View Full Version : 24x conversion questions

July 5th, 2009, 07:59 AM
I have a 1975 Chevrolet Monza 2+2 with a 383 (aluminum Motown block, AFR 195 Competition ported heads, 74219 Lingenfelter cam, ported Superram, etc.) which will most likely be backed by a Tremec TKO 600 five speed transmission, 8.8 ford 3:23 rear with Maximum Motorsports torque arm etc.).

I want to use the EFI CONNECTION 24x system with the 12200411 PCM and the 58mm Drive by wire throttle body ( which has no vacuum ports).

1) I have modified my gas tank to accept the 99-02 LS1 Camaro fuel module. I was originally plannng to gut the internal regulator and run a standard return line back from the fuel rails. Could I keep the internal regulator and convert the sytem to a returnless system? Can tpi style injectors be run continuously at 58psi? I was thinking I could eliminate the rail mounted regulator by replacing it with the same crossover tube that is used at the front of the tpi fuel rails. It has been mentioned that the LS1 returnless system all use fuel pulsation dampers on the fuel rails. I have found a few sources for these and don't see any reason they could not be added to the factory tpi rails. The only drawback I can think of using this system would be the loss of fuel cooling effect inherent in a return system.

2) I am keeping my factory gas tank and charcoal canister. Since the drive by wire throttle body doesn't have a ported vacuum source I am faced with either modifying the throttle body or adapting the Ls1 canister purge solenoid.
My preference is to use the Ls1 canister purge solenoid. I have replaced the 40-240 ohm LS1 fuel sender with a 0-90 ohm fuel sender from a 97 Grand Prix so that my factory gas guage would work properly. Can the PCM be programmed to function with a 0-90 ohm fuel sensor? I will not be using a canister vent solenoid or the tank pressure sensor. If I set the PCM to not display EVAP related codes will the canister purge solenoid still function based on throttle position and engine temperature readings?

July 5th, 2009, 12:11 PM
Just a quick note on the missing vacuum and breather passages of the electronic TPI/LT1 throttle bodies...


The most important requirements were...
- direct fit, no air intake modifications
- use of LS1/LS6 Corvette throttle body motor and TPS

Due to the throttle shaft moving rearward to mesh with the motor's gear, no adequate breather passage could be machined. The throttle shaft location also creates a problem for a vacuum port.

These were acceptable compromises as there are other options for breather and vacuum. Many hot rod guys block off these passages anyway.