[webber]

can you show me the difference between vortex and LT1 heads and can i use LT1 heads on my vortex engines

[DoubleVision]

I think you mean Vortec. And no, LT1 heads will not interchange on to Vortec blocks or any of the classic small blocks for that matter. Why is because the LT1 is reverse cooled. While LT1 heads will bolt on the classic small blocks, none of the coolant ports line up. However you could weld the coolant ports up and drill the ones to match the older blocks but there's no reason to do so due to the time and cost involved. Lastly, Vortec heads were designed after the LT1 heads. They have the same ports and combustion chambers only difference is they are standard flow cooled.

[ap72]

Originally Posted by DoubleVision

I think you mean Vortec. And no, LT1 heads will not interchange on to Vortec blocks or any of the classic small blocks for that matter. Why is because the LT1 is reverse cooled. While LT1 heads will bolt on the classic small blocks, none of the coolant ports line up. However you could weld the coolant ports up and drill the ones to match the older blocks but there's no reason to do so due to the time and cost involved. Lastly, Vortec heads were designed after the LT1 heads. They have the same ports and combustion chambers only difference is they are standard flow cooled.

Having worked several sets of LT1 and Vortec heads I can say they do NOT have the same ports or chambers. I don't know where this idea started but its not at all truth. The "iron lt1" heads may be a copy of the Vortec's but I have not worked on any of those.

[sbchevfreak]

Originally Posted by ap72

Having worked several sets of LT1 and Vortec heads I can say they do NOT have the same ports or chambers. I don't know where this idea started but its not at all truth. The "iron lt1" heads may be a copy of the Vortec's but I have not worked on any of those.

Here is some info on the basis for the Vortec heads:

Starting in 1996 on several GM Trucks and Vans, the L31 Vortec heads came on the scene. Not just a modification of existing heads, but complete redesign using the 1996 Caprice/Impala SS LT1 cast-iron head castings as a base. The biggest change GM made in the new design was revising the water jacket so the new Vortec heads could be used on conventionally cooled small blocks. The idea of using the 1996 LT1 cast iron head as a starting point for a new performance stock head came from the fact that it was the highest flowing LT head used by GM. The 1996 Caprice/Impala heads outflowed the Corvette Aluminum LT1 heads by as much as 20 cfm on the intake side. The cast iron Vortec head was in development six months longer than the aluminum head, and during that time, GM engineers tweaked the intake and exhaust ports for additional flow. The cast iron Vortec heads was one of the first to purposely integrate tumble instead of large swirl numbers in the design.

Information from www.onedirt.com

[sbchevfreak]

Some more, from Sallee Chevrolet:

P/N 12558060 L31 350 Vortec Cylinder Heads (See options below.)


Small block Vortec heads, the head with huge performance gains that everyone is talking about.
This production Vortec iron cylinder head was first used on the 1996 pickup truck RPO L31 with fuel injection. The intake and exhaust port are very similar to Corvette 350 LT1 heads. America’s favorite high performance cast iron small block cylinder head offers big power and bigger value. The Vortec cylinder head's fast burn combustion chamber and high velocity ports combine to produce big horsepower out of the box. The Vortec head can be mildly ported for additional performance and can be milled up to .040” for increased compression ratio. This head includes 1.94” intake valves and 1.50” exhaust valves, springs and retainers, and pressed-in 3/8” studs. This head with compatible valves flows more air than bow tie head P/N 10134392, but the casting may not be as durable. It is a 20 to 40 horsepower bolt on increase over earlier cast iron small block heads. The water passages are the same as the original 1955 small block design. The eight-holt intake bolt pattern is totally different than the early model V8 12-bolt design. The Vortec head REQUIRES a Vortec style intake manifold due to its improved manifold mounting flange and gasket design and raised intake ports. It is not recommended that the heads be modified to accept early design intake manifolds (They will never match up right.). Use new manifold P/N 12366573, 12496820, 12496821, 12496822, or any others that we have listed below for correct matching to the Vortec head. Vortec heads fit all small block engines produced 1955 to present, excluding LT1/LT4 reverse coolant flow engines and current LS1 style “GEN 3” engines.

[ap72]

So simply put, there's no relation to LT1 heads other than the Vortec was developed after the iron LT1 head was?

I wish this would put an end to the "well they're the same except for the cooling" comments, but it won't.

[oldbogie]

Originally Posted by ap72

Having worked several sets of LT1 and Vortec heads I can say they do NOT have the same ports or chambers. I don't know where this idea started but its not at all truth. The "iron lt1" heads may be a copy of the Vortec's but I have not worked on any of those.

More than less an X2. While the vortec and LT1 show some general similarities in the approach to ports and chambers, the detail execution is unique to each.

The iron LT1 heads are much more similar to the Vortec, where the aluminum LT1/4's ports and chambers are more similar to those of the GMPP aluminum Fastburn head.

I don't know whether any of this reflects the limitations between casting processes for aluminum or iron; or whether the differences reflect changes to optimize combustion around the different heat transfer rates of these materials; or whether it's just the result of different performance goals. But when set side by side I agree that they are noticeably different in detail while being similar in general layout.

I always find it amazing that combustion chambers that vary slightly in detail can vary so widely in performance. It certainly speaks to the complexity of events happening in extremely short periods of time.

Bogie

[ap72]

Originally Posted by oldbogie

More than less an X2. While the vortec and LT1 show some general similarities in the approach to ports and chambers, the detail execution is unique to each.

The iron LT1 heads are much more similar to the Vortec, where the aluminum LT1/4's ports and chambers are more similar to those of the GMPP aluminum Fastburn head.

I don't know whether any of this reflects the limitations between casting processes for aluminum or iron; or whether the differences reflect changes to optimize combustion around the different heat transfer rates of these materials; or whether it's just the result of different performance goals. But when set side by side I agree that they are noticeably different in detail while being similar in general layout.

I always find it amazing that combustion chambers that vary slightly in detail can vary so widely in performance. It certainly speaks to the complexity of events happening in extremely short periods of time.

Bogie

Another comment I have is that I'm not so sure the Vortec chamber is "superior" to the lt1 design, both of them have shortcomings and both of them are pretty good but they are different. The LT1 has a distinct advantage of more material there for porting though and IMO can lead to a more optimized head from the valve out- but from the valve in the taller port of the Vortec head is better but the LT1 head has a better short turn (not that the Vortec's is bad because its rather good compared to older heads).