Motorsport Plumbing Systems: Sizing
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Sizing
02.40
| 00:00 | When it comes to the size and considerations for the plumbing of the power steering system, it's all very similar to that of the engine oil system, especially when working with a dry sump. |
| 00:10 | The plumbing to the inlet of the pump will be subject to vacuum and it's important we don't get cavitation from excessive flow velocity from too small plumbing or too much vacuum causing the plumbing to collapse. |
| 00:24 | This means that the plumbing should always be rated appropriately for the vacuum but the size of the line is just as important, particularly the plumbing from the reservoir to the pump, which is typically the largest of the power steering lines for this reason. |
| 00:39 | The return line from the control valve to the reservoir also needs to be big enough to keep the fluid circulating as this is subject to relatively low pressure. |
| 00:48 | In terms of restrictions though, the same ideas from our brake system can be applied here as the pressure between the pump and control valve and the control valve and the rack is so high that the relatively small pressure drops from overly restricted lines are negligible. |
| 01:05 | In saying that, we still want to flow enough working fluid for assistance without too much velocity and if these lines are too large, it could slow the response and cause the steering to be unnecessarily heavy. |
| 01:19 | The reality is that the factory lines will be suitably sized and this shouldn't need to be second guessed. |
| 01:25 | Any aftermarket components will most likely come with instructions from the supplier that will specify the line size so these should clearly be followed and the fittings and ports will dictate this anyway. |
| 01:37 | In a completely custom application where there's nothing to base the sizes on, the following sizes tend to be commonly used, so this is likely a good starting point. |
| 01:48 | The suction line from the reservoir to the pump is commonly a dash 10 or 12. |
| 01:53 | From here, the pressure lines to the control valve and the rack are around dash 6. |
| 01:59 | And the return back to the reservoir could be dash 8. |
| 02:03 | These sizes aren't set in stone and many applications use completely different sizes, but that should give you an idea of the rough sizing for the different lines. |
| 02:13 | So, with that, let's recap the main points. |
| 02:15 | The most critical power steering line when it comes to plumbing size is the one that conveys fluid from the reservoir to the pump. |
| 02:23 | This is subject to a strong vacuum so it must be sized big enough and be stiff enough to not collapse. |
| 02:29 | The other lines are pressurised and will usually be slightly smaller, but the best method is to follow the factory sizes or supplier's instructions. |
