GDT Cylinder 4 Chamber Cooling System

Waste of money or good reliability mod?

 

 

 

 

GDT proudly offers the industry's first DOHC EJ Cylinder 4 Combustion Chamber Cooling kit that increases coolant flow in the left hand cylinder head. Improving the coolants flow improves the reliability by reducing detonation causing hot spots. Each kit includes an assembled hose kit that features a high grade silicone hose, custom machined 6061 anodized fitting, stainless steel "T" and stainless steel pinch clamps.

Never seen it before or even heard of it, so no idea.

Never seen it before or even heard of it, so no idea.

 

Look who’s back!

 

Install info to show where it goes.

 

http://cdn8.bigcommerce.com/s-gfm7bog6j4/images/stencil/1280x1280/products/112/379/installationinstructions__23985.1529724891.png?c=2&imbypass=on

 

http://shop.getadomtune.com/shop.getadomtune.com/cylinder-4-chamber-cooling-system-gd-gc-lgt-up-to-07/

Sounds like it couldn't hurt. How hard is it to install with the engine in the car ?

 

May need to get the plug out from under the car.

"Cooling Kit" -> a T on a threaded hose. I love the naming.

 

Wait? $90??? And you don't get clamps? It might work, but I could see DIY for maybe $20.

 

I wonder what this does to the coolant flow, I tried watching the video, but it's a lot of different moving parts and none of them seemed to relate to what he was saying.

On the order page you do get the clamps. But 100% agree this is extremely over priced.

 

 

This is a diagram of the cooling passages in our motors. I guess they have have a theory that Cylinder 4 runs hot because there is less coolant flow out of that side. The other head sends some coolant out to the turbo on the equivalent port, so in theory has a slightly higher coolant flow rate.

 

The stock per cylinder ignition comp runs 2.11* more timing on that side though, which probably contributes more to running hotter than the lack of turbo coolant flow. This is done because the knock sensor is on that side, and it makes sure the ECU can hear the knock.

 

edit: Found an SAE paper on the EJ series engines... From 1989

 

Subaru has dropped some of the features the motors used to have (piston oil jets) and the the DOHC heads have changed a little, but I the design theory remains the same.

Dom states the reason it is priced at $89 is due to the custom fittings he had to have made. :shrug: EDIT: Also, he's priced it such that he can sell to vendors for a profit with enough meat on the bone that the vendors can make a few bucks also. So likely there is about $15-$20 max in parts here.

 

You might find a metric thread (I'm not sure what size that threaded port on the head is) to 5/8" barb fitting out there somewhere. I know you won't find it at Home Depot or Menards.

 

I'm sure a 5/8" "T" shouldn't be terribly difficult to source.

 

Dom did do a bunch of testing to verify the product works as advertised. I see no reason to doubt that statement as Dom is a reputable Subaru tuner. So I can appreciate that. But once he told everyone how his "kit" works, he has to expect that everyone with a moderate understanding of plumbing fittings would go make their own.

 

I know I will be making my own for my WRX as every line on that car is -AN. I may buy Dom's kit for the Legacy though... mostly so I don't have to go talk to the ogre that works the counter at my local Fluid Power store.

 

Cheers

^ agree with that. I recall the ogre at my local store when we were building the race Honda Civic. I found other places to buy fittings from.

 

everything is out there, you just need to know how to think outside the box.

That’s a strange looking equal length header.

In case anybody is wondering, supposedly the fitting that bolts to the bottom of the block for the oil cooler for the coolant may work. I didn't check if the nipple is for 5/8th hose or it's size/thread pitch. But honestly I just got a m20x1.5 to 10an fitting and a 10an push loc straight fitting. Since 10an push push loc hose is roughly 5/8th hose size.

Maybe this mod doesn't increase the flow on the left side, but equals out the flow between the two sides. Or even the pressure? Or maybe just increases the flow OVERALL in the cooling system.

Here's the maker himself explaining his reasoning

 

[ame=http://www.youtube.com/watch?v=X82Atqn5pX8]Reverse Cooling and how it applies to Subarus - YouTube[/ame]

 

 

[ame=http://www.youtube.com/watch?v=hwvNPYrUB7M]Cylinder Head Cooling Modification Release - YouTube[/ame]

 

 

Sparknotes: Subaru engineer's placed the knock sensor closest to cylinder 4 by design, knowing it will be the most stressed (temps and timing-wise) cylinder and possibly engineering it to be so purposely. It is the canary in the coal mine, as long as cylinder 4 is good so are all others. Therefore, no additional knock sensors required. Dominic is attempting to remedy it so 4 will have closer temps to all others.

Ok, so I ordered one a few weeks ago and have yet to install. Basically, it’s in a tough spot and I need the car higher in the air than I can go. Hopefully it will be on the car next week.

 

What I can speak about at this point is this, it’s a great quality part, yes it’s expensive but I didn’t want to make my own.

Love to hear / see how install is on this. If anyone gives it a whirl please chime in

There is a lengthy discussion of this product here:

 

https://forums.nasioc.com/forums/showthread.php?t=2882734

This is still a tossup for me.

 

Subaru very deliberately designed the cooling system the way they did. I get what Dom is saying and I respect his knowledge, but does he really think that a simple hose rerouting is something that years of Subaru engineering hasn't considered? They put the knock sensor on cyl 4 for a reason. They tune around cyl 4 for a reason. They know it's the most likely to be weak cylinder.

 

Note that you are increasing the temperature of every other cylinder when you do this mod. It's not just a free "decrease cylinder 4 temps!" job, it's "raise every other cylinder and lower cyl 4 so they're equal!"

It appears to me that it depends on what you prioritize. Subaru deliberately made cylinder 4 the most prone to knock - it will knock before any other cylinder does. Do you value the early detection or do you value decreasing the likelihood of the event in the first place, at the trade-off of distributing that risk more equally among all cylinders (as a result of raising temps of other cylinders)?

 

 

For tuners that are meeting the intended limits of Subaru engineers that trade-off is worth it. Cylinder 4 is holding back the other 3 cylinders. There is more power to net reliably by equalizing the temperatures of all cylinders, in my unqualified keyboard jockey comprehension.

Subarus have one knock sensor. They made it so that if any cylinder is to knock, it better be 4, that way you know it's knocking.

 

By equalizing the cylinders without adding additional knock sensors to the other cylinders, you're making it so that if any cylinder knocks, it could be any, but you still only have that one knock sensor on cylinder 4.