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Discussion Starter #1
OK I sent my inj pump & injectors off to have them built/checked out. I'm refrencing cpl# 858 . I told the builder I wanted 150HP & maybe close to 400lbft & check if the injectors match the inj pump. Is this going to be enough HP? He hasn't started on anything yet as the pump will arrive at his location monday. I'm thinking I might have to buy some injectors because 1 or 2 had rust on the tips, if I do what do u guys recommend ? I think I want more than the 105 hp it had but not 250. Any thoughts ?
 

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Is 150 HP enough? That is purley a personal question. 105 is enough........what are you trying to accomplish that you need the extra power. Is the gain desired purely personal? I would start there becuase without the demands, we cannot offer guided insight IMHO
 

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Discussion Starter #3
Since my pump & injectors might have to be built is it worth it to up the hp while their at it. I don't know how the 105 would feel. Trying to get someones opinion that has a motor producing around 150hp. Also how much hp can the stock injectors support ?
 

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In my experience tuning to the numbers you want is very easy with a stock #858. Your pump shop may be able to get you close, but you will still have to advance the timing and do a final adjustment on the pump once its running. IMO I would concentrate on the torque number you want at the rpm you want and let the hp fall wherever it ends up. :smokin:
 

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CHARLIE,
You better stick with stock + 10%. you better listen to old bob . that engine will horse your chevy pickup aroung like it aint nothin STOCK......
BOB
 

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Discussion Starter #6
So Bob, you think a stock build on the pump & injectors ? Then go with advancing the pump ? Turbo has already been upgraded .
 

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Heres my pennys worth Charlie. Cpl 857 (120 hp 4bta) with just a small fuel pump adjustment. It hauls my truck up to speed as well as the 400 2v that came out of it, and whatever speed I decide to run it holds it there much better than the 400, effortlessly.
Hope this helps, Carl

Oh yeah, if you modify it much you better be running an egt gage because these little engines will literaly work themslves to death.


1979 F-250 crew cab 4 x 4
4 bta
ZF S-42 5 speed
Borg Warner 1356 x-case
Dana 60 rear
Dana 44 front
3.55 gears
255/85R16 tires (33.5x10.5)
Hydroboost steering and brakes
Custom 40 gal. fuel tank
Much more later
 

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You need to compare a Diesel's torque values at it's peak torque RPM and not horsepower.
 

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Discussion Starter #10
Carl, those sb 400 Fords run pretty well. I guess its the torque the 4b produces that is going to feel great. I have a sb 400 in my 72 4x4 that really is responsive . How responsive is the 4b ? Bob says that that little motor (4b)is really going to throw around my truck. I've heard other guys say they think its going to be a dog. I hope not. I've also heard a diesel is twice as efficient as a gas motor. Probably since the compression ratio is twice that of a gas motor plus turbocharging.
 

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Torque vs Horsepower

Torque vs Horsepower

The word horsepower was introduced by James Watt, the inventor of the steam engine in about 1775. Watt learned that "a strong horse could lift 150 pounds a height of 220 feet in 1 minute." One horsepower is also commonly expressed as 550 pounds one foot in one second or 33,000 pounds one foot in one minute. These are just different ways of saying the same thing. Notice these definitions includes force (pounds), distance (feet), and time, (minute, second). A horse could hold weight in a static position but this would not be considered horsepower, it would be similar to what we call torque. Adding time and distance to a static force (or to torque) results in horsepower. RPM, revolutions (distance) per minute (time), is today's equivalent of time and distance. Back to horses, imagine a horse raising coal out of a coal mine. A horse exerting one horsepower could raise 550 pounds of coal one foot every second.

Here is an example of another way horsepower could be directly measured. Say you have a horse hitched to a plow. In the hitch is a spring scale (like a fish scale). The horse pulls the plow one foot every second and you see 550 pounds on the scale. That horse would be generating one horsepower.

We see horsepower can be directly measured. However there is a problem directly measuring horsepower of modern day internal combustion engines because they produce rotary motion not linear motion, and unless the engine is geared down, the speed at which they do work (time and distance or RPM) is too great for practical direct measurement of horsepower. It seems logical then that the solution was to directly measure torque (rotational force eventually expressed in pounds at one foot radius) and RPM (time and distance, i.e. distance in circumference at the one foot radius) and from these calculate horsepower. Torque and RPM are easily measured directly. Early dynamometers used a brake device to load the engine. A torque arm was attached to this brake's stator. The brake's rotor was coupled to the engine's crankshaft. A spring scale or other measuring device connected the torque arm to the stationary fixture holding the engine and brake. During a test the brake's application loaded the engine. Torque and engine rpm were observed and recorded.

On modern day dynamometers horsepower is a calculated value. It's important to remember the dyno measures torque and rpm and then from these calculates horsepower. On the dyno it takes more water flow to the water brake to increase the load on the engine being tested. As the test engine's torque rises more water flow is needed. As the test engine's torque drops less water flow is needed. The dyno's water brake does not respond to Horsepower. Major adjustments to water flow are needed as an engine crosses its torque peak but none are needed as it crosses its horsepower peak. In other words the water flow to the brake during a dyno test follows the engines torque curve and not its horsepower curve. Torque is what twists the tire, prop, or pump. Horsepower helps us understand an amount or quantity of torque. (Torque + time and distance)

Now if we are measuring torque and RPM how can we calculate horsepower? Where does the equation HP=TORQUE * RPM / 5252 come from? We will use Watts observation of one horsepower as 150 pounds, 220 feet in one minute. First we need express 150 pounds of force as foot pounds torque.

* Pretend the force of 150 pounds is "applied" tangentially to a one foot radius circle. This would be 150 foot pounds torque.

Next we need to express 220 feet in one minute as RPM.

* The circumference of a one foot radius circle is 6.283186 feet. ft. (Pi x diameter 3.141593 * 2 feet)
* The distance of 220 feet, divided by 6.283185 feet, gives us a RPM of 35.014.

We are then talking about 150 pounds of force (150 foot pounds torque), 35 RPM, and one horsepower.

Constant (X) = 150 ft.lbs. * 35.014 RPM / 1hp

35.014 * 150 / 1 = 5252.1

5252 is the constant.

So then hp = torque * RPM / 5252

Here is another way; Remember we know 150 foot pounds and 35.014 RPM = one horsepower

1hp is to 150 ft.lbs. * 35.014 RPM as X hp is to observed ft.lbs.torque * observed RPM

Example; We dyno test and observe 400 ft.lbs. torque at 5000 RPM

1 hp is to 150 ft.lbs. * 35.014 RPM as X hp is to 400 ft.lbs. * 5000 RPM

When we cross multiply X hp * (150 ft.lbs. * 35.014 RPM) = 1hp * (400 ft.lbs. * 5000 RPM)

X hp * (5252 ft.lbs. RPM) = 1 hp * (2,000,000 ft.lbs. RPM)

Divide both sides by 5252 ft.lbs. RPM

X hp = 1 hp * 380.80

X hp = 380.80 hp

Horsepower = torque x rpm / 5252

Here's an interesting bit of trivia; below 5252 rpm any engine's torque number will always be higher than its horsepower number, and above 5252 rpm any engine's horsepower number will always be higher than its torque number. At 5252 rpm the horsepower and torque numbers will be exactly the same.
 

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Outstanding explanation Bob! Are you married? Seriously, A simpler answer for those of us with half a brain: A gasoline engine with 482 rwh would not have enough power (torque) to propel your heavy truck to a 12 second 1/4 mile like the 930 lb/ft diesel engine will.
Carl
 

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In your CJ-7 I would think it would be plenty.:smile:
 

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First let me clarify my previous posts.
My first post was in agreement with post #4 by brut67
My second post was to further explain torque & horsepower and why I was in agreement. We are now at the point where we are changing the subject and intent of the original thread AKA off topic. :innocent:
 

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Go big or go home. Get as much power as you can with safe EGTs. Why not? If you don't want to break stuff stay off the skinny pedal. Tuning the pump is a fun little experiment anyways. Just make sure you have gauges.
 

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