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Zac's 1998 RX7


ProZac
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Better brace yourself for the constant pile of CVs  'accidentally' left behind after track testing this year!

(I plan on leaving one every session)

 

 

I still remember Prof. Pearse (taught Acoustics in the Mech dept, unsure if he's still there) telling me FSAE was a waste of time because most participants take 5 years to get their degrees without any major additional benefits from having done it, and that UC did not support a team starting up. That was my first year in 2008, so I really hope he's humbly eaten his words after seeing UCM's success.

 

We had a lecturer indirectly badmouth UCM a few years back, really want to put a display case with all the trophies outside their office

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  • 3 months later...

Deja Vu!

 

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After many, many k's (around 20,000 of them) of trouble free motoring... The seven developed some.... Problems.

 

Nothing too serious though. Turbos are very very leaky, causing lots of smoke, and a 1/2" puddle of oil in the bottom of my intercooler (no exaggeration). The sump leaks from the interface to the block, very common issue, and the rear suspension pillowballs are a bit clunky. I've settled into my new job pretty well now, and have a good routine going, so I can squeeze out a little time to get this thing sorted and running its best again. I had been commuting to work in it (around 1250k's a week) and it was surprising frugal! That is a complete lie. It was costing $300 a week in fuel... Not really a long term dooable thing. I got all boring and went and bought a B7 Audi A4 TDI sedan. Its got leather, good stereo, and cruise control, oh and does 1200k's to a tank easy on the open road, so I only have to fill it once a week. So with something reliable to daily (reliable-ish anyway, there is a story there, but is a good argument for purchasing from a dealer sometimes), I've put this in the garage, given it the clean of its lifetime (best to work on a clean car :-) ) and torn into it.

 

There will also be some light modification this time, so really get the best out of this car. I miss driving it already, so hopefully I can knock this out within a somewhat reasonable timeframe.

 

Work Ahoy!

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  • 1 month later...
On 5/14/2016 at 21:33, ProZac said:

There will also be some light modification this time, so really get the best out of this car. I miss driving it already, so hopefully I can knock this out within a somewhat reasonable timeframe.

 

Hah, fat chance old man!

 

Work got a little interesting in the last month... Bossman bought a Lotus T125 (google it, its cool). Actually, he didn't buy just one, he bought the complete defunct Lotus project, lock, stock and two huge fucking smoking barrels in the form of 40-foot containers, that then arrived, with said project contained within. Things at work are therefore a little busy, and haven't left me much time/motivation to tear further into the 7. We got one semi-complete rolling car, but it had no plumbing, or electrical system whatsoever... I run the Electron Management Department at work, so I've had to spend the last month trawling through Lotus documentation (which is SHOCKINGLY appalling / completely absent, by the way) figuring out their initial design intentions, which pieces of the puzzle we have, and getting the rest of the bits on the way... Then actually assembling the electrical system and building the wiring harness in a way that will keep the smoke on the inside. Massive challenge, massive fun, massive time-sink.

 

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I'm the fat one.

 

But, in the evenings when I finally do get home, I wrote up a plan of the minimum I really need to do to get the car back and running it's finest:

 

Rear suspension pillowballs.

Re-seal the sump.

Replace / rebuild the turbos.

Replace all the injector seals.

Replace the headunit with a factory cd-player from an NB MX5, for that factory clean look.

Wire up the airbag on the NB MX5 Nardi wheel I've installed (again, for that factory look).

Build a new wiring harness.

 

I've started by removing the turbos. No real damage to them, just a bit of shaft play and obviously pretty leaky. If anyone ever asks you to come help them remove the turbos from their FD RX7, with the motor still in the car, you go tell them to fuck themselves, right in the ear. What a cunt of a job. Additionally, even more annoying, as I'll pull the motor to re-seal the sump anyway, so the struggling was completely moot. Pricing up rebuild kits for the Hitachi HT12 turbos on the FD was a little frustrating, as the RX7 versions of these turbos don't use a dynamic piston ring seal on the compressor side, they use a friction carbon seal. Makes bits harder to find, and ass-puckeringly expensive.

 

I'm going to try something cheaper (and cooler) first. A buddy had a stuffed pair of R32 GTR T28 turbos kicking about that had both spat their ceramic turbine wheels. I pulled them apart, and there isn't really much else wrong with them, so I have a plan to rebuild the cores with some new bits, and try to cludge them into the factory RX7 exhaust and compressor housings. I ali-expressed some rebuild kits, replacement steel turbine wheels and some fancy billet compressor wheels. I did a lot of boring staring the compressor and turbine wheel maps, figuring out that, yeah, all the sizings should be in the ballpark for some increased efficiency at slightly higher than stock boost levels.

 

We've got a CNC lathe at work which I've been getting rather intimate with... It uses a pretty orphan controller (Anilam), which I've gotten to know pretty well, as I had to write the post-processor our CAM software then uses to output G-Code which will make things not crash into one another. It's all working pretty sweetly now, and was a great learning experience. I'll use that to both measure the profiles of the curves of the compressor and turbine wheels, then machine the housings to match. Simple in theory, but as I'm quickly learning, fixturing this shit so its actually possible to machine is a real ball-ache. Also, we don't have a 4-jaw, so I'm not 100% on how I'm going to get everything completely concentric, but some custom fixturing devices will be made and I'll see how far I can get.

 

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Replacement GT28 wheels(Compressor 49.70 / 67.40mm, Turbine 46.95 / 53mm), Hitachi CHRA bottom right, Garrett T28 CHRA bottom left.

 

Then I did some more googling and it turns out a place already does almost exactly this modification and calls them the BNR Stage 3's. Damn, I thought I was being cool and original. Still I'm only into the modification for around $180, so if I can make it work it'll be pretty sweet :-).

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