Diff between 8445 and 6293 heads ?

[Sleeper]

Does anybody know the actual differences between the 8445 and 6293 heads besides the year?
My 87 motor has stock unported 8445 heads, and I have on my old spare carbed turbo motor some 6293 heads that are ported and polished. I'm wondering if I would be able to swap these to my 87 motor, and if any gains would be had.

Thanks
Paul

 

[b4black]

They are basically the same. There are minor casting difference. Early '6293's don't have the bridge water jackets on the ends. I don't think this is major. Stock to stock, I would go with the '8445's, but in this case I would clearly take the port and polished '6293's.

Use the search feature on the General Tech forum, and you'll see plenty of posts regarding the benefits of ported heads.

 

[Sleeper]

Thanks Rich
Are the valves and seats exactly the same ?

Paul

 

[TurboBuickSix]

Originally posted by b4black
They are basically the same. There are minor casting difference. Early '6293's don't have the bridge water jackets on the ends. I don't think this is major. Stock to stock, I would go with the '8445's, but in this case I would clearly take the port and polished '6293's.

Use the search feature on the General Tech forum, and you'll see plenty of posts regarding the benefits of ported heads.

Not to stick my nose in Rich,but I remember my machinist telling me that the bridges were very important,he mentioned headgasket failures and cracks in the castings.He said not to use them on a turbo motor and this guy has 30+ years experience so I like to tae what he says as gospel.Anyone else??

 

[turbofish38]

Dont forget the 6293 casting number was also used on the Stage 1 hi-perf heads. Maybe thats what your machinist is thinking of. I would think if the bridge is important than every head porter on the face of the earth would prefer those over the 8445's. Weren't the bolt hole threads on the 8445's metric and the 6293's standard? As far as the mounting brackets go. It's a funny thing but every time I've blown a head gasket on a turbo car with steel shim head gaskets they have blown out over that water passage but on the composition gaskets they always blow on the fire ring to the outside of the cylinder. Maybe Buick figured out that the bridge wasn't needed anymore because of the change in gasket types? Just a thought.

 

[Sleeper]

Originally posted by TurboBuickSix
Not to stick my nose in Rich,but I remember my machinist telling me that the bridges were very important,he mentioned headgasket failures and cracks in the castings.He said not to use them on a turbo motor and this guy has 30+ years experience so I like to tae what he says as gospel.Anyone else??

Hmmm
They came on the carbed turbo motor. Now I'm really confused

Paul

 

[b4black]

OK, I'm not a head expert by any stretch fo the imagination, but here what i think I know.

25518445 heads were the final casting for RWD heads (although used on some FWD). They came out in 1983. All have the bridge water jackets.
Photo guide from GNTTYPE 25518445

25506293's were supposedly from 1980-81, but I have an original '82 with them. Most do not have the bridge, but some later unit's do. Stage 1 heads were made from this casting, but most 6293's are not Stage 1.
GNTTYPE 25506293

3.8, 3.8 Turbo and 4.1 all use the same head. Casting is dependent on year, not displacement.

I think Eric's right about the metric vs standard accesory bolt holes.

So the issue really isn't the casting number, but whether or not the bridge is there. If Sleeper's 6293's have the bridge, great! If they don't, his choices are:
Keep the unported 8445 as is.
Port the 8445
Run the ported 6293's.

I guess it depends on the goals for the motor. If he's looking for a 10 sec stock block, then port the 8445 ($$$). If he's looking for something less, than I would think that the ported 6293 would make sense. Is it worth the $$$ to port the 8445's just to gain the bridge? (Again, I'm no head expert, so somebody with experience should answer that question!)

HTH

 

[TurboBuickSix]

Originally posted by turbofish38
Dont forget the 6293 casting number was also used on the Stage 1 hi-perf heads. Maybe thats what your machinist is thinking of. I would think if the bridge is important than every head porter on the face of the earth would prefer those over the 8445's. Weren't the bolt hole threads on the 8445's metric and the 6293's standard? As far as the mounting brackets go. It's a funny thing but every time I've blown a head gasket on a turbo car with steel shim head gaskets they have blown out over that water passage but on the composition gaskets they always blow on the fire ring to the outside of the cylinder. Maybe Buick figured out that the bridge wasn't needed anymore because of the change in gasket types? Just a thought.

As Rich points out below the Bridge is on all 8445's and some of the 6293's.What you said about the gasket pushing out over the water passage,that is EXACTLY what my machinist said happens.I think it might not be an issue unless you want to run high boost levels where severe detonation is possible.Here are some interesting comparisons,seems there are more differences than already mentioned.http://www.gnttype.org/techarea/pictureguides/heads/headguide.html

 

[Ttype83]

Originally posted by TurboBuickSix
What you said about the gasket pushing out over the water passage,that is EXACTLY what my machinist said happens.I think it might not be an issue unless you want to run high boost levels where severe detonation is possible.

I have the 6293 heads...Don't ask how....I had the stainless steel valves installed.
I sat my heads right beside the 8445's and you can not see any diff untill the waterjacket. I blown the HG first between 2-4 & 6 all inside. This time it's blown @ 2-4 inside and I think into the waterjacket due to exhaust coming out the rad.

Now you can have a machist weld a rod in the waterjackets to give you the same support as the 8445's and in a since they would be the same heads...JMHO & .02

Jim

 

[Sleeper]

Thanks to all.
I'm going to post this in the general tech area to see if any other info comes up.

Paul

 

[b4black]

More reading on this from the General Tech:
http://www.turbobuick.com/forums/showthread.php?s=&threadid=69444

 

[b4black]

Came accross these on ebay. '6293 heads with the bridged water passges (center, ends).

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2401235831&category=33617