Honda Insight w/Acura TSX engine - Ecomodding

[Ecky]

Replaced 12v battery with a bank of 3000F supercapacitors. Should be good for a ~25lb weight reduction. Starts the car far better in subzero weather than the battery did.






Engine and transmission are fully assembled and just waiting for a home. Got 50 degree VTC actuator installed, new alternator, new thermostat + housing, new A/C compressor. Turns out the JDM K24A has a different water pump housing which doesn't line up with USDM accessories so I replaced that too. All I need now is for Hasport to release their mounts and axles.

[MetroMPG]

Nice to see an update!

[serialk11r]

Oh, just saw this project for the first time. Not quite what I would expect on these forums haha, but great nonetheless.

Sorry if this was made clear somewhere else, why are you bothering with the exhaust VTC? Most of the gains to be had come from the intake camshaft. AFAIK you can have the cam base circle ground down a tiny bit to add duration and then cut lift to get a more-Atkinson cam, which should get you the equivalent of 10% taller gearing for a very low price.

I'm eagerly anticipating your lean burn tuning, it will be fun to see how lean the K24 can run. Stable combustion at 19:1 would be really good already, if the rumor that a K20 can run that lean is true. The ease of getting parts for and tuning Honda motors makes me envious.

[Ecky]

Originally Posted by serialk11r

Oh, just saw this project for the first time. Not quite what I would expect on these forums haha, but great nonetheless.

Sorry if this was made clear somewhere else, why are you bothering with the exhaust VTC? Most of the gains to be had come from the intake camshaft. AFAIK you can have the cam base circle ground down a tiny bit to add duration and then cut lift to get a more-Atkinson cam, which should get you the equivalent of 10% taller gearing for a very low price.

I'm eagerly anticipating your lean burn tuning, it will be fun to see how lean the K24 can run. Stable combustion at 19:1 would be really good already, if the rumor that a K20 can run that lean is true. The ease of getting parts for and tuning Honda motors makes me envious.

So the K24A which I have, has VTEC (two different cam profiles) on both the intake and the exhaust valves. Not all K series motors have VTEC on both - in most it's just intake. I understand Honda did away with the exhaust valve VTEC on most later motors as it wasn't worth the added cost/complexity. However, VTC != VTEC. The intake cam can be phased forward 25 degrees in the stock configuration, and 50 degrees with the phaser I replaced it with. The reason the motor doesn't come with a 50 degree phaser to begin with is that there's a possibility of the valves hitting the pistons in some scenarios, which is why I put a pin in to limit advance to 40 degrees.

Frankly I would have preferred the later K24Z motor which lacks exhaust VTEC and has an integrated header, but this one was significantly cheaper and is generally considered more desirable by those just looking to make power.

Looks like tuning is going to be... complex. There's RPM, load, AFR, ignition timing, and intake cam phasing, and these must be tuned for both the high and low VTEC cam profiles whose cutover point are then chosen based on where the power curves intersect. I'm not even going to think about grinding cams at this point, though an atkinson profile at low RPM does sound pretty desirable.

[serialk11r]

Yea what I'm saying is, why are you going through adding the phaser when the engine already has much more than enough power?

With a camshaft grind, you go higher duration, keep lift the same with shallower ramp, then set the cam so it opens at the same time as stock, and keep all the cam timing tables the same. That keeps overlap the same, and makes the valves close later. On a cable throttle engine, the cam has to react to the load, so it usually doesn't move all that much, and even if the cam timing isn't optimal, you just lose a little torque.

If it were me I would try to keep the tuning as simple as possible, since introducing lean burn already complicates the spark timing and fueling, as the optimal amount of spark advance is probably greater than what you find in the performance tunes on the internet, and you'll need to empirically determine how lean the engine can go at different loads and speeds. My method would be keep the overlap stock so you don't need to deal with weird combustion instability or affecting internal EGR in a way you can't measure, play around with retarding the intake cam more if possible, and if you want more results, regrind the cam (I think it's only 200 bucks?).

[Ecky]

Ahh my apologies.

I found this to be a very good read:

Fuel Economy Tuning - Tech Review - Honda Tuning Magazine

According to their brief tuning experiment, between the best and worst cam angles is around 3% improved economy as well as more power. Whether or not I can actually make use of this is another matter.




Good tuning tips. I'll see about getting a custom cam down the road. Correct me if I'm wrong but I don't think you can just grind an existing cam for more duration, because what you really need is more material on the cam, not less. So this would be a custom billet cam.

[serialk11r]

Yea I've seen that page before. I believe the dips are EGR and intake manifold resonance related drops in VE. Then as you go more extreme, LIVC effects kick in and drop VE further giving the higher fuel efficiency.
EDIT: My bad, that graph is for cam advance. Higher advance gets more EGR which has a big effect, full retard probably starts increasing pumping losses dramatically at the top of the stroke. Full retard is known to work in Toyota's "VVT-iW" so there's probably some very careful exhaust cam tuning that needs to happen for it to work.

As you can see, going to 50 degrees gets you 1.5% less fuel consumption compared to 10, which is not bad, but it's not that much. I believe hydraulic cam adjusters are slow enough that going to 50 degrees would result in a noticeable worsening of throttle response.

Regarding regrinds, I made a mistake, I thought you could grind down the base circle to get more duration on the Honda since it's got a rocker arm, but I just realized you might have to grind both sets of lobes to make it work, if that would even work at all, and that would cost more money. You could also have the lobes welded with extra material but I heard the reliability is not great with that method.

[hayden55]

Originally Posted by Ecky

Replaced 12v battery with a bank of 3000F supercapacitors. Should be good for a ~25lb weight reduction. Starts the car far better in subzero weather than the battery did.

Don't get pulled over with that six pack of bud light back there!

[Ecky]

Originally Posted by hayden55

Don't get pulled over with that six pack of bud light back there!

They're tallboys.

[19bonestock88]

Got any more info on your super cap bank? I don’t remember seeing anything on it?