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Engine - New 18:1™ 6.5L Longblock Side Mount Turbo Truck
Engine - New 18:1™ 6.5L Longblock Side Mount Turbo Truck

Engine - New 18:1™ 6.5L Longblock Side Mount Turbo Truck

Your Price: $8,933.23
Custom Engine Build Order
  • Condition:New
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New 18:1™ 6.5L Longblock Side Mount Turbo Truck

You've likely heard or read of 18:1™ 6.5L engines compared to standard compression and the various values this change can provide to the performance ability and durability.

Offered on this website is a configuration that Unique Diesel provides that is a completely new engine based on the Optimizer ™ platform. Our new 18:1™ engine uses new production current components (block, heads, parts) and is far superior to any used GM rebuild or Aftermarket Asian parts crafted configuration. This version of our engine can replace virtually all 6.5L side-mount turbo applications used in 1992-2002 models ranging from trucks, Suburbans, Blazers, Tahoes and more. This is the truck-style engine (Non-center mount turbo setup).

About 18:1™ 6.5L Engines

This technology was developed by Peninsular in the 80's as a means to add survive ability for 6.2L engines used in constantly loaded marine propulsion service. At the time this was 19:1, without this modification the standard engine would fail with short hours catastrophically. When the 6.5L engine was introduced in the 1990's a similar modification was made and changed to 18:1™ as this was the best option for the performance levels during work that was desired while maintaining adequate cold starting performance. Today, Unique Diesel owns this technology as we acquired Peninsular's technology for our own continued use. Unique Diesel holds the most real-world applied testing and knowledge of this specific 18:1™ process.

18:1™ 6.5L Engine Pro & Con

Before you decide that this is the engine you need take some time to consider some details discussed here. We've seen a lot of discussion about any towing use or work with a 6.5 engine people recommending that they need an 18:1™ engine. The reality is that's not true, the 6.5L engine is a durable engine on it's own when used properly and kept cool. If you intend to use near stock truck fueling levels and stay with the rated towing limits of the vehicle a standard compression 6.5L will service well with supporting cooling modifications. If you intend to have a 235 flywheel HP on up 6.5L engine that will be worked (towing constantly, or 250 on up) this is where an 18:1™ engine could be considered. This configuration of the 18:1™ engine offered here is capable of supporting worth of 300 flywheel HP reliable engine configuration.

18:1™ Positives
18:1™ Negatives

Supports 240-300 HP Reliable Service
Larger Combustion Area
Capable of handing more Turbo and Fuel duration
Increased Durability
Handles higher working RPM range
More efficient with less pumping loss


Harder to Start or start cleanly
More starting white smoke cold
Overall the engine is somewhat louder
MFI engines need glow timer or manual glow
EFI engine must have glow programming changed
Lower performance when used with stock fueling/boost.

This Engine's Specifications:

  • 18:1™ Compression Ratio - Low Compression Performance Engine.
  • Engine Longblock Assembly (engine, timing cover, balancer, covers, pan, lift brackets, as pictured)
  • Forged Steel Crankshaft (upgraded for performance capability)
  • Diamond Pre-Cup Heads @ 90 Degree Intake Bolt Angle (Trucks & Suv)
  • Mechanical Injection or Electronic Injection capable
  • Block Heater Element (120 volt)
  • Oil Filter (filter and filter fitting)
  • Filled with 15w40 Break-In Oil.
Engine features all metric fasteners, so if replacing a Pre-1999 model Engine, please inquire after purchase about a metric fastener kit after purchase necessary for replacing your existing engine (will need to know year/make/model).
Approximately $95 shipped.

Customization, Options and Changes

This 18:1™ longblock offered on this page is not customizable, this represents an engine configuration package that suits the needs of most seeking this type of 6.5L engine. For a custom performance engine, please see our Custom Performance engine and select the available options there.

If unit is being shipped via Air Freight the engine must be free of oil, new engines come with break-in oil in the pan for leak-check and priming, so engine must be drained of oil and a new filter installed (that is dry).

Payment and Shipping

This item is available for purchase via traditional payments only (no cards please). During checkout you'll be presented with an option to "Check / MO / ACH / Wire / CC" where you will have a blank to specify how you would like to manually pay, example Wire for Wire Payment. After checkout you will be emailed banking information for the Wire if that's what you selected. You will have 1 week to remit payment for Cash Value payment. .

Select the shipping option that meets your need. Items with shipping amounts are for Continental USA shipments only. Flat rate shipping is provided as courtesy and we cannot provide alternative shipping estimates, please select an option provided. Shipments to Non-Continental USA States and International ship via Cargo or Air Freight. Shipping estimates for Air and Cargo can be provided prior to order, but please provide complete address an delivery type, we will use that estimate with your order invoiced separately.

Ordering to Ship timing...

If the website shows "Custom Engine Build Order" that means that the necessary components to build your engine are not available in stock and a standard 7-week ship time applies. It is not common for complete engines to be available, so please always depend on this engine taking 7-weeks to be prepared before shipping. If unit is in stock, a 1-week prepare time is necessary before shipping.

Optional Core Engine Return Process

Core engines left in the field create a negative environmental impact. Unique Diesel requests that core engine be returned for proper recycling both usable and damaged components. This optional core return service provide a $500 voucher towards the core return. Here is how that works. Package the old complete core long block engine in the packaging that the new engine came with, and notify us that the core is ready for pickup. We will schedule truck freight to retrieve engine core engine. Once crate is here we will evaluate core briefly to determine it is a whole core from single engine and issue a credit. The credit will be the offered price less the actual freight shipping costs here. This service available to USA Domestic shipments only.

Note: Residential lift-gate service is not available for core service, the nearest freight terminal will given for you to drop-off.