RB Head Cooling Mod?

[klh6686]

Hello, I've been following the RB motor on several diff forums for quite some time now and have always seen references to the RB head cooling mod, mainly done on gtr's. I understand what it is for i am just unsure of how to apply it on my RB25 head. Now my understanding is that the way coolant flows stock (mainly the coolant tube on the intake manifold) isn't the most efficient way to route coolant and so the manifold gets tapped for new lines. Is it done in addition to the coolant pipe on the bottom of the mani or would it be best to replace that w/ three flanges w/ lines running to them? Where do the lines run to, the heater hose outlet next to the thermo? basically im trying to get a better understanding so that i can apply it to the motor that i'm currently building. I am currently in the process of performing oil modifications as per SydneyKids (SAU) instructions including oil restrictors, drain at the back of the head, oil cooler, etc. Also as a sidenote, does anyone know how to correctly remove the vct on the RB25? Thanks Guys

[Carl H]

you are talking about the 'gt cooling system' jun uses it on their high power cars, i know that its been described on SAU and SDU a few times...unfortunately my memory of it is too rusty to give exact specs.basicaly it allows for more coolant flow thru the head to prevent hot spots.

[klh6686]

you are talking about the 'gt cooling system' jun uses it on their high power cars, i know that its been described on SAU and SDU a few times...unfortunately my memory of it is too rusty to give exact specs.basicaly it allows for more coolant flow thru the head to prevent hot spots.

Yea Carl, that is what i am talking about. It's also the same thing Exvitermini always blurred out on his head in his pictures. So you say its main point is for MORE coolant? My understanding was that the path coolant takes through the stock water tubes allows it to be heated too much by the time it gets to the rear cyls becoming a factor in why the rear cyls lean out. So going by what you say, i would basically add extra paths to push more coolant through. The other option which i was kinda trying to get off in my post was to completely replace the stock coolant pipe and run 3 seperate lines that maybe Y right off the small extension coming from the thermo area. If you could find one of those threads i would appreciate it, i've had a pretty hard time trying to find anything. I even emailed sydneykid, but I asked him several questions and he answered some and didn't even say anything about the gt cooling mod.

[eh?]

[klh6686]

I've seen that picture as well as several others... i'm trying to find a more in depth description of the actual mod. Thanks though

[Carl H]

honestly for a road going car its not worth the time money or effort and is geared twards cars that are gonna be on the track for extended periods of time or generating HUGE ammounts of hp...

[CursedGTR]

The purpose of the GT Head cooling mod as I understood it when I did it was to allow for expansion when the coolant heats up and helps to prevent cavitation in the coolant. However, I am on a government computer in Iraq right now so I do not know how long I even have to write all the little details I can remember about it. I will just get to it and tell you what I did and you can decide if you want to do it later.

I removed the top of the intake manifold and tapped the airholes leading into the intake runners. I then put some threaded 1/4 NPT Plugs in them.

After That, I drilled the 3 water holes and widened the hole all the way into the small water chamber I then tapped it and put 3 X 1/4 NPT to -8AN fitting into the manifold. After that it was pretty much done. Alot of people like to weld this mod in but I decided to go a different route in case something stripped out or something.

When I get back from here I will make a coolant swirl post with 3 inlets for the outlets on the intake manifold and an outlet going back to the cooling hose on the radiator hose I will of course post up pictures when I am done but that is a ways away at this point. I may have put the how to up on zeroyon.com because I know alot of guys personally on that site and tend to post there alot more.