McLaren M20#73

The Main Roll hoop and back stays are all fitted and tacked in place ready for a 'professional' to tig up.
I dropped the rear clip on the chassis for a feel good moment. Out came the grinder and cut offwheel for some surgery. The trans cooler naca duct and engine cowling are not in a position that works for my setup.
The front anti roll bar is nearly done. Hopefully finish that tomorrow.


Hi Andy, Just a quick question, where did you get the parts to make your sway bars and did they break the bank??

Cheers Leon
Got a week off so hopefully will be able to make some progress on the headers.
Made a form to mark 90 degree cut off lines on the 180 degree mandrel pipe bends. Simple and in expensive.
Turned up a bung for the 2” pipes to back purge while welding to prevent crystallisation inside the pipe.
I use a 1m aluminium tig wire to work out how to run the primary pipes. It’s get them all pretty close in length. So with the merge collector, the primary pipes are 1100mm long. 43.3 inches. I’ve got some 3.5” tube to run out the back as the 4” inch was to tight running under the axle and above the bottom lateral link bars. A.


Hi Andy, I was looking back through your posts to see whether you ordered the Limited Slip Diff option on your ST6M like I did, but you don't seem to mention it. My question is, if you are running the LSD, What oil are you considering? The LSD is a metal plate style, so I was thinking Valvoline Syngear 80W-140. I'd love to hear your opinion.
Regards, Udo.
So with the merge collector, the primary pipes are 1100mm long. 43.3 inches. I’ve got some 3.5” tube to run out the back
Hi Andy, looks awesome as usual. Are primaries a bit long - 34'ish would be nearer a conventional calculation? Or are you constrained with packaging? Cheers, Andrew
Hi Udo, Have the LSD. Oil - will be running Valvoline SynGear 75W-140 as specified by Albins.
Andrew, the pipes are long, do you have some pics of your muffler setup and internal design, will have to make a custom muffler for the quiet tracks. It’s going to be rowdy.
Kev, thanks .
So the right side pipes are finished and onto the left.

New inner Alu rim halves have been ordered from White Horse Industries (Melbourne) hopefully won’t be to far away.
Had to order another Super charger damper from Innovators West as I ordered the wrong offset when I got the Procharger.


Beautiful work! I need inspiration, getting started on my Lotus Esprit headers.
How will your inner CV boot fare adjacent to the exhaust?
Hi Dave, thanks, a bit of crystal ball gazing, if there is a issue with a high speed boot failure, a heat shield can be fitted. They do have a outer metal cover which should help, I hope. Things are pretty tight all around the headers/exhaust and suspension components. Trying to keep all the weight low on the chassis.
Hi Guys, You seem to have a reasonable amount of room for mufflers Andy or is it just the photo making it look like it. I have NO room and have made some 150mm long tail pipe mufflers that I'm hoping will knock some noise off it. I was at Scope in CHCH earlier this year and saw some of the F5000 cars with no mufflers and spoke to one of the guys who said most of the tracks have the rule but very few actually enforce it, Puke does because it is close to residential housing Hampton Downs is out in the country as is Taupo and most of the SI tracks. I will have my car at Manfeild on the 7th of August for a test day so will find out how they deal with it. Your headers are looking great and I'm pleased/surprised to see you have the trans inside the rear panel.

Cheers Leon
Andrew R, is your injection Mechanical or Electronic, looking at that photo it looks like a Hilborn manifold. Neat car would love to see it going will you be doing the MG Classic this year? if my test days are successful I may do it myself.

Cheers Leon
Leon, I got plenty of room for could do something similar to Andrew's M1, with a down facing muffler from your top V-Band clamp.

Andrew's reply from his M1 build 2014.
"Leon, it's a Hilborn 2 7/16 unit with EFI injectors hidden in the centre. basically one of their traditional two-peice designs with a new top casting made to accept EFI hardware. Controlled by a Link G4 ecu. See here for details: Hilborn Fuel Injectors. "

Andrew Roberston, what kind of decibel reduction do you get from the down facing tail pipe.
Andrew Roberston, what kind of decibel reduction do you get from the down facing tail pipe.
Andy, it knocks a lot of sound out - it's basically a deep rumble/roar rather than a sharp bark, typical of the flowmaster single chamber sound - probably nearly as much racket coming from the 8-stack. Never had a noise problem with stewards. Cheers, Andrew
Front sway bar finished.
Completed the left header, had to offset the merge collector a little to clear the starter motor and I’ve shortened the the pipe length to 860mm. Welded in the O2 bungs and Vband clamps so mufflers can be added for the quiet tracks.
Will cut up the right side now and redo them to the shorter length.
Still waiting for the Inner Aluminimum rim halves. On their second heat treatment, then rounded up, stress relieved, edge trimmed true, centre bore finished the safety bead rolled. Hopefully not to far away.
The rear drive flanges are being remade to fit the larger 934 CV‘S. What I got made was for a smaller CV. Then the axles can be ordered.


Hi Andy, headers look superb. The V-band collection looks ideally placed for a muffled tail section if you ever get pinged by the noise police. great stuff. Cheers, Andrew
Remade the right side header, finally done.
Have some Stainless bros 12” oval mufflers ordered, so can knock up some tail pipes when they arrive.
The WhiteHorse Industries inner rims turned up. Did a test fit to make sure they had enough caliper and suspension clearance, all looks good so they went off the the engineers to get the holes drilled accurately. That will be a couple of weeks.
Also getting a second set of outer rims cast.
Time to pull the engine out and paint block, final fit of sump and front cover, then mount the front engine accessories, alternator, dry sump oil pump and Procharger F1A94. The Innovaters West Harmonic balancer is a 10% over driven 10 rib with the 2 keyway, thicker blower hub option. It has to have a thinner front cover seal due to the larger diameter hub. Got a couple of top pulleys diameters depending on how much huff is required.