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Head coolant q's

jerryc

jerryc

Active member
Joined
Jun 10, 2004
Location
SF Bay area
I'm prepping a head and turbo to swap into my 93 940T. Head is a 530.
I'm doing minor port touch-ups re: stealthfti's site, lips here and there, using touch to try to get them all the same. I ground down the intake guides also. You don't need those, right? :-P

In looking at the head and at many pics of heads, and some discussion of cooling passages, and that some have said that no.3 cyl runs lean/hot, I was thinking about the holes in the block and hg that do not have matching holes in the head. IOW, the GrpA mod.

I note that the cyls have different coolant passages near them.
No1 has two, 180 apart.
No2 and 3 have two, towards the intake valve
No4 has 3, two at the intake end, one at the exh end.
Hmm; I thought I knew where the pics were of the GrpA mod were, with 6mm and 4mm holes drilled along the cyls and at the back of the head; now I can't find them. Well anyway, I was thinking this was probably a good idea, esp at cyl3.
Comments? And links to pics?
 
So these are what I'm talking about, at the rear. I don't know what head that is, it has small round passages rather than small teardrop ones along the sides, but it seems to have all the holes drilled.

http://forums.turbobricks.com/showpost.php?p=3400016&postcount=37

And later I found more info but no recommendations. Some have thought of it the way I am, though.

"<i>by "group A holes" do you mean the 6mm holes in the back of the head and the 4mm holes along the exhaust side, to take advantage of the holes that are already in the head gasket?</i>"
http://www.forums.turbobricks.com/showpost.php?p=1540513&postcount=15

<i>"I concluded that the GrpA holes were useful as far as assisting in getting some cooler coolant up under #1, #2, and #3 exhaust port structures in the head [#4 already has it]; and that the 2 added holes behind #4 bore would also assist in getting the flow up into the very rear of the head.

BUT, I had some reservations about adding those holes because of what I concluded about the flow through the head.
The flow is intended to go rearward in the block; then rise up into the head at #4 and then come forward to the thermostat housing. [that is the general desired flow path] The passages that let coolant up into the head at #1, #2, and #3 are there to mix in some cooler coolant to the already heated coolant that has gone all the way to #4 and is coming forward...to even out the temp of the coolant; to try to get and keep all four combustion chamber structures at the same temperature.</i>" Stealthfti
http://www.forums.turbobricks.com/showpost.php?p=1541747&postcount=25

Hmm.
 
I remember seeing some details on this much more recently but my googlefoo is weak and I cant find it.

Anyone have teh exact details?
 
Have you thought about using an electric pump only to try and improve coolant flow before drilling into the head and having the interruption of coolant flow like some believe? You'd then remove the draw on the engine from the pump as well.

Just realised you revived a dead post, whoops.
 
Na that not the one. There is mention of it there but there was more detailed post from a Swedish guy.

Electric pumps are race engine only as they just dont last
 
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