Any Rennlisters from New Zealand?
12-08-2015, 04:33 PM
Rennlist Member
If you watch Steve R n a race day he will sometimes bleed those brakes twice! Even on a RSG track tour he would bleed them twice.
Most of the hardcore track guys in the states would bleed them after every weekend.
For a road car using SRF you have a bit more latitude. But its a heavy car. Its time that makes a chunk of this difference as its hydroscopic.
For the GT3 Im about to change mine in Jan when it has its 2 year service. Its SRF and will have been in the car 12 months and 8 track days at that time. Probably a bit longer than I would like. I expect it then to last 2016.
For the 993 with Big Reds it will be 18 months since it was changed when that car is serviced in Feb. It will have seen 3 track days a 3 day targa and 5000 road km (maybe 1000 pretty much at targa pace) by then. Thats probably the longest I would leave SRF.
Pel, I should think you will be just fine with the Turbo.
Most of the hardcore track guys in the states would bleed them after every weekend.
For a road car using SRF you have a bit more latitude. But its a heavy car. Its time that makes a chunk of this difference as its hydroscopic.
For the GT3 Im about to change mine in Jan when it has its 2 year service. Its SRF and will have been in the car 12 months and 8 track days at that time. Probably a bit longer than I would like. I expect it then to last 2016.
For the 993 with Big Reds it will be 18 months since it was changed when that car is serviced in Feb. It will have seen 3 track days a 3 day targa and 5000 road km (maybe 1000 pretty much at targa pace) by then. Thats probably the longest I would leave SRF.
Pel, I should think you will be just fine with the Turbo.
12-08-2015, 04:35 PM
Rennlist Member
The wolves are circling for their own sub 1.20 time (you don't buy Z221s to stay above 1.20) and it's been a long term goal to break under 1.19.57, the time that Steve did under the old configuration, so I'll be going for it. Just need a clear dry somewhat coolish track.
12-08-2015, 05:50 PM
Three Wheelin'
Mike. You sound grounded in this stuff. Im not.
Ive been working with Dean H over the last year or so on an idea for an additional transmission cooler for the 993. Its a bit of a packaging nightmare. We have the circuit sorted and the hardware is relatively easy (Setrab). Space is tight, flow into the cooler is ok (Naca duct from transmission cover) but exit airflow still needs some work. No point having forced air into a space with no exit behind the cooler etc. Power feed for an electric pressure pump is fiddly but doable etc.
The thinking behind this is that the cooler the oil stays within the transmission the less the viscosity and properties of the oil change (within use and over time).
I think that is sound reasoning. However the filtration is something I confess I hadn't considered. I wonder if we would could run an separate filter on that circuit to improve things here. It may not be possible.
Long way from completion on this project but if we supplied the specs once finalized maybe you could suggest a filter spec?
The purpose of this is simply transmission longevity. When I upgrade the engine I will do an additional engine oil cooler. I already have an idea for this based on RUFs BTR cars.
Pic below is a race car (993) with the additional tranny oil cooler. They run with no covers so air pressure system less of an issue.
Ive been working with Dean H over the last year or so on an idea for an additional transmission cooler for the 993. Its a bit of a packaging nightmare. We have the circuit sorted and the hardware is relatively easy (Setrab). Space is tight, flow into the cooler is ok (Naca duct from transmission cover) but exit airflow still needs some work. No point having forced air into a space with no exit behind the cooler etc. Power feed for an electric pressure pump is fiddly but doable etc.
The thinking behind this is that the cooler the oil stays within the transmission the less the viscosity and properties of the oil change (within use and over time).
I think that is sound reasoning. However the filtration is something I confess I hadn't considered. I wonder if we would could run an separate filter on that circuit to improve things here. It may not be possible.
Long way from completion on this project but if we supplied the specs once finalized maybe you could suggest a filter spec?
The purpose of this is simply transmission longevity. When I upgrade the engine I will do an additional engine oil cooler. I already have an idea for this based on RUFs BTR cars.
Pic below is a race car (993) with the additional tranny oil cooler. They run with no covers so air pressure system less of an issue.
I haven't ever run a filter on a transaxle. However the viscosity of the trans oil is similar to engine oil. I would consider a standard remote-mount filter head with a standard engine oil filter.
I would (just to be safe) make sure it had a pressure bypass to avoid killing the pump or filter.
I've got some mind-numbingly boring calculations for determining filter specs so happy to run some calcs once your requirements are known.
ISO 4406 is the standard for particle count in lube oils.
Great summary here:
https://www.hyprofiltration.com/clie...SO%20Intro.pdf
Cheers,
Mike
12-08-2015, 06:13 PM
Was thinking too last night that a very fine tranny fluid filter would have to be pretty huge to avoid overly restricting the flow if placed in series with the transmission cooler, and is another potential point of failure in that circuit. Or, for a more biological take on it, nature didn't put our kidneys in our aorta. I'd imagine that if you decide to fit a ~5 micron filter to keep your tranny fluid clean, you'd be better to add some extra fittings and fit it in parallel, so it can be smaller and operate at a low flow rate away from the main circulation.
Apologies if someone's already mentioned that - only 'skimmed' the thread this morning.
Apologies if someone's already mentioned that - only 'skimmed' the thread this morning.
12-08-2015, 06:19 PM
Three Wheelin'
Mike. You sound grounded in this stuff. Im not.
Ive been working with Dean H over the last year or so on an idea for an additional transmission cooler for the 993. Its a bit of a packaging nightmare. We have the circuit sorted and the hardware is relatively easy (Setrab). Space is tight, flow into the cooler is ok (Naca duct from transmission cover) but exit airflow still needs some work. No point having forced air into a space with no exit behind the cooler etc. Power feed for an electric pressure pump is fiddly but doable etc.
The thinking behind this is that the cooler the oil stays within the transmission the less the viscosity and properties of the oil change (within use and over time).
I think that is sound reasoning. However the filtration is something I confess I hadn't considered. I wonder if we would could run an separate filter on that circuit to improve things here. It may not be possible.
Long way from completion on this project but if we supplied the specs once finalized maybe you could suggest a filter spec?
The purpose of this is simply transmission longevity. When I upgrade the engine I will do an additional engine oil cooler. I already have an idea for this based on RUFs BTR cars.
Pic below is a race car (993) with the additional tranny oil cooler. They run with no covers so air pressure system less of an issue.
Ive been working with Dean H over the last year or so on an idea for an additional transmission cooler for the 993. Its a bit of a packaging nightmare. We have the circuit sorted and the hardware is relatively easy (Setrab). Space is tight, flow into the cooler is ok (Naca duct from transmission cover) but exit airflow still needs some work. No point having forced air into a space with no exit behind the cooler etc. Power feed for an electric pressure pump is fiddly but doable etc.
The thinking behind this is that the cooler the oil stays within the transmission the less the viscosity and properties of the oil change (within use and over time).
I think that is sound reasoning. However the filtration is something I confess I hadn't considered. I wonder if we would could run an separate filter on that circuit to improve things here. It may not be possible.
Long way from completion on this project but if we supplied the specs once finalized maybe you could suggest a filter spec?
The purpose of this is simply transmission longevity. When I upgrade the engine I will do an additional engine oil cooler. I already have an idea for this based on RUFs BTR cars.
Pic below is a race car (993) with the additional tranny oil cooler. They run with no covers so air pressure system less of an issue.
One of these is the ticket, to replace the stock "breather". I would remote-mount it with a bit of pneumatic hose. I can't recommend these more highly, they are GREAT!!!
https://descase.com/breathers/hydrog...ccant-breather
Cheers,
Mike
12-08-2015, 06:50 PM
Rennlist Member
JMc - I don't know who was more upset when you sold your 3.6T - me or you??
I should have sucked it up and put your car on the house.........
Happiness Is A Porsche 911 3.6 Turbo And Nothing Else In Sight
http://petrolicious.com/articles/man...-else-in-sight
I should have sucked it up and put your car on the house.........
Happiness Is A Porsche 911 3.6 Turbo And Nothing Else In Sight
http://petrolicious.com/articles/man...-else-in-sight
12-08-2015, 07:12 PM
Rennlist Member
I'm in love
12-08-2015, 07:15 PM
Rennlist Member
Was thinking too last night that a very fine tranny fluid filter would have to be pretty huge to avoid overly restricting the flow if placed in series with the transmission cooler, and is another potential point of failure in that circuit. Or, for a more biological take on it, nature didn't put our kidneys in our aorta. I'd imagine that if you decide to fit a ~5 micron filter to keep your tranny fluid clean, you'd be better to add some extra fittings and fit it in parallel, so it can be smaller and operate at a low flow rate away from the main circulation. Apologies if someone's already mentioned that - only 'skimmed' the thread this morning.
Mike that breather sure looks interesting. I will investigate that.
Buba. hindsight is a wonderful thing. You don't need another car you cannot drive in anger. You need something you can run in the targa tour, some fast backroad runs etc suggest something already covered with stone chips!
12-08-2015, 07:31 PM
Brake fluid degradation over time, and SRF change intervals
In case it helps, this shows how standard DOT 3 brake fluids' performance declines over time (US average from study):
The above also gives a good guide to DOT 4, which is similarly hygroscopic as DOT3 but starts from a higher temperature base, and has a higher saturation point:
SRF (a special DOT 4 that outperforms DOT 5.1s) is a huge step better again on sustained performance as it is less hygroscopic (so slower to attract water) and has ingredients that neutralise what water does get taken up to minimise degradation of the boiling point.
I don't have a similar graph for it, but reportedly DOT3 saturates (vapour locks) at 3.7%, most good DOT 4s around 7-10% and SRF at 22% (these latter unconfirmed). Castrol say it is for racing, and recommend changing it at least every 18 months - it suffers nowhere near the degradation of pretty much every other racing fluid.
RBF600 is one of the better conventional DOT4s but I've boiled fairly fresh RBF600 in the Turbo in the third session of running 5-7 hot laps of HD, spaced out by 20 - 30 minutes. That was while still stock. So yes, I'm with Paul in recommending frequent bleeds and flushes of regular brake fluids. But despite around 20% more power and higher speeds, SRF has never yet seen the pedal go soft and need the calipers bleeding and is a totally different prospect, so if you're flushing SRF more frequently than yearly I'd say there's almost zero benefit.
Here's how it compares to specs:
Castrol states (here sourced from NZ's Opie Oils site) that it's a racing fluid with up to 18 month change interval:
I researched SRF to death a few years ago before running it.
The above also gives a good guide to DOT 4, which is similarly hygroscopic as DOT3 but starts from a higher temperature base, and has a higher saturation point:
SRF (a special DOT 4 that outperforms DOT 5.1s) is a huge step better again on sustained performance as it is less hygroscopic (so slower to attract water) and has ingredients that neutralise what water does get taken up to minimise degradation of the boiling point.
I don't have a similar graph for it, but reportedly DOT3 saturates (vapour locks) at 3.7%, most good DOT 4s around 7-10% and SRF at 22% (these latter unconfirmed). Castrol say it is for racing, and recommend changing it at least every 18 months - it suffers nowhere near the degradation of pretty much every other racing fluid.
RBF600 is one of the better conventional DOT4s but I've boiled fairly fresh RBF600 in the Turbo in the third session of running 5-7 hot laps of HD, spaced out by 20 - 30 minutes. That was while still stock. So yes, I'm with Paul in recommending frequent bleeds and flushes of regular brake fluids. But despite around 20% more power and higher speeds, SRF has never yet seen the pedal go soft and need the calipers bleeding and is a totally different prospect, so if you're flushing SRF more frequently than yearly I'd say there's almost zero benefit.
Here's how it compares to specs:
Castrol states (here sourced from NZ's Opie Oils site) that it's a racing fluid with up to 18 month change interval:
I researched SRF to death a few years ago before running it.
12-08-2015, 07:50 PM
Rennlist Member
JMc - I don't konw who was more upset when you sold your 3.6T - me or you??
I should have sucked it up and put your car on the house.........
Happiness Is A Porsche 911 3.6 Turbo And Nothing Else In Sight
http://petrolicious.com/articles/man...-else-in-sight
I should have sucked it up and put your car on the house.........
Happiness Is A Porsche 911 3.6 Turbo And Nothing Else In Sight
http://petrolicious.com/articles/man...-else-in-sight
There were a number of people in NZ that missed out on the Turbo 3.6, but you were one of the first. It was probably a reasonable assumption that I would have it for more years and you had time, but that strange turn of events meant it went offshore. I still have the memories and they cost nothing...
12-08-2015, 07:59 PM
Rennlist Member
12-08-2015, 08:10 PM
Instructor
Join Date: May 2010
Location: Manawatu New Zealand
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I hear you John , I too like Paul should have sucked it up , but it's easy to say after it's gone .
I may not now get a 3.6 T , but a nice Turbo either 930 or 964 T will come along one day , I hope .
Congrats on your progress with the 964 , I read every page and it's looking really good , a big job to take on , I'm sure very rewarding
I may not now get a 3.6 T , but a nice Turbo either 930 or 964 T will come along one day , I hope .
Congrats on your progress with the 964 , I read every page and it's looking really good , a big job to take on , I'm sure very rewarding