[ericbecky]

Well last night I made a big mistake.

I left my keys in the car in the “on” position all night; bad idea. I had to give it a jump start this morning and once it started, the battery meter was completely empty.

For the first few miles there wasn’t any assist and continuous charging took place. After about 6 miles of driving, the battery meter was back to full.

Before it was charged up, I got to feel how the car reacts with no assist. Obviously, there was a lot less pick up, but by using the 5 speed, I could make up for most of the lost power. The acceleration was surprisingly tolerable.

It was nearly impossible to stay in lean burn mode, though, because of the “drag” created by the battery charging. Still, I managed about 45 mpg in a section of my commute that is normally about 60mpg.

It would be interesting to be able to drive without the electric assist motor to see what kind of mileage is attainable. Since the car is so light and aerodynamic, it seems that it should be able to get decent mpg on the gas engine alone.

Has anyone heard of someone driving their Insight for a long length of time without the electric motor? If so, what were the results?

 

[Hambone]

I've noticed at times, when the battery is depleted, that the only real difficulty I have is stepping away from a stop on a hill. Without the added power of the electric motor, it seems to me that I have to slip the clutch a lot more in order to get going, in order to allow the engine to get into a part of the rev range where it can really pull the best.

Other than that, I'd concur, the Insight does pretty decent on the gas engine alone(and from my limited time in the depleted battery power state, it seems to me that the Insight would still average over 40mpg on only gas power). At least the car won't be a complete pig to drive if the IMA battery goes out and I have to live with it for a while if forced to wait for parts!

 

[ericbecky]

If the IMA batery goes out, I wonder if the system would continue to try to charge it anyway? If so, it would continue to create drag on the ICE and reduce fuel economy.

 

[Tim Maddux]

Has anyone heard of someone driving their Insight for a long length of time without the electric motor? If so, what were the results?

You can disable the IMA with the breaker, but this isn't recommended since the car depends on the IMA DC-DC converter to keep the 12v battery charged. In other words, the Insight has no alternator and without the IMA the 12v would eventually die and the car would eventually stop running, even on gas.

Also, the IMA is used to balance the inherently unstable 3-cylinder ICE, so running with it totally disabled would be uncomfortable.

Finally there's the poor performance without assist

 

[b1shmu63]

Whoa, Whoa! Inherently unstable? :shock: I don't like to be contrary but odd cylindered engines are inherently smoother! Counter rotating shafts such as found on modern fours are not needed. The IMA motor also allows use of a smaller flywheel as well which also saves weight. The concept is freaking brilliant! 3 cylinder Saab, 5 cylinder Diesel Mercedes, and 3 clinder Kawasaki/ Suzuki/ Honda bikes all dated from the 60s. Several other models exist more recently from Accura and Mercedes.

Please correct me if I'm full of it on this one. My formal training is industrial control, robotics, and aircraft maintenance....not engine design.

 

[Delta Flyer]

I'd love a switch to force a trickle charge instead of having to maintain an unsteady speed to fully charge the IMA battery.

 

[Billy]

Hi b1shmu63; I must agree with you on this one. In-line 3 cyl engines, particularly the diesel Kubota and Yanmar engines, are some of the smoothest, vibration free anywhere! They have a super good reputation for being reliable and smooth. billy...

 

[bfivelover]

I did exactly the same thing about a year ago. Like your's, my battery meter was completely empty until I drove the car for a couple of minutes. I was late for work and pretty upset, so I don't remember what kind of mileage I was getting. I recal seeing on here or somewhere else that someone was driving without the IMA and getting mid 50's MPG.

 

[Tim Maddux]

http://www.insightcentral.net/encyclope ... ation.html

"A three cylinder engine, without balance shafts (which decrease power and thus fuel efficiency), is inherently prone to vibration. To improve idle quality, the IMA motor is used to smooth out speed fluctuations in the engine's crankshaft..."

 

[b1shmu63]

OK, but modern Honda 4 cylinder engines do use ballance shafts, as they are also "inherently prone to vibration". The V6 (2 straight 3s at 90 degrees) doesn't need them.

I was concerned that some gentle reader could be allarmed by the words "inherently unstable". Nuclear reactions, stealth aircraft, nitro glycerine, and me on my fist bike ride came to mind. :lol:

The main drawback to using three cylinders is that it doesn't allow for cylinder idling like the new Accord hybrid. Perhaps the new Insight will be a 4 banger.

 

[Holicow]

OK, but modern Honda 4 cylinder engines do use ballance shafts, as they are also "inherently prone to vibration". The V6 (2 straight 3s at 90 degrees) doesn't need them..

I also thought that multiples of 3 were smoother than the 180 deg crankshaft arrangement of an I-4. I wonder if the "inherent" vibration is just due to the low number of cylinders, rather than the arrangement. A V6 would have 60 deg increments, versus the 120 degrees of an I-3.... what do you think?

 

[Dgate]

Driving with just the gas engine

Most all reciprocating engines vibrate to a certain extent but with fewer cylinders you begin to notice the firing pulses even if they are smooth on vibration.A three cylinder in-line is the lowest number you can go unless you count the two cylinder horozontally opposed type before vibrations become intolerable.A heavy flywheel can damp out firing pulses and correctly designed engine mounts also contribute to isolate this problem.
I have owned and run one,two,three,four,five,six,eight,twelve cylinder,and even a rotary engine and find the three cylinder ideal,and not just the Honda unit.I previously ran a "Three cylinder" Smart car and it was dead smooth without the IMAS.
Back to the thread,Has anyone tested the Insight for fuel economy by locking out the 144 pack and just doing a run before depleting the 12 volt.
I live on the flats of East anglia and have considered putting this to the test as it seems the lean burn is what contributes most to my economy.
Dgate

 

[Aaron Cake]

I find the 3 cylinder to be very jumpy at idle. Also, the sound of valves tapping in the morning isn't exactly music to my ears. However, this is the first car (out of 4) that I have owned that actually had valves and cylinders, so perhaps it's just somthing I need to get used to...

 

[Yves M.]

Hello Aaron,

I am pretty sure that the raison the valves seems so noisy is only because of the "plastic" valve cover. A normal engine will use a steel valve cover and the sound is more damped. But steel is heavier

 

[Dgate]

Driving on only the gas engine

The main reason the valves are noisy when first starting is they are cold and the clearances are greater between the moving parts.As the engine warms the gaps decrease and the clicking subsides,and if it does'nt then the valves need adjusting.Most engines today have hydraulic lifters with oil taking up the slack so they never have valve noise unless there is a blockage in the hydraulic circuit then all h*ll breaks loose.
Most high performance engines have traditionally been of the solid lifter type as the Insight.
Another contributing factor that adds to the racket is the higher idle when cold but I cannot agree its the plastic cover as this should have a dead or dampening effect and does not seem to be relevant when used in other installations.A friend and I previously had identicle cars, mine had a cast alloy valve cover and his being a year newer had a plastic cover and there was no perceivable difference in noise!

Dgate

 

[Yves M.]

Hi Dgate,

The plastic being light will have the sound go through in an easier way that a steel cover. The steel will absorb more of the sound.

Most Honda's have manually adjusted valve clearance (as per a Civic, I use to have an older one) and the noise is considerably less to my taste.

I was not comparing the hydraulic lifter to the manual but comparing manually adjusted Honda's to an other similar.

 

[b1shmu63]

The noise is created by the small gap that is required to assure the valves close properly. If you remove the gap the valves will burn and the engine fail. If the gap is too large the noise will increase and the valves will not open completely. I use 0W30 oil. It seemed to me that the engine ran quieter after switching. Perhaps the light oil and the plastic cover together make the engine a little noisier than other Honda models.

 

[Aaron Cake]

I'm aware of why the valves are noisy. I just find it annoying. I'm used to the silky smooth operation of the rotary. Looks like the Insight is the first and only piston equipped car I will ever own.

 

[Yves M.]

Aaron, my understanding of the rotary engine is that it is less efficient than a piston engine (but more powerfull per engine weigh) so more polution

Therefore I hope that your next car is a full electric (a wish for me too)


To get back on the topic, driving with only the gas engine is not usefull if the IMA is still good as the IMA has the function of giving better car performance on that small engine.
It has a purpose only if someone would not want to pay for costly repairs at the end of the IMA life. An alternator and some work could have the car running without the IMA.

 

[flunkysama]

I blame the valve noise on the fact that the exhaust system is so quiet it makes the value noise seem louder. If it really bugs you, make/get a little sound deading blanket for the top of the valve cover.