Ideal method of engine cooling for most consistent temps
 

I’m looking to achieve the most constant water temps throughout the engines.

Ive drilled and tapped the rear of intake and ran 8 AN from side to side with a T in the middle with a 4 or or 6 AN hose out the transom in the past. My goal has always been to dump the hotter water in the rear trying to achieve more consistent temps from front to rear as the rear is always hotter.

Question is it as equally important to run hoses from front to rear as well in addition to?

Looking for some opinions. Seems like Rookie showed some pics with different size restricters he made but can’t remember how all was plumbed.

Tks

What you are after is supposed to be one of the benefits of the 4/7 swap cams. I think you are on the right track track as you can count me in as one who has lost either 7 or 8 in a marine engine.

you want advice but dont say what the engine / exhaust configuration is

If using Mark IV blocks, read on difference (internet search) between parallel and series cooling for bbc (big block chevy)

I believe rookie had crossover system with bypass and using restrictor in the bypass section for proper block water psi ?? I’m just talking/thinking out loud....surely he’ll reply. :)

Seems as though you recall that same thread. Heck I probably started for all I know but searched and couldn’t find. Rather than the restrictors I had used a ball valve at the transom to regulate pressure.

Builds are dart big m 9.8 565’s. 740-750 NA. 6,300 rpm.

I will be running my x overs and bypass.

My thought if dumping the rear, - would it be non beneficial to run front to rear. Just thinking out loud.

Valako picked up my intakes while up deer hunting however they are the Brodix hv2001’s

Yes SB I finally bought them. Hah

I might suggest dumping both rears of the intake directly overboard with AN -8s all independent of each other, I did this on my engines it helps at sustained higher RPM runs.

I first had to tap out the back end of the intake because my original combination of ported Merlin heads and crossover would take out cylinder #6 #8 valves. With a infrared pyrometer the back of the heads was getting up to I believe 300°F during idle and would take a valve out within a minute once on plane. I replaced 3 or 4 valves during that experiment. (3 different failures) I then switched to Dart Pro 1 heads and ran the same setup. I always some restriction (5/16" hole) in the bypass hose. When I put my power in my Active Thunder from my Panther I then switched to E-tops and plumbed the intakes with -10AN (that's what the exhaust bung is) and had to put restrictors in to keep some heat in the rear of the engines and build a little engine temp. I have always plumed them into my exhaust. It is a fine line when you add the restrictors. It's a juggle between where your water is going and water pressure. Currently I have 3/16" holes on the rear of the intake and 5/16" in the crossover bypass. I just put them in the straight ends so I can remove and drill larger holes as necessary. I run about 15-20 psi H2O pressure. I noticed if it ran over 20 psi my oil temp would rise. I assumed I was restricting too much water and not flowing enough through the the oil cooler. I guess I wasn't hitting the optimum reynolds number for dynamic cooling efficiency. :)
I tried to search for my thread on Boatfreaks about the valve incident, head cooling and cooling passages but I don't believe there is a technical section there anymore. But I did find this beauty! lol
https://forums.boatfreaks.org/showthread.php?t=25599
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I did have an IR gun to monitor and regulate temps and I also run the 2/3-4/7 swap for the even cooling benefits.

Does any of this really change with closed cooling? Or are the issues more prevalent when using a crossover?

Im running -6 an on both rear sides to a Y connector and dumping a single -6 over board on both engines.

I would agree independently to avoid any transfer. I was trying to eliminate the amount of dumps however as Rookie mentioned utilizing the exhaust and that actually may serve two purposes (possibly). Just thinking the exhaust might help pull or suck the water through.

Im probably over thinking but better than under I guess. Lol

Thanks for all the help Jason. I realize every platform will alter and have to adjust accordingly however that’s a good baseline to start. I remember seeing those restricters you posted. Pretty slick and easily adjustable or replaceable.

One thing I’m curious of is what your doing for a t-stat if any. I would assume you are and drilled holes but your advice on that would be helpful. I’m really curious as the size stricter you used for the bypass. Header temps ok prior to stat opening? Again that’s if your using them.

Again thanks for your time and help. I really enjoy experimenting and ongoing look for ways to improve however that’s a great place to start and save me some time. Plus good info for others.

That must have been some chitty days when the valves said good by. Dammm.

More non closed cooling related. Not sure if there’s any improvements to make on closed cooling. Probably though.

Jason did you have any comparison from std firing order vs the 4/7-2/3 swap. That would be real interesting to know also.

Personally I don't like more water in the exhaust then needed, your concerns of more penetrations in the hull is valid.. I use wafers in place of the t-stat settled on the 3/4 hole and dumps off the rear intake and seems to work for my application.. all engines and exhaust systems will react differently. you will fine tune it once it's in the water and running.

Thanks and yes I’m finally on the way to getting in the water. Long project. Business put most on hold. I have dry Stellings to the tip so I’ll have to check that out but certain I will have options. Btw I still need to get john sr on your boat. He’s 80 now even though one would never know it however I wanna get him on the water over 100 mph. 😎

I have 2 -6AN lines coming off my intake.
Thats how it`s always been .
I grab water temp back there too.
I don`t know what it helps or doesn`t lol


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I ran 140°F stats with 4-3/16" holes. This would allow the blocks to generate a little heat. ~110°F while idling. On long runs they would get to 140°F but one block would slowly climb into the 160° (old stats) so I put another hole in it. It's funny that this thread came up. I am now going with 120°F high flow race thermostats.They appear to be able to flow some water. I was just installing them tonight.


No, I have never ran a comparison. Valako and I talked with his Comp Cam tech guy and he said the biggest benefit to the swapped firing order was the cooling aspects and minor HP gain.
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Getrdun - if you use tstats you’ll have to get tstat spacer with that intake or mill the divider i guess

I couldn’t tell by pics but did you reduce the number of holes with the new 120 stats or you going to wait and see how they react. Tks for the info.

That’s a good point. How many times I’ve looked at that intake and saw the divider however never gave it a thought. They went to Jim’s to raise the floors and some porting. I’ll mention to him to remove.

Whats the purpose?

I'm planning on putting the boat up for sale when we return from Arizona for Desert Storm, that's at the end of April, so we need to do it early in the season! or it may not sell at all then we have all summer. Hard to sell a 38FT cat with a full cabin that runs 120 MPH!

It’s always nice to see the pride you take in your work 👍👍👍. Also Tks for the post. I couldn’t tell by pics however from what I could see looks like you dumping individually as well?

Thank you .
Dumping them individually above the drives , yes.. I thought about using them to cool the drives but they never really get hot.
For a bravo it might be cool idea

I did not put any holes in them. They come with 1 hole in them for air pockets. I will probably not drill any holes in them right away. I'll see where my pressure is an go from there. I also just put those in my Merc 420's w/ 500 EFI cam builds. Those engines ran hotter water and oil than I like with 420 stock hardware. Nothing like spending $160 on thermostats. Why do I do this again... lol

Gives it Direction.
Forces water up there vs the two columns of water crashing into each other, then going up. Water flows similarly to air, but with a little mire weight.

I'll cut them out tomorrow while I'm at the shop. lol

Can you quantify mire for me? I must have missed that unit in my engineering classes... :)

I run in water temps that range from 34 to 76 degrees. I have a 524CI BBC that's a GM Mark IV block with AFR heads and a Brodix HV2000 intake, and Lightning headers. I am running the Hardin stainless pump that I have ported for better flow with a crossover and racing 160 thermostat. It came with 3 3/16" holes and I still have the divider under the thermostat. I added a -10 line from back to front to even out the cooling. According to my lab grade IR temp gun the front and rear of my cylinder heads are with 2 degrees of each other. I have slightly modified the headers to allow for more flow as well. When running wide open across the lake I run about 165 on the gauge. idling for any length and I'm 140-150 if the water is warm. When Lake Huron is cold, I'm lucky to hit 130 pushing it. My oil cooler is a bit too small, but with Amsoil as long as I'm under 300 degrees I'm fine. I couldn't ask for a more consistent and even cooling system.

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Yes. My finger pads are worn slanted. I pressed ‘o’ on my phone keypad but got ‘i’. :) So, tried to type ‘more.’
lol

Aside from the hole in the stats and your 5/16 restricter in your bypass is that your only source of cooling the exhaust until stats open?

those lightenings have a sound of their own don’t they... Also good info. Like abones mentioned every application can differ. I will be running large stat controlled oil coolers. I suspect they’ll only open on hard runs with lake mi water temps.

Yes they do, I took the mufflers off last year as I finally got it to idle well at lower RPM for cruising down the rivers. You can really hear when the engine gets on the cam at 3000rpm, it let's out a roar that gives me chills. It's better than drugs.

No, I plumb the rear of the intakes into each header. I don't believe there would be enough flow if I didn't. Also at 120°F I'm assuming they will open relatively fast. I do plan to open the bypass to 3/8".
See 2nd pic post #8

That’s right. I had forgotten that. Yes makes more “since” to me now! 👀.