do i really NEED water lines?

[Tyler]

im only going to run like 8 to 10 psi on a redtop t25, and i was wondering if i really need to water cool it? the turbo has the ports for it but i have read with small turbos that are on street only cars you dont really need to plumb them for water. any info would be great, im asking cause i just read 480's thread on water lines and it seems like a bit of work. thanks, TJG

[zerepdivad]

I hear of a lot of people just blocking them off and running just oil through them. I'm sure it shortens the life of the turbo but c'mon it's an sr t25 they're a dime a dozen.... I personally probably wouldn't. But that's just me.

[480sx]

Nah, you really dont. It MIGHT extend the life of the turbo slightly, but not by much.

The main thing it will do is prevent a good amount of heatsoak and oil coking due to hot shut offs. Its kinda like an added protection against jackassery if you have a turbo. Regardless, if you abuse the turbo its going to fail, its just if you have water running through it you can abuse it more.. heh.

Im getting my information from a professional turbo rebuilder who happens to be a friend of mine.

This all goes out the window however if you have a ceramic ball bearing center cartridge. Maybe any ball bearing turbo im not really sure now that i think about it.

[Tyler]

i think im not going to run them, and just let it sit and cool off real good when im done driving it hard, what can i use to plug the holes?

[480sx]

I would just leave it open as a bug destroyer.

[Tyler]

haha seriously? cause im totally for that, the less random plugs and **** i have to source and buy the better

[480sx]

Lol seriously, theres no reason to plug those holes at all. Nothing in there but casting.

[Tyler]

haha cool, and i know this is of no relation to the thread, but on a low boost low budget daily set up, do i really need to run a catch can?

[480sx]

Idk thats a tough call. Im not sure how the stock PCV valve does under boost, someone else with a stock PCV system needs to chime in on that. This is of course if you still have your stock PCV system intact, if not, you really do need to run a PCV system, and a catch can is the easiest way to do it.

I can hook you up if you want, i made my own and can make another one just like it without to much of an issue. Not free, but i wouldnt charge you much you'v been around a while. I still have enough fittings left over i believe to make another one just like mine without ordering anything. Have a bunch of aluminum stock lying around, we got a killer deal from a Verizon auction on a crap load of aluminum. You would have to order the lines yourself from McMaster, but its like .20 cents a foot so not like your breaking the bank or anything.

Im getting ready to figure out how to hook up the stock PCV breather/separator to the large lines that i use for my PCV system for my next build. Im doing that this week actually. I just need to find out what fitting size i need to use to replace the stock PCV valve itself, the thing that screws into the breather/separator. Not a big deal, just something that i need to get around to doing. If your interested, i can get two of them, one for your setup when i order mine from McMaster.

Oh, this is what im talking about btw. You can see where i mounted mine from the pics in the other thread. It has an oil separator built into it between the two fittings.


Modified by 480sx at 9:27 PM 8/5/2008

[Tyler]

hmm man i dunno, i know i do need a catch can probably cause i wanna be safe, and yours looks super nice. but in all honestly i hardly understood anything you typed, this whole pcv and oil catch thing is throwing me for a loop, i just wanna make sure i get everything i need to install it. and even then im not totally sure how to hook it up.

[480sx]

Alright, well ill try to break it down.

A PCV system is really important for a boosted car, any car really. When an engine is running, especially at higher pressures associated with wide open throttle(or when your getting on it, w/e), a small percentage of the gases that are inside the combustion chamber escape past the rings. These gases go into the crank case, and pollute the oil. When you multiply your cylinder pressures by adding boost, more gas will escape your rings.

Most people disable the stock PCV system when they do a Ka-T setup. It is a PITA and causes vac/boost leaks. I have no idea how the stock PCV valve reacts to boost, but it almost certainly will fail under higher levels of boost. In reality, boosting on the stock valve/stock PCV system isnt such a good idea at all. Your asking for a massive boost leak thats going to be really hard to detect, its just going to blow air into your crank case. Like i say though, i have no experience with the stock valve or PCV system under boost, i just understand how its designed.

The stock PCV valve is a tiny one way valve attached to a breather/separator on your your lower timing chain cover. This is all near your water pump intake, below it. Its a little box looking like thing. The PCV valve itself is a fitting on the end of the box, pointing towards the firewall with a hose sticking out of it.

Basically, a PCV setup keeps your oil cleaner, longer. Without a PCV system you would never get 3000 miles out of your oil, especially on a boosted motor. Whats worse, running with polluted oil will smoke your engine in a quickness. Turbo, head, bearings, you name it.

I learned this the hard way on my last build, the one with a blown ECU. On the plus side i found that my PCV setup was working great, my catch can was filled up nearly half way with nothing but black gas, not even oil.

[Tyler]

wow thanks for taking the time to explain everything to me, this is my first boosted motor and im slowly learning along the way! im almost ready to bolt everything up and hope for the best! so let me get this right, your suggesting i keep the stock pcv system, and also run a catch can? everythinhg else i have been pretty much been able to search around and find answers but this little detail has been throwing me the whole time

[480sx]

No, i think you should disable the stock PCV system and make your own.

[kouki_hmongster]

i've been running w/out waterlines hooked up on t25 for a while now and no problem at all. just leave it unplugged. i recommend doing them now so that later if you decide to upgrade to ballbearing t28 then wouldnt have to worry about doing water lines. and yes small turbos are heatpumps so just to be a little on the safe side do it. also i dont know how hot it usually get but if you have money to spare then custom an oil cooler, thats what i am doing and its for reliability. always be prepared for any driving condition. this is my .02

i'm seriously doing my own pcv system now that i read what 480sx said, still not sure how to but will try.

[Hype]

Very informative 480sx. I've mostly seen oil catch cans relegated to "engine dress up" sections, so it's good to know there is a practical use for them.

[sdtouge]

if its your daily driver i would run water lines, if its a track car on that turbo/s14/15 turbos i dont either. but on my 3071 i do

[brizanden]

Very informative 480sx. I've mostly seen oil catch cans relegated to "engine dress up" sections, so it's good to know there is a practical use for them.

they get rid of most blow by in a boosted setup as well which is really nice and functional.

[WDRacing]

Just to throw in my .02.....

Water lines are easy to plumb. Water cools the turbo extending its life and improving the lubrication ability of the oil by quite a bit. The fact that it IS a small turbo means it will be IN boost more then normal. So if anything, you'd WANT to cool it MORE.

Listen guys...there are only a few things in life that are simple. If you can make something last longer and perform better by taking a few extra minutes and spending like $30 and you don't do it...well you are simply asking for problems.

Take your time, do it right. When you add boost to a NA motor you need to evaluate EVERYTHING...not just fuel add a turbo and fuel. The cooling system is now stressed more, which in turn stresses everything under the hood from the oil itself to the timing tensioner system.

Do you HAVE to do it...no. But how many of the guys that take short cuts are driving a car reliably for years at a time? Did Nissan use water cooling? Does the Silvia run for 200K+ ALL the time? Yes and Yes...nuff said.

WD

[Tyler]

thanks WD, i think im going to run them anyways, cause the motor im going to use is out of the car so it should be easy to plumb. what size fittings do i need for a sr t25? and i know i plumb the feed line from the hose near the throttle body, but where does the return go?

[240sxvaj]

can i use the coolant line right under the throttle body that is a big "U" shape? i look through the thread and it seems like you guys used a different line but the picture looked confusing. maybe is it because i have a 91? (not sure if 95-97 intake manifold are different based on coolant and vaccum lines)

EDIT: sorry i just figure that it is a vac line.
Modified by 240sxvaj at 9:02 PM 8/10/2008

[eazye2000]

Sorry, just got around to checking the forum.And thank GOD you are going to run the coolant lines!

On a turbo that is meant to be water cooled, you need to cool the damned thing. The oil port in one of these turbo's is NOT that big. It is only meant to OIL the turbo, NOT cool it. That's why they put coolant passages in it, for that to serve it's purpose.

So yes, if it's meant to be water cooled, then do it. Your turbo will HATE you if you don't.

On a journal bearing, or oil cooled only turbo, the oil passage is much larger, and is meant to lube, as well as cool the turbo.

I really hope this makes sense.

[nissanfanatic]

The stock PCV valve closes under boost. It is just a one way check valve. When the engine is in vacuum, air is being pulled in the valvecover and exits the lower timing cover through the PCV valve and back into the intake manifold. When boost is applied, air travels the opposite direction as it would in vacuum, which causes the valve to close.

[480sx]

The stock PCV valve closes under boost. It is just a one way check valve. .

This is exactly why the stock PCV system is inadequate for a boosted engine. Also, the stock valve was never designed to see the kind of positive pressures a turbocharger creates.

[nissanfanatic]

This is exactly why the stock PCV system is inadequate for a boosted engine. Also, the stock valve was never designed to see the kind of positive pressures a turbocharger creates.

It wasn't designed to see any kind of positive pressure. I ran mine stock for quite some time, as do a lot of people. Regular oil changes should mitigate the effects.

[480sx]

Your playing with fire with the stock PCV system and boost. Shutting off nearly all crank case ventilation when you need it the most is a horrible idea. Or all of it if you dont have your valve cover vent hooked up to your intake.

Why mitigate something you can eliminate with a custom PCV system, which isnt hard at all to design and implement.

Sure, a lot of people might use the stock PCV system on a boosted Ka. That doesnt make it a good or acceptable idea/practice.

[nelson8708]

Chill......

For low boost applications the stock pvc system is fine. I cant remember if it was on this forum or not but, the stock pcv valve doesnt start to leak until you reach 10psi...Which at that time you can swap the sr pcv valve or go with a custom setup.

Stop preaching so damn much.....you have to have this and this and this is not acceptable.

[480sx]

Sorry if it sounds like im preaching... Not my intention. I do need to relax, im taking some ish personally when i should just blow it off. My fualt for letting that spill over onto the boards.

Heres the way i look at it. When your boosting, your going to have much higher cylinder pressures which is going to cause, or at least have the chance to cause more blow by. With the stock system, your basically eliminating all crank case ventilation when you need it the most.

Never said you had to do anything, just saying i dont think its a good idea when its so easy to rig up a custom PCV system designed to work with boost.