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t4brew wrote: I had the same reaction to that system. So far I have acquired the ECM, chip, harness, throttle body, fuel rail, manifold, injectors, fuel pressure regulator, TPS, IAC valve,MAP sensor, coolant sensor, knock sensor, crank trigger wheel, trigger sensor and 02 sensor for $800. I also spent $20 for a chip definition file so I can modify the settings on the chip. I have already made changes for things like the fuel cutoff RPM, fuel return RPM, radiator fan temp on, radiator fan temp off, injector pulse constant for the S4S injectors and the speed sensor conversion. The GM ECM is very tunable. Tuning the VE and spark advance tables will take some time. The Quad 4 W41 spark advance table seems to be very close to the Lotus 912 advance curve. The VE tables may take some time to get right but should not be too difficult. I still have to purchase a high pressure fuel pump and the additional fuel line. Hopefully I can stay under $1000 for the complete system.
Jenvey has a set of DCOE throttle bodies:GAH! that is over $3000USD for that kit. I don't think I have any more than $700 - $800 in my setup. VASTLY cheaper and I bet works just as well. Three weekends ago I drove my Jensen-Healey with the EFI setup to Las Vegas Nevada and back from Phoenix Arizona. I went there for the national Lotus Owners Gathering. This is a 5 - 6 hour trip each way and the car performed flawlessly except for a tire vibration issue on the way back home. The engine however ran just fine and was quite lively with very reasonable temperatures as well.
Lotusbits sells a kit that includes the Jenvey throttle bodies and engine management
I am looking into using a throttle body, manifold, fuel rail and engine management
system from a Lotus Esprit S4S on my 912 engine. The same engine management
system was also used on the GM Quad 4 2.3 L engine and I plan to use a chip from a
Quad 4 W41 engine as a starting point. The Quad 4 also used the same sensors as the
S4S so parts are easy to get (other than the throttle body, fuel rail and manifold).
Let me also add that now that I have a much better understanding of what it takes to put together an EFI system I understand why kits like the one that Lotusbits sell cost so much. I am sure Mike Taylor at Lotusbits has thousands of dollars of development, dyno and tuning time in that kit and since he will only sell a few of them he has to price them that high to make any money.
Last edited on 11-03-2011 12:44 am by t4brew