GTM turbo coolant line improvement
 

There are a few guys talking about improving the coolant lines on the gtm kits and I thought I would post up a simple solution that requires only $0.60 and WILL make a big effect.

First off I want to put it out there that noone has actually had a problem with the lines the way they come some just want to improve it. If you have a gtm TT kit and you have actual proof of boiling the coolant in the turbo line, or have recorded the drivers side chra temp as over the max spec from garret post it up and then I will change this paragraph. There are many kits for different vehicles that run lines like this with no problems such as the aps, and i think the hks 350z turbo kits so it is nothing new, and because the line runs through both turbos it actually has a stronger thermo syphon effect in the hose due to having two heat sources pulling on the coolant when the car is off. Also lets not forget that water has a tremendous capacity to absorb heat and that the turbo bearings(the important bits) are actually being cooled by both the water and the oil circuits.

Now for the actual modification. This is something almost anyone can do it is very easy and there is no crimping or anything involved, all you need is two 3/4-1" hose clamps or factory constant tension clamps. The way the 370z and g37 heater hoses are run is that the passenger side is supply and the drivers side is return. All we will be working with is the passenger side hose. the factory "union" in the passenger side hose is actually a flow restrictor for the heater core to improve circulation through the core itself. In the GTM instruction manual this union is swapped for the the tee for the turbo coolant feed line. The reason the heater core circuit is used in the first place is that there is a good pressure differential across the two hoses. Because of the restrictor in the passenger side hose the pressure on the engine side of the restrictor is higher than the pressure on the heater core side. What you do here is instead of removing the restrictor, you simply cut and instal the coolant tee in the straight part of the hose between the restrictor and the engine. This way the the pressure differential across the turbo coolant line circuit will be greatly increased meaning more coolant will flow through the line to cool the turbos and the best part is there are no pumps to fail or anything. Also when the car is off it will be much easier for the turbos to syphon coolant because it wont have to go through the restrictor to get to the tee.
http://www.the370z.com/members/1slow...olant-hose.gif

Edit: for the instal manual just google it thats what i did think i searched "GTM Turbo Instructions" Also I had originally posted this in somebodies thread when they were discussing it but he had the mods delete it. Also the miata guys do this and you can actually buy different sized restrictors online if you want. The smallest restrictor that still lets your heater get hot is the best one to run.

Speaking of which... I'm annoyed that the coolant bleed cap was eliminated to tee the hose for the water line behind the motor. You would think there would be a more elegant solution that doesn't eliminate the bleed cap.

What's the part number of the OEM restrictor? If it was removed on my install it was not returned to me.

So for clarity, the OE restrictor is removed in the install. We would replace it, and add the feed "T" to the higher pressure location before the restrictor?

Also, I know you explained this to me a while back. I just haven't had a chance to mess with it yet and the picture is a big help. I'm slow like that. :rofl2:

I can dig up the page from courtesy parts for it that is where i got the picture, and yep thats it. Here you go it is like 5 bucks. Heater restrictor

You had a coolant bleed cap on your car? I thought only the early G37's got that fitting in the drivers side hose. Nissan Eliminated it probably because it is known to fail.

Awesome. Much appreciated.

Yeah it took me 40minutes to find where they had it at first, why nissan decides that the heater hoses need to have there own section in the parts catalog is beyond me, and why they put it under body electrical I really don't know I think just hate us all.

Body electrical. :rofl2: Yeah, that's exactly where that goes.

This might make me get off my lazy *** and swap out the heater hoses for the silicone ones I bought and promptly put on the shelf where they've sat for over a year.

Oooh. Tech wondered and thought that was what's missing. It's a pain to burp this cat let alone rid air bubbles out of the turbo water lines. Actually I never really know for sure. I still hear gurgling sounds after shutting down.

OK a small change to this I was looking at pictures of a 2010 and t appears that nissan changed it from a restrictor to an open fitting latter in production(I have the 100th 370 made) so I might need to see if i can find a G fitting that is still restricted and get the part number for it or an aftermarket restrictor.

Looks like there is a shove in style 79-93 mustang restrictor that you just push into the hose and put a clamp over. Another purpose of the restrictor is to extend the life of the heater core by reducing the pressure the core sees and since the flow through the core is slower it is also supposed quiet the heater core down. There are expensive aftermarket billet ones too but the mustang part is cheap if you cant find the nissan piece. with the mustang restrictor you would disconnect the heater core side of the tee and and shove it into the hose then attach a clamp over it to hold it in place then reconnect the coolant tee.

I heard there's some issue with oil line not having the proper cooling similar to this one... is there a fix for it?

I've never heard anything about this. Tell us more.

It's something about the oil drain line.. maybe i'm mistaken for the coolant issue. I just thought maybe someone here knows more about it

I haven't heard any issues with the oil lines. Where did you hear this? If you can get me a link, I'd like to read it. Lines are cheap and relatively easy, so if there are ways to improve the whole kit by some minor re-plumbing I'm in.