Blocking Off Coolant Bypass On Sbf?

[horseballz]

Hey Guys,
As usual, I'm gonna ask an unusual, lengthy question. A friend/associate/customer swears that one way to increase cooling "efficiency" on an SBF is to block off the coolant bypass hose from the intake to the water pump. His theory and claim centers around the fact that the bypass hose is a little less than about 20% of the size of the upper radiator hose and that it means that about 20% of the hot water just behind the thermostat gets simply mixed with the cooled water from the lower radiator hose and re-circulated through the engine, thus reducing/slowing down the rate of cooling. By blocking/capping off the bypass hose, it forces ALL coolant coming out of the intake to go to/through the radiator to be cooled. In my mind's eye, this seems to not be too much of a problem in hot weather/running conditions, but could cause issues when temps are cold. It seems that the purpose of the bypass is to mix the heated coolant with the radiator cooled coolant to help keep a more even and constant engine temp. It would seem that in cold weather, with the bypass blocked, the coolant in the engine and the engine itself could be quite hot for a while and then when the thermostat opens, you get a blast of fairly cold coolant into the hot engine. This does not seem like a good thing and appears that it could cause a shock to the block/heads and possibly contribute to warpage, cracking and/or blown head gaskets. Have any of you folks heard of this block off procedure and, if so, can you offer some thoughts and opinions? I realize that the bypass is there for a reason, but so are many other systems and features that we routinely modify and/or delete in the interest of performance. Just looking for some information/ammunition to settle a heated debate.
Thanks,
Gene

 

[Sharad]

"heated debate" ... I see what you did there.

Here's my two cents, which doesn't really answer your question-
When I installed my billet water neck, I blocked off the bypass tube in the neck with an included plug, and blocked off the corresponding port in the water pump with a plug that was included with it. My engine builder (Tim Eichhorn at MPR in Boynton Beach, FL) was cool with that. However, when he saw that I had plugged the water ports in the lower intake manifold (near the firewall, inline with the intake bolts) he said I needed to unplug them and run a coolant crossover tube between them in order to equalize coolant flow & temperature between the left and right banks.

Bear in mind, this is a high hp street car in South Florida with no heat or A/C.

 

[horseballz]

Sharad,
You say that your engine builder said:
"However, when he saw that I had plugged the water ports in the lower intake manifold (near the firewall, inline with the intake bolts) he said I needed to unplug them and run a coolant crossover tube between them in order to equalize coolant flow & temperature between the left and right banks."
That's kind of odd, as most after market intakes, for carbs, have no rear coolant crossover passage.
Thanks For Replying,
Gene

 

[iskwezm]

I dont know if it works or not, but mine has been bypassed for a few years now because my electric water pump didnt have a port for it.

 

[horse sence]

not realy sure if it would make that much difference the early mustangs dont have a shut off valve in the heater hose so the water continualy cirlculates the newer cars have a vacume or cable controled valve that shuts the flow off to the heater core. beats me guess you dont raealy need a heater in vegas.what stays in vegas cooks in vegas

 

[horseballz]

My 68 with A/C has a vacuum controlled shutoff in the heater hose. I thought they all did, but that some were part of/installed in the heater box. Your point is well taken, though. when you take the heater loop into consideration, that makes nearly 40% of the coolant not going through the radiator.
Gene

 

[horse sence]

once again you is correct Gene,the AC cars had the shut off valve though i have seen some rinky dink,i know those are words i have heard them before ,manual shut off valves instaled in the heater hoses ,some times leak usualy wont turn
i believe the shut off valve was to shut the water off to the heater when the AC was activated

 

[rbohm]

if you are going to run an electric water pump, then by all means block off the bypass passage. on the other hand, water flows like electricity, it follows the path of least resistance, and as such when the thermostat is open, very little coolant actually bypasses the radiator. not enough in fact to even bother with except to perhaps go to a more efficient radiator if needed.

 

[Sharad]

Sharad,
You say that your engine builder said:
"However, when he saw that I had plugged the water ports in the lower intake manifold (near the firewall, inline with the intake bolts) he said I needed to unplug them and run a coolant crossover tube between them in order to equalize coolant flow & temperature between the left and right banks."
That's kind of odd, as most after market intakes, for carbs, have no rear coolant crossover passage.
Thanks For Replying,
Gene

Honestly Gene, I can't even tell you why he wanted that coolant crossover installed. This is on an over the top street-strip car, and my engine builder specializes in race engines. I just do what he tells me to. I suppose it might be possible for one side to run hotter than the other, so maybe the crossover tube equalizes the temps. But I have zero data to back that up. I was just passing along what I was told.