Hp per lb of boost

[Kc7nwi]

Is there a formula for calculating how much horsepower can be expected for each pound of boost?
I have a stock 85 ranger with a 5 speed that I'd like to put a turbo on and run 7lbs or less boost. What kind of power increase am I looking at? I think its rated at 85hp right now.

 

[forzda]

from what I have read and been told it is approx 10 hp per pound of boost ,

 

[kunar]

there's no set formula, and it definitely varies based on the engine.

think of it this way, a complete vacuum is 0psi. atmospheric pressure is 14.7psi (approx, sea level) above that 0psi in a vacuum. so when the piston draws air into the cylinder, its one atmosphere (14.7psi) of pressure forcing the air into the cylinder in a N/A engine. add another 7psi on top of that (roughly 50% increase in pressure) for your now boosted engine, and expect a proportional gain (roughly 50% increase in power) of course this doesnt account for all the losses in an imperfect system, yada yada yada, but best case would be maybe 125hp.

that's not saying that your engine will handle it, are the internals strong enough, will the fuel system keep up, etc etc... just a quick and dirty guess given your info.

 

[AllanD]

There are a myriad of other variables all of which defy a simplistic correlation.

You say you have an '85 Ranger with 88 Horsepower... an EFI2.3 I presume..

a 2.3 EFI engine with from an '85-86 Turbocoupe typically puts out 155-165hp

The intercooled version of the engine produces 190hp(Factory spec with an intercooler)
along with a very V8 like 265ft/lb of torque.

I feel led to point this out turbochargers (and superchargers driven by other means) produce additionall Horsepower by a secondary effect... What they do is increase torque.

Torque is proportional to how much air is moved through an engine on a per cycle basis.

Horsepower is proportional to how much air is moved per unit of time.

Forced induction pushes more air into the engine, allowing more fuel to be burned...

So 10-20psi of boost pressure will essentially double the horsepower on the 2.3 turbocharged engine.

With proper subtle tuning tricks and a slightly different turbocharger the 2.3 turboengine with the proper more durable forged pistons had been pushed to 250-300 horsepower.


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[Kc7nwi]

Thanks for the replies. Do you all figure this would work on the Ranger?


http://www.ebay.com/itm/FOR-FORD-XR...04&rk=8&rkt=30&sd=231225063231#ht_3446wt_1099