Serious engine builders have for many years used every aspect of engine dynamics to harness more power. As we talked about oiling modifications to the block to free-up more HP and when combined with Synthetic oils even more can be realized.
Now we will look at block pressure build-up from the resultant blow by of spent gases that by-passed the rings. This block pressure will sometimes exceed atmospheric pressure and you have pressure build-up on the wrong end of the engine. This also has a negative effect on the engines performance.
If uncontrolled, this block pressure will back track to the ring pack during the intake event. When Vacuum is present in the chamber and you have high pressure below it at the rings, This will contaminate the fresh incoming mixture and a loss of power will result. Also all this gases will contaminate and break down the oils ability to lubricate and protect the engine.
DRAFT TUBE VENTILATION:
Used in the early 50′s automobiles, It is usually located in a low pressure area of the undercarriage. This will create a negtative pressure (suction) effect and pull crankcase pressure out of the block. marginally effective and you need speed for it to function properly.
PCV VALVE AND CLOSED AIR FILTER SYSTEM:
Works good at idle and part throttle cruising mode, inadequate at full speed and usually pulls all this blow-by gases back into the intake manifold ! Works great on stock engines, no business in a race application.
OPEN BREATHERS:
Every High Performance engine has one in the valve cover area.
Works but not effective enough and more like a chimney when there is pressure, it will exit the gases here. Some breathers are installed on the block or sometimes on the highest part of the engine. Best location is in the front of the engine where the high speed of the incoming air hopefully can pull crankcase gases out.
PAN EVACUATION SYSTEM:
The block is sealed in the crankcase and a tube runs from the block/valve covers and is connected to the headers via the collector area. A one way valve is used between this to keep back-fires from going up to the crankcase and creating an explosion from the combustible gases present inside the block, also exhaust pressure back flow can go this opposite way and pressurises the block.
Effective when not used with a muffler, I have seen attempts by Racers to connect a Venturi tube after the collector, or in conjunction with a muffler but this will be only marginally effective.
VACUUM PUMPS:
Now we are getting serious here. An external pump is used or at the beginning we were using SMOG PUMPS that we modified to create vacuum inside the block.
There were power gains as long as we are around 11 inches of vacuum. Any more will dry up the rings and cylinder bores. Lifters will also be affected so be cautious here.
DRY SUMP OILING SYSTEMS:
Usually has several pressure stages to feed pressurized oil to the block, also has 1 stage to evacuate the crankcase oils from the block. This results on a vaccuum being drawn out at the block.
MODIFICATIONS TO THE BLOCK FOR POWER:
IT IS VERY IMPORTANT THAT YOUR SECOND RING GAP BE OPENED UP TO FACILITATE THE RAPID EXPULSION OF GASES TRAP BETWEEN THE TOP AND SECOND RINGS….
A LOW TENSION OIL RING AND RING PACKAGE IS ALSO VERY IMPORTANT!
THIS WILL CUT DOWN ON THE ROTATIONAL FRICTION PRODUCED BY THE RINGS,HENCE MORE POWER. Be careful when you use “low tension” ring packages when you dont evacuate the block !
Oil consumption may result and smoke can be obvious at the mufflers….
A LOT OF BUILDERS WILL SAY THAT THEY HAVE NOT SEEN A POWER INCREASE WHEN THEY CREATED A VACUUM INSIDE THE BLOCK ! CHECK YOUR RING GAPS AND YOU WILL SEE RESULTS!!!
WHEN THIS IS PROPERLY ENGINEERED THE ENGINE WILL SEE UPWARDS OF 40+ HORSEPOWER ON A V-8 RACING ENGINE.
THIS IS DUE TO THE REDUCTION OF RESIDUAL GASES THAT WAS TRAPPED BETWEEN THE FIRST AND SECOND RINGS THAT WILL BE ” REINTRODUCED” BACK INTO THE COMBUSTION CHAMBERS DURING THE INTAKE EVENT.THIS RESIDUAL GASES ARE LEFTOVER BLOWBY GASES UNDER HIGH PRESSURE FROM THE LAST EXHAUST EVENT…
MOTORCYCLE RACERS:
If you have access to an old pipe, drill a small hole into the pipe where the cylinders meet and connect a vacuum gauge, carefull placement of this hole will yield a vacuum reading at full throttle! And this is where you want to connect back to your block. Make sure to use a 1 way smog pump check valve between this two! DO NOT attempt this on a 2 stroke engine….
If you are running with no mufflers this area is most effective at the collector of the headers where you can put a tube that protudes into the middle of the collector, this is the same for the cars….
BEN ALAMEDA, BENALAMEDARACING.COM
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