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Bill, am I correct that in addition to boring out the opening an additional 2mm (107mm --> 109mm) a groove for an o-ring is also typically cut in the bore opening to help with sealing?
yes, that's the extra groove I referred to above The 109mm spigots use an extra 110.72x3.53mm o-ring in the walls of the cylinder and the bore.
107mm base only use the stock 102x2mm o-ring in the base of the cylinder, PS Wrightwood is the only gasket kit that I've seen that supply's these in the correct size
OK, thanks. I knew I saw that somewhere but didn't even realize it was this thread. I've been doing so much digging through old threads that I'm suffering from information overload.
Switching gears, I inquired with Steve Wong @ 911chips and he told me that as of right now, he still only does OBD1 DME's with removable chips. He did say that he hopes to be able to offer re-flashing services for '97-98 DME's in a few months time.
My current DME was flashed by GIAC via Steve/Rennsport. FVD and Protomotiv also offer '97-98 re-flashing. This is all a long ways out but just thought I'd mention since a few others have interest in this topic and it was also suggested to reach out to Steve Wong.
You might want to check in with FVD. They re-flash for specific parts packages and likely could supply everything you need if you tell them you want to replicate the original kit.
Pete
Sorry- just fully read the above post when I got off the phone and on the computer.....
Bill, what's the intent with this photo? I mean, I see the "issue" but what the remedy? This appears to show a leak between the head and cylinder, not the cylinder base at the cases (o-ring we were discussing). So the inclusion of this photo made me curious.
Another random question, since I'm very familiar with working on old air-cooled Harley motors (Shovelheads, Panheads, etc)...
Is there a re-torque ritual to be followed an air-cooled 911's? What I mean is, in the Harley world after a fresh motor build, it is customary to re-torque the cylinder bases to the case and heads to the cylinders after 50 miles in order to avoid blown gaskets. And yes, they would definitely need torquing back to spec. Granted we are talking about a rigid mounted motor on a rigid frame with no suspension.
Just curious what the school of thought here is because it seems that isn't really possible? Is this not a concern with these motors?
Last edited by boomboomthump; 03-21-2024 at 02:45 PM.
Another random question, since I'm very familiar with working on old air-cooled Harley motors (Shovelheads, Panheads, etc)...
Is there a re-torque ritual to be followed an air-cooled 911's? What I mean is, in the Harley world after a fresh motor build, it is customary to re-torque the cylinder bases to the case and heads to the cylinders after 50 miles in order to avoid blown gaskets. And yes, they would definitely need torquing back to spec. Granted we are talking about a rigid mounted motor on a rigid frame with no suspension.
Just curious what the school of thought here is because it seems that isn't really possible? Is this not a concern with these motors?
Retorquing not needed and not possible. Unlike the Shovelhead farm tractor technology. I used a curved wrench and a hard mallet to retorque the heads in the frame!
I have the feeling that, from your extensive review of engine build options, your 3.8 will evolve almost everything new and fresh like your car build will be
Wherever I land, it will be very "euro RS" or "euro RS+". Still have no intention of going down the ITB + GT3 rabbit hole.
BTW, I just took the first plunge on this endeavor. Since I sold some Lloyds mats and had a few other dollars sitting in my PayPal account, just bought the parts needed to "back date" my cam sprockets. Got OEM parts from Delaware Porsche and $70 cheaper than FVD's kit. Wasn't sure how many shims I needed between the thrust washer and flange but I got extra just in case. Also, crazy that the actual sprockets are $80 yet the smaller "flange" is $110.
Bill, what's the intent with this photo? I mean, I see the "issue" but what the remedy? This appears to show a leak between the head and cylinder, not the cylinder base at the cases (o-ring we were discussing). So the inclusion of this photo made me curious.
That was a bore in 3.8 built w/o the extra RS spigot groove & large spigot o-ring,, It blew the the small stock type base o-rings out when it was first run on a dyno for brake in.
Wherever I land, it will be very "euro RS" or "euro RS+". Still have no intention of going down the ITB + GT3 rabbit hole.
BTW, I just took the first plunge on this endeavor. Since I sold some Lloyds mats and had a few other dollars sitting in my PayPal account, just bought the parts needed to "back date" my cam sprockets. Got OEM parts from Delaware Porsche and $70 cheaper than FVD's kit. Wasn't sure how many shims I needed between the thrust washer and flange but I got extra just in case. Also, crazy that the actual sprockets are $80 yet the smaller "flange" is $110.
That was a bore in 3.8 built w/o the extra RS spigot groove & large spigot o-ring,, It blew the the small stock type base o-rings out when it was first run on a dyno for brake in.
So, are you saying this caused a cascading effect of sealing loss?
Meaning, the extra o-ring was not used at the engine case (machined into the bore). As a result, the cylinder base to case blew its seal, which also resulted in the cylinder head to cylinder (top side of the cylinder) to also show combustion blow out?
Since you can see that ring of carbon between the head and cylinder, I was trying to understand that. If I'm off-track on the above comment, then I don't understand the blow-out between the head and cylinder. The o-ring we were discussing is between the cylinder and engine case.
So, are you saying this caused a cascading effect of sealing loss?
Meaning, the extra o-ring was not used at the engine case (machined into the bore). As a result, the cylinder base to case blew its seal, which also resulted in the cylinder head to cylinder (top side of the cylinder) to also show combustion blow out?
Since you can see that ring of carbon between the head and cylinder, I was trying to understand that. If I'm off-track on the above comment, then I don't understand the blow-out between the head and cylinder. The o-ring we were discussing is between the cylinder and engine case.
OK, thanks for confirming. Makes sense given the heads sandwich the cylinders to the case. Slightly different to what I'm accustomed to with "barn tractors" as Mike put it. In those setups the cylinder to base and head to cylinder are independent of one another. So when I first saw some of that blowout above between the head and cylinder, it didn't immediately click as being one and the same issue.
The following are all the ~3.8L Mahle p/c (piston/cylinder) kits available for 993's along with their applications and compression ratios. Some are for Turbo's, others are stroker setups. I've bolded the two that are of relevance to this thread. Both the 11.4:1 slip-fit application or bore-in kits, which are PS102-022 & PS102-023 respectively.
Hey BoomBoom.
I had about a 1-1/2 hour phone call about 18mos ago w. Colin Belton (9M) on this whole topic. He was very generous and totally talked me out of buying stuff from him.
His take aligns with what others are saying... a good bang-for-the-buck on a v-ram engine without getting yourself in too deep is slip-fit 3.8, RS intakes, "Euro" RS Cams (for the hydraulic lifters), and a re-flash of the ECU. Don't change rockers, springs, exhaust valves. No need to crack the case in this job. You will need to get your heads serviced and ground to fit the RS intake valves.
If you are going to crack the case, you might as well bore it for the non-slip-fit cylinders, and possibly upgrade rods and rod bolts, but rods can be tricky due to interference with the oil pump (Protomotive sells their own rod set that is supposedly "pauter quality without the clearance issues")
Todd at Protomotive can do your ECU based on the specs for your P&Cs, cams, availability of 91 vs 93 octane gas, etc.
The car will start and run without the ECU flash, but the idle will be lumpy and you want have the best power curve. Part of the reason for doing this is to bring the torque curve lower and flatter (IMHO, as a street driver) - you can explain that to Todd as well.
You can get the Cams from WebCams or from Dougherty https://www.drcamshafts.com ... I prefer Dougherty as he's a smaller operation and much faster turn-around, and has been doing this a long time. You will want to order with him on the phone and be clear that you want the Euro RS cam for hydraulic lifters, power steering pump, no scavenge pump. He does NOT list that cam in the list of cams on the website. He'll send you the right ones. The only thing I found odd is that he doesn't include a cam spec sheet and each cam, right and left, has a slightly different lift-onset profile - but this is apparently by design because the cams rotate in two different directions. They should both be set to 1.5mm at TDC. (it's more important that they are both the same at TDC ... being at exactly 1.5 is less important)
I have ALL of the tools - the crank dial meter, the chain tensioners, the holder for the dial, the rod you screw into piston #1 to feel / stop the cylinder and make sure you are 100% exact in finding TDC. Since I'm right up 95 near Fairfield, CT, you're welcome to borrow them, or we could have a good old fashioned beer + cam timing get together at your garage - ha ha! It really doesn't take long to time the cams and lock them down - especially once you learn the tricks.
After talking to Todd at Protomotive, and thinking I'd be doing a SuperCharger or turbo conversion, I wanted to get my feet wet w/o going to far, so I only did the cams. I never pulled the heads. Todd had mentioned that the higher lift cams have a bit more overlap and so are good for forced-induction, and if I decided NOT to do FI, but instead went the route that you are thinking, then I would already have the cams and the knowledge of how to time them.
...oh yeah, on Colin's recommendation, I also got the cam sprocket backdate kit posted by others above. ...Note that even with the little pin in the sprockets, there's still more movement than I'd like, and it takes some fiddling to get it perfect when tightening the sprocket bolt - but doing the timing the "old-way" is just such a cool experience that I'm glad I did it! ... you can see some pics here: https://rennlist.com/forums/993-foru...s-learned.html
Last edited by CosmosMoon; 03-22-2024 at 07:26 PM.
Reason: cleaned up a ton of typos!
03-20-2024, 08:20 PM
