Injector HP Numbers

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dragnsled

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Where exactly did all this injector horsepower rating all start...after all it's in the flow % ? I had this guy come in the shop the other day (he was with a diesel friend of his) and he had no clue about how a diesel engine worked. Somehow injectors came into the conversation and after listening to all this for a good while this guy wanted to know what 150hp injectors were going to do if the engine had 325hp from factory. So an explanation followed and it all came back to flow being the main factor. Maybe I need some schooling here so if anyone got some answers please chime in!!
 
A 100 hp injector should support 100 hp above stock. Results will vary depending on setup- but that should the the difference with boxes off and enough air.

There are exceptions like the rv 275 and 300 injectors are for engines tuned to 275 or 300 hp as opposed to 235 or whatever hp for a vp44'd truck.
 
I think hot rod farmers and over the road truck owners started this whole diesel horsepower thing by putting injectors from very large engines into smaller engines.

My understanding is 150hp injectors add 150 additional horsepower but certain computer limitations have to be disabled. On a VP44 injected combo, the MAP sensor tells the computer when the boost pressure reaches the power limiting point, then the computer tells the injector pump to start reducing fueling to the design spec.
The addition of a boost fooler keeps the computer from knowing when the boost pressure limitation has been reached and the pump continues to send max fuel to the injectors....a power consideration only with stock injectors.
Bigger injectors w/boost fooler allow the VP44 injector pump to pump up to the actual capacity of that particular VP44 injector pump.
To reach the capacity of the injectors, the injector pump has to be "told" to pump beyond the fueling design parameters in the computer by a power module, which a VP44 does a very good job handling if it's well supported with lots of cooling fuel and additives that lubricate the VP44.
The lift pump has to flow enough fuel to maintain no less than 10 psi under full throttle conditions.
My very poor understanding of the Common Rail system is...the right power module can get you monster power with stock injectors and if greed sets in, bigger injectors can get you more power if you support it with a bigger or even dual turbochargers...all help gratefully accepted.
More fuel turns the turbos harder to make more air which lets you add even more fuel which spins the turbo even more....kinda like a puppy dog chasin' his tail.
 
Last edited:
Clunk said:
I think hot rod farmers and over the road truck owners started this whole diesel horsepower thing by putting injectors from very large engines into smaller engines.

My understanding is 150hp injectors add 150 additional horsepower but certain computer limitations have to be disabled. On a VP44 injected combo, the MAP sensor tells the computer when the boost pressure reaches the power limiting point, then the computer tells the injector pump to start reducing fueling to the design spec.
The addition of a boost fooler keeps the computer from knowing when the boost pressure limitation has been reached and the pump continues to send max fuel to the injectors....a power consideration only with stock injectors.
Bigger injectors w/boost fooler allow the VP44 injector pump to pump up to the actual capacity of that particular VP44 injector pump.
To reach the capacity of the injectors, the injector pump has to be "told" to pump beyond the fueling design parameters in the computer by a power module, which a VP44 does a very good job handling if it's well supported with lots of cooling fuel and additives that lubricate the VP44.
The lift pump has to flow enough fuel to maintain no less than 10 psi under full throttle conditions.
My very poor understanding of the Common Rail system is...the right power module can get you monster power with stock injectors and if greed sets in, bigger injectors can get you more power if you support it with a bigger or even dual turbochargers...all help gratefully accepted.
More fuel turns the turbos harder to make more air which lets you add even more fuel which spins the turbo even more....kinda like a puppy dog chasin' his tail.
Click to expand...

Shouldn't injector HP numbers should be the actual gain you would get on an otherwise stock truck...if not so the manufacture should have to state what tuning if needed to get the advertised HP improvement?
 
Good point but it needs to be understood that big hole injectors make about the same power as stock injectors if the MAP sensor is operating in stock parameters. When boost hits 19-20psi, the computer is going to reduce the fueling.
 
I think it depends on the manufacturer. It would be nice if all the manufacturers posted real dyno #'s backing up these gains. I know some have but most dont. They should be rated at RWHP!
 
I gained a true 100 RWHP using 150s on a VP44 truck using nothing but a boost fooler. With the addition of a fueling box, intake, and exhaust, the gain increases significantly. So I consider the 150 rating pretty accurate. Give it enough air in and out, Add some timing for a more complete burn, you get right at 150 over stock.
 
I think saying a hp rating simplifies it for us diesel dummies. I dnt understand what people are saying when they talk about 6x.000 I know the six is for how many holes but dnt know what the other number is. Guessing the size of the holes compared to stock?
 
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