Group A Head

I

IJ.

Grumpy Old Man
Mar 30, 2005
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AcIdBuRn02ZTS;1513388 said:
I know you dont port match an exhaust side... only the intake side... I kinda figured it was common knowledge...

You do want a slightly smaller exhaust port then the manifold/header has... but since no one mentioned that to the op... I can understand your disprovement (if there is such a word):icon_razz

-AcId-
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Spec-DMK3;1513241 said:
port and polish your head.. you could go as far as match porting at home in you garage but any further than that and id prolly trust that to your local matchine shop but do your reasurch dont just take your head anywere.
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^^ Does he mention only matching the intake?

It's common knowledge if you know, the potential for the OP to buy what might have been an rare expensive head and trash it's performance is there if he just blindly followed this guys "suggestion"

LOL'd @ your new word.
 
AcIdBuRn02ZTS

AcIdBuRn02ZTS

New Member
Mar 3, 2009
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No he doesnt... but he did say his own head... so he would have trashed a stocker... but besides that.. thats why I said I understand what you where saying... However I sure do hope that a person getting ready to do ANY kind of head work on their own would research it quite a bit more then one person saying "port match it"... know what i mean?

I completely agree with you

I'm curious... I thought Group A heads had larger valves.... this one says it doesnt...? I thought they had larger titanium valves....
-AcId-
 
I

IJ.

Grumpy Old Man
Mar 30, 2005
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AcIdBuRn02ZTS;1513390 said:
No he doesnt... but he did say his own head... so he would have trashed a stocker... but besides that.. thats why I said I understand what you where saying... However I sure do hope that a person getting ready to do ANY kind of head work on their own would research it quite a bit more then one person saying "port match it"... know what i mean?

I completely agree with you

I'm curious... I thought Group A heads had larger valves.... this one says it doesnt...?
-AcId-
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Can hope all you like experience here has shown me that isn't always the case ;)

Never seen bigger valves mentioned only better material but that doesn't mean they aren't bigger, never had one here to check for myself,
 
I

IJ.

Grumpy Old Man
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And this one is a little different again, looks deeper?
(might just be camera angle though)

trdhead_2.jpg
 
AcIdBuRn02ZTS

AcIdBuRn02ZTS

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IJ.;1513399 said:
And this one is a little different again, looks deeper?
(might just be camera angle though)

trdhead_2.jpg
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Hmm... if the heads are done by hand instead of something consistant... it could explain the differences in combustion chamber shape... and although the valves are different... both appear to be different then stock... the ones in the ebay add dont appear to be oem valves
 
GC89

GC89

1J-THIS
Jun 13, 2007
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My question is what do you plan to do with the car. The combustion chamber design of the Group A heads is great for peak power and flow but I would expect it to fall on its face below that. No turbulance or swirl design = poor mix and power at part throttle and off boost. Just my .02 and all in theory
 
1988ma70supra

1988ma70supra

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I plan to put it on a built block with the following:

1- Forged weisco pistons with coated skirts .20 over
2- Eagle rods
3- ALL clevett bearings
4- BRAND NEW OIL PUMP With extended pick up tube for better oil pressure!!
5- -8 AN fittings/steel braided line feeding the oil pump!
6- Crank scraper !!
7- All arp hardware
8- Polished/balanced crank
9- Block was decked, hot tanked, line honed, new freeze plugs.

This is going to be my semi daily driver. I'm planning on increasing the boost on it and I'm using an upgraded turbo on the car (60-1 TO4E) with 550cc injectors. I'm shooting for about 500rwhp with supporting mods. So are you saying this head then designed for high revving? Is it worth buying? Does anyone know if I will have to make any modifications to put it on my block? I'm planning on using my stock turbo cams, will they fit on this head?
 
gofastgeorge

gofastgeorge

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Jan 24, 2008
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GC89;1513472 said:
My question is what do you plan to do with the car. The combustion chamber design of the Group A heads is great for peak power and flow but I would expect it to fall on its face below that. No turbulance or swirl design = poor mix and power at part throttle and off boost. Just my .02 and all in theory
Click to expand...

Hmm, that theory doesn't stand up to modern 4-valve automotive design, such as the 2JZ, RB, and SR chambers,
all of which look the same, and perform quite well.
More like that head has been brought up into modern spec.s, and out of the stone age.

RB26:
sm_photo_missing.jpg


2JZ:
sm_photo_missing.jpg


SR20:
sm_photo_missing.jpg
 
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89nasupra

Sugar, Water, Purple
Apr 8, 2008
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ok on port matching, lets say some one didn't research and just for a grinding wheel after the ports on the head then finds out later that was not a good idea and may have actully hurt performance. could that person just open the ports on the exhaust manifold to make it like factory but just bigger?
 
GC89

GC89

1J-THIS
Jun 13, 2007
938
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gofastgeorge;1513551 said:
Hmm, that theory doesn't stand up to modern 4-valve automotive design, such as the 2JZ, RB, and SR chambers,
all of which look the same, and perform quite well.
More like that head has been brought up into modern spec.s, and out of the stone age.
Click to expand...

Touche!
All Good points, I would still guess that there are still design features within those heads to incorporate some turbulence at lower flow rates besides the actual cc, but then again maybe not. Not like I was on the engineering team. I would still argue that overdoing headwork on a dd will cause its overall performance to suffer, and a Group A head was definitely not designed to operate in normal driving conditions. Now for a track car I would jump all over that thing.


89nasupra;1514263 said:
ok on port matching, lets say some one didn't research and just for a grinding wheel after the ports on the head then finds out later that was not a good idea and may have actully hurt performance. could that person just open the ports on the exhaust manifold to make it like factory but just bigger?
Click to expand...

In theory yes the exhaust dam effect could be restored but the amount of overlap would need to be correctly sized and there is a possibility it would affect the torque output and curve depending on what was done to the ports. For every action there is a reaction and its still true here
 
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