measure hp - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Hotrodding Basics
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 01-22-2012, 03:26 PM
Registered User
 
Join Date: Jan 2012
Posts: 1
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
measure hp

how to measure hp
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 01-22-2012, 03:40 PM
WDCreech's Avatar
Grumpy Old Goat Herder
 
Last photo:
Join Date: Apr 2006
Location: Anchorage, Alaska
Age: 70
Posts: 1,292
Wiki Edits: 0

Thanks: 3
Thanked 25 Times in 23 Posts
Dynomometer or weight/e.t. calculator!
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 01-22-2012, 04:09 PM
Registered User
 
Last photo:
Join Date: Apr 2007
Location: Seattle, Wa
Posts: 6,450
Wiki Edits: 0

Thanks: 3
Thanked 335 Times in 291 Posts
Quote:
Originally Posted by WDCreech
Dynomometer or weight/e.t. calculator!
A crankshaft dyno will tell you power off the shaft in the configuration the engine is tested with in the dyno room.

The disappointment begins with chassis dynos and et calculators as the power you thought you built goes away pretty fast with the installation. The dyno guys like to use a pretty conservative formula to compute back to crankshaft power. But this formula only takes into account averaged driveline and tire losses. It does not take into account the differences between accessory power consumption dyno to installed nor losses of exhaust and induction which can become considerable with nothing more than pipe length changes or additional bends. These little things add up fast.

Ages ago when I worked in Ford's dyno room we found it was pretty easy to loose nearly half an engine's crankshaft power measured in the engine dyno room to what got delivered where the rubber meets the chassis dyno roller. These were Y-Blocks and early FEs and MELs and the losses of installtions, drivelines, and bias tires of the age were undoubtedly higher than those of today. But I think this makes a reasonable benchmark when playing with numbers for average installtions.

While ET doesn't lie, there's a lot of variables involved, even more than a chassis dyno as now you have the environment, driver reactions, and chassis dynamics involved.

The nice thing about knowing engine room dyno numbers versus chassis dyno, and ET is these things identify the areas that need to be worked to reduce the difference between the the engine dyno numbers and the installation and operational numbers. This also part of tuning, goes back to speed costs money, how fast can you afford to go.

The pros get this data and grind to to grist all the time, makes it hard to run against the big money.

Bogie
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 01-22-2012, 08:23 PM
Landshark928's Avatar
FrankenPorsche
 
Last photo:
Join Date: Feb 2010
Location: Pensacola, Fl
Age: 45
Posts: 459
Wiki Edits: 0

Thanks: 0
Thanked 13 Times in 9 Posts
On EFI cars you can take the Injector duty cycle and flow rate to get close to real world RWHP.

There are decent dyno apps for Android and I-phone that use an accellerometer along with GPS and weight of car to get close.
Reply With Quote Quick reply to this message

Recent Hotrodding Basics posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
How Do I Measure Cam/ Rod Interfearance 406 bug Engine 2 01-13-2008 12:12 AM
More than one way to measure a flywheel? HotRodMan Engine 3 09-01-2006 09:36 PM
how do i measure the flywheel lookatme Engine 4 07-19-2006 11:36 PM
How to measure backspacing stratt134 Hotrodding Basics 5 06-21-2006 02:47 AM
how do you measure track? swoodard23 Suspension - Brakes - Steering 1 10-11-2003 04:32 PM


All times are GMT -6. The time now is 11:22 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.