Top end rebuild on an 89 911 C4 3.6 - Which head studs to use?

[johntorg]

I am doing a top end rebuild on an 89 911 C4 3.6. with 125K miles. It has 4 broken head studs. There seem to be 3 or 4 options.

1. Replace the 4 broken studs: Probably not a good idea since others may break.

2. Use 24 new OEM type studs at $10.75 each.

3. Use 24 new "Dilavar fully threaded" Head Studs at $38.25 each

4. Use Supertec head studs. $650 from Pelican.

I would really appreciate opinions on which head studs to use. Also if anyone knows the benefits of the "Dilavar fully threaded" head studs that justifies the increased price.

The engine will be rebuilt in completely stock form with no additional performance enhancement. It will be used occasionally in a harsh environment (Wisconsin), which I've read is one of the causes of failure in the original Dilavar studs.

Thanks for your help

[hcoles]

there are lots of threads on this - I forget the details .. I think the non Dilvar are considered fine for most purposes - I put in all new 911-101-172-00 in my 89 3.2

[sabeo.m]

johntorg, I also have 4 broken head studs. I've been doing some research and asking a lot of questions on this very topic since last year August. If you plain on using your car as a daily driver and plain on keeping the car for a while then invest on the better head studs. I have a 80sc, I plain on doing a lot of driving this coming up summer, so I'm going to take my friend's advice and spend the extra cash and buy Raceware. Anyhow, which ever after market head studs you decide to go with they will be stronger than the original ones..

[p930t]

I have just changed all of mine to the 993 TT fully threaded ones. I see no good reason for not doing it except for the cost.

It is 30 years since the "dilavar head stud" got its bad reputation. One should think that Porsche have done some progress in those years.
The large tuners in Europe such as RUF etc. all uses the original dilavar fullt threaded ones and my conclusion is that the original fully threaded ones are more than good enough even for heavily tuned turbo engines and they have the best thermal expansion profile.

There are many opinions on this subject, but this is mine.

[Dennis Kalma]

Originally Posted by p930t

I have just changed all of mine to the 993 TT fully threaded ones. I see no good reason for not doing it except for the cost.

I have a lot of the same points of view.....what nuts did you use? Did you use the 993 flanged nuts or did you go with the barrel nut/washer combination?

Dennis

[p930t]

I reused the original barrel nuts and new original washers. RUF shop told me it would be OK.

[JeremyD]

I like the supertec headstuds - course thread for going into the case - fine threaded on the heads. I wanted to just do them once.