The under dive pulley is all that you need ...

I nursed the leak through the DE season with a couple of fluid top offs but will bust a few knuckles and fix it over the winter. I am pretty sure it is one of the hoses on the pump and not at the rack. Anyway, I plan to do the underdrive pulley and am also considering the LN inline PS fluid cooler. Is that worthwhile or overkill?

this runs the water slower. Not what one would want to do I would think.

I'd be tempted (more than tempted) to leave the drive pulley size alone and fit a power steering fluid cooler. The engine gets the benefit of the faster turning water pump and the power steering system gets the benefit of a lower fluid temperature.

It could be regulated to deliver the proper cooling power and would remove another client from the accessory belt.

Lots of models are being sold at substantial discounts to try to cut down inventory.

If they were flooding the market, then they'd be in short supply.

With an electric motor to drive the water pump you're just adding another part (and weight) that can potentially fail. And, it would also be a constant drain on the electrical system meaning the alternator would have to work harder. I don't see how that would be anything gained.

The gain would be the ability to better control the coolant temperature and to let other parameters than rpm such as fuel consumption, engine temperature and air temperature influence the pump output.
May be you are right that these advantages do not outweigh the price in added weight. I was triggered by the apparent need for an underdrive pulley in this thread, but it might be wiser to better control coolant temperature with electrically controlled valves, as metioned by Marc Warden in this thread.

valves to control the temperature of the coolant in the cooling system the valves are a part of. I do not expect an electrical water pump.

Is there a DIY posted for the underdrive install?

Jim

... unless you run by tight corners on a very long track.
Having the pulley also under drive the water pump keeps the engine cooler as well because of the extra dwell time.
Spinning the subsystems less does no damage to the engine or any component.
After all every one of the subsystems is able to perform at idle speeds (700 RPM).
Happy Porscheing
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

hotter, no doubt to be consistent with it fitting the over temp T-Stat too I guess.

While the accessory drives including the water pump work fine at 700 RPMs the engine is working at 700 RPMs as well. It should be obvious that what suffices at 700 RPMs for the accessory drives won't suffice for the engine at 7000 RPMs. Not only is the engine producing a lot more heat its electricity needs skyrocket too. All those active injectors and coils need the juice big time to work right at 7K RPMs.

If anything I'd fit a power steering fluid cooler. An underdrive pulley? I'd leave it on the parts shelf along with the Turbonator.

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

The head water passages have water jets (small tubes) cast in place which direct coolant with some force at the hottest areas to help prevent steam pocket formation.

A water pump pumping with less force renders these water jets less effective.

And for slower flowing coolant is better at picking up the heat, that's a good one. Where does this heat reside when the water flows past at its normal (and faster) rate? There would be localized overheating and the area would get hot enough to melt metal if this were happening. Which of course it is not.

... in all the years that I've see you post here and elsewhere I've never seen you agree that anything that is not Porsche-sanctioned could equal or be better than OEM.
This from your supportive posts regarding Porsche approved oils, coolant, etc. and your dismissive answers to anything that would challenge that.
To me, P-cars are the best in the world. I applaud their design, engineering and the built-in fun-factor, but I also believe that many times there is a better, more efficient way to do things. It's the engineer in me that never settles with the status quo. That's how I come up with my TechnoProducts which I am sure will never make it into the MarcW-mobiles, but thats OK.
Happy Kool-Aiding
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

which because it slows down the coolant flow supposedly improves cooling? Where are the before and after coolant temperature numbers? Where are the numbers for how much HP is saved or not consumed due to a reduction in parasitic loss?

Where is the science to show other vital fluids not on the approved list are at least equal to those approved and in some cases as claimed by their fans better?

An aftermarket part may make it into one of my Porsches some day but so far none have appeared that have anywhere near the science, the engineering, the numbers behind them to make me remove a Porsche part and install the after market part. I'll take Porsche's science and engineering over any 3rd party/aftermarket parts supplier any day.

... any time soon

The science behind most of my parts comes from my two engineering degrees, a master's degree and over four decades of experience in making machines go faster.
I am not in it to become rich, and some times I don't even want to sell a particular part in order to not have to deal with this cr@p.
I'm also not putting in the money to test things as you would like (like Porsche) because I would never make that money back since I won't sell that many pieces.
I didn't invent the concept of the underdrive pulley. Some other racing engineers did that for their own race cars (Chevrolet and Ford) many years ago.
I just adapted it to my beloved Porsches.
We have measured a 4 HP difference on the same car (Boxster S) with before and after dyno runs running with the standard pulley and then with the under drive pulley.
Believe it or not.
I never said that under driving the pulley improves cooling.
What I said was that under driving the power steering pump lowers the power steering fluid's temperature and that's the main reason why most people install one.
I also said that the car will not run any hotter because of the extra dwell time of the coolant.
That's not my theory either. It's one of thermodynamics laws which says that if you slow the flow of a fluid running against a solid there will be a higher transfer of temperature between them.
So, with an underdrive pulley running the water pump a little slower, the coolant will carry a little more heat from the engine (running hotter) until it reaches the radiators, where because of the same extra dwell time, it will cool off more than normal making it awash and therefore you will not notice a difference in the car's temp.

Regarding the approved list of oils, I don' disagree that Porsche, and most if not all of the other car manufacturers, spends an awful lot of money and resources in trying to find the best fluids for their vehicles.
But you must understand that now a days there is an incredible amount of politics involved. From the environmental regs to sponsorship deals to, ... you name it.
The oils on the approved list are fine, but they may not be the very best for your car because of these regs and agreements/contracts.
The best additive for motor oil in order to keep friction (wear) at bay is zinc and phosphorous (ZDDP), but as you well know the catalytic converters don't like these particular additives, so they are controlled by the EPA who regulates how much you can put into the oil.
In my particular car I use the highest amount of ZDDP I can get and therefore use racing oil (which is not approved by Porsche, but approved by me).
The thinning out of the oil formulas (0W) is also due to regulations, in particular the CAFE standards that keep asking more and more MPGs just by the stroke of a pen.
I understand that the new engines have tighter tolerances but speaking with several automotive engineer friends of mine, they tell me that they don't need to go that thin, that it's mostly because of the CAFE numbers.
Enough ranting (for now).
Happy Porscheing
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna




Edited 1 time(s). Last edit at 10/31/2013 11:36PM by Pedro (Weston, FL). (view changes)

on the temp front, most people who do run them ( and i dont actually advocate it) generally do not measure materially different water temperatures.

But i will note that heavily modified cars just seem to have lots more problems.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

If an engine is going to spend a significant amount of time at very high rpms, might an underdrive pulley be useful? Years ago Car and Driver devoloped a project Corvette; the objective, to achieve 200 mph. During early runs it overheated, until it was conjectured the stock pulley (ok, maybe it was the impeller) to cavitate the coolant.

I agree that it is totally unnecessary on a street car but the pulley/pump combination is engineered to provide adequate pressure, etc. at "normal" revs. Based on my little bit or research, in the case of Boxsters/Caymans, the combination of very hot location on top of the engine in a closed area and higher sustained revs under track conditions puts additional pressure on the PS system and some of the fittings are prone to failure over time. Underdriving the pump reduces the additional pressure/stress. Not sure that there is any significant benefit or detriment to engine cooling but I am not worried about it as I have never had a cooling issue, even on very hot summer days at the track here at altitude in CO. Caymans seem to suffer worse from this PS issue as most of the online information seems to be about them.

when (if) the system can't maintain pressure and the impellers are no longer operating in hot coolant under pressure. This is probably what takes out the water pump impellers rather than some bad impeller. The system has a pressure leak -- could be from a leaking water pump which the owner is trying to wring another few miles out of -- and the system's pressure is less than it should be. The impeller spinning in the hot coolant then experiences cavitation which breaks an impeller blade (the weakest one, naturally) which then takes out the rest.

Think back to Grant's arguments as to what oil to use: road-going and what climate/driving style, etc. or racing (and what type,) etc.
For normal public road use/everyday driving pretty much everything factory stock is fine, and likely preferable: do you want to exchange various rubber bushings for Delrin or whatever just because it helps helps retain the suspension geometric precision, while increasing noise, vibration, and harshness? On the other hand, if the car is to serve well at the track, you'll be making all sorts of non-factory mods. Of course, this doesn't totally exclude aftermarket items that could be an "improvement" over stock, even for a everyday car. Doesn't the factory build cars to a certain price point, so why can't the aftermarket offer legitimate modifications for those willing to pay for such things?



Edited 1 time(s). Last edit at 10/31/2013 04:49PM by Laz. (view changes)

Yes,i saw the pissing match below. Not joining.

First, there are many reports of PS failures due to heat, but you have to be pushing it VERY hard. The cooler is not really debatable, except for the usual "its more places to leak".

The under drive pulleys have several benefits and issues. They lower parasitic losses. But you have to ask if those driven things are actually parasites. I actually buy Pedro's argument and have seen evidence that it works as indicated for water temp. That said, my car does not run hot on the track from what i can tell (getting a OBD-II transmitter to see oil temp, then i'll know more).

I have seen a TON of underdrive pulley failures. One thsi weekend kept a guy from the DE at VIR for a day. Moral: get a good one - I would trust the ones Pedro sells just 'cuz its Pedro, but be careful of ones that look too light - apparently they are - including the one sold until recently by Tarrett, another reputable company. I had them ( yes, two pieces) in my hand Saturday night.

Frankly i see nothing in your original post that suggests one is needed. Maybe a new hose, clamp or sundry parts. I follow DFWAB!

VIR rocks.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com