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

[technicalninja]

Once you get the venturi and the booster out you won't have to block anything off.

You WILL have to block any passage below the blades off. Easy button is screw in the air bleed and the idle mixture screw until they seat.

You've got one air bleed screwed up, might cause an issue...

Two 45mm throttle blades is plenty of flow for 200+ HP.

Will you be using two carbs as ITBs?

The only issue I can see is the damaged air bleed.

You should be able to use the air bleeds to adjust idle speed along with ignition timing idle control. Properly adjusted this fairly old method will work FINE!

You will need a TPS.

You won't need an IAC (as long as you solve your stripped air bleed).

Edit:

There is a chance you could use the mixture screw as an air bleed for idle control.
You would have to seal the stripped air bleed.

[VaccaRabite]

I mostly agree with Ninja - except on the part about not needing an IAC. They do a LOT more then just give you an idle speed. They also give you warmup control and easier starting from cold. Its really part of what makes an FI car pleasant to drive.

Implementing an IAC on ITBs is challenging. Its also been done, so you are not starting from scratch. I have it on my current 2258.

I will say this though - PMB is working on a common plenum for stroker engines using a single TB (last I heard, it was going to use Miata TBs). There are good reasons why almost all modern cars have moved past ITBs.

Zach

[emerygt350]

Yeah, for simplicity the single can't be beat. Not only do you need the iac for warm up etc but in some cases it feathers the throttle when you snap it shut, keeping the engine from dying. If I were to move away from d-jet I would keep the injector locations and runners and just use a single TB + modern equipment. Although the itb would of course look so much cooler.

The first fuel injected (tbi/cfi) mustangs attempt at all of this without an iac is rather instructive. It has a 'kicker' that is used to catch and slow the close of the throttle, a kick that rescues it if it does dip too low, and another kick for when the AC is on, and finally a kick used to knock the throttle off of the cold start cam (all vacuum operated). The actual idle itself is controlled by the computer modifying the timing.

[technicalninja]

I HOPE they don't use stock Miata throttle bodies...

I have 4 Miatas, two MSMs. and NB1 and a NB2.

The stock throttle body has a known failure point.

The shaft is too thin, it cracks with high vibration and drops the butterfly screws into the engine.

TARGET DOWN!

The "fix" is a "Skunk II" T-body that need a bunch of mods before it can work. Hogging out the IAC passages is one of the mods. Too wimpy throttle return spring is another.
They are commonly referred to as "Junk II"...

IACs and ITBs together has never worked worth a shit for me.
Making the "plenum" so the IAC can feed all cylinders NEVER works like you think it will.

In the case of a T4 with digital FI I believe I could make warm up smoother via a bit higher RPM idle setting and computer control of ignition timing. Adding 5-8 degrees IS worth 2-300 RPM on most vehicles...

I live in a climate that does not get stupid cold. This might be more important at 20 below.

Now something with a single throttle body and plenum is SET UP for IAC.

Only issue I have with an IAC now is the cost of a Bosch Motorsports ETB...

Here's a 60mm one. Included in it is a T-body, TPS, and idle air control.

https://www.summitracing.com/parts/bch-0280...p433MYHjhtqmRJo

If I was setting up a "new" plenum system this is what I'd use over ANYTHING...
Gets rid of so much crap and only adds a bit of wiring and a throttle sensor/pedal assembly.

Another member on this site posted about 2005ish Acura TSX throttle sensors. They are remote to the pedal and operate via a throttle cable.

Don't know if they will work but it's worth investigating...

[mb911]

Once you get the venturi and the booster out you won't have to block anything off.

You WILL have to block any passage below the blades off. Easy button is screw in the air bleed and the idle mixture screw until they seat.

You've got one air bleed screwed up, might cause an issue...

Two 45mm throttle blades is plenty of flow for 200+ HP.

Will you be using two carbs as ITBs?

The only issue I can see is the damaged air bleed.

You should be able to use the air bleeds to adjust idle speed along with ignition timing idle control. Properly adjusted this fairly old method will work FINE!

You will need a TPS.

You won't need an IAC (as long as you solve your stripped air bleed).

Edit:

There is a chance you could use the mixture screw as an air bleed for idle control.
You would have to seal the stripped air bleed.

Not necessarily. I use my triple Webers as TBs and don’t use a TPS

[technicalninja]

Not necessarily. I use my triple Webers as TBs and don’t use a TPS

@mb911

My GOLDEN rule is "There are always exceptions to the rules"

Someone will ALWAYS prove your wrong...

Now, without a TPS (or something else) an electronic brain cannot ANTICIPATE increased load.

You effectively have no accelerator pump circuit.

A non-TPS system will ALWAYS be "catching up" and does not have the ability to add fuel BEFORE it sees a change in either RPM (ignition) or load (MAP/MAF/airflow meter)

Unless your guru has come up with another way to add fuel at throttle tip in, I'm positive that adding a TPS will improve throttle response.

Do you log?

I'd WANT to know what my AFRs did during hard acceleration.
With no acceleration additions I'd expect it to show lean.

Bosch's simplest electronic FI was the mono-jet (TBI for GM, CFI for Ford).
This system has four main inputs. TPS, O2, RPM, and engine temp.
It had NO "load sensing" at all.

One thing to remember, a TPS shows throttle position AND rate of change.
You hammer the throttle; the FI will provide more fuel than if you opened it slowly.

The TPS is a requirement in my book...

[GregAmy]

If you're reeeeeellly interested in doing this...I have a pair of the below TBs, with IAT and TPS and injectors and electrical terminals and Weber intake manifolds and air cleaners for the 2L Type 4. All pretty much bolt-on except for gaskets and a thorttle actuation system (I use the Tangerine cable system but I may keep that to update my Dells race car).

I've been threatening for two summers to convert my D-Jet Microsquirt (see sig for blog link) to these. I've failed two summers in a row to do it. and I drove my street 914 about 500 miles this year so it's low priority (I bought a 968 that required some maintenance and repair attention this year).

I was looking at all this in my garage last week, doing some soul-searching and questioning myself as to whether I'd ever actually do this. I could not answer my question.

So if you're reeeeeellly interested in doing this...maybe this is the better way.

https://thedubshop.com/dual-idf-throttle-bo...injectors-vwss/

[emerygt350]

Not necessarily. I use my triple Webers as TBs and don’t use a TPS

@mb911

My GOLDEN rule is "There are always exceptions to the rules"

Someone will ALWAYS prove your wrong...

Now, without a TPS (or something else) an electronic brain cannot ANTICIPATE increased load.

You effectively have no accelerator pump circuit.

A non-TPS system will ALWAYS be "catching up" and does not have the ability to add fuel BEFORE it sees a change in either RPM (ignition) or load (MAP/MAF/airflow meter)

Unless your guru has come up with another way to add fuel at throttle tip in, I'm positive that adding a TPS will improve throttle response.

Do you log?

I'd WANT to know what my AFRs did during hard acceleration.
With no acceleration additions I'd expect it to show lean.

Bosch's simplest electronic FI was the mono-jet (TBI for GM, CFI for Ford).
This system has four main inputs. TPS, O2, RPM, and engine temp.
It had NO "load sensing" at all.

One thing to remember, a TPS shows throttle position AND rate of change.
You hammer the throttle; the FI will provide more fuel than if you opened it slowly.

The TPS is a requirement in my book...

Handling tip in comes up quite a bit when I researched the Ford cfi on the gt350. There were many variants in just Ford alone between 83 and the last of the cfis and even across applications during any year. It is neat how d-jet handled it.

[mb911]

Not necessarily. I use my triple Webers as TBs and don’t use a TPS

@mb911

My GOLDEN rule is "There are always exceptions to the rules"

Someone will ALWAYS prove your wrong...

Now, without a TPS (or something else) an electronic brain cannot ANTICIPATE increased load.

You effectively have no accelerator pump circuit.

A non-TPS system will ALWAYS be "catching up" and does not have the ability to add fuel BEFORE it sees a change in either RPM (ignition) or load (MAP/MAF/airflow meter)

Unless your guru has come up with another way to add fuel at throttle tip in, I'm positive that adding a TPS will improve throttle response.

Do you log?

I'd WANT to know what my AFRs did during hard acceleration.
With no acceleration additions I'd expect it to show lean.

Bosch's simplest electronic FI was the mono-jet (TBI for GM, CFI for Ford).
This system has four main inputs. TPS, O2, RPM, and engine temp.
It had NO "load sensing" at all.

One thing to remember, a TPS shows throttle position AND rate of change.
You hammer the throttle; the FI will provide more fuel than if you opened it slowly.

The TPS is a requirement in my book...

Correct it uses rpm and map off my 6 restricted vacuum ports to single manifold which leads to the map vacuum port on the ECU. I will have to grab a screen shot next time I log which will be 5 month or so from now(snow) from a driving experience it has identical throttle response to what it had when running carbs. Also a broader power band but that is also because the wideband is making adjustments. Very happy with my simple system. My biggest complaint is how loud the fuel pump is and that’s all

[cgnj]

Actually, What started me on this was many years ago I read this threadStock 2.0l plenum and runners on 2270, It will flow enough air I just opened the box with all the parts I collected for this. It also has a 2.1 water boxer plenum (reworked to accept 914 throttle cable) and the TB. Then I started working on my other project cars. They are all finished now so I'm back to disabling a good running 2270 motor.

Availability of reasonably priced ITBs is the problem. CB appears to be the only company with them. Can't be ordered from Mario atm.

If @GregAmy decides to sell his stash, I would be in the market. Good article regarding your microsquirt conversion. You should post it here so it can go into the Lapuwali Classic Thread Forum.

[GregAmy]

If GregAmydecides to sell his stash, I would be in the market. Good article regarding your microsquirt conversion. You should post it here so it can go into the Lapuwali Classic Thread Forum.

There's a thread about when I was going through it. The blog is there and it's free to use for anyone that wants the info.

After posting that later tonight I've gone back and forth. But at the right recovery-of-costs price I'd let it go because I kinda don't think I'm that motivated. But it's winter so who knows.

As for the D-Jet induction...I've got a 2056cc with a FAT Performance EFI cam (less lift and duration than a Web Cam 86 null) and around 9.5 compression. I'm tuned pretty good with the Microsquirt. As I review the latest logs I did notice that my MAPs at full-throttle runs (per TPS) were all around 98kPa...even to the 6000 redline. And that's with the stock D-Jet throttle body.

Does that not imply a damned-near no restriction? Would a bigger throttle body even give me much more power?

That's exactly why I wanted to do this ITB experiment. Dyno the car as it is now (I still have not done that since the engine rebuild) and then swap it to these ITBs, and then see if there's really any difference. If I were a betting man...I'd suggest that the ITBs on this engine would not offer a significant increase in performance.

On a big-cam 2.4? Yeah, probably. But on this one? Eh...

Which is pretty much why this experiment has stagnated. Seems a lot of work to prove something that I think I already know...and am not likely going to bother to build a bigger engine to find out.

I'll gather up all the parts to see what I actually still have.

[JamesM]

On a big-cam 2.4? Yeah, probably. But on this one? Eh...

Doesn't even need big displacement to be a restriction, just a motor that wants more air. on my 2056 even with a 52mm throttle body my manifold pressure increasingly drops to about ~8% on WOT runs above about 4k RPM.

You can calculate roughly the power level where a certain size TB becomes a limiting factor. Im going to guess your 2056 is built to somewhere in the 120-130hp range?

[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