Ben's 914 TURBO Official World Premier, 'cuz it didn't blowd up. Options

[airsix]

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.

[airsix]

James, that was some great info about turbo application history. I always wondered how it was that late '90s turbo's like the Eclipse and Supra could run such high boost levels and such high static compression ratios. What you say makes sense.

Thanks for the compliment about my strategy. I'll tell you what, many times over the past 2 years it didn't seem like the right thing. It's been a steep learning curve dealing with the EFI and learning to tune with it. I think the best money I've ever spent was that LM1 wideband O2 sensor. Tuning without the wideband was like taking tests and only being told if you passed or failed, never knowing what you did right or wrong. Using the wideband O2 is like getting your test back so you can see what problems you missed.

I hope others do this sort of project. If anyone else wants to do a turbo-4 I think you could do it very inexpensively with a good junkyard turbo and megasquirt EFI. I am happy with my EFI, but I bought it pre-megasquirt. Is Kit Carson's EFI going to support forced induction? If so, I think one of those two systems would be the way to go if you're on a tight budget (Perfect Power makes some nice mega-feature ECU's if you want to spend a few $100 more). Let's say you go with megasquirt, a junkyard turbo, and an LM1 wideband O2 for tuning (I can't stress enough the value of the LM1). You could easily keep the whole project under $1,000 if you do the fab work yourself. My total cost to date including the EFI is about $750. Megasquirt would have been a couple $100 less. That's cheaper than carbs! Don't underestimate the cost of "the little stuff". After the EFI was on and working it cost another $175 to do the turbo install. Only $50 of that was the turbo its self. $125 was all the little bits and pieces of nickle and dime stuff (hose clamps, fittings, exhaust tubing, etc).

-Ben M.

ps - so what do you guys think? Intercooler or water-injection? (The age-old problem: I just can't think of a practical way to get airflow over an intercooler)