Welcome to my Cobra Replica build blog.
Please contact me if you would like to know more detail as i progress."CR3514@live.com.au"

Monday, December 23, 2013

Inlet manifold - 3

Home for Christmas this year, and Mr. Postman had turned up with some boxes for me with some goodies to play with over the next few days.

A quick un-box, out to the shed, sit them in place, stare for a while.

Starting from the Top,
Twin Stelling & Helling 8-1/2" Chrome Air Cleaners.

Twin Holley Billet Throttle Bodies,
Part # 112-577,
1000cfm, 44mm bores, with either 1 to 1 or progressive secondary bores.
Comes with IAS and TPS.
Ports for Evap Solenoid and other vacuum or atmospheric devices.

Under the quads sits a 1" bored spacer,
While they purportedly improve torque, i purchased them to bring the height up enough so that the air-cleaners would be visable through the bonnet scoop and the engine would have an overall height in proportion to the original carby heights of about 3 ", the EFI quads are about 2" in height.

Next step is to design the MAP Sensor Mount, and Evap Solenoid Mount, Evap Solonoid Piping to connect up with canister line.
Machine up adapters for the small LS3 EV6 injectors to fit the space normally occupied by the larger LS2 injectors.
Make a Dual Quad Linkage, and a throttle cable mount.
Make a jig to hold the manifold and a port face plate so I can accurately match the ports between the Cathedral Port Inlet Manifold and the LS3 Heads.
(Mod - See future post for change to LS3 Dual Quad Inlet manifold)
Air cleaner plenum tray to fit between the Quads and the Bonnet.
Put Studs in the Heads instead of inlet manifold bolts, and studs in the manifold carb flange in place of bolting the Quads on.

Have a great Christmas all.

Friday, December 13, 2013

Inlet Manifold - 2

(Mod - See future post for change to LS3 Dual Quad Inlet manifold)

So, searching the web for port diagrams displaying relationship to manifold bolt holes or even comparisons of the difference between Rectangle Port and Cathedral Ports on the LS engines doesn't turn up much good info other than photos.

First step in determining if I can port match was to get some accurate measurements from the LS3 heads.

This shows the right bank.
If you look carefully, you can see that the ports aren't parallel to the block face, they are rotated about 2 degrees

Next step was to lay some card over the ports and tape in to space, then using a tack hammer, tap around the edges of ports and manifold locating bolt holes effectively cutting through the card without damaging the head face.

In this pic, you can see where the furthermost front locating hole is punched through the card.

Next step was the manifold purchase.

There is a story that goes along with this purchase that further reinforces my belief that Australian retailers are a rip off and offer lousy service to go along with it.

Nice looking casting until I noticed the manifold is faulty.

Yes, that's where the mill cut through the side of the lower dual plane port into the upper port while machining surfaces,

How this type of defect gets through inspection, I'll never know.

Here's the view from the opposite port.
I understand these things happen, and had the process to replace been quick and efficient then no problems, but the hassle to get it replaced was ridiculous.

This is from a major Australian performance parts supplier, they should change their name from Eagle to Turkey.

Same process with the Manifold Ports.

After profiling the ports, I could overlap the ports to see the variance.

I micrometer the parts and verified on the cut outs then overlapped the measurements in CAD

Here you can see the variance in the overlapped ports when mounting holes aligned.
The blue areas are the Cathedral Port.
The grey groove is the port seal groove in the inlet manifold around the cathedral port.

The Red area is the LS3 rectangle port profile that would need to be machined from the manifold to match.
The dark blue area is where the cathedral port would need to be filled to match the rectangle port.

There appears to be enough material in the manifold flange and port wall thickness to easily achieve the match, but the machining of the port would come right up to the edge of the seal groove.
Some compromising will need to be done if I head down this track, with a few millimeters of clearance to the seal.
Considering the CFM flow of the manifold is rated at 700hp, and my target is 500hp, should have some scope without restricting airflow.


In Progress

More to follow.

Inlet Manifold and Throttle Bodies - Prelude

The more Cobra pics I collect, the more I love the old school look..... Twin Carbs.
But, I love the modern tech and modern materials as well so I'm going with the retro look of  dual quad throttle bodies.

This is one of my favourite Cobra pics, Ken Miles's number 98.
Particularly the shroud surrounding the air cleaner,
It seals up against the underside of the hood.

I also like the twin air cleaner look of the original Stelling & Helling filters with the chrome tops, should look good nestled between some carbon fibre and billet bits.

This is the look I'm going for, modelled in Sketch-up, it gives me some perspective on the overall dimensions and look

There are a few manifold candidates for the LS motors from the big names like Edelbrock, Holley, Wilson, etc etc, in Single and Dual Plane and also some custom manufactured versions, but the high riser singles are too tall and don't have the right look for me.
So, I've settled on the Holley Dual Plane Mid Rise Dual Quad Manifold #300-121,
This was because of the excellent flow rates detailed in several on-line magazine comparisons.

This pic I took off a You-Tube clip when I was trawling for throttle body candidates.
Its the same manifold with twin 1000cfm billet quads, also Holley part #112-577

The fuel rails come with the manifold.

The issues with this set up is that the manifold is made to suit Cathedral Port heads,
My engine is an LS3 with the Rectangular Port Heads.

The 2 options I'm looking at for this is:

option 1. Port match the manifold to suit the heads if possible, initial measurements suggest i can get very close to the same cross section so flow and pressure differences are similar, by widening the Cathedral port and adding some fill to the base of the cathedral port to match heights with the LS3 heads,but,
if there isn't enough material in the side walls of the manifold, then,
option 2 is to fit a pair of Mast 245 heads that have similar port lengths and combustion chambers but with Cathedral ports.

More on my efforts in the next post

Sunday, November 10, 2013

Emission Canister

Classic Revival suggested the VZ emission carbon canister, i did buy one of these new, and they aren't expensive, but i also had a VE commodore canister i picked up from a wreckers, which looked like a better fit in the space between the boot floor and the diff.

The canister sits between the chassis rails behind the battery box above the diff.

Here's a view from the boot area  looking back towards the diff.
The canister sits neatly behind the diff.
The canister has 2 ports, one to the fuel tank, and the other to the purge solenoid on the factory inlet manifold.

Need to investigate where and how this works on a non factory manifold.

To mount the canister, i needed to make some mounting brackets.

This pic also shows the canister breather tube.

Mounting Brackets Milled from some 6mm flat Aluminium bar stock.

The finish straight of the mill.

The finish after tumbling in a Vibratory Tumbler for 24 hours.
Super smoothed, could be easily polished or anodized at this stage depending on the finish.
I like the burnished Titanium look and will leave them untreated.

Oil Cooler .......continued

After staring at the oil cooler shroud for a few months, I decided I didn't like it, looked a bit busy, so its now hanging on the shed wall, I'm too proud to throw it our yet, decided to simplify with just an upper and lower mount.

Also made up a tab mount to secure the upper oil cooler plate to the front outrigger that fits between the radiator opening and the oil cooler opening instead of "P" clamps.

Lower Oil Cooler Mounting Bracket,
8mm RivNuts inserted into the chassis,
The bracket sits on 3 bushes.

In this pic, you can see the tab plate welded to the out rigger and the Mocal 16 row oil cooler.
Oil cooler fitted with -8AN fittings.

View from the top,
Aluminium cover plate secured to the top oil cooler mounts and the chassis tabs.

Assembled view.
Just need to sand and paint the out rigger again.

Monday, September 30, 2013

Oil Cooler Shroud

Made some progress on the oil cooler mounting today,
I designed the shroud in Sketchup, converted into DXF file and imported into my CAD program Cut2D.
From here, I can generate G-Code to run on my converted CNC Mini Mill.

Sketchup is free and a great tool for quickly modelling up ideas easily.
It has some limitations with drawing exchange, but 3rd party converters are available to support DXF and STL conversion to other modelling software.

I convert the lines in Sketch-up to Poly-lines and export as a DXF file, then open up in Vetric Cut2D Program.

Here you can see the tool path and a 3D representation of the finished part.
Due to the size of my mini mill, the part needs to be flipped during milling to cut the other half of the component.

Cut2D outputs the tool paths as G-Code.
G- Code is the language the machine controller uses to tell the servos on the mill how far to move the mill axis.
The code is very simple commands specified in X, Y or Z axis reference relative to a home or Zero position.
i.e, a command of; g0 x100y50z25 will move the tool position to 100mm along the x axis, 50mm along the y axis, and 25mm up on the z axis in 1 move, (vector), straight line to that point in space.

The part pictured is the upper shroud part.

First half complete, before flipping to run the program again.

When milling sheet or any thin materials that may flex during cutting, I put some MDF timber on the mill slide as a slave sheet, so I can cut through the part without damaging the slide, but still supporting the component.

Ready to cut the mirror half of the upper shroud part.

Finished Part before bending the tabs on the end for the side deflector components.
The holes in the tabs are for rivets.
The other holes are for mounting the cooler and cooler inlet, outlet clearance.

Front view after bending the tabs on the upper and lower parts with side deflectors riveted in.

View from rear with a Mocal 16 row Oil cooler sitting in place.

Mounted in place on the chassis.
Final positioning will be done once the body is in place to line up with the radiator inlet opening.
Height of the cooler can be adjusted with spacers between the lower chassis mount and chassis or Oil Cooler, to fine tune the height.

Next part to make is the tabs on the chassis outrigger to secure the top of the shroud.

Sunday, September 15, 2013

Oil Cooler

Here's some pics of my oil cooler efforts,
While the engines an LS3, its fitted with an LS1 front sump.
The oil cooler aux ports are located above the filter.
Improved Racing make an oil cooler adapter to fit the front sump when using Holden accessories.

Improved Racing make this oil cooler adapter block for the LS1 Front Sump, Part Number

Comes with 2 additionl 1/8"npt accessory ports for oil temp or pressure switches.

The -8AN Black Braided Hoses flow up over the steering rack and into a Mocal Oil Cooler Thermostat.

The thermostat cycles the oil back to the filter block when the oil temp is below engine temp requirements and opens to allow flow to Oil cooler when temp reaches 82 deg Celsius, (180F)

The oil cooler thermostat is fitted on the LH Suspension chassis frame.
Mocal Part Number A0T2 -8AN.

Exiting the thermostat is 1/2" aluminium tubing shaped to fit the chassis.

The oil cooler feed tube converts to a Black Braided Flex Hose and Black anodized Aeroflow -8AN fittings to a Mocal 16 Row oil cooler.

The alloy tube is bent to clearance around the side of the radiator.

The Oil Cooler Return line exits to the drivers side  of the chassis and converts back to alloy hard line and parallel with the brake tube sharing chassis mounts back across to the passenger side mounted thermostat.

Oil Cooler mounting in progress.

Still need to make insulators for the brake and oil cooler hard lines where they are chassis mounted.

This is the underside of the oil cooler with my Home made CNC mounting bracket.

The louvres are so debris doesn't get trapped between the oil cooler rear and the chassis.

Next step is to make up the upper Oil Cooler Mount and shroud.

Saturday, September 14, 2013

Brake Lines

Pretty much finished running the brake and fuel lines,
I started off running 3/16 stainless steel, but changed my mind to steel coated lines, the colour is much nicer and looks better against the chassis. The steel lines are far easier to bend, fit and flare.
I bought a K-Tool flaring tool, and had a few goes at routing the lines till I settled on the final position.
I was also a bit worried about the proposed CR rear brake hose location, probably would have been fine, but the flex hose needs to be deformed a bit and tied away from its natural set position to avoid touching the rim, so I changed the location of the hose end for better clearance.

This is the Front LH Brake Hard Line coming across from the RH Front Brake Line 3 way.

The line exits at the side frame for the suspension arms where it connects to the flexible hose.

In this pic you can see another one of my tube mounts, the lower 1/2" hole is for my Oil Cooler return line.

The Front LH Brake Flexible hose fitted to the chassis side wall.

The Flex Hose has a bow in it to allow enough length to cope with lock to lock steering.

Front LH Caliper banjo connection.
Brake hoses made by BrakeQuip in Pakenham, see Lindsey the owner for good support and quality components.

Rear Brake line travels along the drivers side chassis rail along side my enclosed battery cable.

The chassis clamps are my own design milled from 6061 Aluminium with a 4" radius to suit the chassis.
Tumbled in ceramic to polish and debur before being clear anodized for a Titanium look, then fitted to Rivnuts inserted into the chassis,

The black insulators are fitted to all brake and fuel lines lathed up from plastic rod.

Both tubes sneak between the body floor and chassis rail.

Brake tube travels along the upper rear control arm mount to a 3 way on the rear of the chassis.

The Caliper flex line exits one of the 3 way ports eliminating the provided chassis mount.

The set on the flex hose clears the suspension arms and spring / shock assembly.

Flex hose fitted to the Rear AP Racing Caliper.

3 way fitted on the rear upper control arm mount.
Drilled and tapped a stud into the mount, then fitted 3 way and flanged nut.

The line then continues across the chassis to the LH rear caliper.

Another 3 way fitted on the LH rear control arm mount, 1 port plugged, the other port used for the Caliper Flex Line.