Forged Billet 4340 I-Beam Con Rods, Toyota 1HDT, 1HZ-T, 1HDFT - Set of 6 matched connecting rods
Diesel Performance Parts
CRTO350B
| Article number: | EKTO350 1HD-T Engine Rebulid Kit |
| Availability: | In stock (1) |
The current in-stock engine has 0.50mm 1st Oversize pistons
Engine Kit prices may be subject to change without notice.
• The kit that is in stock has 1993 & later Standard or 0.50mm OS size pistons. Please specify size.
• The bearing sizes can be selected from the "Kit Contents" selection below with the exception of cam bearings which are only available as Std. at this time.
• If you require a different piston size or need a kit, please send a request and I will order them in for you.
Special Order Items - Please carefully read the description below prior to ordering your engine kit by writing a detailed message to RADD Cruisers.
Engine kits are typically custom prepared for each engine rebuild depending on what parts sizing you need for pistons, bearings and the other parts you need to complete your rebuild.
As availability allows, items may be subbed in or out of the kits if you would like higher performance options for your rebuild and the kit price adjusted accordingly. A common request is for the ACL Race Series bearings to be used instead of the Japanese-made Taiho bearings which are what is supplied with the kit. Taiho is an OEM supplier of engine bearings for Toyota.
--> Performance options are listed at the bottom of this description
Other items are sold as add-ons, you can select other items to place in your shopping cart, or if they do not exist on this eCom site yet please contact us directly.
The process:
The engine rebuilding process typically starts with carefully tearing the engine down and having the parts inspected and measured by your engine machinist against the factory specifications. Once the wear has been determined, the various components can be machined for the correct fitment of new parts according to the available sizes.
Fitment of the head gasket is one of the last things that takes place, and is determined by careful measurement of the piston protrusion at several points for each cylinder across all 6 cylinders. It is important for smooth running that the piston protrusions are identical between bores, or at least very, very close.
Pistons may be "topped" by your machinist to correct for very minor discrepancies in piston protrusions. Discuss this with your engine machinist, otherwise you're going to have get your rods adjusted for operating length through resizing the big end.
Pre-topped piston sets may be ordered for your kit at additional cost; these piston sets are pre-topped 0.15mm in compression height to correct for block decking that may cause interference when even the thickest head gasket is used.
Early vs Late pistons
There should be some discussion about early vs late 1HD-T pistons and the connecting rod bearing problem.
For the 1993 model year (starts 08/1992), the 1HD-T received pistons that had design changes to the dimensions of the combustion chamber. The overall volume of the combustion chamber remained unchanged, however the physical dimensions are quite different and the bowl is somewhat larger in diameter and correspondingly shallower.
Research into the con rod bearing problem has pointed to oil cavitation occurring at certain RPM ranges due to engine harmonics causing premature bearing failure. I feel that it is worthwhile that anyone who is rebuilding their 1HD-T consider upgrading their pistons to the later design as this may reduce the magnitude of the problem.
NB: It is critical, however, when this is done the appropriate later vintage injector washers are also used as these correct the injector nozzle height in the combustion chamber for the later piston design.
I do not have objective, well-researched information about early vs later engines and how the con rod bearings hold out, however my subjective response is that there appears to be a reduction in the con rod bearing problem with the later piston design.
Some engine tuners have also speculated that they feel engines using the later piston design may produce slightly more power and less smoke.
Engine Rebuild Specifications Sheet - Toyota 1HDT - Engine Australia (May 2020)
Kit Contents:
Other parts to Consider (not included in kit & available at additional cost):
ARP 2000 Head Stud Kits (26 studs)
There are two options for using ARP head studs; while the 1/2" studs are stronger, the 11mm items require no additional machine work to fit and are by far the most popular way to go.
• Drop-in fit 11mm - direct fit replacement for the stock TTY head bolts. Typically 40% greater head clamping force over the stock head bolts.
• Machine in fit 1/2" UNC Stud Kit (requires drilling & tapping the block, increasing the diameter of the bolt holes in the head).
Performance Piston Sets with Ano/Ceramic Crowns & Teflon Moly skirts - available in Std. 0.50mm & 1.00mm
Pistons are available in "Performance" versions, and can also be ordered as 0.15mm (0.006") pre-topped if you need extra clearance for your head gasket after decking the block. These have anodized and ceramic coated crowns, along with teflon/moly coated skirts. These pistons are also strutted and have Alfin inserts in the top ring grooves.
Gapless Piston Ring Sets by Total Seal (USA) - available in Std. 0.50mm & 1.00mm
Improves performance and efficiency, and reduces boost pressure induced blowby.
Total Seal Gapless second ring
High Performance Head Gasket by Cometic available in Grade 3, 5 & Grade 7.
The Gr. 7 gasket is a special item for times when there is too much piston protrusion (0.726 - 0.825 mm) in your 1HDT rebuild.
ACL Race Series Connecting Rod Bearings (6B8396H)
• Available in Undersizes: Std., 0.025mm, 0.25mm
ACL Race Series Main Bearings (7M8397H)
• Available in Undersizes: Std., 0.025mm, 0.25mm
• ACL Race series bearings are also available in sizes that permit for extra oil clearance of -0.025mm in both con rod and main bearings. These are known as the HX Series, and are special order items.
Forged Billet Connecting Rod Sets
High performance Chromoly forged connecting rods
Stainless Steel Frost/Core Plug Kit (PKETO330A)
31 piece all stainless steel plug kit
Oil Filter Cooler Adapter
to run an external oil cooler
Head Saver Shim
0.25mm gasket shim to correct for excessive piston protrusion beyond what the Gr. 5 gasket will permit. Typically this is used when there has been additional material removed from the deck of the block beyond the factory tolerance.
Front Timing Gear Inner Case assembly with oil pump installed
Front Timing Gear Outer Case assembly when wear is evident at the injection pump support & drive gear bearing
Over-length oil pressure relief valve (corrects for worn valves and bores which can generate oil pressure spikes)
Performance Intake and Exhaust Valve Sets
Performance Valve Spring Sets
Heavy Duty Hi-FLow Cooling Fan & Clutch
Testing indicates an average 4-8C drop in engine operating temperature, and a corresponding improvement in AC condenser cooling. Some testing has shown greater than 8C drops in temperature, depending on engine configuration. Available with either a 32mm or 42.5mm long adapter spacer.
Electric Water Pump conversion kit
Allows the use of an external electric water pump
An electric radiator fan must also be fitted
This product description is being actively updated as new information becomes available - November 2022
I want to run a more efficient/higher boost/higher output engine, what do I need to consider for reliability?
It's very common to want to increase the output of your 1HDT, 1HDFT or 1HZ engine - and there are a good number of considerations that must be factored in before you take on all the work of making the changes needed to do this reliably.
I will outline what I can here:
1. It's very important to 'begin with the end in mind' - everything you do depends on having a reasonable, or even a unreasonable plan, and then sticking with it to see the kind of results that you wanted. Starting without a very clear plan is a non-starter, do not do this - as the saying goes: failing to plan is planning to fail.
2. There are a many "must have" and a bunch of "nice to have" changes and updates/renewals of parts that must be made. Cutting corners will kick you back to point number 1, above, and you will fail in your plan and fail in your desired results.
3. Nothing about building a better or more efficient stock rebuild, or a higher output engine is going to be inexpensive. Do not try to do a quality rebuild on a tight budget. Do not try to cut corners to save cash or you will be disappointed and you will revisit point number 1 again.
4. The Grinch of Engine Rebuilding will curse you if you cut corners. "...then he got an idea an awful idea, the Grinch had a wonderful, awful idea!" - don't try to outsmart your engine rebuilder, the recommendations of the injection pump shop specialist, or the turbo and intercooler experts... because you cannot ultimately beat the laws of physics with ignorance and bucket loads of cash.
The basics:
Making more power, generates a lot of additional heat. Everything and anything that contributes to keeping things cool needs to be carefully considered and probably replaced with a new OEM unit or an upgraded unit.
Turbo (ditch the factory turbo) - a high quality efficient modern design aftermarket turbo that starts to build boost at relatively low RPM is generally going to be the most driveability friendly style.
Intercooler - top mount vs front mount vs air/water - top mount is clearly the most effective with relatively low complexity (PDI Australia). Not running an intercooler if you're wanting to add performance is a huge mistake - improves charge density, reduces heat input.
Intake system/Air cleaner housing/snorkel - the stock air box and intake system is ok, as are a Safari style snorkels - for stock or a bit more than stock output - but they both become increasingly restrictive as your boost and performance demands increase. An aftermarket air cleaner box with a plate style Genuine Toyota air filter element, usually from something like a 200 Series, are important (PDI Australia)
Radiator - replace it on spec with a Genuine Toyota/Aisin radiator if it's at all old or slightly questionable. Most under-performing cooling systems can be directly linked to an old internally clogged radiator and an old worn out and under-performing fan clutch (or one that someone has attempted to modify). Avoid aftermarket aluminum radiators, especially hideously expensive ones that say "...performance...".
Fan clutch - orange fan clutch (Toyota/Aisin or NPW), or a high performance high-flow aftermarket item (Engine Australia)
Radiator obstructions - the usual suspects typically have no substantial effect, such as driving lights, winches etc.
Engine bay air flow - ensure the rad support foam tape, fender aprons, other items that direct air flow are in place to prevent air recycling/recirculating
Exhaust system - 3" mandrel bent, low restriction
Transmission cooler - every Toyota Land Cruiser with an automatic transmission absolutely needs a larger transmission cooler, preferably with thermostatically controlled fan where possible
Transmission - Valve body replacement, consider a torque converter upgrade, and run synthetic fluid
Clutch & flywheel - if you have a manual transmission, you're going to need an HD or XHD clutch and freshly machined flywheel (don't forget the flywheel step - it's important).
Oil cooler -
Turbos provide more air, which means you need more fuel. Increasing the fuel delivery volume from your injection pump affects the pump's internal pressure, which affects the fuel delivery timing curve.
Injection pump - needs to be tuned specifically for the boost you desire to run in mind - a stock pump simply cannot perform as well as a performance built pump
to ACSD, or not to ACSD
Fuel injectors
- must be rebuild or serviced at time of rebuilding your engine, and by an injection pump shop/tech that actually has the tooling and expertise to rebuild these two-stage injectors (many shops say they can, not very many actually can)
- no appreciable gains when making them "larger"
Pistons - use the later design that started in with the 1993 model year, and use the correct injector washers for this vintage of piston (hint: they are 1mm thicker than the previous ones).
Piston rings - consider Total Seal gapless second ring piston ring sets to reduce piston ring blowby at higher boost levels
Engine Bearings & rod bearing replacement intervals (prevention) - use the best bearings you can get, which are almost always going to be ACL Race Series bearings.
Boring and honing
Head bolts vs head studs
Surface finish of head and block
Engine performance monitoring
EGT
Safe EGT ranges - absolutely never exceed 1250F
Boost
Oil Pressure
AFR gauge / wide band diesel oxygen sensor 20:1
Coolant temperature
Tuning / dyno tuning
Power expectations and reliability - limit to 200 RWHP / 450 lbs ft torque for reliability vs diminishing returns of going higher
Engine Oil - high quality regular dinosaur oil until break-in, and then run a high quality synthetic
Engine Oil filtration - use an Toyota or Denso/Drive Joy filter, or another brand that uses the "toilet paper roll" bypass filter section to reduce soot loading of the oil. There are several brands that have the toilet paper roll bypass section such as the Wix 10457A and the
8708.99
2022 11 15
2025 05 07 minor updates, added some links to parts pages
2026 03 03 minor updates, added parts links
