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Scott, I had assumed they were 3.6 Turbo heads, though the 3.6 Turbo is rare enough that I've never seen another set. I think the 993 RS/RSR wouldn't have had the port for the secondary air injection and would have had two extra threaded holes for the 993 stud orientation.
These are more likely to be the cylinder heads of the 965 3.3.
Also noteworthy that AR has left the SAI in place. I can imagine two possible reasons for this: either he knew that the oxygen injection into the exhaust tract creates a kind of afterburning of the unburned hydrocarbons that makes the turbo spools faster. Or it was simply a concession to emissions regulations. My money is on the first variant.
From a EBAY listing. You could have 993 RS injector blocks. Let us know if they are 3 bolt. Your possible 993RS heads were not machined for the extra holes.
Looks like your injector rails are 993? I'm not expert. Just bringing up a discussion.
These are more likely to be the cylinder heads of the 965 3.3.
Also noteworthy that AR has left the SAI in place. I can imagine two possible reasons for this: either he knew that the oxygen injection into the exhaust tract creates a kind of afterburning of the unburned hydrocarbons that makes the turbo spools faster. Or it was simply a concession to emissions regulations. My money is on the first variant.
Fritz
Fritz,
I'm not an expert on this, so genuinely asking: Is that because of how they look or because the car was born as a 3.3?
Ruf built the 3.8 starting from a complete 3.6 Turbo donor motor (which the PO purchased for $19k in 1996).
I would have guessed they'd reused parts from the 3.6 T motor, but as I have no idea what happened to the 3.3 motor that came with the car, it could be anything.
As for why the SAI was on the car, the PO asked them to retain the stock exhaust system because he didn't want the car to be too loud. It may be that they left it as a result of that request.
I do know that they later disabled the system by removing the SAI drive belt when there were some tuning issues.
to be honest it was more of a guess because of the 3.3 base and the rarity of the 3.6. I have attached a picture below of a 3.6 cylinder head, they look on this small cutout very similar to yours. The 3.3 heads are but do not look dramatically different. If you want to know exactly: on the edge of the lower cooling fin is the part number cast.
Clear to me that the SAI have to be disconnected for any adjustment or measurement that based on the exhaust gas, the air injection changes the exhaust gas composition directly behind the exhaust valve decisively.
The 3.3 heads are easy to differentiate from the above 3.6 - the oil return tubes stand 'proud' of the fins on the 3.3 (whereas on the above 3.6/3.8 examples they are semi-sunken into the fins), and the 3.3 exhaust port and studs are flush with the top of the cooling fins. I can't see 3.3 heads having enough material to have as much machined off the exhaust side to the point where they would look similar to the above 3.6 examples, at least not without getting dangerously close to the exhaust valve stem.
Standard 964 3.3 heads and barrels.
Please excuse the obvious exhaust leaks!
Last edited by Megatron-UK; 04-02-2023 at 01:08 PM.
Yes, I've been terrible and haven't updated this thread in a while, but mostly because things continue to progress slowly.
Since my last post, the car has left my garage and is now at the fab shop waiting to be stripped down to bare metal before seam welding the chassis.
I'm still slowly accumulating parts for the rebuild. The brakes were redone as seen above but I also had the turbocharger rebuilt by Chris at Turbokraft and have replaced the wastegate with a modern TiAL unit.
It turns out that I got the exact same wastegate that RUF is using on their current RCT Evo builds, which I know because instead of staying home and cleaning all the parts I've taken off the car like I should be doing, I flew to Germany and visited the RUF factory in Pfaffenhausen.
If you get the chance, I highly recommend it. Not only is what they're doing there super impressive, but they're lovely people. I met the gentleman who built my motor back in 1997 as well as all of their current team of fabricators, engineers, etc. They could not have been more supportive of this project and gave me lots of advice for how to make some of the upgrades I'm doing the "RUF way." A high priority was sitting in the various seats they have on offer, and I now know that I just barely fit into the their largest Lollipop shell, which is great. I anticipate more shipments full of RUF carbon fiber goodies in my future.
They did ask that I not share photos of some of the things they're working on and the detailed shots I took for reference, so I'll just share a couple of inspirational ones here: a riviera blue RCT that also started life as a 965 as well a signal yellow full-carbon-monocoque monster that might look like an air-cooled 911 but shares almost no parts with one.
Okay, you thought I forgot about you or gave up on this project... nope!
Everything just goes a lot more slowly when it's on a shop's timeline rather than mine.
We had to remove a huge amount of undercoating from the chassis but it is finally ready for seam welding.
The chassis was blasted with plastic media which is supposed to put less heat into panels and should be softer than the galvanized coating on the metal.
Once the seams are all stitched, it will be time to work on the integrated cage!
Having seen their facility, it would be great to have RUF doing the work but if I had that kind of money I'd have bought a completed car!
At heart this is a DIY restoration, and I am doing everything I can do myself (i.e., everything but the paint and body work).
However, I'm lucky enough to have factory support for this project, and I have even more RUF goodies coming over on pallets from Pfaffenhausen, including some made especially for me -- just the parts cost of this build is eye watering.
I also got the chance during my visit to talk through my plans for the project with the mechanics and fabricators at the factory and get their guidance on the "RUF way," including some offers to come help if I flew them to the US!
In the next phase of the build, we'll be using 3d scans of the car to ensure correct integration of the cage as well as some other surprises.
That's a fantastic level of support and assistance from RUF, I suppose you pay for it, but there are plenty of examples of companies that charge eye-watering amounts and don't come close to that level of customer service.
I don't have a chance of owning one of those beasts, my 3.3 is expensive enough to keep on the road, but it's reassuring to see that they care about keeping their older cars and conversions running.
03-31-2023, 10:23 AM
