From my understanding this modification was used on later 935 heads, just before they started pumping water. I'm running them on my next build, until then I won't know how effective this mod is. I've been playing with higher boost levels on my current build and monitoring temps, you can't keep the heads cool enough thus my decision to use the 350RR heads, valve guide oiling mod. and 930 sodium filled valves.

Do you plan on running a single wastegate or two? I'm curious as to the pic you posted in the OP.

A930,
What are you going to do with that distributor? I am interested in a twin-plug setup for my 965 also and it would include a JB Racing internally triggered distributor, plus some other components.

(P.S. This could be a thread hijack...)

Mark

Mark, had originally planned on using on my 3.2SS build. However, decided it would be better for the turbo motor, as better flame propagation means both cooler heads and safer (not necessarily more) horsepower. The factory used twin plugging on the 2.1 RSR and other early turbo motors, so figurered if it was good insurance for them, would be for me as well. A lot of guys here (sand_man and others) have gone to twin plug as well.

Lite75, VERY interested in how your oil-modification heads work out. The factory did a lot of cool stuff when reaching the HP limits of the aircooled 935 heads before eventually going to water-cooling them. Please keep us posted on your progress.

Dont worry about hijacking. As someone put it before, these thread have a life of their own, and go whatever way they will.

Nice score! I was planning on bidding at the last minute, but got tied up.

If you use small port SC heads, why not keep the 930 heads?

Craig, i dont have a set of Turbo heads. The 'turbo' motor i'm building is actually based on a spare 3.0 SC motor. The small port heads that are being rebuilt are what i have at moment (gotta draw the line budget-wise on a hobby somewhere). Also, as it is a 'learning engine' in which i plan to eventually put better heads and P/C on it in the future, i want to see how the small port heads work in comparison to later Carrera heads which will eventually be used.

Just use the SC heads and be done with it - with that budget in mind you mentioned.

I have the 935 oiler mods in my heads. I get a little start-up smoke. It oils directly on the center of the exhaust guide and you run no stem seal. The orientation of the guide allows the oil to drain toward the spring ( for the most part) and the exhaust pressure is usually higher than inside the crank case/head.

930turbo,
Thanks for that explanation, it was the missing link for me. Now let me see if I have this right: A 3 x3 mm (?) groove is made from under the edge of intake spring seat on a slight angle (?) and it leads to a 3mm hole (?) that is drilled in the middle of the head but offset to miss the studs and at such an angle that it bisects the exhaust valve guide which has no stem seal because the oil is constantly running out of it due to gravity and the exhaust port pressure.

Is that it? Brilliant! I suppose the flow of oil could be controlled by the size of the groove/hole, but at some point you need flow. And it would be important to keep the cam tower sealant to a minimum in the immediate area of the groove.

Do you mind strenuously if I ask you who did the work and, if outsourced, how much it cost?

I see no reason not to do this mod to every turbo engine. I wonder what Henry would say...?

Mark