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Minor, and rather pointless, update: Duracool conversion still going strong, but DANG is this air conditioning noisy! I used the R12 expansion valve/orifice/filter thingy that I got from FCP, I don't know if that's the reason behind it and that I should have used the more modern, updated, variable-orifice one for the R134 systems (not the original R134 one), but there's a hissing/slurping noise at the evaporator. It's mostly at idle and it's nothing that the radio can't overcome, and it's not too annoying, but it's far from silent. Maybe I used too much oil, I dunno.
Anyway, it works great. Blows nice and cold, though we haven't had any crazy hot days for me to really evaluate it yet. Just after it was buttoned up we had a fairly warm day (in the mid-20s) and it kept up just fine. Strangely I haven't noticed if the compressor turns off when the temperature gets to the setpoint or not. Something I should look into I guess.
I'm also still chasing this annoying exhaust resonance. It's not like the pipes are vibrating, or that the system is hitting against the body, or anything like that. It's a tuned resonance. I think I noticed that the RPM range that it was happening at seemed to drop by a few hundred RPM when I put the manifolds on, and if the longer sections of 2" downpipe (compared to the relatively short 2" header collectors) have anything to do with it, I thought that maybe I could install a crossover in the exhaust to "shorten" the length of the pipes, and change the frequency at which it sings.
So I butchered something in place, that essentially divides the length of pipes into 2/3-1/3. I figured at worst it would do nothing, but ideally it would cut down on the 2300-2800 RPM resonant frequency and maybe move some more into a higher RPM range, where I would welcome the added noise. It sort of worked, a little. The note sounds a little smoother in the lower RPM range and when the exhaust is fully warmed up, it starts singing at about 3000 RPM and not as loud or for as wide a range. The downside is that 120 kph = 3000 RPM. I suppose that if I put the headers back on I might gain another couple hundred RPM out of that annoying zone and put it out of the daily driving range, but the headers made their own noise by virtue of being so thin.
The “warmed up” part concerns me a little. Since I added all this stiffness to the exhaust system, and since the downpipes are restricted in their growth capability, I’m wondering if part of this noise is from misalignment at the joints when the system is cold. When I originally built the system there was a ton of flexibility in the header primaries and a bunch of flexibility in the exhaust, but now everything is pretty rigid. I’m going to try a quick test and ditch the support bracket, letting the downpipes move around with the exhaust, and see if that makes a difference or not. If so, I’ll do a soft support on the exhaust, and if not I’ll put the bracket back on. Other than that, I’ll live with this for the year I guess. I’ve got a cat from Roberta’s 850 and if I get really tired of this system I’ll do something more conventional, like an unequal length 2-1 collector, run the exhaust straight up the right side, and make it all 2.25-2.5” diameter mild steel. Screw it.
These Bilstien HD struts are nice on the highway and I’m sure they’d be nearly essential on the race track, but driving around Calgary they’re killing me. I’ve ordered some Bilstien TC struts and will be installing them as soon as they show up. The spring rates, ride frequency balance, and dampening rates are all over the place. Once I get the front end to absorb bumps I might need to soften the rear springs with “standard” Toyota Previa springs (rather than the progressive “overloads” that I have). It’ll then ride like a Volvo, I suppose, but I’ve been moving more and more towards making this a comfy tourer than a sporty car, and this is just one more step. I guess the next step will be some 195/65 Goodyear Affinity 100,000 mile all-seasons, and a grampa hat.
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(Her Highlander would leave my car in the dust...)
