UnderCover Porting of Cylinder Heads

Hidden Horsepower "UnderCover Porting" to Cast Iron & Aluminum Cylinder Heads

Looking for additional horsepower and a stock looking port?

“UnderCover Porting” will get you there.

At 6000 rpm, "UnderCover Porting" produced 27 additional horsepower.

TEST ENGINE: 355, flat top pistons, flat tappet cam, headers 10.5 to 1 compression ratio and 500 Holley 2 barrel carb. NOTE: The intake manifolds and heads were the only components changed.

Acid Intake UnderCover dyno

While retaining a stock looking port, “UnderCover Porting” will add 15 to 30 horsepower to your engine combination. We achieve this remarkable improvement by researching each particular head to learn which areas need to be modified to gain the most air flow yet keep the ports looking stock. Since all the porting work is “covered up” and a wide bottom angle is maintained below the valve seat, “UnderCover Porting” is very difficult to detect, even if the heads are pulled off. The intake port volume is increased just a few cc’s.

View the flow charts comparing stock vs. "UnderCover" Ported heads.

“UnderCover Porting” includes:

  • Intake ports modified
  • Exhaust ports modified
  • Chambers modified in some cases
  • Modifications are “covered up”
  • Heads are pressure tested
  • A flow bench developed valve job is performed to heads on a Serdi or Rotter machine
    NOTE: The valve job is not “rolled” into the port
    A very distinct sharp edge remains under the valve seat

Yes, we can work on your bare or complete cylinder heads.


If you want even more horsepower read about our acid porting services.


Free Custom Camshaft: Now, with your purchase of a complete set of modified heads and a matching, modified intake, we will supply a custom ground flat tappet camshaft designed specifically for your application. The custom flat tappet camshaft will cost you nothing!


Cylinder Head Design Form: Fill out our online form for a recommendation and pricing on a set of heads built specifically for your application. Also, here is a link to more detailed information on our Complete Cylinder Head Assemlies.


Brzezinski Racing Products, Inc. The #1 Name in Cast Iron. Call us toll free at 866-236-6300


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