Follow along with my engine rebuild
03-10-2006, 09:39 AM
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Join Date: Apr 2002
Location: Sydney, Australia
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Apologies to anyone waiting for me to post the photos of my rebuild. I've been completely snowed under by work committments lately and haven't had the time to put the website together. It will appear in the near future, though.
As for the car, I've covered 1700 miles (2800km) so far, and everything's going rather well indeed. I've only recently started to take it up near the redline occasionally, after staying below 5000-5500 rpm for the first 1000 miles. I'm using a low additive dino oil for the purposes of running in at the moment. I don't have the specs on how this oil holds up under extreme pressure, so I'll stay away from the top end of the power band until I change to a synthetic that I expect will give me considerably more protection under high loads and elevated operating temperatures. I've learned a lot about oils lately, and will put this knowledge to use in order to minimise future wear on this engine. The one thing that was worn more than I would have liked was the cylinder bores. They're at bottom spec right now, and will no doubt go out of spec some time within the next 50,000 miles or so. I want to do what I can with regular oil maintenance to limit the wear. It'll be interesting to see how things hold up. I intend to have oil analyses done on the used oils too, so I can get some hard data on how they're holding up and how much of the engine's metal is ending up in my oil!
For those who are curious, I'm currently running a 30 weight oil, and will change to a 10W40 at the next change. Temperatures here seldom go as low as 0 degrees Celsius, so I don't need any more flow at colder temperatures. I believe that a 40 weight at the hot end of the scale will be enough, based on the research I've done on the oil I'll be using. Time will tell.
The 30 weight oil is labelled as a "Running In" oil. It's formulated to be nothing more than a good quality mineral oil with minimal additives. It's intended to be in the engine for only short periods of time compared to more typical oils, especially if compared to extended service oils, which are becoming popular these days. This is the third dose of the "running in" oil I've had in the engine so far. The first dose was used only for the initial 20 minute static run. The second dose ran for 600 miles (1000km), and the third and current dose will stay in until 1850 miles (3000km). Oil usage so far is within spec, although a little on the high side. This is possibly due to two things (1) the rings are still bedding in, and/or (2) a 30 weight oil is on the thin side, especially when it gets hot. We'll see if the change to 10W40 reduces oil consumption. Of course, the engine is plenty more run in than it was when I did the last oil change, and that alone should see a reduction in oil consumption in the near future.
It's interesting to watch the oil pressure gauge while driving. Cold starts at 20-25 deg C / 72 - 77 deg F show an instant 4.5 Bar on the gauge, which drops to around 1.5 Bar at normal idle temperatures of 80 deg C / 175 F. On the few occasions that I've given it a short duration 8/10ths thrashing over the past week, I've watched the oil pressures drop slightly as the oil temperature rises. I don't know what the oil temperature is because I haven't installed a gauge, but I figure it's somewhere around 10-15 degrees C above the water temperature when being driven quite hard. This equates to around the 95-115 deg C / 195 - 240 deg F range. Oil pressure at 5000 rpm drops to just below 4 Bar at these warmer temperatures. I'd like to see it hold pressure above 4 Bar at all revs and temperatures, and that's my goal with the 10W40. I'll give it a good few tests on some excellent driving roads I have near my place, but it will be a while before I take it on a race track and push it right to its limit. Here's hoping the 40 weight is a good choice, because I don't fancy carrying a 50 weight around for the 95% of the time the car is used as a daily driver in urban traffic. Fuel economy would definitely suffer if I did that.
Speaking of fuel economy, I've been checking it since the rebuild, and I'm getting above 24mpg (that's 20.5 miles per US gallon) in city driving when I roughly obey the speed limits. This drops to around 22mpg (US 18mpg) if I give it a bit of a caning occasionally. Seems to me that these figures are excellent. They compare to the published city figure of 19.2mpg (US 16mpg) quite favourably. If I tried, I reckon I could do even better. I haven't done any highway driving yet, but I plan to on the weekend. If I can work it out accurately, I'll have a go at estimating economy for highway use. This is on 98 RON fuel, by the way. Not sure what MON it is, but I can find out if anyone wants to know.
The other interesting thing is the lightweight flywheel. I couldn't have asked for a better outcome from that product. I've always been annoyed by the leisurely time between gear changes in the 968. It simply took too long for the revs to drop back in time for the next up-shift. Now, with the new flywheel, I can change gears around 2-3 tenths of a second quicker. It's amazing how much more responsive this feels. I can't wait to try it on a circuit. I expect it'll be worth at least a second or two. The other thing I've found is that rev matching on down-shifts is very easy. All it takes is a little dab on the throttle between gears, and the engine syncs up with the road speed easily. I didn't think I'd see such a change in this area, but the change is definitely for the better. The downside is increased NVH at 2000-2300rpm, but I can live with that. It is a sports car, after all.
So there you have it. I consider it to be pretty much run in by now, and once I change the oil in the next few weeks, the task will be complete.
Oh, one last thing. I did a compression test when I came home from work tonight. On a warm engine the results were:
Cyl 1: 200
Cyl 2: 200
Cyl 3: 200
Cyl 4: 200
Can't complain about that, can I?
Clayton
P.S. Hope someone is reading this.
As for the car, I've covered 1700 miles (2800km) so far, and everything's going rather well indeed. I've only recently started to take it up near the redline occasionally, after staying below 5000-5500 rpm for the first 1000 miles. I'm using a low additive dino oil for the purposes of running in at the moment. I don't have the specs on how this oil holds up under extreme pressure, so I'll stay away from the top end of the power band until I change to a synthetic that I expect will give me considerably more protection under high loads and elevated operating temperatures. I've learned a lot about oils lately, and will put this knowledge to use in order to minimise future wear on this engine. The one thing that was worn more than I would have liked was the cylinder bores. They're at bottom spec right now, and will no doubt go out of spec some time within the next 50,000 miles or so. I want to do what I can with regular oil maintenance to limit the wear. It'll be interesting to see how things hold up. I intend to have oil analyses done on the used oils too, so I can get some hard data on how they're holding up and how much of the engine's metal is ending up in my oil!
For those who are curious, I'm currently running a 30 weight oil, and will change to a 10W40 at the next change. Temperatures here seldom go as low as 0 degrees Celsius, so I don't need any more flow at colder temperatures. I believe that a 40 weight at the hot end of the scale will be enough, based on the research I've done on the oil I'll be using. Time will tell.
The 30 weight oil is labelled as a "Running In" oil. It's formulated to be nothing more than a good quality mineral oil with minimal additives. It's intended to be in the engine for only short periods of time compared to more typical oils, especially if compared to extended service oils, which are becoming popular these days. This is the third dose of the "running in" oil I've had in the engine so far. The first dose was used only for the initial 20 minute static run. The second dose ran for 600 miles (1000km), and the third and current dose will stay in until 1850 miles (3000km). Oil usage so far is within spec, although a little on the high side. This is possibly due to two things (1) the rings are still bedding in, and/or (2) a 30 weight oil is on the thin side, especially when it gets hot. We'll see if the change to 10W40 reduces oil consumption. Of course, the engine is plenty more run in than it was when I did the last oil change, and that alone should see a reduction in oil consumption in the near future.
It's interesting to watch the oil pressure gauge while driving. Cold starts at 20-25 deg C / 72 - 77 deg F show an instant 4.5 Bar on the gauge, which drops to around 1.5 Bar at normal idle temperatures of 80 deg C / 175 F. On the few occasions that I've given it a short duration 8/10ths thrashing over the past week, I've watched the oil pressures drop slightly as the oil temperature rises. I don't know what the oil temperature is because I haven't installed a gauge, but I figure it's somewhere around 10-15 degrees C above the water temperature when being driven quite hard. This equates to around the 95-115 deg C / 195 - 240 deg F range. Oil pressure at 5000 rpm drops to just below 4 Bar at these warmer temperatures. I'd like to see it hold pressure above 4 Bar at all revs and temperatures, and that's my goal with the 10W40. I'll give it a good few tests on some excellent driving roads I have near my place, but it will be a while before I take it on a race track and push it right to its limit. Here's hoping the 40 weight is a good choice, because I don't fancy carrying a 50 weight around for the 95% of the time the car is used as a daily driver in urban traffic. Fuel economy would definitely suffer if I did that.
Speaking of fuel economy, I've been checking it since the rebuild, and I'm getting above 24mpg (that's 20.5 miles per US gallon) in city driving when I roughly obey the speed limits. This drops to around 22mpg (US 18mpg) if I give it a bit of a caning occasionally. Seems to me that these figures are excellent. They compare to the published city figure of 19.2mpg (US 16mpg) quite favourably. If I tried, I reckon I could do even better. I haven't done any highway driving yet, but I plan to on the weekend. If I can work it out accurately, I'll have a go at estimating economy for highway use. This is on 98 RON fuel, by the way. Not sure what MON it is, but I can find out if anyone wants to know.
The other interesting thing is the lightweight flywheel. I couldn't have asked for a better outcome from that product. I've always been annoyed by the leisurely time between gear changes in the 968. It simply took too long for the revs to drop back in time for the next up-shift. Now, with the new flywheel, I can change gears around 2-3 tenths of a second quicker. It's amazing how much more responsive this feels. I can't wait to try it on a circuit. I expect it'll be worth at least a second or two. The other thing I've found is that rev matching on down-shifts is very easy. All it takes is a little dab on the throttle between gears, and the engine syncs up with the road speed easily. I didn't think I'd see such a change in this area, but the change is definitely for the better. The downside is increased NVH at 2000-2300rpm, but I can live with that. It is a sports car, after all.
So there you have it. I consider it to be pretty much run in by now, and once I change the oil in the next few weeks, the task will be complete.
Oh, one last thing. I did a compression test when I came home from work tonight. On a warm engine the results were:
Cyl 1: 200
Cyl 2: 200
Cyl 3: 200
Cyl 4: 200
Can't complain about that, can I?
Clayton
P.S. Hope someone is reading this.
Last edited by gnosis; 03-10-2006 at 09:55 AM.
