Ben's 914 TURBO Official World Premier, 'cuz it didn't blowd up. |
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Ben's 914 TURBO Official World Premier, 'cuz it didn't blowd up. |
airsix |
Sep 13 2004, 01:04 AM
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#41
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I have bees in my epiglotis Group: Members Posts: 2,196 Joined: 7-February 03 From: Kennewick Man (E. WA State) Member No.: 266 |
Ok, so it isn't as cool as Chapman's 914-6 Turbo 3.0, but it's a turbo 914 all the same. Ladys and Gentlemen, at about 10:00 PST I got boost and there was much rejoicing. I took the car out, filled it with premium, tuned it with the laptop a little to make sure it got plenty of fuel under boost, and the mission was a sucess. Boost starts to come on at ~2,700rpm and is going full-steam by 3,500rpm.
I stand (ok, sit) here before you my brothers to declare that yes indeed, you can turbo a 914. (IMG:style_emoticons/default/clap56.gif) Details: Engine: '73 1.7, stock internals EFI ECU: Perfect Power MIC3 (Cost ~$500 to get on the car and running 3 years ago) Misc EFI stuff: Subaru 1.8T injectors, Holly throttle body off a 3.0 Chrysler, BMW 5xx fuel pump, foam motorcycle aircleaner (temporary) Turbo: IHI off 1.8L Subaru (including wastegate) Misc Turbo stuff: Bosch blow-off valve (for a Saab I think). Cheap. Plastic. Works great. Total cost to add turbo: $175 (EFI was already on the car. Use Megasquirt+turbo and you can do this for <$400 easy) I tried to modify my fuel pressure regulator with a boost-reference port like the in the dune-buggy.com article but I broke off a wire guage drill bit about 1.5" deep into the bolt. Dang. Only had about a quarter-inch to go too. So I just bolted it back on the car and set the fuel pressure at the 30psi I have the ECU turned for. I tried to crank up the injector pulse width under boost to compensate, but they hit 100% duty cycle at 5,000rpm because at that point they only have 20psi effective pressure (because there's 10lb of boost by that point). So I'm keeping it under 5k rpm until I get a rising-rate pressure regulator. The wideband O2 says mixtures are just fine below that point. I estimate I'm getting 110hp (That's not a WAG. I really did the math) which doesn't sound like much but is sure better than the 80hp I had before. I would still like to add an intercooler which could put it in the neighborhood of 130hp without getting too boost-happy. Even as it is now I would say it's 100% more fun to drive. I'm really happy about it. I'll get the pressure regulator issue squared away so I can run it up to 6k and I think it'll keep me happy for quite a while. Rick said "This thread is worthless without pictures" so here's the best I could do. If you missed the earlier thread I'll throw in one of the earlier pics too. I tried to make a video but all you hear is wind noice and the blow-off valve between shifts. |
lapuwali |
Sep 14 2004, 02:49 PM
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#42
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Not another one! Group: Benefactors Posts: 4,526 Joined: 1-March 04 From: San Mateo, CA Member No.: 1,743 |
QUOTE Are they set up for adequate cooling with oil alone? Wondered about that myself. As I understand it, the primary reason water-cooled bearings came into being was that even the oil-only turbos had cooling problems, esp. on shutdown. The oil would fry once the pressure went away after shutting off, coking to the bearing. I supposed what one could do is use a small heat exchanger (like an oil cooler) with lines to and from the bearing. If you mounted the cooler more or less level with the turbo, there would be some thermo-siphoning effect to keep the water moving even w/o a pump, and this would work even with the engine off. Would work best if you ran the hoses parallel to each other, one above the other, so one was the "cold" hose, and the other was the "hot" hose. Hot water would rise in the bearing housing to the hot hose and sink in the cooler as it lost heat, pushing the cooled water at the bottom of the cooler along the cold hose into and up into the bearing housing. Pretty cheap to do. The air hose from the fan housing currently blowing air through the bearing housing could instead blow it against the cooler. I have no idea if this would be adequate, but it sounds like it would be better than just relying on the oil alone. |
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