Oil sump or not?
06-19-2018, 07:06 PM
#31
Rennlist Member
A little bit of math I did:
The 1.2L pan is 0.95cm lower than stock to add 1.2L oil so it adds 1.2/0.95 = 1.26 liters per 1cm of lost clearance.
The 2L pan is additional 1.27cm lower than the 1.2L pan to add 0.8L oil so it adds only 0.8/1.27 = 0.63 liters per 1cm of lost clearance.
Looks like the first added 1.2 liters cost the least amount of lost clearance. The extra 0.8 liters in the 2L pan come at a much larger cost in lost clearance, making the 1.2L pan a reasonable compromise. Thoughts?
The 1.2L pan is 0.95cm lower than stock to add 1.2L oil so it adds 1.2/0.95 = 1.26 liters per 1cm of lost clearance.
The 2L pan is additional 1.27cm lower than the 1.2L pan to add 0.8L oil so it adds only 0.8/1.27 = 0.63 liters per 1cm of lost clearance.
Looks like the first added 1.2 liters cost the least amount of lost clearance. The extra 0.8 liters in the 2L pan come at a much larger cost in lost clearance, making the 1.2L pan a reasonable compromise. Thoughts?
06-24-2018, 02:45 PM
#32
Rennlist Member
As a data point, mine with Mantis 2L deep sump on a 70k mile donor after about 10 hours of track work lost the motor with rod knock. I have it in the shop now. No idea if it was due to oil starvation, could have been any number of things. It was on street tires and I didn't have a money shift or anything that would have explained it. It was on one of the first few laps of the day so the current temperatures weren't a likely factor (although perhaps the previous track day the damage was done).
Along with an IMS replacement, fresh AOS, a several coolers, etc., I'll be adding an accusump - whether or not they work, they won't hurt anything assuming a correct install.
Along with an IMS replacement, fresh AOS, a several coolers, etc., I'll be adding an accusump - whether or not they work, they won't hurt anything assuming a correct install.
06-24-2018, 09:10 PM
#33
Rennlist Member
Thanks for the data. I'm getting more and more confused with possible oiling issues and how to resolve them.
Deep sumps don't seem to be the magic bullet, neither is accusump and I see posts about a 'better' dry sump system that appears to be pre production.
Do you monitor oil pressure with a gauge?
I raced Honda DC2 Integras in an entry level series as a way to keep my 964 out of the fray and ended up lunching two engines. After the second engine went I decided the platform was not for me as mods to improve reliability were not allowed.
The Spec Boxster should be better as I can modify the system but I'm not sure of the way forward.
Deep sumps don't seem to be the magic bullet, neither is accusump and I see posts about a 'better' dry sump system that appears to be pre production.
Do you monitor oil pressure with a gauge?
I raced Honda DC2 Integras in an entry level series as a way to keep my 964 out of the fray and ended up lunching two engines. After the second engine went I decided the platform was not for me as mods to improve reliability were not allowed.
The Spec Boxster should be better as I can modify the system but I'm not sure of the way forward.
06-24-2018, 10:02 PM
#34
Rennlist Member
Thanks for the data. I'm getting more and more confused with possible oiling issues and how to resolve them.
Deep sumps don't seem to be the magic bullet, neither is accusump and I see posts about a 'better' dry sump system that appears to be pre production.
Do you monitor oil pressure with a gauge?
I raced Honda DC2 Integras in an entry level series as a way to keep my 964 out of the fray and ended up lunching two engines. After the second engine went I decided the platform was not for me as mods to improve reliability were not allowed.
The Spec Boxster should be better as I can modify the system but I'm not sure of the way forward.
Deep sumps don't seem to be the magic bullet, neither is accusump and I see posts about a 'better' dry sump system that appears to be pre production.
Do you monitor oil pressure with a gauge?
I raced Honda DC2 Integras in an entry level series as a way to keep my 964 out of the fray and ended up lunching two engines. After the second engine went I decided the platform was not for me as mods to improve reliability were not allowed.
The Spec Boxster should be better as I can modify the system but I'm not sure of the way forward.
Another local shop here takes a different approach than most - they just leave the factory oil sump and baffles alone completely and throw an accusump on every car. The thought is the accusump will be enough to prevent any prolonged starvation so why bother with other things. There’s really no data so it’s hard to say what’s best.
And I’m sure it depends on the track!
Chris Cervelli’s dry sump thread is the only thing I can think of that had a lot of data. If I’m not mistaken, they first used the LN sumps for a while (one of the go-to options anyway) and they developed that dry sump system after being unsatisfied with the performance of the deep sump approach in their endurance races. If I had a Cayman S race car with the higher engine cost, the dry sump would be a good value, but Boxster 2.5L motors are still cheap and his solution isn’t legal (yet) for he PCA SPB class. It does fit the spirit of the rules so there’s no reason it couldn’t become legal. Chris was focused on endurance races with 2.7L Boxsters in Colorado so the 986 platform was shared but the PCA SPB class wasn’t the focus.
06-26-2018, 05:52 AM
#35
Rennlist Member
Raced Spec Boxster for 5 years with same Motor because I had the Tarrett Oil Baffle in and always ran with the oil level at max mark! Many on the left coast have gone this route...
My $0.02,
-Chuck
My $0.02,
-Chuck
06-26-2018, 07:55 AM
#36
Rennlist Member
The best fitting deep sump that I have used is the Mantis and I have used all of the major vendors . Because it is one piece it eliminates the spacer plate lessening the areas where a leak can occur. The key to any deep sump is the sandwitch plate that keeps the oil from riding up the walls of the sump on hard corners.
06-28-2018, 02:07 AM
#37
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We ran our SPB on "full" oil and it leaked from the breather on the driver's side AOS tube and the car seemed down on power. Tried running at 1/3 dipstick and seemed to pickup power and no more leakage from the breather. When we get our new SPB together we would like to log oil pressure, or just get a junkyard 2.5L and keep it on standby!
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Last edited by RennPart; 06-28-2018 at 03:03 AM.
06-30-2018, 04:51 PM
#38
Rennlist Member
I have a 996 oil pressure sender and VDO gauge on the way. That will allow more detailed monitoring while I track the car on street tyres. While I like the look of the Mantis, I’m (perhaps unfairly) worried about the rod reference above and for an extra $400 will go Accusump.