Fabrication Archives - Promotive Engineering

More GT2

February 5, 2017 by Promotive

The GT2 has been moving ahead at a glacial pace! There is now a renewed push to get this car finished and on the track, so I dusted the cobwebs off the chassis and finished off the rear wing and engine mounts and a lot of those fiddly jobs that take so much time yet are never seen.

I decided to keep the turbos in a reasonably standard position but just make the headers so there was enough room for the external wastegates. It is a tight squeeze! There is just enough room so they don’t become intimate with the massive wheels when at full bump travel. It is simple and more efficient compared to the standard Turbo pipe work. The intercoolers have an o-ring seal onto the larger GT2 drive by wire throttle body to make mounting simple and the location is perfect to take advantage of the big roof mounted air scoop.

I am not looking to the next jobs of fabricating the fiddly firewall infill panels, replacing the firewall template with a carbon one with rear window, and then trying to work out how to mount the widened rear body work. It will be exciting to see it looking like a car again though!

Never enough room in the engine bay…

February 2, 2017 by Promotive

The current 911 trend of backdating and Singer look makes life hard when you are also trying to squeeze a couple of turbos under a ducktail or electric wing. I am a huge fan of a normally aspirated engine with throttle bodies or flat slides, but sometimes you just need more power and bigger flames. With a Masters Degree is Tetris, you can get a decent size intercooler to fit without needing an aggressive tail (as seen in the photos below of previous projects). The problems are compounded when you are trying to increase drivability by using long intake runners, and then need to find room for an air conditioning compressor.

The other option is to use water to air intercoolers. These are quite effective in a road going 911 because there is enough thermal capacity in the system to sink the heat generated by relatively short bursts of power, and the average road speeds are less than on a circuit so where the airflow over an air to air intercooler comes into its own. A current project uses twin barrel intercoolers on a twin turbo 3.4 engine arranged so there is ample room in the engine bay for easy maintenance and an electric C2 wing. The base motor hasn’t been touched so there hasn’t been an opportunity to tidy the old muffler up and detail the engine. Unfortunately it is function before form on this build…

The engine is being run by the enormously capable Vipec Thunder ECU. That allows me to data logging everything from EGTs, dual lambda and every pressure and temperature we can think of. One advantage of having so many inputs and outputs on the ECU is being able to take over the control of the electric tail to make it heat and speed dependant; and more importantly use a drive by wire throttle body. I try and use DBW on all the projects here these days, the simplicity in setting up traction control, and idle control make me look good! This engine had an old school throttle kicker for antilag so that was also eliminated and updated.

The easiest way to make everything fit nicely is to cut the manifold balance tube and reweld it on a shallower angle. The standard throttle body holes were welded up and redrilled to suit the 996 Turbo DBW throttle body which also has a larger butterfly. This 3.2 manifold had already been put on a flow bench to equalise the flow through the runners so the whole job was fast and painless. Just the way I like it!

One other upgrade we did while the engine was being rewired is ditch the old coil packs for the twin plug setup and update to coil on plug. These have plenty of spark energy for the amount of boost that this engine will run and clean up the engine bay.

This engine has a date with the engine dyno before it is put back in the car so I can see how efficient the barrel intercoolers are compared to other systems I have tried. We are going to continue of our fuel testing with this engine as well to show what a massive difference the ETS Racing Fuels make to power and throttle response….

Retirement for Old Porsche Cup Cars…

December 17, 2016 by Promotive

Back in the old Porsche Cup days, the early shells were the cars of choice to chop up and turn into race cars. It made sense – they were light and plentiful, and who would want a stylish long nose car when Miami Vice influenced the trends of excess. Everyone wanted a 911 that looked like the outrageous Gemballa Avalanche and Konig Road Runner specials that had tails so big you could land a helicopter on them. Heck, I still want a Scarab and a pet crocodile just like Sonny Crockett…

The dilemma now is what to do when you have a one of those early shell Cup Cars… With the price of the early model cars, particularly like a 1969 E like this one the choice is quite difficult. One option is to rebuild the car back to standard, find the matching number engine and pretend that owning a car that has the power of the average lawn mower actually excites you. Or you could go down this path and build a toy that can be used on the road and on the track…

This build is not cutting any corners at all! Unfortunately the firewall was substantially cut out as was the trend for the old school Porsche Cup Cars. New panels needed to be welded in and I needed to form a new transmission tunnel to suit the stronger G50 gearbox while retaining the standard look. The full cage was cut out and replaced by a beautifully welded bolt in cage to make it road legal again. The car already had MCA shocks which are as good as money could possibly buy, so only the spring rate needed to be adjusted to suit other than replating everything and making sure everything was spotlessly clean.

I have never been a fan of the 993 GT2 look so it was quite a relief to cut the quarters off the old yellow car. They were replaced by rear flares that could be best described as ‘911 ST flares plus a little bit of extra width’. The whole body was taken back to bare metal. Every dint in the body and place in the floorpan where the car was jacked up where it shouldn’t have been, has been repaired. The shell really looks amazing as repainted in Ivory White.

To sum this build up with a few dodgy photos really doesn’t do it justice to the amount of work to get it to this stage…

Audi S1 E2 Group B Replica – update

November 15, 2016 by Promotive

This project is moving along at a glacial pace… To be fair, there are still a few customer projects that were booked in before this one so I can’t really get stuck into it yet.

The shell has been stripped and shortened by about 320mm. That makes the wheelbase of these Group B replicas about an inch shorter than a short wheelbase / pre 1969 911! Scary! At the same time the windscreen angle needed to be changed by using the ‘A’ pillars from Audi 80 roof welded in at the firewall plenum, which in turn was chopped down and replaced with the period correct shape Kevlar roof and ‘C’ pillar section. Sadly (or not) we sacrificed an entire Audi 80 just the windscreen frame. The amount of parts being reused from the original the Quattro could be counted on one hand too, I guess the more parts that are sent metal recycling, the more collectable these things get!

The correct roof is actually wider at the top than the standard heavily raked Ur Quattro screen and roof so luckily everything lined up nicely once the frames were widened. The ‘B’ pillars also needed to be chopped down and made narrower to be more authentic, and the correct door frames were then grafted on to match the rake of the new roof. A great job if you think jigsaw puzzles that don’t have the correct shaped pieces are fun…

Next, an oversized centre tunnel was added to make roof for the hefty sequential gearbox, an exhaust system and water cooling lines for the rear mounted radiator. The rear floor was replaced by a sheet section and some temporary wheel tubs were added.

It is pretty exciting to have the shell recognisable as a car! I will have to hang the rest of the panels on it so they retain their shape, but the rollcage and fabricated strut towers are the next items on the substantial job list…

1957 Gaggia Monte Carlo Restoration

November 15, 2016 by Promotive

This is not the normal type of project here, but copious amounts of coffee is absolutely critical to my thought process!

I have had this late 1950’s Gaggia Monte Carlo two group lever coffee machine sitting around begging to be restored for just too long. I recently I found the seals and parts that I have prevented me from using the machine, so I thought I would spend a little bit of time to give it a new life.

: The original heads in a sorry state after years of neglect!

: The frame was blasted and powdercoated. The boiler had previously been blasted and new elements installed.

: It was easier to machine new nuts than try and find original ones.

: The finished nuts next to the originals.

: TIG brazing the dints and pinholes in the heads.

: The first polish, almost ready for a copper coating before repolishing

: The parts as they came back from Pacific Plating. They look amazing!

: The pistons were hard chromed but one needed a thread repair which was achieved by welding a new base onto the rack.

: Dummy assembled (in more ways than one!) to test the fit with new seals and boiler control.

It is a sensational looking machine! It is almost done now, with a bit of tuning and a pair of original steam wands and a bakalite knob and an original indicator bezel – the coffee will flow once more!

Motorsports can be so frustrating!

November 9, 2016 by Promotive

So, so frustrating!

Targa Tasmania was going so well for car 806 until an unfortunate overtaking accident left made a mess of the car…

After all sorts of delays with available panels and parts, I finally got the car back here with only three weeks to get it ready for the event, Targa High Country. While the panel shop did an amazing job of straightening the shell out (everything fitted and wheel aligned / corner weighted perfectly); it wasn’t just a case of bolting it all back together. On top of the normal pre rally prep and a couple of upgrades, there was fire damage to the wiring loom, impact damage on every corner where every bracket and part needed replacing or repairing, as well as repairs to the engine and exhaust, crack testing and inspections for the gearbox and drivetrain.

We got through the job list in the limited time available. The car even had time to get a new wrap job and a test. Even the air conditioning was re-gassed! I finally caught up with some sleep thinking we did a pretty good job!

That was until I got a call from the event… After all that work and late nights – the fuel pump randomly decided it was time to stop working! It wasn’t even that old! So frustrating – who would have picked that to fail!

And yes, I have CAD drawn up a new fuel tank top insert for a dual pump upgrade before the next rally…

Reverse Engineering with Ease (Relatively speaking)

September 10, 2016 by Promotive

The 3D printer has been fantastic for prototyping and checking CAD parts before I send them to the CNC for production. It has saved countless hours on designing parts like the roller tip rockers for the Lycoming engine. Changing motion ratios and optimising the tip geometry couldn’t have been done easily or as quickly any other way without a complete and accurate 3D model of the cylinder and other critical parts.

The parts still needed to be created on CAD with no accurate reference to the original part. Until now! Parts like the standard Lycoming rocker couldn’t easily be measured with my digitising probe or the camera loaded into the CNC so I have been exploring other options…

Metrology grade 3D scanning can easily be outsourced these days but the time and cost of relying on other companies is just painful – I haven’t had much luck with either! After a bit of research and a few trials I settled on a fairly new release to the market which on specification seemed to fit my requirement nicely.

I haven’t had a huge amount of time to play with the scanner yet but the first results seem really promising, especially with the automated turntable. I scanned in the standard Lycoming rocker to see the quality of the model which made measuring the standard angles and dimensions really easy. As a test, I also scanned in one of my 3D printed roller tip rockers. I sent the resulting model to the printer to compare the scanned model with the original and amazingly, there were no real differences that could be measured with a vernier caliper! Pretty impressed with that! The advertised resolution drops off when scanning larger parts like body panels but I haven’t tried that yet.

I tried a twin plug 911 head that was lying around to see if my dreams of easily making a billet head were going to come true, but it seems there isn’t a lazy option with the complex geometries. The resolution is amazing with the texture camera. You can see every little surface mark, but I really need spend a bit more time with the scanning technique. It looks a lot easier in the sales video! What they don’t also tell you in the sales video is that after the initial purchase, you need to spend the equivalent cost of a car again on yet more software to make it easier to create the solid model from the scanned model so the scan is useful for actual reverse engineering. Otherwise it is only really good for making high resolution bobbleheads and simple changes to existing parts.

I know there are a few motorsport teams that are using this scanner now so it will be interesting to see how it works out for me!

Ceramic Coating – bling with function!

November 24, 2015 by Promotive

I have never really understood the appeal of chrome. It really only points out that the part hiding underneath is low tech, over weight and its only trump card is that the part is shiny. You could argue that it prevents corrosion on ferrous parts but there are a lot of better options.

One of those high performance options is cadmium plating which has all sorts of great additional properties such as prevention of galling and a neutral galvanic coupling when used with dissimilar materials. I guess that is why Porsche used it so much in the past and why it is still the coating of choice for aviation. Unfortunately is becoming more difficult and expensive to use.

One of my other favourite coatings is ceramic. As seen in the photos, it has a lot of bling to it but has the performance to match. It isn’t only for exhausts systems, I use it for other external parts like aluminium manifolds and internally on piston crowns, combustion chambers and valves to encourage more heat out the exhaust.

The photo of the valves above show one pair that is coated next to the uncoated spares. The beautiful swirl polish finish of the custom valves is gone but heat reduction into the valve is measurable. The intake valve is cooled by the intake charge so it is normal just to coat the combustion side. The exhaust valve has a harder time so coating both sides can be an advantage and take some heat away from the guides. The same goes for the pistons like the GT2 pistons pictured above except a dry film lubrication is applied to the skirts. The coatings on the pistons are such an advantage that I don’t build engines with out the coatings these days…

I just had to include a few photos of the Lycoming 540 cold air induction manifold I just made and had coated. The thing is a monster! It looks like a giant spider – well, a spider that only has six legs anyway… It has injector bosses for calibrated injectors to be fired by a Motec M1, as opposed to the ridiculously basic aviation injection that makes K-Jetronic look like something out of Star Trek; tapered tubes, bellmouths in the plenum and all of those little details that take ages to fabricate and aren’t really seen! The Lycoming cylinders are not crossflow so the exhaust is in very close proximity and the entire exhaust and intake manifolds are therefore coated. (The picture of the merge collectors above are for the same engine).

Another round of Golf…

November 10, 2015 by Promotive

More pictures and less words this time…

I wanted to take some photos of the hidden parts of the classic rally Golf while it still looks half reasonable. There are plenty of hand made goodies underneath like the control arms and equal length driveshafts and associated bits. I guess I should have washed it before shooting the photos but after a special stage or two it won’t really matter.

The brakes are probably worth a shot too. It isn’t hard to work out which end is which on a front wheel drive car! These stoppers are about as big as I can fit sensibly fit under the Compomotive rally wheels. The massive front MCA struts make me smile every time I see them – you can’t get a better damper!