Go Back  Offshoreonly.com > Technical > General Q & A
Rear Crossover on intake manifold >

Rear Crossover on intake manifold

Notices

Rear Crossover on intake manifold

Thread Tools
 
Old 10-22-2007 | 08:59 PM
  #1  
Thread Starter
Registered
20 Year Member
 
Joined: Oct 2004
Posts: 319
Likes: 0
From: Upper Chesapeake Bay
Default Rear Crossover on intake manifold

Anyone ever put a rear crossover tube on the back of the intake manifold to help eliminate hot spots in the cooling system (heads) and have a more even water temp. You would run a tube from one side to the other with a T in the middle and run a small discharge hose overboard.

Mike
Noise Pollution is offline  
Reply
Old 10-22-2007 | 09:33 PM
  #2  
US1 Fountain's Avatar
Ginger or Mary Ann?
25 Year Member
Charter Member
 
Joined: Oct 2000
Posts: 11,030
Likes: 9
From: L
Default

I ran tubes from the rear passages up to the front passages. I'd think your's would work better. Just didn't want to add any dump ports in the hull.

Last edited by US1 Fountain; 12-02-2011 at 11:13 AM.
US1 Fountain is offline  
Reply
Old 10-22-2007 | 09:47 PM
  #3  
Thread Starter
Registered
20 Year Member
 
Joined: Oct 2004
Posts: 319
Likes: 0
From: Upper Chesapeake Bay
Default

Originally Posted by US1 Fountain
I ran tubes from the rear passages up to the front passages. I'd think your's would work better. Just didn't want to add any dump ports in the hull.
Can't view you pic, but I get the idea. I think running a dump would help with high water pressure also. I peg the gauge at wot.
Noise Pollution is offline  
Reply
Old 10-23-2007 | 12:51 PM
  #4  
Strip Poker 388's Avatar
Rob
20 Year Member
VIP Member
 
Joined: Aug 2001
Posts: 21,637
Likes: 9
From: Ms
Default

Originally Posted by US1 Fountain
I ran tubes from the rear passages up to the front passages. I'd think your's would work better. Just didn't want to add any dump ports in the hull.

Nice lines
__________________
.

The Only Time You Have To Much Ammo Is When Your Swimming Or On Fire.
Strip Poker 388 is offline  
Reply
Old 10-23-2007 | 12:56 PM
  #5  
Registered
 
Joined: Aug 2007
Posts: 373
Likes: 1
Default

I have run mine from the rear to the front 3/8 lines work well. Others I have known to just dump them over board. Dyno testing proved without mild and up built BBCs didnt last long without the mod.
turbo2256b is offline  
Reply
Old 10-23-2007 | 03:51 PM
  #6  
US1 Fountain's Avatar
Ginger or Mary Ann?
25 Year Member
Charter Member
 
Joined: Oct 2000
Posts: 11,030
Likes: 9
From: L
Default

Originally Posted by Noise Pollution
Can't view you pic, but I get the idea. I think running a dump would help with high water pressure also. I peg the gauge at wot.

I agree with it lowering the water pressure. I did not have a pressure problem, so it wasn't a factor on my setup. I know of 1 member who did dump the rear jackets into the exhaust tubes at the transom for a cleaner look and to control his pressure.

My current boat also pegged the WP gauge at 3500rpm. Stock 502MPI's. Easiest fix was the Merc relief valves.
US1 Fountain is offline  
Reply
Old 10-23-2007 | 05:07 PM
  #7  
Scarab28's Avatar
Registered
25 Year Member
 
Joined: Dec 2000
Posts: 552
Likes: 7
From: Roch, NY
Default

OK - you guys confused me, would you do this mod to lower water pressure or reduce temperature hot spots in the heads? Uneven temps would be my concern.
Scarab28 is offline  
Reply
Old 10-23-2007 | 07:47 PM
  #8  
Thread Starter
Registered
20 Year Member
 
Joined: Oct 2004
Posts: 319
Likes: 0
From: Upper Chesapeake Bay
Default

Originally Posted by Scarab28
OK - you guys confused me, would you do this mod to lower water pressure or reduce temperature hot spots in the heads? Uneven temps would be my concern.
Do it for both. Thats my idea anyway.
Noise Pollution is offline  
Reply
Old 10-23-2007 | 08:09 PM
  #9  
Banned
 
Joined: Feb 2005
Posts: 1,459
Likes: 1
From: Cleveland, Ohio
Default

We have been doing that for years. I usually run # 8 Aeroquip hose from front to rear. As discussed earlier this mod works very well for equalizing chamber temps. It will never hurt you.
mrhorsepower1 is offline  
Reply
Old 10-23-2007 | 11:54 PM
  #10  
Strip Poker 388's Avatar
Rob
20 Year Member
VIP Member
 
Joined: Aug 2001
Posts: 21,637
Likes: 9
From: Ms
Default

On my Scarab I ran a #12 from the rear to the front T ing into the front then going to the headers.

My Hustler Whipples came with a 1/4 line dumping overboard.

I guess its releaving steam/air pockets.

Scarab pick ya kinda can see the #12 T fitting on the front
Attached Thumbnails Rear Crossover on intake manifold-oil-cooler-4-02-07-010-medium-2-.jpg   Rear Crossover on intake manifold-aa-scarab-engine.jpg  
__________________
.

The Only Time You Have To Much Ammo Is When Your Swimming Or On Fire.
Strip Poker 388 is offline  
Reply


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.