Like Tree0Likes

horsepower gains via weather

Reply
Old 11-24-2010, 09:17 PM
  #1
Registered
Thread Starter
 
Join Date: Jun 2010
Location: Ft Lauderdale
My Boats: 2008 Donzi 38 ZR
Posts: 180
Default horsepower gains via weather

Hi guys, curious as to the difference in horsepower down here in florida now that we have some cooler weather. Figure it is 20 deg cooler with 20% less humidity, and idea how much power I will pick up? I ran 88.7 in the summer months, now have new plugs, props (same pitch), and cooler temps, hoping to get 91-92 out of the boat but don't know if i am being greedy or not, lol. Thanks in advance.
Scott
GoFastScott is offline  
Reply With Quote
Old 11-24-2010, 09:25 PM
  #2
Registered
Trade Score: (2)
 
Join Date: Mar 2002
Location: Miami Beach
My Boats: 2009 37 Spectre Diesel CC
Posts: 2,063
Default

I had an Eliminator 28 Daytona that would 85-87 in summer maybe 88 light on fuel, and it would do 90-91 in winter, miami beach area. With hardly any fuel and a nice 50 degree day you should be just getting to the rev limiters if the boat is set up right. You'll have to come down to biscayne bay to find out though no where to run in broward, when the weather is right the ocean is to rough.
pstorti is offline  
Reply With Quote
Old 11-24-2010, 09:37 PM
  #3
Registered
Thread Starter
 
Join Date: Jun 2010
Location: Ft Lauderdale
My Boats: 2008 Donzi 38 ZR
Posts: 180
Default

Nice 50 degree day haha i have lived in florida too long, I would probably have a snowmobile suit on
GoFastScott is offline  
Reply With Quote
Old 11-24-2010, 10:36 PM
  #4
Platinum Member
Platinum Member
 
TomZ's Avatar
 
Join Date: Feb 2001
Location: Virginia Beach, VA
My Boats: '88 Formula 311 SR1 "Beach Party"
Posts: 1,511
Default

I haven't pushed my micro too hard since I blew up the 383, but I can say from being out a couple of weekends ago, that the increase in midrange acceleration/power is quite apparent. Most of the summer was spent running in 95 degree-plus heat (external air temp... small engine bay had to be REALLY hot), and the last time out temps were in the 50s. She's always been powerful in the midrange, but this was bringing an even bigger smile to my face!
TomZ is offline  
Reply With Quote
Old 11-24-2010, 10:58 PM
  #5
Registered
 
Join Date: Mar 2007
Location: Lake Dallas, TX
My Boats: PQ 260/Laveycreft 29MCOB/ Now Boatless :-(
Posts: 1,087
Default

I saw a 8 mph difference between 68 degree water and 96 degree water temperature. I swore something was wrong with the engine, after tearing it down multiple times and conducting every test know to man, I took it out when the lake cooled down to about 82 degrees and it was back up to norm. Made a huge difference at least with my boat.
bert4332 is offline  
Reply With Quote
Old 11-25-2010, 07:32 AM
  #6
Registered
Thread Starter
 
Join Date: Jun 2010
Location: Ft Lauderdale
My Boats: 2008 Donzi 38 ZR
Posts: 180
Default

Wow, 8 mph is a huge swing! Thanks for your comments guys, and have a Happy Thanksgiving!
GoFastScott is offline  
Reply With Quote
Old 12-03-2010, 07:51 PM
  #7
Registered
 
Join Date: Mar 2009
My Boats: 2017 Nor-Tech 39SV
Posts: 79
Default

Quote:
Originally Posted by GoFastScott View Post
Hi guys, curious as to the difference in horsepower down here in florida now that we have some cooler weather. Figure it is 20 deg cooler with 20% less humidity, and idea how much power I will pick up? I ran 88.7 in the summer months, now have new plugs, props (same pitch), and cooler temps, hoping to get 91-92 out of the boat but don't know if i am being greedy or not, lol. Thanks in advance.
Scott
What are you running for engines? The EFI blower Mercs compensate for air temperature and output is pretty constant. Naturally aspirated or carburetted blowers, not so.
FasterFaster is offline  
Reply With Quote
Old 12-04-2010, 10:41 AM
  #8
Registered
 
Join Date: Jan 2009
Location: Riverside, CA
My Boats: 2004 3600 Nortech
Posts: 309
Default

Talk to someone with a Dyno. A built supercharged engine can vary 100+ H.P. on a given day just because of weather conditions.
bobsbillets is offline  
Reply With Quote
Old 12-04-2010, 12:12 PM
  #9
Platinum Member
Platinum Member
 
4mulafastech's Avatar
 
Join Date: Apr 2005
Location: Washington, MO
My Boats: 2006 Formula 292 FasTech / 2007 Ranger Reata 190VS
Posts: 1,416
Default

I found this calculator a while back that calculates the effect temperature, humidity, pressure, and elevation has on horsepower. The correction factor is based on the HP level at SAE J1349 conditions: 77F, 29.235 inches Hg, 0% relative humidity and at sea level.

http://wahiduddin.net/calc/calc_hp_dp.htm
4mulafastech is offline  
Reply With Quote
Old 12-04-2010, 02:54 PM
  #10
Registered
 
Join Date: Mar 2009
My Boats: 2017 Nor-Tech 39SV
Posts: 79
Default

Quote:
Originally Posted by bobsbillets View Post
Talk to someone with a Dyno. A built supercharged engine can vary 100+ H.P. on a given day just because of weather conditions.
OK. How's this?
http://www.mercuryracing.com/blog/dyno-mighty/#more-917
FasterFaster is offline  
Reply With Quote
Reply



Posting Rules
You may not post new threads
You may not 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



All times are GMT -5. The time now is 03:52 PM.


Copyright 2011 OffShoreOnly. All rights reserved.