The only advantage I can see would be faster warm-up cause you could have it off and not circulating the coolant......you could block off the bypass hose and drill a small pressure relief hole int he T-stat and that would aid in warming up. I see no other use on a street truck....on a full race motor same would apply as with a drag car....lees accessories driven off the crank will make more power....but it's a minimal gain and only if you are searching for that last increment of HP would I do it on a street driven motor. I have a friend with a Stroker 340 that did a rear wheel dyno test with only the WP swap....there was a 5hp difference at the rear wheels vs the crank driven pump.
I would never stop the coolant from circulating at least a little, it seems like that would lead to hot spots around the cylinders not by the thremostat.
A few other advantages to the electric pumps are that they won't blow freeze plugs form over spinning the water pump at high rpm and they allow you to leave the pump on to circulate coolant and allow the engine to continue to cool after the engine has been shut down. This works exceptionally well with electric fans.
I gues I should have said that differently......about blocking off the bypass hose....I meant o make it smaller so it doesn't flow as much. For a drag or pulling truck I can understand it but for a street truck......I don't think it's needed.
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