#17

Foster#17

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Apr 1, 2015
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Hi guys, we got my buddies truck back together with his 100% over injectors. He has to run his stock turbo for a while until he gets his new setup. With his stock injectors the truck was making 44psi pretty easily and now with the bigger injectors its only making 37 psi but is significantly faster? We tried everything thinking something might be leaking but there are no boost leaks. We thought the wastegate might be opening so we unplugged the solenoid, installed the wastegate fooler and no difference. The only thing different is, we installed an aftermarket intake horn and a larger billet aluminum intake(The piece the intake horn bolts to) The only thing I can figure is, now its flowing a larger volume into the engine with less restriction and thats why its making less boost and more power. Anyone have any ideas??
 
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37psi is all the MAP sensor will read. You reading with a manual gauge or electronic?

Lavon
 
How did you check for boost leaks? Usually whenever work is performed on any of the intake/boosted piping and boost pressure drops, a leak has developed.

It is possible to make more power with the same boost pressure with bigger injectors or quicker injection rate/shorter injection window, but you didn't mention anything about tuning changes so the boost pressure shouldn't drop with a simple injector upgrade on the same tuning.
 
Big Blue24 said:
How did you check for boost leaks? Usually whenever work is performed on any of the intake/boosted piping and boost pressure drops, a leak has developed.

It is possible to make more power with the same boost pressure with bigger injectors or quicker injection rate/shorter injection window, but you didn't mention anything about tuning changes so the boost pressure shouldn't drop with a simple injector upgrade on the same tuning.
Click to expand...

But he did remove a restriction! better air flow equals lower boost numbers!
AND better power like he has!
 
That's not much of a flow restriction with a stock turbo, I'd definitely be looking for a boost leak around the intake. On a side note, I changed my intake horn and plate and it made 0 difference in my boost and I was running compounds.

Sent from my SM-G930V using Tapatalk
 
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Big Blue24 said:
How did you check for boost leaks? Usually whenever work is performed on any of the intake/boosted piping and boost pressure drops, a leak has developed.

It is possible to make more power with the same boost pressure with bigger injectors or quicker injection rate/shorter injection window, but you didn't mention anything about tuning changes so the boost pressure shouldn't drop with a simple injector upgrade on the same tuning.
Click to expand...

It is now tuned with udc
 
LAmiller said:
37psi is all the MAP sensor will read. You reading with a manual gauge or electronic?

Lavon
Click to expand...

From a dead stop flooring it the boost gauge will hit 40psi and then drops off in no time to around 37psi, and the gauge kinda flutters around. This is why we thought the wastegate was the issue, opening at 40psi which is the max limit with udc. So like I said, I unplugged the wastegate to try and be sure but no difference from that. It's just weird because the truck is so much faster but boost is so much lower, it just makes me think there's an issue. And I see people getting 50+psi out of a stock turbo(obviously isn't good) but I just can't figure out what they're doing to get them that high.
 
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