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Cedric · Joined: 27 Aug 2004 Posts: 2771 Location: Sweden

Im glad you are out boosting around in the car!

I wish paint wasnt such a nightmare to do and/or shitloads of money.
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1980 924 Turbo
www.instagram.com/garagecedric/

Carrera RSR · Joined: 08 Jan 2010 Posts: 2312 Location: Somerset, UK

Beartooth · Joined: 05 Apr 2022 Posts: 305 Location: Roberts, MT

That's actually a very similar color, and level of oxidation, to my 560SEL. I half-like the look, except I've got some rust peeking out on the R rear quarter panel (isolated problem, thankfully). I'll probably repaint it at some point, but other than the rust, the look doesn't bother me much. So don't sweat it unless the car just isn't pretty to you anymore. My 931 looks waaaay worse, but people still think it's cool. The "patina" scene has gone a little far now that it's common to actually fake it, but I'm glad there's been some push-back against the ridiculous expectations in some crowds. It probably rules out taking the car to a proper car show, but all the real car guys notice and appreciate the car as it sits anyway.

Paint is a ton more work than you realize until you actually paint a car. What I came to realize in painting my 560SEC is it all boils down to your time and expectations. Once you've got the equipment, the budget side of it isn't too bad, although you're going to spend close to a thousand at least in materials on a paint job you really care about. For someone interested in a DIY, but without facilities to do the actual paint, probably the best thing is to find a body and paint shop that'll work with you so you can get it ready to spray (or close anyway), then have them spray it. Some will rent out a paint booth, but until you have some practice, it's pretty easy to waste the money you save in paint and mediocre results. DIY, even short of the paint itself, is a messy and fiddly process, so not for everyone.

For someone looking to have a shop handle it all, you've gotta research research research, and shop shop shop. And it might involve taking the car a few hundred miles to get the price and quality you want. It's easy to dump a bunch of money and get so-so results, especially if you're in a hurry. A lot of times, a small - maybe one-man - operation will get you the best result for the money. The thing there you have to be careful of is avoiding the shops that promise all kinds of things, then either sit on the car, or keep upping the price. Unfortunately, horror stories are fairly common on the bigger forums. Anyway, after doing my own work a bit, I can see why show-car paint jobs cost so much. You end up cutting corners on a typical respray because going down to bare metal and demanding perfection in every nook and cranny takes many times more work, and unless you're entering it in car shows, or you really cheap out, you're the only one who'll notice where you could have done better. I'm hoping to get going on the body and paint on my 931 this winter; I'll definitely start a thread on that when I do. Whether you DIY all, some, or none, it's a fun process when it goes right. I've found few things more rewarding than to see a fresh-looking, shiny thing of beauty emerge from the dust created by all the sanding, filler, sanding, primer and sanding sanding sanding it takes to get to the point where you can lay down that shimmering new paint.
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1980 931 diamond in the rough

Cedric · Joined: 27 Aug 2004 Posts: 2771 Location: Sweden

Yeah, i repaired and painted a front wing/fender, front panel and roof lid many years ago, it was soooo much work to get it to a nice finish, sooo much sanding and cleaning. and paint dust everywhere. I wouldnt use my own garage for paint

Here is a plot i made of calculated boost temp at 65% compressor efficiency, at normal 20degC ambient. As Steve says, its fairly simple thermodynamics

So 1 bar of boost should end up around 125degC or 257F, if you for example had a better compressor with 72% efficiency it would lower the temps to 116degC or 240F. And it would take less back pressure to reach the target, which makes the engine breathe a bit better.

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1980 924 Turbo
www.instagram.com/garagecedric/

chuck21401 · Joined: 20 Feb 2005 Posts: 590 Location: Annapolis, MD

re: paint

Yes. More research to do. I've considered DIY but also taking to a shop.

At this point I'm thinking about just getting the hood done....and save up to get the whole car painted. The cost to get it done right is far more than the car is worth. So I guess my goal is "presentable." I don't even notice the paint job when I'm driving the back roads.

re: simple thermodynamics

Interesting graph. I'm running the K26 2664 G4.10 turbo, probably good enough for me at this point. I'm impressed with the performance of the top mounted intercooler at the boost levels I'm running in terms of keeping the intake temps under control.

Here's a 20 second video. Not easy to see the numbers on the gauge...but essentially the air temp after the turbo hits 255F on boost while air temp after the intercooler at the intake hit 105F. Ambient air temp was 75F. Temp of the water circulating through the intercooler to the heat exchanger hit 86F. https://youtu.be/W8yftEC8Llw

re: less back pressure

I'm running stock exhaust/muffler with a cat converter that was hollowed out by a previous owner. I like the way the car sounds now, it's fairly quiet. When driving on a two lane road through the woods you can hear the turbo spooling up. I'm not sure what that's called. I have a 2016 VW Jetta with a turbo as a daily driver and I can't even tell that it's there most of the time. Anyway, I like the idea of a free flowing exhaust but would want something that doesn't make a lot of noise.
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1981 Porsche 931 w/S1 engine & euro g31 transaxle. Water-cooled intercooler