Been a bit of a busy bee in the last year.
Got home from the States, and found a black steering wheel in my Ford Laser parts hoard (that I didn't even realize I had). It will have to do until I track down a proper grey one. At least the horn pad I brought back from the States is the correct colour, but the disparity will probably annoy me for a while. Yes, I know, I'm a sad pedantic bastard.
And then I managed to make some headway with the acceleration hesitation problem. This is how far my secondary throttles were opening at WOT:
And this is how far they're meant
The culprit, I'm pretty sure, is that confounded thing from the previous post:
...which is some kind of fandangled arm that's attached to a diaphragm that's collapsed, and can no longer extend fully to allow the secondary throttles to open.
I temporarily disconnected the diaphragm from the rest of the throttle body and cable tied it out of the way, went for a drive, and whoa, the difference was like night and day - no more shitty hesitation, stumbling or loss of power at 4000rpm anymore! Now the engine revs quickly and freely until the turbo drops off sharply (and the stock exhaust starts choking flow). Fixing or removing the diaphragm entirely has been added to the "to do" list.
Also, after noticing a series of loud clicking noises coming from the emissions "rats' nest
" on top of the engine in time with the part-throttle hesitation/idle flutter I've been trying to chase down, I replaced the vacuum solenoids, which definitely made the problem less noticeable:
The 12A turbo only has three solenoids compared to the US-spec 12A carby in the link above that has six.
Fixing the secondary throttles, replacing the solenoids, and releasing a whole heap more power and drivability spurred me on to try and get the car in a presentable state. So with that in mind, I commissioned Alex @ MLR to purchase a set of lush J.D.M. Zoom Down Force
lowering springs direct from the manufacturer in Japan.
These drop the height all round by ~40mm (up to a claimed 45mm on the website).
Not pictured - the leaflet which has a little diagram saying "CUT HERE FOR MAXIMUM LOWDOWN"
Had it up on the hoist while it was at the workshop for its bi-annual WOF, and we ascertained that the exhaust is pitifully small and is definitely strangling performance up top. I was originally of a mind to bin the catalytic converter and replace with straight pipe, but the car is still going to be held back by the 1.75" peashooter pipe from the downpipe back. I didn't want to get too carried away with the exhaust on what is essentially a stock car, yet I wanted to unlock that trademark turbo rotary "buzz"... so after some careful debating we settled on a 2.5" straight through system from the downpipe back, with two mufflers, and twin tailpipes similar to the original ones.
Woo-er, the 45mm ID stock exhaust is definitely not
Stock downpipe is nicely sized though - 50mm.
First section off the downpipe tacked together.
The mantra here is "rotaries need to breathe."
Shiny rear tip.
Here's what we pulled out of the car, all of this garbage weighs an absolute ton. This is Yuck!
We also took this opportunity to install the ZOOM springs.
And the final result? Well, here's the video evidence:https://www.youtube.com/watch?v=Ei1OZjaQJ7Ihttps://www.youtube.com/watch?v=ghdATRvmQf8
Huge thanks to Karl and Casey at Autoworks East Tamaki for the use of tools, hoist, endless guidance, and some plainly awesome fabrication and automotive skills. Those late nights were definitely worth it. As you can see in the first video the car sits a LOT lower... with the added bonus of handling a whole heap better too, with less boating around corners.
Next I went on a trouble-free 857km road trip around the Coromandel Peninsula southeast of Auckland. After discovering the back felt a bit too skittish when hitting mid-corner bumps, I firmed up the factory adjustable front dampers a bit and softened it one click in the rear. Otherwise it gripped well and absolutely flew.
The beauty of the rotary engine is that it's so smooth and builds momentum in such a linear fashion that you can keep winding the revs out and the car just slingshots itself around corners. Still needs the wheel alignment sorted as it doesn't track too well in a straight line, but I'll get onto this ASAP.
The exhaust stayed in one piece and sounded absolutely mint echoing through the Coromandel hills... there is nothing quite like the unique buzz of a turbo rotary on song above 4000rpm. Most of the odd surging and performance issues seem to have disappeared now that the exhaust has been opened up for better flow, but I'll continue to try improving some of the niggly drivability things.
If anything, all of the low-rpm pops and bangs and occasional lumpy/brappy sounds give it more character with the new exhaust, whereas before with the stock exhaust they were just plain annoying - quite possibly because there were no audio cues to work out exactly what was going on!
Speaking of niggly drivability things, a big annoyance that's plagued me ever since I got this car seven years ago is how difficult it is to find drop-in air filter replacements. Mazda and all of the usual filter manufacturers have discontinued making them, and the best anyone can do locally is order new old stock from Australia at exorbitant cost and hope it's still sitting in a dusty warehouse somewhere ($180 for a Ryco!)
But after doing some research I found that the air filter is identical to the American 13B injected Series 3 GSL-SE, and K&N made a drop-in replacement up until the late 1990s. After a few emails back and forth with K&N and a bit of googling
, I managed to obtain a part number (33-2016
) and found a couple of vendors on Amazon who happened to still have old stock.
As luck would have it, one of the vendors had a single brand new 33-2016 left, without box, on clearance for US$25.00+shipping. Excellent!
One Youshop payment and nine days later...
The state of the old air filter was shocking, to say the least. For all the supposed meticulousness of the previous owner in Japan it looked like it hadn't been changed in about ten years, and one of the corners had even started crumbling away. Umm, okay then
Airbox cover off, ready for the swap. I felt a bit guilty tearing open the sealed wrapper, knowing there are fuckall of these things left!
K&N part number.
All fitted and ready for the airbox cover to go back on. Good for another 5 horsepowers, you reckon?
Regardless of whether you think K&N filters are any good, hopefully it'll make a difference in the long run as the old crusted-up air filter definitely
wasn't helping things. The completist in me will probably buy another K&N from one of the other Amazon vendors, just for the box and associated gubbins.
Adding up all of the minor victories has been so satisfying