Scott
Lifetime Supporter
Bob, are you using one or two pumps?
Joel, it would be interesting to see how they plumbed the left/right intake-manifold-char air coolers. Perhaps there is a dedicated pump/circuit for each cylinder head. My supercharger has two inputs and two outputs so I could follow a similar approach. That would add complexity, weight and cost, but the serial vs. parallel decision is mute.
Cam, it would be useful to know which statements you take issue with. I’m just trying to understand the car’s systems and build the best car that I can. I’m no expert and I haven’t done a thermo calculation in 30 years, but I’m confident in the turbulence, delta-T and dwell time statements for rational SL-C purposes. In any event, I’ve spent time/money having C&R design/fabricate a custom radiator and I’m going with an electric pump which flows less than the OEM one that it’s replacing… so, I shouldn’t have any issues with turbulence or dwell time.
I’m not sure what your point is about what happens at 1,000 gph. That’s >6x what the mechanical pump does at redline. Mach 1 is only 5x faster than a SL-C doing 150mph… do you worry about sound barrier issues when discussing aero mods?
With less confidence… it’s my understanding that the LS7 (and I assume most) mechanical pumps flow too much fluid at speed. However, rather than creating a dwell time / overheating issue, the increased flow overcools the coolant. This causes the thermostat to restrict flow to keep the engine at the target temp. This is why an electric pump which flows only 1/3 of what a mechanical pump flows at max RPM can keep the car cool. I’ve spoken with two endurance/road teams using the same electrical pump that I’m using and they have seen a max 75% duty cycle. The mechanical pump is a slave to engine RPM and to get it to flow enough at idle it overflows at speed.
I’ve always wondered if the HP gains claimed by electric water pump manufacturers were BS because converting mechanical to electrical and then doing the reverse doesn’t save power. However, if the mechanical pump is overflowing and over cooling, then it’s wasting energy fighting the thermostat. The electric pump’s ECU reduces the duty cycle in this scenario which means that the alternator does less work… and I assume that’s where the power savings come from.
If you’re referring to the one vs. two or the serial vs. parallel parts, then those are the areas that I was looking for feedback.
I’m not very familiar with the twin-turbo car, but it’s clear that it’s an air-to-water and not an air-to-air cooler. There are two turbos and two coolers. I’m not sure if there are one or two pumps/circuits. If we assume a ¾” line that’s either ½ or the same size as the line used for the engine cooling system. While the heat exchangers are angled to the air flow, they are going to get a lot of air. They are higher quality than the radiator that ships with the kit and the two of them combined are probably almost as large as the radiator. In addition, the air isn’t preheated by the condenser. My guess, it that the system works well.
Joel, it would be interesting to see how they plumbed the left/right intake-manifold-char air coolers. Perhaps there is a dedicated pump/circuit for each cylinder head. My supercharger has two inputs and two outputs so I could follow a similar approach. That would add complexity, weight and cost, but the serial vs. parallel decision is mute.
Cam, it would be useful to know which statements you take issue with. I’m just trying to understand the car’s systems and build the best car that I can. I’m no expert and I haven’t done a thermo calculation in 30 years, but I’m confident in the turbulence, delta-T and dwell time statements for rational SL-C purposes. In any event, I’ve spent time/money having C&R design/fabricate a custom radiator and I’m going with an electric pump which flows less than the OEM one that it’s replacing… so, I shouldn’t have any issues with turbulence or dwell time.
I’m not sure what your point is about what happens at 1,000 gph. That’s >6x what the mechanical pump does at redline. Mach 1 is only 5x faster than a SL-C doing 150mph… do you worry about sound barrier issues when discussing aero mods?
With less confidence… it’s my understanding that the LS7 (and I assume most) mechanical pumps flow too much fluid at speed. However, rather than creating a dwell time / overheating issue, the increased flow overcools the coolant. This causes the thermostat to restrict flow to keep the engine at the target temp. This is why an electric pump which flows only 1/3 of what a mechanical pump flows at max RPM can keep the car cool. I’ve spoken with two endurance/road teams using the same electrical pump that I’m using and they have seen a max 75% duty cycle. The mechanical pump is a slave to engine RPM and to get it to flow enough at idle it overflows at speed.
I’ve always wondered if the HP gains claimed by electric water pump manufacturers were BS because converting mechanical to electrical and then doing the reverse doesn’t save power. However, if the mechanical pump is overflowing and over cooling, then it’s wasting energy fighting the thermostat. The electric pump’s ECU reduces the duty cycle in this scenario which means that the alternator does less work… and I assume that’s where the power savings come from.
If you’re referring to the one vs. two or the serial vs. parallel parts, then those are the areas that I was looking for feedback.
I’m not very familiar with the twin-turbo car, but it’s clear that it’s an air-to-water and not an air-to-air cooler. There are two turbos and two coolers. I’m not sure if there are one or two pumps/circuits. If we assume a ¾” line that’s either ½ or the same size as the line used for the engine cooling system. While the heat exchangers are angled to the air flow, they are going to get a lot of air. They are higher quality than the radiator that ships with the kit and the two of them combined are probably almost as large as the radiator. In addition, the air isn’t preheated by the condenser. My guess, it that the system works well.