Underdrive Pulley Help/Questions

[jb92563]

DRGETZ forgot to consider/mention that the coolant system is under pressure ~5-15psi and that the Radiator fluid itself is also increasing the boil temp and decreasing the formation of steam bubbles.
https://durathermfluids.com/pdf/techpapers/pressure-boiling-point.pdf
http://auto.howstuffworks.com/how-does-radiator-cap-work.htm

Honestly if you do end up boiling the coolant then you are already in deep trouble and your gauge would be flashing long before that.

Note that your temp guage is centered at 185 F and if it got to 200 you would definitively be thinking of starting to bring her down gently and still have at least a 40F or more margin before boiling.

The higher the coolant velocity the more turbulence and more drag so if you were to measure the actual difference in coolant velocity through the system, I doubt it would be much different with the UDP and perhaps may even prevent pump damage by not having the pump cavitate at high rpms.

Its all speculation and theory so us mortals just learn from the racers empirical results and take their word that UDP's work and cause no ill effects.

I have a Tarret UDP and although not raced much it has been working fine and I feel like I'm saving wear and tear on the accessories and gained some faster responsiveness when hitting the throttle.
I noticed a postive change immediately when switching to a UDP
Perhaps a bit of torque increase at the low end as I'm feeling like a rocket launching from 1st to 2nd as the rear is gripping hard and thrusting me back in the seat. Love that feeling in my S.

[DRGETZ]

Thank you for your replies thstone and jb92563.

Thanks for increasing my Boxster knowledge and taking part in my Porsche education pursuits.

I've chose to share the information below to explain why I plan to just replace the OEM belt and leave the pulley upgrade for (perhaps) another day. But after writing the response (and finding virtually nothing about Porsches and Okinawa online) I realized some may benefit from my Boxster S buying experience on a small approximately 70 miles long by 2-17 miles wide Japanese island that hosted the horrific and WWII-ending battle against the Japanese imperial military forces and cost over 240,000 lives in less than six months.

My concerns have more to do with the need to alter a part of the engine (the boss) that many have reported as important to an efficient IMS bearing replacement.

I live on Okinawa. The nearest Porsche dealer and Porsche authorized/trained mechanic sits on another Japanese island (part of mainland Japan) nearly 500 miles across the ocean.

(My particular Boxster S did not come with the amphibious option. Spotting a few non-amphibious Porsches testing the ocean waters during some 2011 Tsunami videos has ruled out any ocean-crossing attempts unless by ferry.)

Okinawa Population approx. 1.25 million; Porsche population: probably less than 100. You can drive months without seeing another Porsche unless you head towards the capital city of Naha.

The previous owner of my car and I searched for several weeks trying to find a Porsche specialist but did not find one. We found plenty of mechanics willing to work on the Boxster S but that seemed like a gamble that could likely result in more problems and less money.

The first garage he recommended, because the original owner specialized in performance foreign (non-Japanese) vehicles, had two boxsters sitting in their bays that had reportedly been collecting dust for over a year. The owners apparently did not want to pay for what the garage/mechanics claimed as necessary repairs. If I didn't see all the dust and what appeared to be half-completed work started months, if not years, ago I would not have believed the abandonment tales so easily. So, before I negotiated a price for the externally excellent looking Porsche, I knew I'd personally perform as much maintenance, preventative maintenance, and repairs as possible rather than ending up in an Auto Mechanic Extortion Scheme of Some sort or "A MESSs".

I plan to do as much work as I can on my own as I trust my own mechanical abilities, attention to detail, thoroughness, ability to learn, retain, and apply new information and technique combined with the patience, persistence and willingness to do things correctly over some questionably-skilled mechanic that has neither driven nor seen a Porsche engine: and, due to language barriers, does not have access to the wealth of Porsche technical information and tutorials available in English. Nor do I trust any mechanic with two Boxsters collecting dust in their bays along with a BMW. The only clean car of the five, a late model Ford Mustang - probably the mechanic's.

Though I have yet to locate a Porsche specialist on Okinawa, I do have access to hydraulic lifts and ramps through the US Military Autoskills Facilities as well as their extensive array of tools and some general technical support from the Autoskills Center employees.

I purchased the car after raising her up 5 feet and performing my own 3 hour Pre-Purchase Inspection that included an oil and filter change and an inspection of both oil and filter. Also purchased a BlueDriver OBD tool that showed no trouble codes.
Plan to buy the more thorough Durametric: and, purchased the car knowing I would perform the following:

1. Replace Fan belt, Air and Cabin Filters
2. Replace the engine mount
3. Replace Spark Plugs, Tubes and Connectors (and coils if needed/cracked)
4. Replace Pads, Rotors, and install stainless steel brake lines
5. Replace both rear axle assemblies
6. IMS Bearing retrofit/replacement

The previous (2nd) owner stated he only changed the oil every 5000 km or at least once a year for the last 12 years. Only mechanical/electrical replacements included a new water pump, fan belt, window drop regulators, MAF and O2 sensors. Knowing that he had done little in terms of parts replacement and preventative maintenance (and probably even less by the original owner of 4 years) I knew I'd need to perform several replacements and some preventative maintenance.

My pre-purchase inspection aided me in negotiating from his initial listing price of $17,500 to $11,700. During our month-long inspection/negotiation process, he actually had a new glass-windowed top installed that he purchased from a stateside Porsche dealer during a recent trip to the US. The top looks great and functions well.

The previous owner also "threw in" several hundred dollars in new oil & air filters, two new O2 sensors, three window drop microswitches, a dozen different new light bulbs, two new brake sensors, two liters of Porsche Transmission fluid, all of the manuals, an unused Porsche car care kit, an unused Blue "siren light" that came with the Stuttgart-built Boxster S, jack and Porsche tools as well as a few other items.

I'd like the extra hp boost that coincides with the UD pulley upgrade but not at the expense of a less difficult IMS Bearing replacement.

I asked about the TDC locking alternative to using the "boss" and no one has replied even though I posted the question on three forums (Rennlist, 986, Pelican); so, for now the UD Pulley upgrade goes to the back burner. It only made it's way to the front of the line after searching and reading about fan belt replacement on the Boxster.

Whether or not I perform the IMS Bearing retrofit/replacement, or hire someone to do it, the task seems daunting enough without adding another time-consuming aspect to the already lengthy and difficult task by rendering the boss useless.

I welcome any knowledge/experience you wish to share... love learning so thanks in advance.

Respectfully,
Mitchell

Originally Posted by jb92563

DRGETZ forgot to consider/mention that the coolant system is under pressure ~5-15psi and that the Radiator fluid itself is also increasing the boil temp and decreasing the formation of steam bubbles.
https://durathermfluids.com/pdf/techpapers/pressure-boiling-point.pdf
How does a radiator cap work? | HowStuffWorks

Honestly if you do end up boiling the coolant then you are already in deep trouble and your gauge would be flashing long before that.

Note that your temp guage is centered at 185 F and if it got to 200 you would definitively be thinking of starting to bring her down gently and still have at least a 40F or more margin before boiling.

The higher the coolant velocity the more turbulence and more drag so if you were to measure the actual difference in coolant velocity through the system, I doubt it would be much different with the UDP and perhaps may even prevent pump damage by not having the pump cavitate at high rpms.

Its all speculation and theory so us mortals just learn from the racers empirical results and take their word that UDP's work and cause no ill effects.

I have a Tarret UDP and although not raced much it has been working fine and I feel like I'm saving wear and tear on the accessories and gained some faster responsiveness when hitting the throttle.
I noticed a postive change immediately when switching to a UDP
Perhaps a bit of torque increase at the low end as I'm feeling like a rocket launching from 1st to 2nd as the rear is gripping hard and thrusting me back in the seat. Love that feeling in my S.

[Gilles]

Originally Posted by DRGETZ

I'd like the extra hp boost that coincides with the UD pulley upgrade but not at the expense of a less difficult IMS Bearing replacement.

I asked about the TDC locking alternative to using the "boss" and no one has replied even though I posted the question on three forums (Rennlist, 986, Pelican); so, for now the UD Pulley upgrade goes to the back burner. It only made it's way to the front of the line after searching and reading about fan belt replacement on the Boxster.

I welcome any knowledge/experience you wish to share... love learning so thanks in advance.

Respectfully,
Mitchell[/FONT]

Hello Mitchell, this is my story

(background)..
Many years ago, I installed a BBI UDP after burning two steering pumps on the track with the SoCal summers, and also installed a small oil cooler on the return port of the steering rack.

Then a few years later, after removing the gearbox to replace the input shaft bearing, I noticed that the IMS cover was leaking a bit and to replace the seal, I first installed the two cam lockers (thanks to BYProdriver and Healthservices..), and then locked the crankshaft at the rear, using two metal straps bolted between the bell housing and the crank (at the flywheel mounting flange), then removed the chain tensioners before removing the IMS cover.

This worked out for me because after removing the gearbox I knew that it was not going to be easy to remove the large bolt on the UDP with the flywheel and the gearbox supports removed.

Good luck with your car, are you going eventually be relocating to the Iwakuni base?

Regards,
Gilles