Technology Archives - Promotive Engineering

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).

Dyno upgrades

July 2, 2015 by Promotive

I have been busy lately on a few big builds and have managed to find some time to do some upgrades to the engine dyno that I have been wanting to do for too long. While some of the upgrades are purely practical and allow engine changes to be quicker, I have also added significant over capacity to the cooling system to engine temperatures can be optimised.

I have become really interested in the fuel testing lately and comparing different race fuels. I have added a flex fuel sensor to the dyno now which show how the ethanol content some of the cheaper competitors race fuels have and the consistency (or lack thereof!) ! It is a cheap way for them to increase knock resistance but it isn’t the best way of producing power…

I have upgraded the knock sensing in the cell as well. In addition to the two channel Vipec knock amplifier and headset, I have added a dedicated vibration sensing module. It is now easier to fine tune the knock sensors on a setup so there is less false readings and make it easier and faster to setup individual cylinder tuning. The new system will also analyse the vibration signature of an engine over time (FFT) and will show well balanced the engine is and the point of the imbalance. By looking at the spectral analysis you can distinguish the imbalance from a weak cylinder, a clutch or the cooling fan etc. Cool stuff!

Just need a more room on the console for all the readouts and instrumentation now! Maybe a lounge chair as well.

KnockLink

April 7, 2015 by Promotive

Every now and then I come across a cool little tuning tool that actually works.

I have been using a Vipec knock ear on the dyno for a few years now. They have an algorithm that filters out background noise quite accurately. When used with a matching Vipec ECU, they have a similar system to Motec in that they listen to a tuned frequency within a specified window. It takes a fair bit of time to set either system up but it is the only way to set up accurate individual cylinder knock control.

The new little KnockLink is made by Link who also manufacture the Vipec ECUs. This great little light is really simple. You just need to mount a suitable knock sensor (or use the existing ones on 993 or later engines) and fasten the light with the supplied mount. The wiring is simple too. Two wires go to the sensor plus 12V power and earth. It self calibrates on engine start up and will flash to warn if knock is present. It won’t adjust the timing but at least you will see that you have a problem!

Very handy for early model 911s that aren’t running fuel injection or good quality fuel!

I have a few of these in stock now. The RRP is $275. I can also supply a suitable knock sensor.

What is that burning smell?

April 6, 2015 by Promotive

They say that technology is here to save time. I have a lot of technology so why do I never have any spare time?

Anyway, the other day, after commissioning the new wiring loom in the classic rally car that is being entered in the Australian Rally Championship I noticed something wasn’t quite right… No smoke or anything dramatic but there was a problem in the loom somewhere. It was a bit strange considering that the harness had been tested prior to powering it up.

Anyway, FLIR to the rescue! No, not Fleur, a girl I used to know years ago, but the thermal imaging type of FLIR. It is really becoming a handy tool around here. The heat signature from the plug showed that the problem was a defect in one of the new aftermarket tail lights. A simple fix to a problem that could have taken a lot longer to find!

Now, why doesn’t this technology save any time? Once you get a new toy you spend too much time playing with it! Predator style vision is so cool!

I was going to make a comment about a ‘hot dog’ but that would just be silly…