Converting IDF/DRLA to throttle body Options

[cgnj]

I have always wanted to do ITB FI for my 2270. I found a box in my stash of parts with a DRLA 45 with one of the air bypass screws stripped. I found this thread on STFSTF IDF/DRLA to throttle body.. I guess I would have to block off everything above the throttle plate, and machine my manifolds to for injectors. Feedback on this idea is appreciated

[JamesM]

to many posts to respond to each one individually so ill try to summarize my points to keep this as short as possible.

1. Quad 45mm throttle plates is a LOT of air to try an modulate on a 2.3. Your throttle is going to be pretty touchy, especially around tip in and you most likely wont have decent enough vacuum to run a speed-density fueling algorithm properly so you will be stuck with alpha-n which is sub optimal. If you keep the vents and choke them down to ~40 or less you might be ok, but you still have a 45mm throttle plate... might as well just start with 40mm ITBs to begin with.

2. You don't need an IAC. When a motor is tuned properly an IAC does absolutely nothing at idle. They can compensate for for a bad tune or other issues the motor can be having but that is not necessarily a good thing as they then MASK problems you might otherwise be aware of. These cars run just fine fixed timing at idle but additional idle stabilization can be had just via timing control, no IAC needed.

3. IACs with ITBs can potentially be problematic. In order to get enough air flow though the IAC to the individual cylinders to make a difference you have to run a pretty big line to each of them from a distribution block which then connects all your runners. This then allows the intake stroke from one cylinder to pull air/fuel from another disrupting the mixture of individual cylinders. In addition most ITB setups for type 4s place the injector in the throttle bodies themselves near the throttle plate leaving the only place to add lines for the IAC BELOW THE INJECTOR!!! This means air can now flow under the fuel charge rather than through it which can be especially problematic if you attempt to rely solely on airflow through the IAC for starting.

4. Depending on the ECU and fueling algorithm you use you DONT need a TPS for acceleration enrichment. On a speed density based system with decent vacuum signal rate of throttle change can be calculated via rate of manifold vacuum change. I can show you datalogs where the TPS state and manifold vacuum state mirror each other perfectly. That said I would still choose to run a TPS and it should be considered mandatory if you are going to run 45mm ITBs as you will most likely have to run Alpha-n.

5. @GregAmy I would suspect you will have a worse experience if you convert from d-jet plumbing to ITBs and potentially may even loose torque and tuneability. Might benefit power if you had more cam but with your current setup I suspect the cons will outweigh the pros.


And then we have this... (IMG:style_emoticons/default/smile.gif)

[GregAmy]

Im going to guess your 2056 is built to somewhere in the 120-130hp range?

That's my WAG.

I wanted more cam but in the build process there was some miscommunication between me and FAT regarding "EFI" and they installed their "EFI cam" that is much too tame, .398 actual valve lift/252 duration, 1.3 ratio.

Drives nice though. Decent street cam but could use some more nut.

BTW, I'm not running an IAC valve on this Microsquirt conversion. I have enough leeway with ignition advance that I can use it to idle up a tad bit during cold, as well as it cores the idle very well when warm. I'm not suggesting that cold warm-up is awesome but it's pretty damned good for the application.

GregAmy I would suspect you will have a worse experience if you convert from d-jet plumbing to ITBs and potentially may even loose torque and tuneability.

Completely agree, and I think the driveability would suffer...but it would sound really good...

This is/was to be an experiment to prove that negative and ultimately it would get converted back to the D-Jet induction, with the bits *maybe* saved to go on the big-valve 2056cc 7500-RPM race car (currently on Dell 40s).

But the street car is currently running nice on the D-Jet bits, and the race car is currently running nice on the Dells, so it all comes down to my motivation...which is flagging. - GA