 |
PM |  | |
Quote | | |
Reply | | |
Full Topic | |
| Joined: | 03-17-2005 |
| Location: | Warmond, Netherlands |
| Posts: | 216 |
| Status: |
Offline
|
The extra nipple provides an extra return flow path back to the waterpump in addition to the one through the intake manifold water passage, which indeed cools the head slightly better.
GGLOTUS quote: "The turbo pump would provide a little extra cooling for a safety margin on hot days. Upgrading to a turbo water pump would be a nice optional extra." unquote.
You guys are right: in my set-up there is no EXTRA cooling near cyl 4 just because of the fitting.. However I do not have the stock 907 2.0L head (which seemingly suffered from a cooling design flaw), but the later modified 2.2L head & 2.2L manifold which has slightly wider water passages and improved cooling design.
Just like in the stock 907 my engine returns the coolant from the head to the inlet manifold water passage towards the pump. As soon as i open the heater valve, then water goes from the rear of the head towards the interior heating system, rather then from the rear of the inlet manifold water passage towards the interior heating system as in stock set up.
According to Garry Kemp an extra return from the rear of the 2.2L head towards a turbo waterpump or in case of 907 towards the hose running from the interior heater to inlet manifold (via a 3-way valve) isn't necessary ...especially not in my climate.
Why have the fitting at the rear of a 2.2L head? If it turns out I need the extra cooling on a hot summer day then i could fairly quickly tap in a fitting at the rear of the inlet manifold, fit the 3-way valve piece and connect the hoses. Having the head drilled to install a fitting there and having it flushed is a lot more work.
It is more likely that on very hot summer days, the engine needs extra cooling when idling in traffic. For this purpose i will soon install an electric fan and replace the original mechanical fan...and as a bonus gain another 5/6 HP :)
When one is rebuilding a stock 907 2.0L head/manifold then i would certainly have the extra fitting at the rear of the head and connect it to the stock heater hose via a three way valve with bypass.
Dan, I remember you saying that Gary Kemp advised you to open up the water passage near the waterpump in the head a little more, correct? I assume you are rebuilding a stock 907 2.0L engine & head, correct?
I will go into my garage this evening to make the pictures.
Last edited on 01-10-2007 09:21 am by Harkes