New Splayed Main block using GEP 6.5L Diesel Engine Block
For Side Mount Turbo SMT and Non-Turbo applications.
Please
note that this product page is primarily used to display the base
engine block that has been modified to utilize splayed main caps on the
center 3 main caps. This product is best purchased as an option on a
Custom Engine build.
Well folks,
it's finally available, and long over-due but a proper solution for the
6.5L engines that crack the main webbing. This splayed block solution
provides a tremendous amount of improvement in rigidity on top of many
improvements made by AM General that greatly improved upon the GM
variants. This is the first time this has been offered for new engines.
About Splayed Mains
Splayed
main caps have long been a go-to strength improvement to allow an
engine block to produce higher power numbers. This is a widely
successful and understood modification used on performance gas engines
using cylinder blocks that are of the shallow-skirt design. Common
examples of other shallow-skirt engine designs are most of the GM
Chevrolet V-8 Gas engines like the 350 and the 454 and variants in
between. This modification either converts a 2-bolt main block to a
4-bolt main block or abandons the outside bolt holes on a block that was
already a 4-bolt main. The problem with 4-bolt main blocks is while it
creates better clamping of a main cap to a block, the placement of the
fastener threads in the block is in a weak part of the block where the
cylinder bore partially intersects the main webbing bridge. Removing
material to drill and tap for threads weakens the main web, then the
stress of the bolt being stretched and cycled in a running engine causes
stress and can eventually break the block (which is what we see in 6.2L
and 6.5L Diesel engine blocks). The splayed mains address this by using
a wider cap that enables the outside bolt hole to go beyond the weak
spot of the main webbing and places the bolt into a more solid part of
the bottom of the block where there is more material. The wider cap also
helps create more rigidity. The angled bolt hole compared to the
factory bolt that is installed straight into the bottom of the block
also helps clamp the cap in place by having alternating angles which
pull the cap outward and onto the block reducing the chance of the cap
from being able to move on the block at all (cap walk eliminated).
The
process implementation of splayed mains is not just for modifying
factory blocks, performance race engine blocks come with them from the
beginning. Even deep-skirt blocks like found on the LS-series GM engines
are starting to receive splayed mains within the railings of the deep
skirt block design in aftermarket blocks in an effort to further improve
performance handling abilities in the block.
The Process of Installing Splayed Main Caps
To begin we start out with a new 6.5L block.
The
block is loaded into a CNC engine block machine and carefully squared
up in precise fixturing. Then the number 2,3,4 main caps and fasteners
are removed from the block and discarded. The block then receives new
parallel cut registers that are much wider than the former factory cap
registers. Splayed caps are placed onto the block is their new
registers. The caps receive studs in the center mounting holes, after
being carefully aligned on the block. Once the caps are mounted to the
engine block, the fixture holding the block is rotated to accommodate
the precise angle to drill the block for angled bolts. A specific
measured depth is specified from the block floor holding the cap to
drill into the block bottom rail where there is material. The holes are
then threaded using a bottoming tap to the end of the drilled hole.
Specific numbers are used in the depth to both maintain excellent full
thread engagement for the cap fastener and leave material in the block
and keep the hole away from the water jacket, the holes retain material
for safe blind holes.
The block then receives
the hardest part of the entire process. A proper align bore has to occur
to bore the new caps to specific sizes and maintain full main alignment
and sizing between all 5 mains. The block receives all replacement
studs and bolts on every cap. Each cap is held on with studs, adding
studs to mains 1 and 5 and studs along the entire crankshaft center
line. The splayed main caps receive studs in the middle and bolts on the
outer holes. Everything is lined up and torqued. The block then
receives a full align bore on a CNC block machine ending in a precise
and repeatable housing size on each main. Factory blocks are machined by
align bore only, and we are matching that process down to the final
.0001" (ten-thousandths).
Unique Diesel is
extremely detailed in demanding exacting standards, tremendous efforts
have been accomplished to ensure that the process to create these
splayed blocks either meets or exceeds an OE standard. We want it right!
Splayed 6.5L Vs. P400 6.5L
All
things considered, we have worked with both variants. The Splayed 6.5L
can handle the same power as the rated power level of the P400 engine.
The Splayed 6.5L beats the P400 in application, availability,
support-ability. The Splayed 6.5L is the replacement for the P400.
Application...
The
Splayed 6.5L as an engine assembly can replace all 6.2 and 6.5 Diesel
engines in their original vehicle applications. The P400 can not
directly replace all variations of engines without modifications (like
custom oil pan). The P400 is really only applicable to a Humvee, and
does not readily install in civilian vehicle applications.
Availability and Support...
The
Splayed 6.5L is currently in production because the base engine used to
produce the Splayed 6.5L engine is newly available. All of the
internal parts of the Splayed and production GEP engines are readily
available and in production and many parts are supported by the
Aftermarket.
The P400 6.5L was fully
discontinued by the manufacturer back in 2023. Prior to formal
discontinuation only old stock parts were being sold as the engine was
long out of production. Currently, only new-old-stock versions exist at
great expense, and the same can be said for the proprietary replacement
parts that were discarded by the manufacturer. No support parts exist
from the original source. The P400 is obsolete and creates many support
and rebuild issues due to many proprietary components that are
unsupported even in the aftermarket.
Splayed Block Compatibility
Block is compatible with former
6.5L block and rotating assembly components. Replacement for blocks
with casting numbers ending in 6.5L Diesel casting 599, 141, 929, and
506.
This block comes bare as seen in the
pictures and only comes with the 5 expansion casting core plugs, all
other necessary block hardware items are not
installed including cam bearings. All the hardware block components are
available as a product
option hardware kit containing the necessary items. Block comes with a
light rust preservative (why cylinder bores are dirty looking), not
responsible for rust storage issues once shipped, take necessary steps
to preserve block if not being used immediately. Recommend cylinder hone
to match your specific piston usage using a torque plate.
The
block hardware kit provides all the threaded plugs, press-in plugs, oil
spray jets, dowels, and bypass valves. This is an extensive kit with
all the hard to find and hidden items.
Ordering Process
This
product is a Build to Order item whereby we will order the proper block
then perform the processes on that block. Typical processing time for
this is 12-weeks. We may have blocks already processed on-hand, but they
are only utilized for custom engine builds, ordering of this product is
considered a special order.
