Building the Ultimate Turbo Small Block Chevy Part 2, The Making of 1100 Hp!


The All Pro heads have super big 2.20″ intake valves and huge 1.65″ exhaust valves.  How do you control the valve motion of such big and heavy valves at high RPM?  Simple enough, the valves are made by Xceldyne Technologies out of titanium. Titanium likes to gall other metals so these valves have a Titanium Aluminum Nitride coating applied to the stems to prevent galling.  Titanium valve tips also tend to mushroom. To prevent this the valve tips have a hard cermit tip coating.  F1 trick technology here! Since titanium has poor thermal conductivity, copper valve seats are used to remove heat from the valves.  The seats are blended to the ports and have a multi angle valve job.  The soft copper seats need leaded race fuel to survive.
Jesel roller rockers are used.  Fulcrum pivoting rocker arms are the most problematic part of any pushrod OHC engine but having shaft mounted, low friction roller rockers fixes this.  No wrong motion is even possible. The intake rocker ratio is 1.6:1 but the exhaust ratio is a more radical 1.7:1 which effectively increases the area under the lift curve on the exhaust side.  This increases blowdown which helps spool the turbos faster.
Here is one of the main reasons why the port geometry can be improved and such large valves can be run.  Look at the offset on the intake rocker arm!  The intake rocker is offset 0.650″ to get the pushrod out of the way of the intake port and to make room for the bigger than Big Block valves! What a cool trick to modernize the old dog!
You can see the extreme intake rocker offset here as well as the steep intake pushrod angularity.  Note how the pushrods extend out into the rocker cover rails.
To help reduce the pushrod angularity the Brian Crower roller intake lifter has had its pushrod cup offset by 0.160″ to the side as you can see here.
The WPC treated Brian Crower valve springs are topped with Brian Crower titanium retainers to reduce weight.  The engine’s valvetrain is beautiful to look at.

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