Thanks to everyone who gave me advice on why #3 intake had black deposits above the valve. I checked the injectors as suggested. Unfortunately it isn't a leaky injector. A 100PSI leak down shows #4 exhaust valve is leaking (96, 94, 95, 40!). I don't know the actual cause yet (burnt, bent, spring...), but I'll know once I get the head off. I suspect I'll need to get some significant work done or exchange the head.

So far I'm looking at Powerhaus, Huntley, and EBSracing for replacements or rebuild. Does anyone have experience with modified heads on a mildly modified '89 951? Or even just some good experience on what mods (5 angle cuts, shaved deck, ported, polished, o-ringed) are worth the money. My car sees mostly street use and 1-2 DE/yr. I run 16.5psi peak boost, a Huntley MAF and LBE. The rest of the engine is stock.

Thanks,
CSD

 

I have 285hp with a stock head and recommend a stock head. What I would do is Porsche, at any of their dealerships will sell you a rebuilt head for around $1k and your old head. Let them do the R and R and you have two years warranty on parts and one year on the labor. Get a discount with your PCA membership card. The more trouble you ask for the more you will get.

 

Didn't see the thread on black deposits, but I found between 2-3cc of oil on top of all my intake valves when I was replacing my turbo. It had worn seals and was dumping 1qt every 3000miles through my intake. Burnt oil deposits can be messing up your seals causing leaks.

Definitely worth upgrading the head on top of a stock rebuild. Huntley has the best deal on rebuilt-heads w/upgrades. About $700-900 for the following:

Also do the following while you're at it:

This will be worth about 30-40hp with your current set-up. Will also aid additional upgrades you have later like bigger turbo with more boost.

 

Try Garrity at Auto Werks in St. Louis. He rebuilds (new valves, guides, seals), ports and polishes, and mills head for around $600 I believe. Thats were my head's going when I get the time the $. He said realistically about 20 hp when compared to my old 200k head.

 

Check Brumos Porsche, they ran an add in the latest Panorama, $425 for a rebuilt head. Not sure if anything had been done to it , but it sure sounds like a great price. It was complete, valves, springs and all.

 

for serious perfomance check with BCE Racing Heads in Rancho Cucamonga (909)944-8097. Bill Craddock(owner) has been doing race heads for years. http://www.bceracing.com