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  • Chamber cooling under boost

    What do ya'll think about feeding coolant directly to the back of the heads to cool the chambers under boost? The heads are symmetric and they have the water passages in both the front and the back. The fronts feed the crossover and the thermostat. I was thinking feeding coolant straight from the pump to the backs of the heads with an electric valve operated by a hobbs switch to help cool the chambers down under boost. Am I asking for a cracked head? Will it make any difference?
    Central TEXAS Sleeper
    USAF Physicist

    ROA# 9790

  • #2
    Re: Chamber cooling under boost

    Smokey Yunick made a piece of piping in a Y configuration

    to feed both cylinder heads from the front for circle track SBCs.

    That was his "cure" for the asymmetric design deficiencies of the

    water passages & coolant pathways of the (then) available castings.


    That was done as an attempt to "cure" a known problem. Is there

    a design flaw in the heads that would benefit from compensation?

    Comment


    • #3
      Re: Chamber cooling under boost

      I don't have any good pictures with the coolant lines in place but this gives you an idea of we did with my brothers engine... We ran -10 lines front to rear along the top of the valve covers on both sides of the engine to increase circulation. I think the switch and valve would be overkill.

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      • #4
        Re: Chamber cooling under boost

        Was it feeding off the water pump or just pulling the water from the back of the heads to the front and skipping the internal flow?
        Central TEXAS Sleeper
        USAF Physicist

        ROA# 9790

        Comment


        • #5
          Re: Chamber cooling under boost

          Back to front on both sides... Sorry I don't have any better pictures.

          Comment


          • #6
            Re: Chamber cooling under boost

            Ok, that isn't really what I was thinking of doing. You're increasing the flow capacity by pulling the coolant off the back of the heads faster so that the coolant comes up from the block faster into the heads. I'm talking about putting coolant straight from the pump into the backs of the heads. When the boost gets up to the activation point the valve opens and lets water coming straight off of the waterpump go to the backs of the heads without going through the block.
            Central TEXAS Sleeper
            USAF Physicist

            ROA# 9790

            Comment


            • #7
              Re: Chamber cooling under boost

              Summit Racing sells a kit for small block Chevys that run two lines from the front thermostat crossover to the rear of the manifold to even out the water flow...and if you are like the rest of us, you are in boost all of the time...right?

              Comment


              • #8
                Re: Chamber cooling under boost

                Well currently the engine isn't even assembled but I see it as a way to lesson my dependence on the methanol injection system and/or allow me to run more boost on 87oct. With a 4000+lb car and a 256cid engine I'm going to be in the boost pretty frequently.
                Central TEXAS Sleeper
                USAF Physicist

                ROA# 9790

                Comment


                • #9
                  Re: Chamber cooling under boost

                  Be sure to have the combustion chamber, piston tops

                  & valves coated for maximal CC heat management 24/7.


                  Might want to call Gale Banks shop and/or Ken Duttweiler

                  and run this by whomever is answering Tech questions.


                  Might get some free data w/o re-inventing the wheel

                  or investing more time & energy into something w/o

                  a corresponding reward in improved performance.


                  Or is there some inherent design flaw or expected problem

                  with these heads that this proposal might prevent or "fix"?

                  Comment


                  • #10
                    Re: Chamber cooling under boost

                    You might disrupt the flow of coolant trying to make it's way from the block into the heads. That could lead to steam pockets, or at least adding more heat to the cylinder bores than if the block were designed for the changed coolant flow.
                    Adding a return line near the top of the block would probably help.

                    Comment


                    • #11
                      Re: Chamber cooling under boost

                      Originally posted by Two Lane Blacktop
                      Or is there some inherent design flaw or expected problem
                      with these heads that this proposal might prevent or "fix"?
                      He's basically trying to make a temporary reverse flow cooling system to keep the chambers as cool as possible during boost.

                      Comment


                      • #12
                        Re: Chamber cooling under boost

                        Bingo Rendid! Well not quite, I'd call it a Temporary Priority Chamber Cooling system. The coolant is still going in the block and out the heads but its getting a boost in non block warmed coolant. The feed line will only be 1/4in since thats the biggest 12V DC valve I can find thats not over $100, so its not going to be a swamping amount of coolant. Part of what stired this on is the fact I have an ex dragster front cover piece (thats another story) that already has a fitting in the drivers side coolant passage and thought I'd make use of it instead of welding or plugging it up.
                        Central TEXAS Sleeper
                        USAF Physicist

                        ROA# 9790

                        Comment


                        • #13
                          Re: Chamber cooling under boost

                          Originally posted by CTX-SLPR
                          Am I asking for a cracked head? Will it make any difference?
                          No & I doubt it.
                          Until I had data saying I needed it I wouldn't have it...... oh ya on a Chevy you need to add water to the head at the siamese exhaust port but on a Buick I don't see the point. We didn't do it on the Indy Buick V-6's at 980 hp for 500 miles, but hey, I could be full of it.

                          There are very few people in this world who's opinion I value, you are not one of them.

                          300 in 1999

                          Comment


                          • #14
                            Re: Chamber cooling under boost

                            Sorry for the length of this. I can never seem to relay what I need to without writing novels <g>. If this gets too boring just ignore the rest.
                            ** ** **
                            While perhaps not quite what you were asking, I chased boost-related heat issues with my BBC for quite awhile and was able to resolve a lot of them. My hotrod is a lot better behaved now and I know the circumstances when it's going to act up.

                            To start with, I have an iron block/iron head 427 BBC running a 9% underdriven 671 Weiand blower with 2 x 750 Holleys. I'm spinning a standard belt driven, six blade steel fan and high volume BBC water pump. I have a standard aluminum radiator with an additional 14" electric fan mounted on the front of the radiator. This car sees quite a lot of street driving, occasional romps down the freeway and will be flogged on occasion down at the track.

                            I was having pretty bad boil-over problems and heat spikes during and after boost events. During throttle up you could literally watch the temp needle climb the dial. During different driving conditions or after shutting down I might or might not lift the 18 lb radiator cap and puke coolant to my overflow tank. Its just not cool to rumble up in your wicked blown ride, shut it down and then have everbody watch it puke on the ground.

                            To address some of my coolant flow issues (air and steam pockets in the block) I used an AN -3 line to connect the left and right water jackets at the rear of the block then ran an AN -3 forward to the *outside* of the thermostat housing (see pix below). My intention was to make certain I kept a full slug of water in the block by venting any trapped air or generated steam from the very top of the coolant chambers. I gather BBC's are notorious for trapping air in the block and heads and then suffering later as a result. This is made worse by throwing a power-adder (read 'heat/steam-adder') into the mix.

                            After adding these waterjacket vents things improved a lot. An added benefit is when filling the cooling system. Fill the radiator, start the engine, run it for a short bit, shut it down and top off the radiator. Do this a few times and you will have pushed all of the air out of the block (or so the theory goes).

                            To help address heat energy issues, I increased and sustained radiator airflow after boost events by adding the auxillary fan. I wired the fan relay into a temp sending unit located at the rear of the water jacket, the point furthest from the water pump and radiator (green wire on the left in the pix). I can toggle this setup on or off as needed, and when on, it will kick the fan on any time the waterjacket temps exceed 165 degrees or so.

                            Again, the theory is that maximum mechanical air flow through the radiator will decrease *after* a WOT event which generated the increased cylinder heat to begin with. Stated otherwise, by the time the increased heat energy from boost state reaches the radiator you're already out of the throttle and down in RPM with decreased mechanical (engine fan) airflow through the radiator, trapping and recycling this excess heat right back to the block. Adding this thermostatically controlled fan helps bridge and mitigate these WOT-to-idle heat energy states. Once temperatures drop back to normal the fan cuts off.

                            Here's a view from the rear, showing the AN -3 line connecting the left and right waterjackets. The green wire on the left is for the fan thermostat switch. The red AN fitting on the right is for my dash temp gauge sending unit.



                            And here's the front view, showing the -3 line venting outside the thermostat.



                            Sorry if I've beat this topic to death or boldly stated the super obvious. Again, I can't seem to relay a topic without writing the Great American Novel <shrug>. I hope this was been of some help to you. I know that you were looking for something more extreme, but this is what seemed to work for me.

                            Harry

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                            • #15
                              Re: Chamber cooling under boost

                              Originally posted by Dynoroom
                              Originally posted by CTX-SLPR

                              Will it make any difference?
                              I doubt it.

                              Until I had data saying I needed it I wouldn't have it on a Buick

                              I don't see the point.

                              We didn't do it on the Indy Buick V-6's at 980 hp for 500 miles

                              Roger that.

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