HPR and GSpeed team up on a 468 cid LS Road Race build - Part II
Moving forward.
In sticking with our target of building a reliable big displacement road race engine while using currently available shelf parts without going to crazy on our budget. We are sticking with a hydraulic roller camshaft and OE rocker arms and using current on the market head.
A lot of thought and planning had to be done when it came to the camshaft design. Unlike a drag engine that sees only seconds at WOT, this engine is going to see up to 40 mins at a time on track. Louis at GSpeed, Mr. Godbold at Comp Cams, and ourselves spent a good amount of time working together on choosing the correct pieces to fit within our design and budget layout. More on this later.
First off the easy stuff.
Lifters. In keeping with a 'shelf' part and affordable hyd. roller build we are choosing to use the GM COPO spec lifters made by Johnson. These are the same ones you will find in the 8000RPM factory COPO drag cars and retain the OEM lifter buckets and stock lifter dimensions. Erik has used and tested these in the past, and when used with the proper supporting hardware, prove to be a very solid lifter design.
Some of the highlights of these lifters include:
COPO lifters oiled and ready for install
Cylinder heads
GSpeed and ourselves when over a number of head designs and options out there from LS3 to LS7 style versions. For the purpose of having a solid power band through as much of the RPM range as we could, we settled in on a set of Mamo Motorsports reworked Trick Flow 260 LS7 head.
Louis at GSpeed spec'd these out with a lightweight 73 gram Titanium intake valve and equally light 85 gram stainless exhaust valve. Tony Mamo did his thing on the ports and chambers for what should be a very well flowing cylinder head (flow numbers not available at time of this writing - updated when I have them).
MMS 265 LS7 reworked TF260's
Trick Flow 260 LS7 casting
Tear down for measurements
chamber with valves installed
chamber with valves removed
intake port
Now the camshaft. Mr. Billy Godbold, the mad scientist at Comp Cams, is probably the leading authority when it comes to actual cam designs and testing valve train systems. Because we are working with an engine designed for lengthy run times on track. A very soft and stable ramp profile of Billy's was chosen along with a new finish of his own working as well on the camshaft. Just shown for the first time at SEMA this year, you will be seeing this much more in the future from Comp Cams.
"We changed our grinding wheels and dress parameters to maximize the load distribution and then wanted a light treatment just to take the fuzz off the top of the topography (like running a finishing mower across a baseball or soccer field). Many of the treatments left a dull finish, but the best one we tested included the burnishing fluid and denser media that also resulted in that more mirror like look. I just don’t want anyone to think it was supposed to be so good looking, but the best finish we developed just had that as a side effect." - Billy Godbold
COPO lifters, GM lifter trays, 4 pole cam gear, C5R timing chain, Comp Cam, and hardware
Close up of the new finish on the cam
Sliding the cam into the 468 lubed with plenty of Motul break in oil
NOTE: Like any doctor we do respect the privacy of our customers so the actual cam specs are not disclosed publicly or to other customers unless GSpeed would like to post them.
For valve springs and rocker arms. Using Billy's own data along with specs from the rest of the build we decided to use a new Comp single spring the 7230 conical. Billy has been using these in his own enduro LS running 8-12 hr races without issue. These will be finished off with a Tool Steel retainer for life, and since they are so small, there is no weight penalty compared to a larger dual spring Ti retainer.
Comp 7230 spring and Tool Steel Retainer
The master himself, our own Erik Koenig checking cam timing.
Stay tuned as we finish out assembly and completion of the long block coming up!!!
In sticking with our target of building a reliable big displacement road race engine while using currently available shelf parts without going to crazy on our budget. We are sticking with a hydraulic roller camshaft and OE rocker arms and using current on the market head.
A lot of thought and planning had to be done when it came to the camshaft design. Unlike a drag engine that sees only seconds at WOT, this engine is going to see up to 40 mins at a time on track. Louis at GSpeed, Mr. Godbold at Comp Cams, and ourselves spent a good amount of time working together on choosing the correct pieces to fit within our design and budget layout. More on this later.
First off the easy stuff.
Lifters. In keeping with a 'shelf' part and affordable hyd. roller build we are choosing to use the GM COPO spec lifters made by Johnson. These are the same ones you will find in the 8000RPM factory COPO drag cars and retain the OEM lifter buckets and stock lifter dimensions. Erik has used and tested these in the past, and when used with the proper supporting hardware, prove to be a very solid lifter design.
Some of the highlights of these lifters include:
- Heat treated forged steel body
- high flow disc style check valve for better reaction at high RPM
- improved internal oil metering to supply rocker arms and valve springs without loss in oil pressure
- needle roller bearing with high chrome steel axle
- controlled slow leak down piston
COPO lifters oiled and ready for install
Cylinder heads
GSpeed and ourselves when over a number of head designs and options out there from LS3 to LS7 style versions. For the purpose of having a solid power band through as much of the RPM range as we could, we settled in on a set of Mamo Motorsports reworked Trick Flow 260 LS7 head.
Louis at GSpeed spec'd these out with a lightweight 73 gram Titanium intake valve and equally light 85 gram stainless exhaust valve. Tony Mamo did his thing on the ports and chambers for what should be a very well flowing cylinder head (flow numbers not available at time of this writing - updated when I have them).
MMS 265 LS7 reworked TF260's
Trick Flow 260 LS7 casting
Tear down for measurements
chamber with valves installed
chamber with valves removed
intake port
Now the camshaft. Mr. Billy Godbold, the mad scientist at Comp Cams, is probably the leading authority when it comes to actual cam designs and testing valve train systems. Because we are working with an engine designed for lengthy run times on track. A very soft and stable ramp profile of Billy's was chosen along with a new finish of his own working as well on the camshaft. Just shown for the first time at SEMA this year, you will be seeing this much more in the future from Comp Cams.
"We changed our grinding wheels and dress parameters to maximize the load distribution and then wanted a light treatment just to take the fuzz off the top of the topography (like running a finishing mower across a baseball or soccer field). Many of the treatments left a dull finish, but the best one we tested included the burnishing fluid and denser media that also resulted in that more mirror like look. I just don’t want anyone to think it was supposed to be so good looking, but the best finish we developed just had that as a side effect." - Billy Godbold
COPO lifters, GM lifter trays, 4 pole cam gear, C5R timing chain, Comp Cam, and hardware
Close up of the new finish on the cam
Sliding the cam into the 468 lubed with plenty of Motul break in oil
NOTE: Like any doctor we do respect the privacy of our customers so the actual cam specs are not disclosed publicly or to other customers unless GSpeed would like to post them.
For valve springs and rocker arms. Using Billy's own data along with specs from the rest of the build we decided to use a new Comp single spring the 7230 conical. Billy has been using these in his own enduro LS running 8-12 hr races without issue. These will be finished off with a Tool Steel retainer for life, and since they are so small, there is no weight penalty compared to a larger dual spring Ti retainer.
Comp 7230 spring and Tool Steel Retainer
The master himself, our own Erik Koenig checking cam timing.
Stay tuned as we finish out assembly and completion of the long block coming up!!!