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Extreme A12 Head mods
Just can't stay away
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2015/10/19 0:47
From Lyngby, Denmark
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Hello guys

I had a A12 head ported but the galleries was hit, and the head is now basically a paper-weight... The walls are too thin for welding.

I was then thinking of just going full out, because I remember seeing a A12 head where they had machined out everything, inserted and welded in some tubes at an high angle and made it a super high port head.

Can't seem to find it anymore, but would like to know how one would go about doing so?
You can weld around the tube, but what about in the bottom?
High temp solder/brazing?
Epoxy/chemical metal? How hot does it get? Would the brazing melt?

Going to turbo it, and it's not gonna be driven lightly anyway, but I'm an engineer and will do the supporting of the surrounding conditions adequate, good cooling, ECU, ect.

Cheers, Toby

Posted on: 11/15 12:41
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Re: Extreme A12 Head mods
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I remember seeing that photo of the downported head myself and it is probably saved on on old computer. I think it was posted by Ernie "bige" who owns ATE race engines.

Would a shrink fit even be acceptable?

Posted on: 11/15 17:38
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Re: Extreme A12 Head mods
No life (a.k.a. DattoMaster)
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I remember it as well; it was quite as extreme as the Ford/Cosworth MAE where they are near vertical. I've given thought to this as wel as I have a damaged head that might be worth playing with.

Posted on: 11/16 3:41
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Re: Extreme A12 Head mods
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There are several ways to weld aluminum. Very thin aluminum can be welded
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Posted on: 11/17 23:23
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Re: Extreme A12 Head mods
No life (a.k.a. DattoMaster)
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2002/10/28 6:49
From Melbored
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japs hit the water jacket all the time intentionally
and epoxy them as the inlet doesnt need water so much
with all the fuel air at big cfm colling them down.

There is also jbweld and HTS 2000 brazing alloy rods
that work great and stronger the jb or other epoxies

https://www.youtube.com/watch?v=c_4CevueRWQ

Posted on: 11/18 1:12
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Re: Extreme A12 Head mods
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Posted on: 11/18 6:14
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Re: Extreme A12 Head mods
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Here is a downport head that I have had for a few years and have just passed it onto a friend rebuilding a 1200 coupe race car. A friend of mine, Robbie who is on here flow benched it for me when I purchased it - attached for reference

Attach file:



jpg  received_457384734847488.jpeg.jpg (184.98 KB)
16379_5dd23950787e5.jpg 1016X1920 px

jpg  received_526734601426183.jpeg.jpg (169.00 KB)
16379_5dd2396138007.jpg 1016X1920 px

Posted on: 11/18 6:27
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Re: Extreme A12 Head mods
No life (a.k.a. DattoMaster)
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Comes alive over .4
But would need a big cam and rocker ratio to use it

Posted on: 11/18 11:20
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Re: Extreme A12 Head mods
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Open in new window

Posted on: 11/19 21:08
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Re: Extreme A12 Head mods
No life (a.k.a. DattoMaster)
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Some very clever suzuki bike racing guys spent quite some moneys
to raise the port of their drag race bikes and at the end
the result was 5% gain over their usual stock ports.
However the gain was right at the top end but sacrificed torque
in the low and mid range range enough to achieve slower times.

Toyota has achieved over 40% efficiency by going back to
less angled ports and biasing the inlet flow on one side
of the inlet valve and shrouding the other as much as possible.
This allows the charge to go deeper and with less turbulence
to achieve a very efficient and uniform swirl with small bores
but long stroke setup.

The deep chambers rather than shallow seem to also be the reason
Pontiac Buick nailhead v8s are so successful in racing since the 50s.
Getting the charge to miss the bore wall as much as possible but
swirl deep all the way to the bottom of the stroke is todays practice.

small high ports and smallish valves are better for very high rpm
which is usually a pig to drive on the street. Street tuner beware.
It all depends what you need but rebuilding your engine often and
changing the oil every day you drive it to its limits is not for every1.

Stock heads and ports are pretty decent performing units for street apps.

Posted on: 11/20 10:59
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