Author: desmodave

Dakota Digital VHX is the easiest way to add a complete gauge cluster system for both the LS and LT engine series.

Dakota uses the signals from the OBD connector in the GM Performance wiring harness to display speed, rpm and water temperature. The oil pressure must be driven by Dakota’s proprietary sender 03-8 which can be installed in the oil filter boss that contains a stock GM sensor.  To drive the signals you need BIM-01-2.
Here’s the VHX control panel mounted in the dash.  DD uses cat 5 conventional computer cables to connect the gauges into the control box (lower right corner).
The installation manual is here for the VHX and here for the BIM-01-02.

Here’s a quick concise guide for those of you who are considering installing the new generation of LT engines. 

” The LT1/LT4 instructions states the VSS input is optional unless running a Connect and Cruise transmission, this is incorrect. The LT1/LT4 control system MUST see VSS, if it does not see VSS the ECU will limit throttle to 30%. It does this to protect the engine from over speed.”  The above information comes directly from GM Performance and Powertrain dated October 2016.

There needs to be an updated and improved I-sheet for the T56 install kit because nowhere in the I-sheet is there anything about the electrical connections that are needed or where they are located.  Now that we know that the VSS is needed, it’s critically important that installers get the right info or deal with an engine running in “limp mode”. The VSS signal connector on the end of the LT1/LT4 harness looks like this:
 
It’s a 2 pin clip-on connector that will only work in the Solenoid lock-out connection, not the VSS connection.  The T56 magnum VSS connection is on the passenger side, opposite the lock-out connection as shown below:
The connector shown below is generally referred to as a Ford T56 VSS connector, this should be part of the T56 install kit, but it isn’t. To use this connector you’ll have to cut off the connector that’s there and wire in the new one. Since this is a reluctor (magnetic) generated signal, either side of the connector will work.

In my previous LS installs, I did not connect the VSS signal into the ECM because I ran the signal directly into the electronic speedo.  The LS3 engines, from what I can tell are all set up for automatics rather than manual transmissions (even though I thought I ordered the manual version), so the signal the ECM is looking for is double what you get from the T56, so it didn’t work.  On the LT4 ECM, it’s looking for 40 pulses which is what the T56 produces, so for this installation it will work correctly.  Some T56 transmissions produce a 17 pulse signal.

To drive both the ECM and a digital speedometer from the same signal follow this schematic from Autometer.  Circuit 821 is the positive wire for the VSS in the GM controller wiring harness and it’s purple/white, use this wire to drive the sender signal on the speedo if you have problems with the VSS out signal from the bulkhead connector.
The other issue in the LT1/LT4 I-sheet is that signals from the bulkhead connector will drive a speedo and tach, but the oil pressure will require it’s own sender. The only way you can use the oil pressure signal from the bulkhead connector is to use a factory style gauge. There is no provision to add a water temperature sender on the LT1/LT4 engines, but you can add one in the radiator hose or the radiator itself, or you can modify your water pump as shown here. For detailed installation instructions for Autometer gauges click here.

Dakota Digital VHX gauges offer an BIM -01-02 module that takes the signals from the OBD-2 connection, rather than the bulkhead connection and converts the signals correctly to run their gauge packages. For more information see my Dakota Digital post.

Still double checking everything. Dip stick doesn’t register until 7 quarts, capacity is 12 quarts including oil cooler.  Engine is in “limp mode” and won’t rev beyond 3,000 rpm because of the VSS signal (see next post).

After 8 months of constant custom fabrication, endless phone calls to the GM Performance Power train division, the Z06 Camaro is just about there.
You never know until you close the hood for the first time whether everything’s going to fit.  This time it worked, the Z06 Gen 5 LT4 crate engine fits into the stock engine bay of a 1968 Camaro.

This view shows the new style PCV system with the intake plumbed with the stock lines from the Cadillac CTSV.  These are metric fitting and aren’t easy to adapt to, so I used a aftermarket Spectre vacuum accessory kit to plumb into the intake.  You can see the line with the extra foam rubber wrapping around the line that goes into the intake.

On the right side is one of the Intercooler lines hooked up and connecting to the expansion tank (far left square alloy tank.)  Right below to the right is the MAF (Mass Air Flow) connection that has to be a minimum of 10″ from the engine.

The engine wiring fuse panel is the same item that’s used on the LS series of engines.  I’d hoped to install it on the firewall, but there just wasn’t enough space available, so it ended up on the passenger side inner fender well.

One of the great features with both the LS and LT engine management systems is that they take control of all electrical requirements including both the fuel pump system and the fan(s).  On the LT engine there are two fan controllers whereas on the LS there is only one with the stock harness.  After the main battery/alternator/starter feed is connected any additional electrical demand is feed into the body wiring fuse panel.

For this build I knew I wanted a dual fan setup, so the search was on.  Most of my buddies spend big bucks and use Ron Davis products, but his build time was too long and the price was around $1,300.  I’d used offshore all aluminum radiators before and had good results, but for this build I wanted something made in the USA. I finally decided to go with Entrophy Radiator in Illinois.
It’s made beautifully and it’s a fair price for the quality.  Once installed I needed to re-manufacture the shroud because there wasn’t enough room for the intake.

I lowered the driver’s side fan mounting location 1 1/2″ which gave me just enough room for clearance for the Spectre 4″ 75 degree inlet.  If you look closely you can just see the stacked plate oil cooler that I’ve plumbed in to replace the factory cooler on the side of the pan.  I’ve also eliminated the water cooling feature and only using air to cool the oil.  I’ll also be adding the same type of cooler to use for the Intercooler.

Another advantage this radiator has is it’s already plumbed with both a steam port vent and a coolant temperature sensor.

Hold on to your hat boys, this thing is huge. Compared to the ECM (E38/67) on the LS3, the new generation ECM is more than double in size. To get this thing to fit, I cut off the back side of the heater and boxed it in. You have to use a big block heater system because the small block core coolant pipes exit in front of the back of the block.If you don’t want to mess with that approach, it’s best to install a Vintage Air system, throw away the old school heater core and install a blanking plate. This is what the factory did on the 1970 SEMA Camaro.After much deliberation I decided to drill mounting holes through the thin sides and use the existing heater box mounting bolts. Add a nut union and you’re good to go.