Auxiliary Fuel Injection controller VS an FMU

As some of you have seen (and po poed) I am looking into bolting a turbo onto my Honda Insight. The two things that I need to decide on is which teeny tiny turbo to use and how to make the engine happy when that little guy spins up.

There are two schools of proven builds for the Insight. The cheap way is a standard, off the self rising rate FMU. The other way is to build/buy a Auxiliary Fuel injector driver. Who has experience with these? I am a little worried that the FMU is a little less than reliable, however, for a small bit of boost (5-6) out of a tiny turbo (GT15 or similar) it might be ok. I know that one guy that was running a turbo from a Swift, I think, on stock management and was only getting lean issues over 4K. He then went to a home built aux injector driver and drove the car for 250K miles! The guys that sell kits just use a Vortech FMU, not sure of the ratio though.

Fmu can be made to work for a few psi and generally run well. Make sure your pump can deal with the additional pressure.

Used to make over 400whp with 6 19lb/hr injectors back in the dark ages.

So how does the ratio come into play? I am still a little vague on how to determine the appropriate ratio.

Edit: the internet told me how.

MegaSquirt Plug and Play?

I can ship you a Assembled and tested MegaSquirt with bluetooth. For Free! All you have to do is ship me a MS3 kit

On a Honda insight? Right now I am researching using an arduino to control a 4th injector.

I see now, you have to know what an insight is. Hybrid

Does the ECM do the motor only? or is it integrated?

If it was me, I'd dump the Insight and get a real car to boost.

Or keep the Insight and buy a pre-smog car to boost.

Well it is me and I am keeping the car.

Also, I live in MO. Why should I care about smog?

Not so much "smog" but pre-OBD. The computers in modern cars can be smart enough to "undo" any "fixes" that you do to it, throw codes, put things in limp mode and shut it down if it gets really grumpy.

That being said, using a MS as an injector driver is pretty easy if you can get an rpm signal sorted out.

I think for a light boost setup, the RRR is the way to go. I bought one for my parts collection that may one day end up on my Insight.

I think if you were going for real power you'd want more control, but if 'all' you want is a 60% increase in WHP i think the RRR is the simplest way to get there as far as 'tuning'.

Also, if i remember correctly there is a need to clamp the map sensor output to avoid freakouts but that CAN be as simple as a $3 zener diode.

FMU (etc) is one step above a carburetor, with all the analog failure modes that includes. Solid state is the way to go. We used to use FMUs, I haven't missed them once since they all got binned for aux injector controllers. BTW, what we do on low-boost kits is use a device that basically extends the pulse width of the stock injectors under boost. No changes at all off-boost, no fuel pump issues. You're limited to how much fuel the stock injectors can provide, but there's usually a fair bit of headroom.

Check to see what Jackson Racing does with their CR-Z supercharger kit. I'll bet there's some commonality with the Insight.

The stock injectors are only 140cc so I am not sure that they could handle much boost. Unfortunately, the turbo that looks like a good choice (Volvo T6 TD03) is internally gated at 8 psi. I would rather have 5 psi but if I run something like an AEM FIC with 185cc injectors (From the Civic CX no less!) would handle 8 psi decently on 91 octane. There are guys running 87 octane on 5 psi without water/meth or whatever.

Keith - Do you have any suggestions for simple aux injector controllers?

The term you're looking for is "Hobb's switch."

Also: kinugawa makes billet adjustable wastegate actuators for cheap that you could likely get to work on that turbo to get you the less than 8psi you want.

What does the Hobb's switch help me do? It allows me to activate something when the boost kicks in, but I am a little lost to what I am activating...

I check Kinugawa. Cool site but nothing for that particular Volvo turbo. Not saying I am 100% on that one but it is a solid choice.

On the obd1 cars we used to do one of two things to add/increase boost. Either the coolant temp sensor mod ( add resistance to fool the computer to add fuel ) via a Hobbs pressure switch, or activate a cold start injector the same way to spray extra fuel when you need it. I suspect the obd2 car won't let you fool the cts, but you could use either a cold start injector in the inlet tract, or an appropriately sized injector to spray fuel when you need it. Both are a little crude, but for what you want to do, totally appropriate. If you're handy with electronics, I have plans to build a simple extra injector controller that works, but you need to know how to make a circuit board.

All you need to do to lower the minimum boost is cut and thread the wastegate actuator rod to make it adjustable and then loosen the tension, or add another spring working opposite of the one in the can to effectively 'weaken' it.

In reply to Vigo:

So essentially I would be adding a few "psi" preload to fool the actuator into thinking that it was at its preset limit when is was actually where I need it. Nice.

In reply to Zomby Woof:

I am a little rust but am confident I could pull together a board. E-mail sent!

Hobbs switch is too binary. It's very crude unless you're using it to mask the effects of positive manifold pressure to the stock ecu. We've used them to tweak O2 readings in order to achieve a very specific result.

Fun fact: the first Miata turbo kit used a Hobbs switch to block off the return line on the fuel rail when the car went into boost. Even in 1989, it sucked.

We use a device of our own called a Voodoo Box to take advantage of existing overhead in the stock injectors. I haven't seen any mention of power goals here. What's the goal, and what's the fuel pressure? Only then can the injector sizes be evaluated.

the first Miata turbo kit used a Hobbs switch to block off the return line on the fuel rail when the car went into boost. Even in 1989, it sucked.

Now that is crude.

He said he wants to run 5-6 PSI, so very little extra fuel should be required. A pressure switch (there are much cheaper alternatives to a Hobbs switch) to activate a very small injector will do the trick. At that power level, in that situation, the power difference between the crude simple injector and properly controlled injectors will be insignificant.

singleslammer wrote: What does the Hobb's switch help me do? It allows me to activate something when the boost kicks in, but I am a little lost to what I am activating... I check Kinugawa. Cool site but nothing for that particular Volvo turbo. Not saying I am 100% on that one but it is a solid choice.

You'd want the universal unit. Then you'd just mount as appropriate.

My goals are to add a bit of much needed power. I would very much like 30 crank up. Fuel pressure is 43.5 psi. The pump should hold up to my goals without issue, based on others experiences.

30 crank hp more. According to Honda, the car has 98. So you're looking for 130 crank hp. That may be possible on the stock injectors at stock pressure - which I suspect is actually higher than 43.5.

If you run stock pressure with an electronic controller, the pump shouldn't have a problem. If you start jacking up the pressure, the pump may not have problems at first - but it could very well as time goes on. We see that with the Miata kits - cheap and nasty kits add a fuel pressure regulator with the stock pump, and it works fine for a while. Then the pressure starts to tail off as the pump slowly fails. Makes much more sense to put the right pump in the first time.

Experiences of other folks on forums need to be evaluated VERY carefully. There are many shortcuts taken without immediate consequences.

I have a first gen Insight (2000) - 73 HP with IMA so low 60s without.

I am with you on raising fuel pressure though. The choices are now down to either adding a 4th injector using a controller like Zomby Woof mentioned or running an AEM FIC or similar piggyback.

Just snagged a killer deal on a NEW Garrett GT1241 Turbo. It is rated for .4L to 1.2L and up to 130hp so it should be perfect for my low revving 1.0l Three banger.

So you only want 100 crank hp? Stock injectors and pressure should do that.

I'd rather see you run an FIC than a single extra injector. The fuel distribution of a single injector is bad.