Engine dyno to chassis dyno numbers - 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> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 06-19-2011, 08:23 PM
80 SS El Camino
 
Last photo:
Join Date: Jun 2008
Location: USA!
Posts: 114
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Engine dyno to chassis dyno numbers

I have a 385 stroker Chevy I put together and actually watched the dyno the day it was born. It pulled a few 450's and topped out at 460 hp. Great, two years later and only 1200 miles on it I had the opportunity to chassis dyno it. I was a little disappointed at a 337 hp at the rear wheels. That's a 123 hp drop from the flexplate to the rear wheels, or 23% drop.
IS THAT NORMAL?
I have a built TH 350 that's pretty stout and the torque converter is pretty solid too.
Anyone else experience numbers like this?

ds

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 06-19-2011, 08:39 PM
68NovaSS's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Working with chromed bolts
Last journal entry: New to me T-Bucket
Last photo:
Join Date: Sep 2002
Location: Nine Mile Falls/Suncrest, WA
Posts: 5,271
Wiki Edits: 9

Thanks: 110
Thanked 138 Times in 129 Posts
I've never measured the difference of drive train losses on mine, and it seems like a lot, but parasitic loss can be big compared to the bare motor on a stand. Add accessories, the turbo trans, differential drag, on and on, I suspect you aren't alone. Also keep in mind the motor dyno test is conducted under ideal conditions, temperature controlled, etc.
__________________
Boost adds dignity to what would otherwise be a vulgar brawl...

Midnight Sun Street Rod Association
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 06-19-2011, 08:41 PM
WDCreech's Avatar
Grumpy Old Goat Herder
 
Last photo:
Join Date: Apr 2006
Location: Anchorage, Alaska
Age: 71
Posts: 1,331
Wiki Edits: 0

Thanks: 3
Thanked 35 Times in 33 Posts
~20% is about normal for drivetrain loss in a street car. Also, when you had the engine dyno done the first time, were there accessories on the engine, power steering pump, alternater/generater, fan, etc? A race only car might only loose 10% in the drive train, but they rarely get on a chassis dyno.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 06-19-2011, 08:56 PM
80 SS El Camino
 
Last photo:
Join Date: Jun 2008
Location: USA!
Posts: 114
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The motor was set up on the stand the way it sits in the car now. March serpentine kit with 1 wire alternator, aluminum water pump and ps. Nothing else. I run an electric fan now as well. I guess if +-20% is normal then I won't beat myself up on what could be wrong.

What I might try next is a tried and tested TCI torque converter and stepping up to 1 3/4 headers instead of the 1 5/8 I have now. (running 3" exhaust)

Thanks
Reply With Quote Quick reply to this message

Recent Engine 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:
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
chassis dyno hp to engine hp zephyrc General Rodding Tech 1 06-16-2011 03:19 PM
Can someone tell me dyno numbers. TGCheeseman Hotrodding Basics 7 12-05-2010 04:17 PM
Chassis Dyno vs Flywheel 428ho Hotrodders' Lounge 1 10-23-2006 07:55 AM
Chassis Dyno Question gt2betubbed Hotrodders' Lounge 5 05-16-2004 08:35 PM
How many of y'all have run on chassis dyno bentwings Engine 2 11-16-2002 04:24 AM


All times are GMT -6. The time now is 12:15 AM.


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.