Have always wondered if spraying lots of oil inside the valve covers would be worth anything which has lead me to investigate the world of "piston squirters".

Here's an interesting assortment of parts used on BMW's and other German Makes:

http://www.e30m3performance.com/installs/i...ls-3/squirters/


And I really have to admire this guy... he made his own system including the nozzles from scratch for his Volvo Turbo:

http://www.pbase.com/polc/sqrt



When BMW redesigned the R100's into the R1000 "Cam-In-Head" flat twin motorcycle engines, they got nicknamed the "oil heads" because that was the major source of cooling for this otherwise "aircooled" engine.

Of course, if you can't get the oil to circulate around the exhaust valve guide on the Type IV, there probably isn't any point to pumping additionally "cooling only" oil to the heads..

Some food for discussion..

Actually the delivery of oil to the rocker area is never an issue- many times its a problem... Most of the time at high revs too much oil get to the rockers and doesn't get back to the sump fast enough and the kills rod bearings...

In most race applications we weld the tips of the pushrods closed and deliver the oil through rails fited into the valve covers and fed from the main oil galley.

These rails incorporate solex main jets and allow the oil delivery to be adjusted infinately... This along with a valve cover equipped with a window gets the oil in the valve cover area just where it belongs- These squirters can be aimed directly at the valve guides and springs for superior lubricating and cooling.

I use piston squirters on many of our race engines- BUT with thermal barrier coatings and friction reduction coatings their need is drastically reduced.

So Jack,

It's my understanding the the TypeIVs are similarly weak as the TypeI's in that the exhaust valves are the weak link. Overheating, and they break (or gall up and seize). In your estimation, is this also the weak point (thermally) of the Type IV?

Well first off the oil doesn't cool the heads worth a damn.... It may reduce stem/guide friction and some temps through that but you can bake your heads and have oil cool as a cucumber....

What thermally kills the engines is mistuning and high head temps from that. There really isn;t a "weak link" with the integrity of one given component, but when a few things add up all hell breaks loose.

What really overheats exhaust valves is mistuning and high EGT from that. This is multiplied by valves that may not be seating correctly due to misadjustment typically related to over expansion directly related to OVERHEATING!

The key is keeping the head temps down through correct tuning, correctly driving the vehicle (no lugging) and keeping the cooling fan clean.

If you want to reduce stem/valve friction then look into DLC coating the valve stems. I run some of these valves at as little a .0002 stem/guide clearance with no issues at all, when conventionally .001 is insanely tight and scary. The DLC coating is "Diamond like Carbon" and you can see some fine examples of it on my site here

http://www.aircooledtechnology.com/coatings_2.htm

The parts pictured are in my 914 as we speak. The cost is pretty extreme but it damn sure works through insanely reduced friction.

The key to cooling is to NOT generate the heat in the first place- then it doesn't have to be cooled.... For more friction/ windage reduction check this link out

http://www.aircooledtechnology.com/r_d_superfinish.htm

I want to add that with the valve technology we have today that thermally damaged valves are really a thing of the past. The valves I use can withstand seriously elevated EGT and not fail. The stock valves that failed so many years ago were technology of the 1970s and some dude wearing Plaid designed them!

The last valve failure I had was in 1997, we haven't even had one in a race engine since then. (knock on wood)

thanks for the data dump, Jake! Good info for all!

Just buy a 911 motor. They've had all this stuff built in since the early 70s.