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84_S12

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Posts posted by 84_S12

  1. 1 Find and use a drill press if you can - a hand drill is going to be tricky to control

    2 Not too much pressure - you're not drilling steel or wood :wink:

    3 Keep it cool (spray water or a light dribble from a hose while drilling)

    4 Consider drilling from the other side when you're nearly through to reduce the chance of chipping, or reduce the pressure to almost nothing.

    5 Profit

  2. Bear in mind that a diamond bit is less like a drill bit and more like a dremel - the goal is to let the bit grind it's way through the glass rather than applying pressure, so don't rush.

    If you're not confident, you could just try a glazing company of reputable name?

  3. If you are simply changing the 2 pin plug into each alternator as you replace it, be aware that these may have different polarities between say lucas and mitsi types for example.

    I had similar problems when I changed out my original alternator for a refurbished Lucas, cottoned on to the fact that the DC in was always energised even with the ignition turned off. Cut the stupid plug off, put a couple of female spade terminals on and physically swapped the wires on the alternator... Never looked back or had a problem since.

  4. The cost of getting it repaired is going to be more than it's value so I'd just get round to replacing it man

    Probably a short across the transistors, assuming it was connected properly and working before it failed.

  5. Please review the edited post lol

    Bearings take a hammering and so too does the impeller and seals. Put it this way: Energy in = Energy out so if you are putting a lot of electrical energy into a pump that is not converting that energy into water movement, where does the energy go? Heat and vibration, both pump and motor killers.

    I say if you are going to engineer something that is to protect what is important to you (ie the car's engine in this case) then do it right.

  6. Running an oversized pump achieves greater required input power and a reduced lifespan. Nothing more. It is however possible to partially bypass the pump to reduce head pressure (This principle is commonly used in refrigeration systems to control refrigeration effect, and sometimes in jetboat jet units to maintain efficiency at differing speeds)

    With an undersized pump you can usually stop cavitation installing an I/R valve or flow regulator on the discharge side of the pump to bring it back on it's curve. You could then use whatever radiator is practical and adjust flow to suit based on your pump selection.

  7. The pump needs to be sized for the required rate of flow and the anticipated head or it will cavitate and kill itself, or never achieve/maintain flow as required.

    The point of best efficiency (BEP) for a pump is smack bang in the middle of it's efficiency curve. Fans also show similar characteristics, and demonstrate very different performance running in free air or correctly ducted/shrouded.

  8. eke_zetec_rwd sums it up

    Rejecting more heat thru the radiator means you increase the ΔT between the hot air from the turbo and the entering water temperature at the intercooler. Heat is not being rejected at the pump, or any of the interconnecting pipework really either, so the time spent by each litre per second of water in the heat exchanger, where again there is a ΔT between the airstream and the heated water from the intercooler is a critical figure unique to the heat exchanger used.

    Bear in mind too that the specific heat capacity of water is many many times higher than that of air.

  9. I think you'll find the faster the flowrate the better. No matter what, more mass-flow = more heat transfer rate.

    Actually in truth the heat exchanger will have an optimal water flow rate for maximum heat transfer/rejection, but you're partly right in that a greater flow rate of the secondary heat exchange medium (ie air) over the heat exchanger will reject more heat

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