differences between stock head castings

[CamoDeafie]

whats the real differences between say 8445 Iron heads and the other Iron heads offered in TRs? I've searched high and low and never quite found concrete explanations as to why the 8445 heads are better than the other TR heads except for aftermarket heads....can someone explain this to me? does it have to do with flow numbers, or is it just because they're used in the SFI engines?

 

[charlief1]

At each end of the head they allowed for a bridge in the middle of the coolant passage. That makes the head more stable. It's one of the first mods that were done to the stage heads when they came out in the early 80's.

 

[CamoDeafie]

so its more about structural integrity than flow numbers? alrighty cool, now I understand why 8445s are better, structurally compared to the other stock iron castings, right?

 

[charlief1]

Basically that's it. Aj has been using them now and has had less of an issue with blowing head gaskets now. There are minor differences as to core shift ect but all the heads flow about the same stock. The 293 castings are the same number as the stage I heads but have EGR passages.

 

[bison]

Ive ran both bridged and non bridged heads. I didnt notice any difference as far as rigidity at 700hp with RJC or Cometic gaskets. They are both equally weak on the intake side of the combustion chamber. The flow numbers are very close on all of them. Still limited by the size of the spring that can easily be put on them which is not much more than a stock diameter without a lot of expensive mods. Flow doesnt mean crap if you cant rev the engine enough to take advantage of it. The heads are more spring limited in a turbocharged application than flow limited.

 

[bison]

Basically that's it. Aj has been using them now and has had less of an issue with blowing head gaskets now. There are minor differences as to core shift ect but all the heads flow about the same stock. The 293 castings are the same number as the stage I heads but have EGR passages.

Some of the production 6293's are bridged and some are not. I tore down an 83 t type engine and the heads were 6293 bridged.

 

[charlief1]

Some of the production 6293's are bridged and some are not. I tore down an 83 t type engine and the heads were 6293 bridged.

Didn't know that Brian. Thanks.

 

[dank GN]

I just pulled these from a NA block both are 293 castings and one has the bridge on doesn't

 

[earlbrown]

whats the real differences between say 8445 Iron heads and the other Iron heads offered in TRs?

8445 heads are the only head that came on TR's. (not counting the TTA of course)

 

[dank GN]

I'm done porting one of them

 

[bison]

8445 heads are the only head that came on TR's. (not counting the TTA of course)

I've torn down many turbo engines and the casting numbers are year specific not engine code specific. That statement may be true for 84 model year and later but it's incorrect for other years.


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[Mike T]

They are both equally weak on the intake side of the combustion chamber.

Every time I've lost a HG it's been on the intake side. What causes the intake side to be the weak link?

 

[turbo nasty]

Lack of a fastener first. And second is the water jacket in the head deflects as well.

 

[earlbrown]

I've torn down many turbo engines and the casting numbers are year specific not engine code specific. That statement may be true for 84 model year and later but it's incorrect for other years.

I had a feeling I'd get called out on the TR that don't count.

 

[Mike T]

Lack of a fastener first. And second is the water jacket in the head deflects as well.

You would think that the intake being bolted in place would stiffed that side up a bit but I guess not.

I've never though about this but now I'm a little intrigued. After looking at the above photos I began to wonder how much if any mechanical lifting force is applied to the intake side of the heads though valve train?

 

[bison]

Every time I've lost a HG it's been on the intake side. What causes the intake side to be the weak link?

The combustion chamber has little rigidity on that side. It deflects under the pressure. The aftermarket heads have a lot more material in those areas


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[turbofabricator]

I use to pin the decks of the stock heads to shore up the head gasket. I have posted pictures before of how it is done. Requires a good machinist to do it right. If someone needs detailed info, I can post pictures (again) and how to do it.
Now that we can run 88 lb/hr injectors and have good pumps available, I don't need to do it anymore. Fuel, octane trump the need for pinned decks. Now.......if you are running in a stock appearing class, I have lots of head mods that will help you succeed.