Power calculation

[blownstanger]

Ver helpful Dal, thanks.

 

[Dalamar]

YW

 

[musclemustang94]

Jesus I was planning on putting a turbo 351W in my car this winter possibly and run 10 lbs of boost. I figured 325 horse on the motor and with 10 psi I should be at 588whp? Maybe I am thinkin a little high with the 325 horse on motor.

 

[a_lil_red_302]

[(22lbs/14.7)+1] x 325=811! :banana:

 

[95 svt cobra]

whoah nice! even if my numbers are a little lower than this calculation ill be happy. My setup + 9psi = 483?

 

[justinschmidt1]

The calculation looks about right for my car....maybe a little generous


(11/14.7+1) x 215= 375 HP

according to that my car would make 375 at the wheels if it makes 215 at the wheels n/a

 

[Dalamar]

here's what mine should do at 12#

[(12# / 14.7) +1 ] x 285 = 517

that's HP, the torque curve on the Rotrex with my stroker should put down a really good torque curve.
anyway, that's what we're thinking, we'll see what she does.



Some things to keep in mind, real rear wheel HP is usually lower than you read about.
for example my NPI 2V was rated at 215HP, but I had it dyno'd before I did my PI headswap, at my elevation It put down 184 RWHP. WHOOTY!
So elevation, temperature, tune & interweb hype can throw your numbers off!!

 

[94turbostang]

Do you ever find yourself saying:

"how much power will this add?"
"how much boost should I run?"

I find this equation handy:
[(boost / 14.7) +1] x base HP

best to add rear wheel HP because it accounts for your drive train loss.
plug in base HP and boost - this is very close to what your power will be.


Other factors to keep in mind:
posative displacement or roots type blower will give you a longer torque curve.
Centifical gains are more on the top (obviously)
Turbo's are a little different because they don't take power off the crank to operate.


Hope you guys find this info helpfull. ;D

this equation is useless for turbo setups. reason being is turbo size/efficiancy.

running 20 lbs on a small knock off turbo will produce low numbers realistically. running 20 lbs on a bigger turbo/more efficient will produce much bigger numbers. like comparing a garrett 44 trim to a hks t-88 turbo with both making the same boost.

think of it this way, stick a small straw into a balloon, and blow the balloon up. now take a large straw or whatever and try blowing it up. youll notice how much faster the balloon fills with air using the larger diameter straw. straw=turbo.

this is also without factoring ambient air temp and elevation. im almost at denver elevation. take my car to see level and id see a huge difference in numbers. elevation plays a huge factor with cars under forced induction because your trying to compress air to fill the cylinders with more air than the pistons would naturally suck in. colder air= air molecules are closer together. hot weather= air molecules are spaced further apart.


im not trying to knock anyones math or calculations. i hope this doesnt cause any drama. im just trying to expand the knowledge

 

[Dalamar]

that's why it says it's for superchargers.

turbo's are a different animal, and are more efficient.

 

[Dalamar]

I've seen the Turbo calculation, and it's about 3x longer than this supercharger calc.
Can't find it on a search...

Came up with some other stuff
This site has a number of usefull conversion calculators.
the second one is for Turbo's, but it doesn't seem to work.
http://www.dsmtuners.com/forums/articles-miscellaneous/226187-useful-calculators.html


here's a few other calculators that are handy:
http://www.cprparts.com/HPcalculator.html

 

[bottlefed97]

[(18psi/14.7)+1] x 277 = 616

Wow I hope it will make that much, especially since the pulley will make 18-21 psi

Then with a 50 shot to cool the charge off... :headbang:

 

[GREG@SN95]

interesting...

 

[nicostang]

Do you ever find yourself saying:

"how much power will this add?"
"how much boost should I run?"

I find this equation handy:
[(boost / 14.7) +1] x base HP

best to add rear wheel HP because it accounts for your drive train loss.
plug in base HP and boost - this is very close to what your power will be.


Other factors to keep in mind:
posative displacement or roots type blower will give you a longer torque curve.
Centifical gains are more on the top (obviously)
Turbo's are a little different because they don't take power off the crank to operate.


Hope you guys find this info helpfull. ;D

this equation is useless for turbo setups. reason being is turbo size/efficiancy.

running 20 lbs on a small knock off turbo will produce low numbers realistically. running 20 lbs on a bigger turbo/more efficient will produce much bigger numbers. like comparing a garrett 44 trim to a hks t-88 turbo with both making the same boost.

think of it this way, stick a small straw into a balloon, and blow the balloon up. now take a large straw or whatever and try blowing it up. youll notice how much faster the balloon fills with air using the larger diameter straw. straw=turbo.

this is also without factoring ambient air temp and elevation. im almost at denver elevation. take my car to see level and id see a huge difference in numbers. elevation plays a huge factor with cars under forced induction because your trying to compress air to fill the cylinders with more air than the pistons would naturally suck in. colder air= air molecules are closer together. hot weather= air molecules are spaced further apart.


im not trying to knock anyones math or calculations. i hope this doesnt cause any drama. im just trying to expand the knowledge

you are right on everything except that F/I cars have less problems with elevation. This is due to the fact that air is being compressed. It might take a bit longer to spin but the power loss of a F/I car should be less than with N/A cars. N/A cars have a VERY hard time with altitude because air is sucked in by a vaccum.

Pressure is the key. F/I cars can retain certain pressure under boost, while N/A cars have to deal with current atmospheric pressure at that elevation.

All of this is under boost and refering to MAX numbers, and not the whole curve.

Taken from: http://www.m3post.com/forums/showthread.php?p=7295661
NA engine
Psi at sea level - 14
Psi at 3000 ft - 12.5
Power loss 10.7%

Turbo engine
Psi at sea level + turbo pressure - 14+10=24
psi at 3000 feet + turbo pressure - 12.5+10=22.5
power loss 6.3%

In order to "solve" this, what you can do is set your blow off valve to discharge air at higher PSI.
So, Regarding the example stated before:

Turbo engine
Psi at sea level + turbo pressure - 14+10=24
psi at 3000 feet + turbo pressure - 12.5+11.5=24.0 <--You Raise your PSI by 1.5 and you are back to where you were
0% power loss

So in few words, you have a LOT less issues with elevation when you run boost!

Have fun, and please give feedback on what you think

 

[Dalamar]

That is great information.
thanks for adding that to this thread.

to sum it up: Boost is bedda

 

[nicostang]

Yup, that's one of the reasons why suppercharged/turbocharged planes DOMINATED the AIR in WWII. They could reach higher altitudes with less power losses. That meant better speed and maneuverability, and also made them able to attack enemies from higher altitues. :icon_salut:

 

[Dalamar]

true that. I believee the origional supercharger was designed to improve a planes performance and allow it to fly at higher altitudes.
it's pretty interesting.

 

[coleton22]

ok guys im new on here and i need some help i have a 94 gt with the h.o. and i have scat rods summit racing pistons 30 over and a blue printed and balanced crank and gt 40 heads. i want to twin turbo it i want to know what size injectors should i run and how much boost can i run without blowing everything up

 

[330CubeGt]

[(10PSI / 14.7) +1] x 265 = 445.27

Guessing the stock 94 302 would make some where in the ball park of 265 (High Side? with the GT40 Upper/Lower Trick Flow elbow and 70mm t body? ? ? Who knows....

 

[mike97gt]

Vortech V3 @ 8lbs
((8/14.7)+1)x227rwhp = 350rwhp

n/a put down 227/262 on a dynojet at horsepower solutions in Edmonton, Alberta.
f/i put down 326/313 on a mustang dyno at the mustang shop in Calgary, Alberta.
Equation is fairly close to what a dynojet would show.

-Mike