292 cam on airboat direct drive - 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 05-27-2011, 10:47 AM
Registered User
 
Join Date: May 2011
Location: florida
Posts: 19
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
292 cam on airboat direct drive

putting an inline 292 on airboat. prop will turn 3000 max. if I spent money got a cam made. how much could I increase horsepower at 3000. Would it be 10 horse power or more. maybe horsepowr is not the hole ball of wax. maybe its torque. any thoughts.

I know you can get lots of horse power by increasing rpms, but don't have that luxury.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 05-27-2011, 04:02 PM
curtis73's Avatar
Hates: Liver. Loves: Diesel
 
Last wiki edit: How to find cheap parts
Last journal entry: Found an LQ9 today
Last photo:
Join Date: Dec 2005
Location: Carlisle, PA
Age: 41
Posts: 5,298
Wiki Edits: 16

Thanks: 20
Thanked 20 Times in 15 Posts
F-bird... that's a fine idea, but airboats like to explode props above about 3000. He's limited to about 3000 prop RPM.

If you're intent on sticking with a direct drive, your engine needs to peak its HP at 3000. That means a tiny cam. If you increase your HP at 3000 rpm, then you will (like F-bird says) increase prop pitch to keep it at 3000.

For the most part, direct drive applications that want more power require more cubes. The best way to increase torque (and consequentially HP) when the RPM limit is fixed is to increase displacement. That's why most direct drive airboats use big blocks. Most small block airboats with big power need to use a reducer gearbox. That way you can spin the engine to 5000 and make nice power while maintaining safe prop speed.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 05-27-2011, 04:43 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 13,310
Wiki Edits: 326

Thanks: 838
Thanked 1,151 Times in 950 Posts
A gearbox is the first thing that popped into my mind. Heck, set it up with a 3-speed manual trans (low buck) and run it in second gear. You could also run it in first gear for low-speed, high-torque. Or run it in reverse to back up. "Hey dude, check it out, my airboat backs up". Build the motor at 9.5:1 with a tight squish and Crane 204541 cam, 216/228, 112, 0.530"/0.560" power range 1800-5400.
http://www.summitracing.com/parts/CRN-204541/
For coming right off the crank to the prop, the stock cam will probably produce the best torque numbers at 3000.

Last edited by techinspector1; 05-27-2011 at 04:51 PM.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 05-27-2011, 04:48 PM
crowerjunky's Avatar
JOHNNY
 
Join Date: Aug 2009
Location: FLORIDA
Age: 44
Posts: 92
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
call dave at waterthunder performance his site is www.waterthunderperformance.com
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 05-27-2011, 07:28 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 9,476
Wiki Edits: 0

Thanks: 20
Thanked 386 Times in 362 Posts
Make the tq curve run parallel to the prop efficentcy curve, whil making it as high as you can under 3000prm.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 05-28-2011, 08:31 AM
curtis73's Avatar
Hates: Liver. Loves: Diesel
 
Last wiki edit: How to find cheap parts
Last journal entry: Found an LQ9 today
Last photo:
Join Date: Dec 2005
Location: Carlisle, PA
Age: 41
Posts: 5,298
Wiki Edits: 16

Thanks: 20
Thanked 20 Times in 15 Posts
Quote:
Originally Posted by techinspector1
A gearbox is the first thing that popped into my mind. Heck, set it up with a 3-speed manual trans (low buck) and run it in second gear. You could also run it in first gear for low-speed, high-torque. Or run it in reverse to back up. "Hey dude, check it out, my airboat backs up". .
I had a similar idea, but it involved a powerglide
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 06-02-2011, 12:16 PM
Registered User
 
Join Date: May 2011
Location: florida
Posts: 19
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
thanks

Thanks for the replys, I thought about a gearbox (reduction drive) Right now I am running a 250 inline it does surpriseingly well. I have a 292 on the garage floor and ready to put in boat. will post video one day. I do have an adjustable pitch prop. currently set were it turns max 2600 rpm.
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
Direct Drive Gears. afsog Engine 25 11-08-2010 02:47 PM
Direct drive, converter only, no gear box Augusto Transmission - Rearend 24 06-21-2010 02:09 PM
Direct drive or Belt driven mikeweb Garage - Tools 18 07-16-2007 12:09 PM
a500 no reverse or direct drive when hot dgm Transmission - Rearend 0 04-29-2006 07:34 PM
Direct drive crank driven supercharger. Super Chevy Engine 10 04-18-2006 06:47 PM


All times are GMT -6. The time now is 05:24 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.