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.

[Evill Ed]

UPDATE:

Well, I drove it to work today. I'm really liking this boost thing. (IMG:style_emoticons/default/biggrin.gif) But the 'not going past 4k rpm' part got old real quick because that's when thing are just starting to really get fun. If you recall this is a self-imposed limit because I haven't finished converting the fuel pressure regulator with a boost-reference port and the injectors can't keep up past around 4,700 rpm. So tonight after getting home late from work, and spending time with Jamie and Kimberly I went back out to the garage to try to figure out a way to get the broken drill bit out of the fuel pressure regulator adjustment bolt. No joy. So after wasting a bunch of time on that dead-end I scrounged up an 8x1.25 bolt and made a new one (square cut threads and all). This time I drilled it right by making a tooling plate to hold the bolt perfectly vertical. That worked. Bored it straight down the center. I then drilled the head of the bolt to press-fit a piece of tubing for the vacuum hose. So far so good. I got it back on the car and adjusted the pressure to 30 psi. Went to hook up a vacuum hose and the stinkin tube pulled out. Ok, going to have to solder it. Can't believe it pulled out. I had to press it in with an arbor press. Oh well. I need a vacuum hose 'T' anyway (I was going to temporarily steal the line to the BO valve). Tomorrow I'll grab a 'T' on the way home from work, solder the tube into the bolt head and see how it works.

This boost stuff is really a new tuning experience. I thought I had my ignition advance curve roughed in pretty good but I found out today that it'll need some more work. I had roughed it in by doing some second-gear pulls from idle to 5k rpm. But what I found out today is that I'm going to need to refine the boost-retard settings further because If I rip through the gears there is more boost the second time through the rpm range. For example if I'm loping along in 2nd @ 2,000 rpm and floor it I might have around 3 lb. boost by the time I get to 3,000 rpm. If I take it up to 5,000 rpm and grab third I find myself into a lot more boost than I was at the same rpms in second.

Ed(s), and others who've done this sort of tuning... What kind of advance settings are/were you using? My ECU will allow me to subtract from the advance angle at various manifold pressures. I put in a linear boost-retard from 0 at atmospheric to -10 at 10psi. (For example the advance angle at 3,000 rpm and 10 psi would be 27 - 10 = 17 degrees). I really don't know if this is even anywhere near close. (no intercooler)

Thanks for keeping the chatter up. This is fun.

-Ben M.

Ben, 1 degree of retard per pound of boost is a good guide line.
I found that I needed to be at 24 degrees for anything over 8-psi. Your system is more adjustable than mine was so you will have to experiment. I would start a little higher, 24 vs 17 and back it down as necessary. Too little timimg is no good either and will cost you power.

Regards,
Ed