Trans cooler issues 4L60, 4L65 & 4L70

Dave’s Tech Tip from Larry Cleeton,

My Hot Rod Buddy, Pierre was having issues with his brand new GM Performance 4L70e transmission and LS3 525hp crate engine this summer having shifting issues.  I had driven it locally when we went to our favorite joint for lunch, Jersey’s Mikes in Sammamish and seemed like it shifted great.  On Pierre’s return trip from Everett, he had problems once he got into stop and go traffic and at low speeds, it just wasn’t shifting right, Pierre called the local transmission guy, had them check it out and it still had problems.

Just by chance I was talking to Larry Cleeton and mentioned it and Larry not only had the same issue, but had solved the problem.  It turns out that these electronically controlled transmissions have a built in safety that locks up the torque converter when it gets too hot.  GM figures that by reducing the slippage of the torque converter (which produces heat)  it will protect the transmission from failure and get you home in more or less “limp mode.”  I had experienced the same type of issue on my LT4 engine which had a oil cooler attached to the engine sump, but was cooled by radiator fluid.  Larry said that the cooling in the front mounted engine radiator was insufficient to cool down the transmission enough to prevent lockup.

Most of the aftermarket swap radiators have an option for transmission cooling in the bottom or side of the newer style aluminum radiators.  This is a separate coil that is cooled by the radiator fluid.  As is the case with the supercharged LT4, why would I want to try and cool down hot oil or hot transmission fluid with a radiator that was at 200 degrees or more?  Most of the Gen IV and Gen V engines run at or around 200-208d before the fans kick on.  I thought that was a poor idea and plumbed in an external oil cooler in the front of the vehicle.  My thinking was why not take a clue from the off-road buggy guys that run the Baja 1000.

I’ve been looking at these compact Derale fan cooled radiators for sometime now thinking that I might want to upgrade and try them out, they also come in a single fan configuration.  I suggested this to Pierre and he jumped on it and solved the issue right away.  Here’s a few pictures for your review:

LT4 Supercharged Wrangler

The Jeep guys tell us how they like the Supercharged LT4. Different application, but you get the same results, massive instant horsepower with a docile idle. Gen V with VVT and direct injection make all the difference. Unless you get a ride in one of these conversions you don’t know what you’re missing.

’66 Suburban Red Rig


Project is a 1966 Chevy Suburban two door that started with my dad who owned it until I brought it home four years ago.  It is a complete tear down with everything from sheet metal patches to frame off rebuild.  I used a donor 1985 Blazer chassis and used the rear end and rebuilt with gears and Auburn Posi Tract, driveline to fit rear and transmission and the whole front end bolted into the existing holes on frame.
Upgraded frame with CPP ‘66 Tubular Trailing Arm kit with coil, poly mounts and cut-out frame bracket.  CPP 12” large brakes for 5 on 5 1985 disc kit with large drilled and slotted rotors.  Spaulding’s in Spokane supplied a 2017 GM 6.0 L96 Express iron block engine with 50 original miles on Express van and 6L80 trans. 150Tunes.com supplied the wiring harness and ECU.
AlumiTech radiator with built in trans cooler with Spal duel fans complements steel 26 gallon tank from Brother’s, FiTech Hy-Fuel Tight-Fit Retro electric in-tank fuel pump and filter kit. Installed AC kit from Vintage Air and rebuilt controls then relocated AC compressor with LSX Innovations LS AC Bracket Kit and stainless headers. Powerhouse Alternator and CPP’s firewall Midnight Special master cylinder.  
The interior seats from new Traverse donor from Spaulding to use second row folding passenger seat as passenger front bucket seat as it needed to fold down to cross-over to reach backseat. The third row donor seats used now as second row. The interior upgrades include a tilt chromed Ididit column, Brother’s ‘66 dash stereo with all modern features.  Dakota Digital RTX Digital instrument system tied to PowerPlus 20 wiring kit from Painless. Lokar’s tap shifter for 6L80 six speed floor shifter.  
Forrie McIntosh 425 864-9223 (Cell)

Serafin’s ’55 Chevy truck LS swap

Part 1
An ongoing series showing the steps necessary to swap an LS drivetrain into a 1955-1957 Chevy truck. 40 year old build that features a 1978 Camaro Z/28 clip welded onto the factory truck chassis.

Part 2
Prepping the drivetrain and adding the motor mounts

Part 3
Final welding of the Speedway motor mounts, plus Serafin comes by and gives us some history on the truck.

Part 4
With the help of CPP (Classic Performance Products) the 6L80e transmission finds a new home.

Part 5
Weekend update bringing viewers up to speed on everything that’s been done since part 4. We delve into the beginnings of the electrical conversion to GM’s CANBUS

Part 6a
LS2/6L80e swap harness rough-in. We lay out the swap harness from 150tunes.com in Spokane. This L76 is an Australian built Holden that Pontiac used up until their demise in 2010.

Part 7
Driveshaft installation from Quality 4×4 parts in Port Angeles. 6L80 adapter mated to a Slip n stub.

Part 8
We retro-fit a Hyper-fuel intank pump

Part 9
Weekend update on Swap 2.0 L76

Part 10
Start of the 4 -bar triangulated rear suspension from Johnny Law Motors in Portland

Part 11
We complete the 4-bar triangulated rear suspension from Johnnylawmotors.com

Part 12
Engine and drivetrain are in and running

Part 13
Short drive around Cape George to see how “El Poncho” rolls

GM Gen V ECU & TCU part numbers

All ECU’s after 2019 appear to be encrypted, just like the TCU’s are after 2017. Gen V E92 ECU’s from 2016-2018 can be reflashed via HP Tuners software, 2019 ECUs are unknown at this time. The 2019 ZR1 Corvette LT5 engine introduced the E99 ECU which is further encrypted with on an over the air update service which requires a Factory Immobilizer Reset Service that is hard-coded to the vehicle’s VIN. The same will hold true for the 2020 C8 Corvette which uses the E99 ECU. HP Tuners offers an updates to both the E99 and E90 ECUs, plus the T87a transmission controller (see below). At this date I do not have current information on the actual part numbers for 2019 & 2020 ECU’s & TCU’s other than what was produced in 2018 that carried over like the T87A.

How Gen V Direct Injection works

The all conquering supercharged LT4. Drawing by David Kimble

GM’s Gen V engines use direct injection which requires a proper fuel supply. There’s a lot of misunderstanding about the fuel delivery system because most enthusiasts are not familiar with PWM (Pulse Width Modulated) style fuel pumps.

The Overview:
For daily driving, you would normally see the engine target the stoichiometric AFR (Air Fuel Ratio) of 14.7:1 (also referred to as Lambda), if you have a wideband gauge hooked up. However, with 10% ethanol in most pump gas today, you see the program setup for 14.1:1 to account for that blend. When you step on the pedal and go wide open throttle (WOT), the vehicle goes into what is called “PE Mode” or “Power Enrichment Mode” looking for values approximately 12:1. This defers to another table that has modifiers of your aforementioned stoichiometric AFR values. The Mass Air Flow (MAF) tables and the Dynamic Airflow (VE) or volumetric efficiency tables that provide the basis for the manipulated fueling requested, taking into account factors like injector size in lbs/hr, the requested fuel line pressure and the Start Of Injection (SOI) which tells the injector when to fire.

Cross-section shows the direct injection of fuel into the combustion chamber

How it works:
The system uses two fuel pump technologies. The low side in-tank pumps are the pumps in the fuel tank that are controlled by the Fuel Pressure Control Module (FPCM) also called Fuel Pump Pressure Module (FPPM) for power output to the high pressure fuel pump which then supplies the fuel rails. The system requests approximately 50 PSI during normal driving and jumps up to approximately 72 PSI when going WOT.

The High Pressure Fuel Pump (HPFP) is located under the supercharger on the valley of the engine, in-between the cylinder heads. The high pressure pump has command technology which references it’s position as the plunger rides up and down on a specifically ground lobe on the camshaft to pressurize the fuel as it goes through the pump producing up to 2,900 psi fuel pressure (similar to diesel technology).

Factory bent high-pressure lines in the plenum. High Pressure fuel pump is shown right above the flex plate between cylinders 7 & 8.

The pressurized fuel enters the CNC (Computer numerical control) bent fuel lines and travels to the rails, and then enters the injectors. These injectors, unlike previous years port injection are located in the cylinder head with the tip projecting into the combustion chamber. Since the engines are direct injected, the fuel is fired into the cylinder from 1,500 -2,900 PSI on the intake stroke for a very short period of time (5 mil-seconds). The injected fuel will vaporize before the piston reaches top dead center (TDC), which allows for much more predictable fueling and more accurate/higher target AFRs . The benefits are less wasted fuel, better fuel delivery and a better AFR potential which results in increased mileage and reduced emissions.

For more detailed information on Gen V fuel delivery issues please ready my recently updated Gen V installation guide located here: