i haven't bought the E12 yet, but i'm trying to make that happen pretty soon. i think it'll be far enough under challenge budget that the DIY turbo wheels are spinning in my head. so, does anyone know if L-Jet can be boosted?
i haven't bought the E12 yet, but i'm trying to make that happen pretty soon. i think it'll be far enough under challenge budget that the DIY turbo wheels are spinning in my head. so, does anyone know if L-Jet can be boosted?
Fiat did it in 1982
Most of the major Japanese companies did it in the 80s. Nissan, Mazda, Subaru, and Isuzu used L-jet or Hitachi-licensed copies of L-jet on their turbo cars. (I don't know if Toyota or Mitsubishi did or if they used their own EFI)
Pretty sure Volvo and SAAB did, too. The German companies, oddly enough, tended to use K-jet because masochism.
Volvo used K-jet in the beginning, and went to LH later. I think Saab was the same, but not sure.
As others said, lotsa Japanese Turbo stuff was L-jet.
Datsun used L-jet with their l28et, iirc. I've even seen non-turbo L24's fitted with NA L28 L-jet parts and boosted. There was a way to widen the fuel pulse with the L28 bits, though I can't remember exactly, apparently that was the key. Also keeping it cool, but that's a given.
There are two things you need to account for on a boosted L-Jet that wasn't set up that way from the factory, assuming you don't ditch the ECU for a MegaSquirt 
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The flapper air flow meter is pinned fully open under full throttle in most applications, on a stock motor. The ECU won't "see" more airflow. If you can't reprogram the ECU (some of them are hacked) and use larger injectors, you could use a rising rate fuel pressure regulator.
The ECU doesn't control timing; you'll need some other means of dealing with that.
The L-Jet was one of the first modern EFI systems, so it isn't fundamentally different from other boosted EFI setups. And, as I hinted at earlier, L-Jet components can be used easily enough with other, more tunable controllers.
One of the hacks with making power with K-jet involves increasing the control pressure to widen the span of airflow that the air valve will meter. The L-jet analogue would be increasing the spring tension on the flapper.
As you point out, if the flapper maxes out at 160hp of air then it is not going to measure any more than that, so you have to increase its resistance so that it can measure more. Yes, this is only one part of a series of modifications, and will decrease fueling without doing other things. (Just like simply plugging a 3-bar MAP in where a 1-bar used to be will decrease fueling in a speed-density car)
It also slightly reduces the power the engine can make because it will increase the resistance to flow for a given amount of airflow, but it's a necessary compromise.
Now, if you want your brain to be boggled, RX-7 guys have successfully put the airflow meter on the pressure side of the turbo. I can see how that works with a MAF but not an AFM, since an AFM only measures volume, not mass, but I'll accept that it can work if you know what you're doing.
Include a MegaSquirt in your budget...
The datsun system is a rip off not an actual Bosch system. The Toyota 3sgte gen 1 and 2 used a very similar system. There are other system line on the 84-89 turbo 300zx that canbe hacked with a romulator for better tuning and you loose the afm
It's not a "rip off" if Hitachi built it under license...
In reply to MadScientistMatt:
PM'd. Forgot to say thanks in PM, so THANKS!
It can be done, Alpina sold a turbocharged e12 back in the day. You can probably find help on Scottie Sharp's website at http://bmwturbos.scottiesharpe.com/ Todd at TCD may be able to offer help, but he is in the business of selling new turbocharging equipment so I wouldn't lean on him too hard for free advice: http://turbochargingdynamics.com/
Zane Coker down in Florida built a killer turbocharged e12 that put out over 700hp at the rear wheels, but it was a very heavily modified car. http://www.firstfives.org/carmonth/jan2000.html
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