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Turbocharger
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  The turbo is from an '88 Impulse 2.0 L engine. It came from the junkyard with the exhaust manifold, the down tube out of the turbine housing, the stepper motor for wastegate control, the intercooler and a whole bunch of miscellaneous hoses, tubes, fittings, etc. More importantly, it is *much* cheaper than a new turbo or supercharger setup. Even if it is used, it's warranted to work and I'm looking for even the smallest amounts of boost right now so I think it's well worth it for what it cost me. I'll be giving the whole cost break-down and parts list when I'm done. Also try the DIY_EFI website and mailing list. The members of this list form a truly astounding knowledge base for just about anything related to engines. It's specifically intended for EFI related items, but continually covers performance questions outside of that as well as embedded systems questions in general. Forced induction and alternative fuel systems are a couple of big ones. The list is archived as well. If you're looking for an answer, check the archives. It's probably been answered several times before. If not, ask the list. I find it unlikely that someone on it hasn't had the same question or tried the same thing before and knows the answers.
Updates: Most Recent This will likely be the last update of the turbo. I've removed it now, likely for good. The reason is that I've acquired an Eaton supercharger that I'm in the process of fitting. See those details on my new page here. I did want to update what I ended up with on the turbo though. I ran most of the time with boost set to a maximum of 12 - 13 psi. To control detonation, I'm using several things. One is an ERL AquaMist water injection system with a 2 gal tank under the hood where the stock air box used to be. Another is an MSD 6BTM. This is basically their MSD 6AL ignition with their Boost Timing Master built in that retards ignition as boost comes up to a max of 12 or 15 degrees retard. I'm not sure which it is any more. I'm also running spark plugs that are two heat ranges colder than stock, and I run premium fuel. The ignition retard is adjustable with a dash mounted knob from 0 to 3 degrees of retard per psi of boost and I ran it around 1 - 1.3 or so. I opted to get the ignition and retard as one unit, but they do sell just a boost sensitive ignition retard for much less money. I think this would be fine by itself for the boost levels I'm running, but it's hard to say. I've had problems occasionally under boost with the engine missing. I've fixed that by closing the gap on the plugs down to 25 thousandths, which is common for boosted engines. For the fuel needed, I had wanted to use larger injectors and modify the MAF signal, but that proved not easily done because of my oddball shaped injectors. The early 2.6's used a standard Bosch type injector that's easily upgraded. Mine are made by JECS and I wasn't able to find a larger replacement without changing the fuel rail and possibly machining the intake manifold for them to fit. So, I ended up using the Cartech rising rate fuel pressure regulator. This is a regulator that raises fuel pressure from 1 to 6 psi for each psi of boost. I have it set to raise fuel pressure around 4 psi / psi of boost. This maxes fuel pressure out at around 100 psi @ 12 psi of boost. This is very high. A little too high for comfort actually. A lot of people will state that 60 - 80 psi is the max the injectors will work with. Some say 100 - 120 psi will be OK. It depends on who you talk to and what injectors you're talking about. Regardless, I'd highly suggest larger injectors, or even additional injectors over raising fuel pressure for anything over 6 or 7 psi of boost. Now to get that kind of pressure, I had to upgrade the stock fuel pump as well. That won't pump more than about 60 psi and that was at idle. At WOT, it's likely much less. To do that, I got a secondary Bosch external EFI pump off EBay. It came from an early 80's Jetta, but they came on a bunch of vehicles so they're common. The pump is mounted in series/parallel to the stock pump. Meaning that it's in series with the stock pump, but there is a bypass around it with a check valve as well. For normal driving, the 2nd pump is not running and the fuel flows around it through the bypass. When boost hits about 3 psi, the 2nd pump kicks in. The check valve in the bypass keeps the fuel coming out of the pump from re-circulating around to the intake side of the pump. This does 2 things. It allows me to run the 2nd pump only when needed, and if it craps out (and I don't blow up the engine in the process), it allows me to still drive home (somewhat sedately) with just the stock pump. With this second pump, fuel pressure will go up well over 120 psi. That's as far as my test gauge went, but I know it was going higher. I also upgraded all the fuel lines to a higher rated 250 - 300 psi line from Earl's. I also had my stock cam reground to work better with a turbo. I don't know the actual specs, but I had them maximize lift and duration while reducing overlap as much as possible. The difference was amazing. The turbo spooled up *much* quicker from low rpm, cutting the lag time almost in half. It also made the engine much more detonation resistant. With all these mods in place, I ran as high as 16 - 17 pounds of boost for a week or two. I was gradually turning the boost up over a period of several days just trying to see how high I could go. I did notice that even at this maximum, I didn't have much trouble with detonation, but that after about 12 - 14 pounds of boost, additional boost didn't seem to add a whole lot. I think this is just the limit of the rather undersized turbo I'm using. This is so far out of it's efficiency map, that the back pressure and heat of compression it was making was offsetting any additional boost I dialed in. Due to this loss of additional performance, and the fact that I really didn't have a satisfactory solution for additional fuel for this much boost, I dialed it back to 12 - 13 psi which seemed to be the sweet spot. Even this is on the high side for a rising rate FPR I think. Anyways, the turbo was great and I managed to keep the engine in one piece despite running it for hours on end at 8 - 10 psi of boost (open road, high speed and stiff head wind. Long story). I had originally wanted a supercharger though, but the turbo turned out to be a relatively easy and cheap option at the time. I ready now though, to try the SC route. With such a small motor on such a heavy vehicle, I think the SC will feel quite a bit different (and nicer) than the turbo did. We'll see....
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