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Discussion Starter · #1 ·
I deleted this thread from tech.(more chance of response here)

Last week I was taking the head off my spare N/A engine(I'm going to rebuild it for my Turbo engine).
- My first crack at the 7M head(Practice makes perfect :))
I noticed that on one side of the block the coolant galleries on the block side were half the size of the galleries on the head side, However on the other side of the block the galleries on both sides lined up.
This is also evident in the OEM head gasket, It has room for a full passage (not half) for both sides of the block.(This is the main reason I'm asking this question)

Can anyone tell me why this is? or should I just trust the Toyota engineers?

some pics -- 2 more coming
Note how the galleries on both side of each cylinder are the same size

Super Moderator
13,826 Posts
You just described the differences between the HKS and Greddy MHG's pretty well. The HKS's coolant passages match up with the head, and the Greddy's match up with the block.
Notice also that the 1/2 size passages on the intake side of the block do not fully match up to one side of the double-path pattern on the OEM and HKS gaskets, leaving 1.5 or 2mm of full gasket material blocking the path on the block.

The short answer is that yes, it works but looks wierd. Some turbulence in a coolant path is good but I do not know why they chose to use the gasket to do that.

On another note, this difference in the cooling channels is the reason the Greddy MHG is preferred my some over the HKS, as the Greddy matches up perfectly with the passages on the block.

Edit: Note: my reply was composed before pics were posted.

the clever guy
785 Posts
I'm going to guess that the passages are smaller on the intake side because well, it's the intake side and less heat needs to be drawn from that side. Lot's more heat on the exhaust side. I don't think the differences in head gasket design make a difference.

Those last two pics look familiar for some reason...:scratch:
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