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Thanks Mark. We are going to give it our best shot. If we miss this weekend, I'll still be there with my green 997.2, and the RSR will be at the next one for sure.
All parts were overnighted yesterday and should arrive today. Had to get special 52mm valves from CMW because they rebuilt the heads back in 2006 and installed oversized valves. The reason that some of them mushroomed was because they are Chevrolet valves that had the stems cut. The tips of the stems are hardened, but not the entire stem. Thus, the hardness was lost. CMW has apparently since changed their manufacturing method for these valves and has assured it will not be a problem anymore.
We also sourced replacement flame rings from them. For $100 a piece.
Black Forest Racing is going to start reassembly this evening. There's hope.
Well, the new flame rings and other bits arrived, and... it isn't going to work.
CMW apparently changed the flame ring design from the one these heads were cut for at some point in the last 10 years. The "foot" of the "T" is offset a little bit more to the outside edge of the ring, rather than the inside edge like on the ones we have. Here's a picture of the replacement next to the old one.
So.... the engine isn't getting built for this weekend. But now we can slow down a bit and not be building it under total duress. We have to figure out our options for the heads. CMW has suggested we send the heads back to them, where they will weld the flame ring area and then re-machine it to take their newer style part. I suppose our other options are to find a nice rebuilt set of RSR heads and use those instead. New ones just aren't really available and if they are, they are RIDICULOUSLY expensive.
We will do some other minor engine upgrades and reliability improvements while we are at it.
... So.... the engine isn't getting built for this weekend. But now we can slow down a bit and not be building it under total duress...
Thanks for keeping us updated. Lots of tough news lately. We all hate reading about it... She's a honey though, and you will definitely be rewarded in this journey. Just not right now. Many good times ahead!
Sounds like you are in good hands with the rebuild. Slow down and build it up right. You will soon be terrorizing the East Coast tracks for years to come.
Enjoy driving the 997 to/from the track. Enjoy the simplicity of taking a driver to the track... No trailer!
Yes, the 997 has been a fun car for the track, but after 2 years of using it for that purpose, it now needs a paint job. I should have put on paint protection film. Too late, oh well...
I have plenty of other track time scheduled this spring / summer, racing a 944 and an E30 with the ChumpCar series and headed to Bertil Roos at NJMP in May. So it's frustrating but certainly not keeping me from driving! We will get it built right.
Quick update: The heads were sent back to CMW to be welded and then re-cut for their modern copper flame ring. The old flame ring was a custom job completed for when the car was still raced in Germany, and there were none left. Additionally, all intake valves were also replaced, still with 52mm size, but now the valve stems have been hardened properly so they will not mushroom. Heads are due to land back at Black Forest Racing early next week.
We also made the decision to upgrade to a slightly hotter cam grind from Web Cam. I'll get the specs posted up soon.
The guys at BFR also are sending the engine tin off for powder coating, after they repaired some areas where holes were cut that were no longer in use, rust had started to take hold, etc. So hopefully the motor will start to go back together (again) next week.
Awesome car and project! Thank you for sharing. Sounds like the pain and $ will soon be worth it. We look forward to its maiden voyage and future stories..
To be honest I went with MegaSquirt instead of Motec because of it's hack-ability and the fact that even if I didn't know tons about EFI, I'm a software engineer / entrepreneur by day, and appreciate the ability to tinker with things as much as possible. In the end, you are right, the money aspect of things really isn't the issue, and if you wanted the "professional" solution Motec would probably be the answer. However, I haven't seen anything that Motec can really supply that can't be had with MegaSquirt, at least in this application.
Running into Cody Forbes at Black Forest Racing was a major blessing as well. Without getting his input this project might have turned into a Motec one a while back! But it didn't, and he has been a really great resource, a true car guy, and I'm very thankful.
So basically what I see here is that the intake lift is a bit higher than RSR spec (13.2mm vs 12.5mm); the duration; the lobe centerline angle is narrower (the RSR cam is 108º intake, 110º exhaust), which should move the power up(?).
The specs I have show the 993 3.8 RSR cam having the intake open at 80º BTDC; close 114º after BDC; exhaust open 104º after BDC; close 65º after TDC. The specs on this one are clearly significantly different. Gonna have to rely on Web Cam and Black Forest on this one; not quite sure what that means.
The engine is starting to go back together. Hoped to see it mostly assembled this weekend but we got the wrong cylinder base gaskets in so we had to re-order, and that slowed progress. However, we have the case sealed up and everything is going well so far.
Pistons and Cylinders are back on. Goal is to have the engine re-installed this weekend. We will need to do some additional dyno work because of the cam changes and the valve changes (we definitely weren't optimal with the previous ones being mushroomed).
The huge multi-device crank pulley is getting changed to a Rothsport one, but we received a 993 one instead of a 964 one so had to send it back. This engine is an interesting combination of 964 (bottom end) and 993 RSR (top end) parts.
The new copper gaskets / flame rings now fit the head groove that has been re-machined, but protrude JUST ENOUGH into the combustion chamber to interfere with the piston at TDC when they are bolted on. So, the rings are going to the local machinist to be slightly trimmed on the inside circumference.
It will be worth it. It will be worth it. It will be worth it...
03-09-2015, 01:03 AM
