P.J

I made the mistake of chiming in on Diesel Truck discussion on a commercial lawn maintenance forum I browse. The thread was asking about "chips" so I figured I would pop in and comment on the overwhelming response to the new Smarty programmer. Well, the discussion turned to Turbo's.


How much actual HorsePower comes from ever psi of boost? Is it measureable, if so is there a standard equation that fits any and all engines, gas & diesel??
I feel the need to trump this guy.

BigBlue

IIRC, the general rule of thumb is 10hp for every 1psi but that doesn't apply to our trucks. You could up the boost from 20 to 30psi on a stock truck and not gain anything. Now on a heavily fueled truck you might see a difference.

AlpineRAM

There's no one size fits all formula- first there is some difference in displacement and engine speed- then there's the volumetric efficiency for a given set of the two above.
Also a diesel engine will get it'S torque from the amount of diesel burnt per powerstroke, so just adding air won't do nothing. But if you add so much diesel that it ain'T getting burnt (lack of air) you won't have more torque.
The formula BB mentions should read somewhat like that- for a B-series Cummins 6 cylinder every psi of boost needed to clear up the exhaust at rated speed translates roughly to 10 hp.

HTH

AlpineRAM

P.J

Okay, since I was pretty much right on, I'll let you guys read what the resident Diesel Guru on that forum has to say about the topic.
Post #10, I plug DTR as place they can go and get real information.
http://www.lawnsite.com/showthread.p...ghlight=diesel

Abbynormal

What Big Blue was saying is Air and Diesel combined is what makes the power. Extra boost without extra fuel really gives no benefit. Now start throwing more fuel in and to some degree you HAVE to have more boost / air to help burn the fuel otherwise your just wastin fuel up in smoke and its not burning completely.

getblown5.9

wow...we have an expert over there who got his info from the advertising on prochargers website...amazing

im gonna put a ht3b single on my truck that will make 70psi so i can get 1750hp with no other mods

P.J

Yeah, he dug into me in a hurry. I can only go on what I have learned here, that's why I reverted back to here to see if I was a s stupid as he was trying to make me look.......

HOHN

In the gasser world, increasing boost almost always increases power because more air always brings with it a proportionate amount of fuel. Remember FUEL makes power, not air.

That's why you can crank up the boost on a diesel and not make any more hp at all-- more air doesn't necessarily have a direct correlation to the rate of fueling.

There are "rules of thumb" for certain engines, but they only apply to those engines, and only within a narrow range, and only with the stock turbo. So the "10hp per psi" is just loose guidance.

Obviously, you have more than 10hp at 1psi of boost, right?

Clearly, corrlation isn't very high, and certainly non-linear.

This should help you answer the "guru" among lawnmower men