I use the following types of heads

Look over the flow numbers very carefully.

Compare the flow at the lift matching your camshaft.

Some heads flow more at .500" compared to another head, but may flow less at .600"

DO NOT choose a head with larger ports than you need.

Horsepower is a function of RPM.
As such big horsepower numbers require high port flow.
If you are building torque for a street performance vehicle using overly large ports will result in reduced torque, poor acceleration.
This is because airflow through the port will be slower than desired.
The engine will come alive above 3500rpm, but if you are not revving it pass 6000 you will not realize the full potential of the ports.
Using a larger port works best with long duration and high lift camshaft and the use of a high speed torque converter.

Typically 180cc is considered as large as you would want for the average high performance street engine below 390cid.
A 400 to 420cid may work well with 200cc.
However aluminums heads such as the Air Flow Research street performance, Canfield and TrickFlow Twist Wedge heads all work very well with 195cc ports.
This is consider the result of more effective port design.
You will notice a larger port does not necessarily flow more.

While I do not attempt to favor one head manufacture of another,
AFR heads are consider by many to best the best performing overall.
They cost just a little more and until they get the new production shop up and running at full capacity, a set of Chevrolet heads must be order anywhere from 6 to 10 weeks in advance.

Flowing is a long list of heads you can compare. Look very carefully at the numbers and comments.
I will be more than glad to help you choice a pair of heads for your engine.

When trying to choose between an iron or aluminum head, consider the fact that aluminum dissipates head more quickly than iron. Retaining heat in the combustion chamber produces more power.
As a result the compress ratio needs to be high in an aluminum head to produce the same power output as an iron heads.
However, an aluminum head will allow you to raise the compression more than just the compensation requirement before pre-ignition or detonation (pinging) becomes a problem.
The result is additional horsepower and torque.

Maximum compression rations will vary due to attitude, octane rating of premium gasoline where you live, the camshaft duration and final drive ratio.
Building a motor with too high of a compression ratio will result in pinging which prevents further power increase and will over time pound out rod bearings and break ring lands. In extreme situation you may pound a hole through the top of the piston.
Running a compression ration .2 to .4 below the maximum recommended compression ratio for your application will only cost you 5 to 10 horsepower, but buy to a much longer running engine.

In studying head flow numbers keep in mind that they are only a guide. High flow numbers don't always equal more horsepower, and more horsepower doesn't always equal faster acceleration. It can be frustrating to choose the best head and the best camshaft for an application. So many choose, and all manufacturers cliam their product is the best. Dyno or track testing is the only real way to know for sure, but who can afford to do all that testing. I look to my experience the experiences of other engine builders, and magazine test articles to help, but that's all they are a help, until the engine is run, we all have to wait and see.

One last note. If you must pass a smog check your choices will be limited.
Some Edelbrock and TrickFlow heads are 50 State legal, carrying a CARB number.

Over the last few years coatings have become increasing popular. this is due to the fact that a coating can reflect heat back into the expanding gases during the power stroke.
This not only produces more power but will allow a higher compression ratio before detonation occurs.
Coating a piston cost about $20 to $25 each, but for the full effect to be realize you should also coat the combustion chamber and valves.
As a result of these added cost, this process is considered a premium for engine builds with a higher budget.

I can supply Mahle pistons for some applications (350s and 383s and some Ford engines) for about $550.

These pistons are very strong forging, come fully coated, are some of the lightest weight pistons available and have come unique narrow rings for less drag and more horsepower included in the purchase.
Ask for details.

The following is a reprint fro Chevy High Performance Magazine.

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Intake Port cc & CFM @. 500" Lift

Chevrolet  Production 441 Iron Head  155/201

The 882 head may have out-flowed this head but with the addition of larger 2.02-inch intake valves and some decent pocket port work these heads will out flow the 882’s. Keep in mind that with a small 155cc port volume these heads are great for making torque.

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Chevrolet  Production Iron 882 Head  151/205

  This head had the smallest port size of all the heads we tested. A set of 2.02/1.60-inch valves can be swapped in but be aware that without blending in the short side radius, the results usually find lost airflow.

This head was a small chamber head used on 327ci motors until the end of 1968. The flow can be improved a little with larger valves and port work but the additional cost of this is impractical in comparison to what you can by some other aftermarket casting for.

This head can be seen as a sleeper when compared to other GM production heads. It outflows the LT-1 aluminum Corvette head on the intake side, plus its mid lift numbers are very impressive. This head is perfect when iron heads are required. GM designed this head and put it on trucks as well as on the later Impala SS but with a different intake bolt pattern. As for production pieces these are one of our favorites.

Chevrolet  Production L98 TPI Aluminum Head  163/196

This aluminum head was used on the Corvette TPI engines from the mid-Eighties until the LT-1 1992 motors were introduced. The 882-iron head out-flowed this head across the board. This piece is not our first choice for a performance head considering that the largest valve this head fits is a 2.00/1.55-inch combination and it has a 58cc chamber.

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Chevrolet Production GM LT1 372 Aluminum Head  170/214

The LT-1 head was the next generation head developed for the small blocks after the L98 head. This head uses a reverse-cooling system, which means it can not be swapped onto older blocks. The 0.400-inch airflow numbers are great and with some port work, the addition of 2.00/1.55-inch valves can really wake these heads up.

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Chevrolet Production LT4 Aluminum Head   195/250

The LT-4 is substantially different from the LT-1 casting, and the flow numbers explain why. The larger intake ports are definitely a contributing factor. For a production head these babies put up some pretty good flow numbers. Remember, like the LT-1 the LT-4 can only be used on a reverse cooling system block.

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Chevrolet LS1 Aluminum Head  204/240

GM won’t be left out of category 3 with these heads. This head has great 0.400-inch lift numbers as well as a good E/I ratio. They also feature a more flat valve angle (15 degrees) in order to promote a better combustion chamber that’s shaped like a kidney to help direct combustion and reduce possible detonation. Remember that this head will not interchange with pre-‘93 small-block heads.

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AirFlow Research 180 Aluminum Head  181/250  

This head is the smallest of AFR’s line. It is intended for engines up to 350ci. The flow numbers are especially impressive on the exhaust side of this head, leading us to believe that a single pattern cam may be the best choice here. The E/I relationship is outstanding with and 84%, almost higher than any other head in this category.

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AirFlow Research 190 Aluminum Head  191/262

This head has the best flow numbers of all the category 2 heads. Offering great flow throughout the entire lift range you can see this head doesn’t just put up one big number at maximum lift. If you’re looking for great flow from a mid-sized cylinder head this is definitely one of the top contenders.

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AirFlow Research 210 Aluminum Head  215/271

 

Here is an extraordinary head. It has larger intake ports but with 240cfm at 0.400-inches of lift who cares? The E/I ratio is an incredible 75% making it hard to find anything wrong with these heads. This head may be a little much for a mouse motor but it is perfect for a big mouse somewhere in the 383 inch range up.

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