Welcome to... The Age of Enlightenment
One of my favourite things about... stuff... Isnt just making something but also optimizing it however possible. Kerbal Space Program is a good example, of the benefits of optimizing things. (You build space ships)
You can have a ship that works well, but then doing things like reducing the amount of fuel in each container to just how much you need for that particular stage of your rocket, reducing thruster power to the optimal speed to minimise drag, and so on. Can make a ship that looks the same massively faster and go massively further.
In terms of how this relates to my car, currently its at the point where I've just slapped some shit together and seen that it works, which it does.
But some things suck for a variety of reasons, or are okay but could be better. It could benefit from some time spent optimizing stuff.
For example, I have these fucken massive vented rear brakes, which I then need to use a bias valve to turn them almost completely off in order to not lock up the rear.
Do I really need a 5kg vented disc on each side of my live axle, and a big steel caliper that's probably about the same? Probably not.
Switching to an aluminium MX5 caliper and a non vented disc, I can drop a fair chunk of unsprung weight annndddd my brake bias will actually work better. Cool.
My goal is to lighten the car in a way that doesnt make it any less useful as a street car, or any less useful on the track.
I want to try and get somewhere into the 6 litres per 100km mark, do a 13 second quarter and do a sub 1:20 laptime at Hampton.
Making the car lighter helps work towards all of these goals.
So essentially my plan is to just make a lot of tiny iterative improvements everywhere, (Which may seem like a waste of effort when viewed in isolation) that will add up to a bigger picture change. (Maybe). And learn some some new stuff to stave off insanity a little longer and keep my brain ticking over.
Before I started doing anything I weighed the car with approximately a quarter of a tank of gas, full interior, all of the seats, etc.
Came in at 1020kg without driver.
So it will be super easy to get it under 1000 and I think closer to 950 or 900 will be achievable.
So here are a few things on the to do list:
-Swap in dual VVTI engine, (for better fuel economy thanks to exhaust side VVTI, and more power thanks to slightly higher CR)
-Swap to the 2NZ Alternator which saves ~4kg for same amperage.
-Cast some aluminium engine mounts instead of the steel ones with sloppy old rubbers.
-Downsize rear brakes.
-Remove blower assembly, heater core etc from under the dash as none of it works particularly well and it's quite heavy. (done)
-Depending on how engine mounts go, possibly cast an aluminium gearbox xmember as well. (I will 3d print a shape for the local foundry to do these)
-When I had an oil cooler, when I had the oil cooler fan going the radiator fan NEVER needed to come on. Even on a hot day. Since there's a water to oil cooler on the engine, I've removed my oil cooler and my large radiator fan. I have put the oil cooler fan on the part of the radiator with the highest temperature differential (Right by the top hose) and surprisingly enough the car doesnt overheat with this tiny fan. Even on a hot day. Which leads me to...
-Remove the radiator fan entirely and use a radiator sprayer bar. Since I need a washer bottle to spritz the window for WOF, I can have a valve on it which uses the water to mist the radiator instead when needed. Currently its only in stop start traffic or moments below 35-40kph where needs the fan at all. Also, at high speeds where a fan cant actually assist to cool your car, evaporative cooling can. (Still tossing up this idea but it sounds fun to experiment with. Will leave fan in place as a backup while testing)
-Remove rose jointed t3 Castor arms, and go back to standard ones with stiff poly bushings. The weight difference is ridiculous and I'm not convinced they're particularly better than standard configuration.
-Remove the rear muffler and cast an aluminium rear part of the exhaust pipe that has a butterfly in it which I can control with the ECU.
This has the benefit of making the car a lot quieter when cruising along, annnddd, I can introduce pressure to the exhaust system in order to increase EGR effect of VVTI at cruising conditions. Which I believe may help improve fuel economy, as counter intuitive as it may sound.
-Reduce idle speed as low as possible to save fuel (Already done) With MAF based tune I can now get a stable ~670-700rpm idle, but I've used a few tricks to make it more drivable and not stall. Such as increasing goal idle speed above 5kph and when the engine is cold.
-Find a way to optimize cam timing at cruising conditions for best economy.
This one has been on my mind for a long time, it seems very difficult to quantify how to best set the cam angle.
So I have been working on an arduino based canbus project which can communicate to the ECU and show a live fuel economy value.
I can turn knobs on the box to increase or decrease a trim table that affects cam timing, fuel, ign, or injector timing, or whatever else and get within ballpark this way.
For version 2.0 of this, I am planning on having a closed loop ignition timing control that turns on when cruise control is active. It will float the ignition timing a few degrees eithe way, find the most economical value and then update a trim table in the arduino.
Work in progress...
I'm also considering having an overlay trim table in the ECU that changes ign timing based on current AFR seen at the oxy sensor - A leaner mixture needs significantly more timing. So it can do this dynamically.
-3D print all the things!
Lately I have jumped on the 3D printer bandwagon, and this will be an elemental part of the process for some of the stuff above.
Not only can I print PLA prototypes, or ABS/Nylon functional parts. But I can also make molds for making other parts out of fun stuff like Polyurethane or Carbon Fibre.
I made a test mold to see how Carbon Fibre would work and it turned out friggen awesome:
So I'm going to make some more carbon parts, it's such a fun process and seeing the results is exciting.
Stuff is so strong and so light, cant wait to make some more stuff out of it.
Tying into some of the above (3d printing a new dash housing, and using ARduino knowledge to build the screens) I will put together a canbus based digidash that will be cool. Will try and make it look like an 80s spec digidash as much as possible, but also have some context sensitive functions in it. (So screen will show different values when cruise control is on, or if you are at a trackday, or whatever) This isnt strictly something that makes the car better, but I'm already 90% of the way there by building my fuel tuning box thingy anyway so why not.
-Get rid of heavy battery and move it closer to the engine bay.
It's currently in an annoying spot in the boot space, so going to a gel cell battery or similar and moving it closer will save a non insignificant amount on battery weight and thick cables that run the length of the car currently. (ha)
I can only name 2 or 3 occasions on which anyone has ever sat in the back seats of this car. The seats, belts, and rear parcel tray arrangement are over 40kg worth of stuff.
So I'd like to ditch them completely but dont want an ugly looking bare rear half of the car. For privacy reasons I want to keep the rear parcel tray so I'll remake something from maybe carbon fibre or aluminium. If the seats go too then I'll make some sort of firewall type thing and try figure out a non ugly way to cover up where the bottom half of the seats went.
Currently each front seat is over 20kg (including rails)
So will get some lighter ones, maybe with fixed rails if I ditch the rear seats.
-Radiator Support crossmember
Currently I am using an oversized piece of a 2nd crossmember that I chopped out of another carina, so I can unbolt this to take the engine out.
Since its an easy shape I'm going to 3d print a mold to make a carbon fibre replacement for this, and the bonnet stand. -Get rid of the glass and replace with Lexan
This is something I'm not interested in doing.
It's good weight savings but it's a ball ache because you need an authority card or whatever, I can barely deal with trying to get WOFs on this bloody thing as it is haha.
I'll learn new things as I go, doing the above. So I might come up with some new ideas or decide to ditch some of the above.
But it feels like there are some exciting new things to learn, which I'm happy about.
A lot of these things only save 1kg here or 2kg there etc... But they all add up.
Since my gearbox is toastedd and trackdays are starting to become significantly less affordable or accessable. I'm happy to just have the car off the road again for a while, while I geek out a bit. The only thing I can say for sure, is that fun times are ahead and I'm excited to learn some new stuff, especially regarding Arduino programming, 3d printing and some carbon fibre stuff.