blown 944

I am wondering if anyone knows of an "extended time" relay for the turbo pump.

I am trying a new idea for engine cool down. I had the turbo pump on with the ignition switch feeding the back of the cylinder head. (If anyone has read my past threads they know why I did this).

I am looking for a longer timed relay so the pump will stay on for ~ 3-5 minutes instead of ~45 seconds.

anyone know of one??

theedge

You could plump in the temp sensor, since it runs until the coolant passing the sensor cools down to a certain temp.

VWaddict

If you open up the relay, there's an 8-pin timer IC in there which is of the generic type NE555V. (there'll always be a "555" in the part number of any IC which meets this criteria somewhere...)

Pin 1 is closest to the little recessed "dot" in one corner of the IC, or a half-moon at the pin 1/pin 8 end... see this illustration:


Pins 6 and 7 will very likely be joined together by a circuit board trace, and there will be a capacitor between them and pin 1 (ground) which determines the monostable time period, which is what you want to change.

If you can MEASURE this capacitor, the I can tell you what the new value will need to be. -Basically you want to increase it by a factor of about eight to go from thirty seconds to about 4 minutes.

I have a spare one at home, -IF I REMEMBER, I can measure it for you, and show you what to add between pins 1 and 6/7 in order to increase the monostable period.

Keith

blown 944

Brian, I had thought of that but for 2 reasons I am trying to stay with the relay and the factory stuff.
1 changing a relay is pretty easy (I am lazy)
2 a lot of people have converted to oil only turbos and using turbo pumps factory circuit to add cooling to rear of the engine seems like a good idea and other can do it very easy if the factory stuff is used


Keith, if you could do that I would appreciate it. I am not the most electronically technical guy so some "hand holding" may be in order

Clutch10

Not to stray from this post but how catastrophic would it be if you completely take the turbo pump relay out and allow the car to run 1/2 a minute after each drive?

bearone

my turbo pump runs for the 30 sec or so and i still do a min cool down.

87951
95sl320 dd

blown 944

Speaking only to the use of the pump for the turbo.

short term not much damage, long term turbo would be ruined.

the stock turbo, or any watercooled turbo for that matter, have far less area for the oil to cool the turbo and just not designed to run w/o water for extended periods.

I would ask why do that though, as it is there, and any extra cooling is beneficial.

eniac

You could just wire in a new time delay relay like this or something like it:
http://www.kfz-relais.com/html/Time_...ustable_en.htm

How did you plumb the turbo pump into the rear of the head? I assume it goes into the port from the heater core into the head, is it plumbed inline of this hose? Is your turbo then not water cooled?

blown 944

Ha, that would be great if I actually understood any of that data. If I am understanding this correctly it is doing the exact thing the stock relay does, just adjustable for time. I bet I could figure out a way to make an adaptor to replace the stock unit with one of these. Or wouldn't it be nice if it was a drop in

Yes I am running oil cooled only.

I have the line plumbed in where most people put the "steam vent" fitting

eniac

Not much chance of this one being a drop in but this there are many relays to choose from, it is possible you could find an adjustable drop in relay if you looked hard enough. Wiring in a new relay isn't as bad as it looks. Most relays have their wiring diagram right on the top or side of the housing.

For this paticular one:
All diagrams: The supply voltage is applied to terminal 30/87z. If the signal voltage is applied to terminal 15, the relay switches on. Is signal removed the relay switches off after the delay time has elapsed.




Constant power would go to terminal 30/87z, switched power(from ignition or termo switch) would go to terminal 15. Terminal 87 is the power going out to the pump. Pretty much any relay works in this manner, whether timed or not. The diagrams on the plastic cases say what goes where.

VWaddict

Well the stock relay has permanent power and then also gets a feed from TWO places: -One is a 'simple' trigger from the 'engine running' and the second is the thermal trigger measured at the turbo itself. It runs its delay after the 'engine run' trigger is REMOVED, and then it cycles off and on if the turbo temperature is above trigger threshold. -For that reason, the earlier linked product above is probably not an easy plug-n-play solution...

They sell variable-delay octal (and 11-pin) plug-in delay relays everywhere, but these possibly won't do, even if you adapt the base... can't say for sure though, as I've never tried.

Porsche engineered the turbo coolant pump relay to be fairly specific to that task, so a third-party plug-in may not work very well... although if you're changing the WAY that the cooling is done, that may or may not be a good thing for you?

I'll take photos of the dismantle-ment if you like.

Capacitances ADD TOGETHER in parallel, so luckily for you you don't actually have to remove the existing capacitor; -you can just solder one in parallel with the existing one. -I have a full selection of caps at home and here at work, so I can send you whatever you need to make it work, along with posting pictures of where to solder it.

Keith

blown 944

Keith that sounds great.

I guess all I need to know is where to solder it and what I would need to get. I can probably figure that out by where the current capacitor is??

As far as what I am doing I just feel that the ball was dropped in regards to equal cylinder cooling from front of engine to rear and I am compensating with a spare part (it may not be the best choice but it is free)

On my other car I will use a decent electric pump with feeds at each cylinder. However this little experiment is teaching me how to make a delayed shutoff setup

eniac

This was just one example of what could be used. I'm quite certain it cannot be dropped in but it really wouldn't take much effort to wire one like this in using the existing wires. To have it act as stock the "engine run" trigger would go to terminal 15 as shown and the the thermo switch would go to 87a so when the ignition is turned off, it starts the timed delay. When the delay switches off, the power contact flips to 87a. If the temp is still high enough, the pump will continue to run until the thermo switch turns off... hmm but ran in this manner a second basic relay would be needed for the thermo switch or you could simply retain that portion of the stock relay. There are timed relays with stuff like this built in and there are tons of different options depending on how far you want to go with it.

blown 944

very nice write up here: http://forums.pelicanparts.com/showt...turbo+pump+fix

theedge

Bad link.