Gen V LT1/LT4 header collector gasket and flange

When I was making up my collector flange for the exhaust system, we designed a template that acted as both the design for the gasket and the flange itself.  I searched high and low, but was unable to find anything available off the shelf other than direct from GM, this is a unique flange/bolt arrangement that appears to be only used on the GEN V engine.  GM wants $57.00 for a gasket and almost $600 for each downpipe that connects to the header, so here’s a simple solution.

This is the header system that the template will fit, click on the image for a higher resolution view.

Collector template -download this PDF file for fabrication.

This template is scanned full size on a regular sheet of paper so when you print it out, please print actual size so the image doesn’t get distorted.  The actual diagonal distance between bolt holes is about 3 7/8″.  The pipe diameter is 2 1/2″, but we elected to design the flange so the exhaust tubing entered into the hole rather than be welded on the outside, for thickness we used 5/16″ thick steel.  It’s your choice, but adjust the diameter of the exhaust hole based upon the size of the exhaust tubing your’e using.

For the gasket we used aluminum and heat tempered it so it was pliable, worked great and saved a ton of money.

GEN V LT1/LT4 VSS and tach signal generation

I’ve had quite a few inquires lately in regards to how to power and drive your conventional mechanical or electronic speedometer from the new GM 8L90E 8-speed transmission.  After talking at length with GM Performance and Powertrain they have provided a few solutions that should work.

The 8L90E transmission is a second-generation model that uses an electronic controller built within the transmission itself.  If you’re using the GM “Connect and Cruise” system it includes a separate controller (black rectangle with blue connector above right) that communicates back and forth between the engine ECU and the transmission itself.  This system is part of the CANBUS or GMLAN electronic control system and is for all practical purposes standalone, they don’t want you piggybacking off the system because you can potentially disrupt the network transmission protocol.  For the 8 speed automatic transmissions, the vehicle speed information is fed to the transmission controller over the CAN lines. The Vehicle Speed Sensor connector (on the wiring harness) is not used because there isn’t one on the 8L90E to plug into. The ECM is programmed and looking for 40 pulses per revolution.

I have successfully piggybacked off the VSS signal from a T56 manual transmission and generated the correct speed using the Dakota Digital VHX gauge package with their BIM 01-2 module.  Using the VSS signal from an ECM this way requires a single wire input into the Dakota Digital bus.  Since the signal is generated outside the GMLAN, a simple pulse generated inductive signal from a magnet, I believe it doesn’t disrupt the signal going to the ECM (see my LT1/LT4 installation guide for more guidance).  This is necessary because both the LT1 and LT4 Gen V engines require a VSS signal, without one they go into ‘limp mode’ and run at 1/3 throttle. Set up this way my engine and transmission appear to function correctly because I do not get any check engine codes of MIL lights.

GM Powertrain has brought to my attention that pin 14 (grey/blue wire) out the transmission controller (as referenced above) will provide a non-CANBUS raw signal (pulse generated) that should be able to drive a conventional electronic speedometer. This is an inductive type signal so voltage output is dependent on speed.

One simple solution available is a conventional shaft mounted VSS signal generator like this:

Summit Racing sells this part: https://www.summitracing.com/parts/dak-sen4165/overview/. This is a VSS magnet kit with pick up coil. Normal rear wheel drive domestic installation takes four magneta on the drive shaft with a pickup coil mounted approx 5/8″ away.  It seems odd that you would use a old school mechanical magnets spinning around on the outside of your driveshaft to get a signal that your speedometer can read, but it’s a least a solution.
A little bit more elegant solution is this split-collar speed-sensor that is used on data-acquisition systems:

Another option is a GPS driven signal like this:

The best solution seems to be the recently released STA-100 ODBII interface that not only handles the speedometer issue, but also provides a tachometer signal.  There is also pin C (white wire) output from the bulkhead connector that provides engine speed, but it’s a CANBUS signal and will not drive an aftermarket electronic tachometer unless it’s OEM.

The STA-1000 plugs directly into the OBDII diagnostic connector, providing a user-adjustable traditional Speedometer, Tachometer and Check-Engine output for your choice of aftermarket instruments.

Features:

  • Fully compatible with common aftermarket electronic speedometers 
  • User selectable output of: 4k, 8k, 16k PPM signals, Sine or Square wave options 
  • +/- 35 percent speed signal correction, compensating for tire size or gearing changes
  • Adjustable 4, 6 or 8 cylinder tachometer signal output
  • Check Engine light output provides a grounded (-) output to activate a check engine light of your choice
  • Automatically calibrated output for an aftermarket cruise control can be activated by making connection to the higher-resolution fixed VSS sensor
  • Small footprint measures 4-3/4″x 3″x 1″ making it easy to hide
  • Compatible with J1850 and CAN OBDII protocols

Stay tuned for more….

 

Gen V LT1/8 speed “Connect and Cruise” install on a ’55 Chevy 2 door post

I have made a wee bit of progress, the two steps forward part.  Motor is in, small amount of cutting and grinding and welding…well, ok, a lot of that.  Note I cut off a bit of the motor mount to have access to the oil port for my oil pressure gauge.  Put on the Drive Junky belt system today.  Found out that I can use a rack and pinion steering which takes care of the header clearance problem. 

The fuel tank is ready to be TIG welded (Rick’s Tanks).  However the 500 # gorilla is still in the room, that’s the 8 speed, and yes, you are right, 1st gear is like 4.56,  I found out that the rear end is 2.20:1.  Not sure if that is within the parameters of the ECM, might have to swap gears later.  I have to get the steering in before I can move the car back over to the lift side and slide the tranny under the car.  Then I can see how much of the 60 year old floor I have to cut away.  Anyway it is some progress. – Harry Abbott, Oak Harbor, Wa.



 

Phase III – Triangulated 4 bar & mini-tubs

Well, it’s been about 18 months since I started this project and for us in the Northwest the car season is about done for 2017.  So for this winter’s project we’re cutting out the wheel-wheels and adding in Detroit Speed’s mini-tubs.  This is a lot of work and takes persistence, a lot of cutting and grinding tools, and a good welder (Lincoln 140amp MIG).

For the rear I decided to go with the RideTech bolt on 4 link system because I’ve always been impressed with it’s simplicity and ease of installation.  After these modifications I’ll be installing 305/30/19 rear tires and 265/35/18 front tires.

Gen V L86 6.2LTruck Engine

Here’s a surprise from last weekend’s cruise-in, a new L86 Truck engine installed in a ’56 Belair, 430hp and 470 ft/pds of torque.  They machined up some spacers and managed to fit a Vintage Air serpentine belt system.  Turns out the guy’s son lives a few doors down from me.
The truck engine L86 (6.2L) and the L83 (5.3L) have this funny upward tilt to the intake manifold, which is exactly opposite to the LT1 and the LT4, and presents a challenge trying to plumb in an intake system.


One of the fastest cars in the world – 2017 Camaro ZL1

If you want to understand what the Supercharged LT4 engine is all about watch the latest episode of Motor Trend’s “Ignition Series”.  This really explains it much better than anything I can describe what my car is like to drive.  I thought it was interesting that the manual 6-speed was just a touch faster than the new 10-speed paddle-shifting automatic. Randy Pobst really has a great overview of all the current supercars because he gets to road test them all.

1968 Z06 Camaro – On the road for a final shakedown cruise

After about a year of effort the new Z06 Camaro hits the road for a high-speed shakedown cruise. Power is off the charts, acceleration is instant (faster than 0-60 in 3.5 secs) and the ride quality from the Morrison clip is miles ahead of the original chassis.  Even with solid body mounts the ride quality is excellent and it never comes across as harsh, the first few inches of travel are extremely compliant. With the increased camber and C7 cast aluminum A-arms the front end will handle anything, exhibits no body lean or roll and the high speed stability is rock solid.  The performance mirrors sex, drugs and rockin’ roll, is highly intoxicating and you can never get enough.  

The only way you can experience even a small amount of the available performance is on track only, this car is faster and has a higher performance level than 99.9% of the cars on the planet.  If you want to build a Supercar, this combination is hard to beat.  Since this car has no modern computer driven driving aids such as stability control, ABS, launch control or various track modes, you can exceed your human given abilities quickly, so you have to give this car a short lease to keep things under control. Do the math, right now this car has a performance level exceeding some of the fastest cars made – 4.3 lbs/hp. Even the new Dodge Demon 840hp drag special is only 4.7 lbs/hp, it’s always about the power to weight ratio. If you haven’t watched it yet, check out the ZL1 at Nurburgring.

The current rear-end gears (4.11) will be changed out for 3.73, only because I have them available. Phase III – 4 bar link, mini-tubs and wider wheels will happen later after I put some miles down. Even with the 4.11 gears I’m still only pulling 2,100 rpm at 70 mph.  This engine is much different than the LS, it spins freely at 3,000 rpm and never feels stressed like a typical SBC.  It has tremendous torque, but likes to rev quicker due to the direct injection which is a completely different feel than the LS3.  There is a fuel-cut off switch that is part of the wiring harness and once I connect it to the clutch pedal will allow much faster shifts because the supercharger has a tendency to extend the engine’s deceleration curve. “Speed is relative, floor it.”