Different kinds of Horsepower

[SCAATY]

I am confused (nothin new)!!!  In trying to calculate HP needed to run a certain speed all my numbers seem too low.  I am trying to give our engine builder some real HP numbers we need at different RPM.  I want to be sure we can pull a tall third-gear ratio in the tranny, possibly a Auto Gear M22 with a 1.17 third.  Of course then I would calculate HP needed to run our target speed.  See how this all ties together?  After reviewing dyno HP numbers vs actual speeds run on cars similar to ours it looks like you loose 15 to 18 percent to driveline/friction.  Does that sound about right guys?  I noticed in a recent thread here on HP Rex Schimmer suggested plotting aero HP over engine HP.  I "think" I am looking for an Aero Horsepower Formula.     Am I confusing rwhp with aero hp???                                                                                                                                                                         

Thanks to any and all that respond to this.  As I said in my recent introto this forum, I am a newbie at this and really appreciate the help.  Now if I could just get this figured out maybe I could get some sleep at night!  Naw,  probably not!!  See ya on the Salt.

[maguromic]

Just plug your data in. http://www.wallaceracing.com/Calculate%20HP%20For%20Speed.php  Tony

[dw230]

Give your engine guy a bucket of maney and bring all the HPs you pay for.

DW

[PatMc]

The way to go fast =

Run, measure what's happening, and fix what's wrong.

Uh...  I don't need another nasty call so cut this short.

[Jonny Hotnuts]

What was your speed with your known HP?
What speed do you want to go?
What is your new HP?

~JH

[hotrod]

You might look at this thread for a start.
It should give you a ball park idea of where you need to be if you have reasonable information about your frontal area, CD (coefficient of drag) and target speed.

http://www.landracing.com/forum/index.php/topic,7775.0.html

Page two has a simple program I wrote and WOODY@DDLLC converted it to a spread sheet.

http://www.landracing.com/forum/index.php/topic,7775.msg126539.html#msg126539

After reviewing dyno HP numbers vs actual speeds run on cars similar to ours it looks like you loose 15 to 18 percent to driveline/friction.  Does that sound about right guys?

Yes that is a typical range for assumptions of drive line loss, although I was told by a former engineer at superflow dyno that it is not actually a simple percentage. Each drive line has a characteristic power loss due to things like throwing gear lube around and bearing friction that is relatively independent of power going through the drive train, then a second loss that is mostly power related due to pressure friction between the gear teeth and such that does follow the power to a limit.

Drive line loss can also be impacted by what weight gear lube you are running and tire pressures (actually rolling resistance) and also what temp the gear lube is.
A hot transmission has less fluid friction loss due to the thinner hot gear lube.



There is also some other interesting reading in the "formulas" sub forum.

Larry

[Buickguy3]

  The Salt Cat formula: Run what ya brung, break what ya brought. Works every time.
     Doug 

[Peter Jack]

Great picture Doug. 

It expresses the sentiment perfectly.

Pete

[SCAATY]

Thanks guys.  This is my first attempt at post and reply on this forum, sorry for the slow response time.  This is a new car so we have no previous data.  Its a '53 Studebaker that will run in CC.  I used Hooleys numbers for Cd and frontal area.  Actually I adjusted them up(worse).  We are just trying to figure out all we can before we go but I do realize nothing beats real experience.  Maguromic, thanks for that link.  Hotrod that sounds like exactly what I am looking for.  I will be trying that info.  Whoa Buickguy, was Fireball painted on the car BEFORE that happened   Does the bucket have to be adjusted for target speed

[WOODY@DDLLC]

  The Salt Cat formula: Run what ya brung, break what ya brought. Works every time.
     Doug 

Doug, it looks like your aluminium flux convertor is nearly perfected! 

Have you tried the old lead into gold conversion yet? 

Or is it like the others and only converts gold into lead? 

Thanks for a new screensaver! 

[Buickguy3]

   That got me thinking. If a piece of hot alloy metal is hammered into a die, to make a forged piece, what does a hot forged piece that is hammered into the head become? Twice forged junk?
  Doug 

[PatMc]

  The Salt Cat formula: Run what ya brung, break what ya brought. Works every time.
     Doug 

Those meteorites sell for big bucks!

[Rex Schimmer]

Scaaty,
I think you e mailed me through Land Racing and I tried to reply but the Land Racing address would not work. Please e mail me at: rexschimmer@gmail.com.

Rex

[kiwi belly tank]

Doug, back in the day, we used to hear the term "drop forged" & "impact extruded", kinda sounds like what you have going on there!
Dropped a hunk of ya piston & impacted the mutha in the head.
  Sid.