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Discussion Starter #1 (Edited)
Today, I've ordered a set of the wrong index spark plugs, to fit in my Insight.

Why? Well for a start, they were going cheap - but my decision was based on more than just that.

I understand the logic of indexing. I'm assuming that plugs A,B,C,D are all identical bar the electrode being 90 degrees different to the last, orientated to the thread. From reading here, it appears that virtually all insights are mostly B, or failing that, an A.

To me, that indicates that Hondas manufacturing was pretty precise, but the exact back of the engine for most engines is somewhere between plug A and B, nearer to B. The exact back could be up to 22 degrees off of where the plug electrode actually ends up before a different index plug would of been used.

Now in my logic, the idea of indexing is less about having then electrode at the back, and more about not having the electrode at the front where it would get in the way of the fuel air reaching the spark. So as long as the electrode is within the 180 degree back area of the chamber, the engine is going to run virtually identically.

My engine has Bs marked on it, and I've ordered a set of As. I should add, if the correct index plugs were easily available, I would have ordered them. These were much cheaper though. They are genuine honda ones.

Hopefully they will arrive tomorrow, and I can fit them at the weekend and report back. Fingers crossed my logic holds up. :p
 

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You could always mark the electrode location on the insulator top with a sharpie, then use washers to space the plug so it seats where it needs to be.

Yeah, Ive been tempted to try diff plugs in the newer insight, but its 2 per a cylinder. :confused:
 

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Discussion Starter #3
You could always mark the electrode location on the insulator top with a sharpie, then use washers to space the plug so it seats where it needs to be.
Yep, I plan on doing this, as opposed to using a torque wrench. I was going to mark my spark plug tool, line the plug up in it, and not remove it from the plug as I do it up (it's not a ratchet).
 

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Indexing the plugs in the Insight has nothing to do with the front and back of the engine.

You want the open end of the electrode to face the non-VTEC intake valve; the one that opens all the time.

This is one of those things where you aren't going to be able to tell a difference without sophisticated equipment. If the "A" plugs cause a 1HP loss in power, you're going to be hard pressed to find it with all of the other variables present out on the road.

So in my opinion, it's best to leave well enough alone in this case. ;)
 

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the exact back of the engine for most engines is somewhere between plug A and B, nearer to B. The exact back could be up to 22 degrees off of where the plug electrode actually ends up
I've no clue what you mean by "back". Back of what?

I suspect as the plugs are removed and replaced, the thread gradually lengthens and the plug is not precisely aligned. Or you might have a mechanic who doesn't care & just twists them on without regards how "deep" they go into the hole.
 

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Discussion Starter #6 (Edited)
I've no clue what you mean by "back". Back of what?
The engine?

This head schematic shows what I mean. The plug electrode is facing the back of the engine in this diagram.



In reality, even if you have the correctly indexed plug, it could be nearly 45 degrees out. (Not 22 - got my angles muddled).
 

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That diagram does not show and is not meant to show the plugs as they are in the cylinder head when properly indexed. It's just an exploded view.

This is what properly indexed plugs look like from the combustion chamber side:



Again, the open end of the electrode needs to face the non-VTEC intake valve.
 

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That's a nasty looking head... one of yours?
 

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Nah, it's a picture I found online a long time ago. Indeed, it looks like the center cylinder was burning a lot of oil.
 

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Discussion Starter #10
Thanks Eli, that's really useful. So the plug gap faces west, north west in the car? Rear facing north.
 

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Thanks Peter,
Any chance of test fitting and torquing a couple of off the shelf NGK iridium LFR5AIX-11. and Autolite 4469
as suggested in eq1 post on fitting.
Savings would be substantial compared to sourcing from Cdn Honda dealerships!
 

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I cant speak for the older insight, but in my experience ac has a significant impact on mpg rather in eco or non eco mode. Ive also had a guy on ecomodder tell me to run a honda compressor takes around 1.2 hp tops.

So, I could infer that 1.2 hp = 15 mpg in my run to work where use of ac impacts mpg 15 mpg. Id like to try a cooler plug and the V grove if not some other wizbang plug thats designed for mroe efficiency and reduction in knock, pinp, preignition or what ever the hell its called.

This is one of those things where you aren't going to be able to tell a difference without sophisticated equipment. If the "A" plugs cause a 1HP loss in power
 

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I run Econ A/C and haven't noticed much impact. I set the fan to maximum and the AC to 80. It keeps me cool enough to tolerate the hot sun beaming through the window (and also removes sticky humidity from the air). I am still able to get 89mpg on the interstate.

After the sun goes down, then I turnoff the AC and set the temp as low as possible.
 

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I'd be curious how much merit the 1.2HP figure has. If that's true, I'll have to notch down my estimates for how much power the engine is producing in lean burn at 55MPH from 10-12HP to 6-8HP.

The A/C cycling on in the Insight is easily capable of a 20% reduction in fuel economy. It's like stepping on the brakes. I was assuming it used more like 3-4HP to operate.
 

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My figure came from a guy on ecomodder who made an ev from a honda using lifepo4 cells and stuff from another ev he had. Keep in mind hes turning it at a constant speed, not accelerating at load as he has a second electric motor to spin the compressor. :)

I know a standard 80 amp alternator at full load takes 3 hp from the parts shop I use to visit that tested them.

I know the ac in the prius 3 at least the 2010 model will only run like 7 minutes at full output before the engine starts.

Those numbers sound right at least to my sg2 using the x-guage, 6-8 hp to maintain 55mph, not counting the ima assist. Its still unclear if the gen 2 has any form of lean burn, however it seems to have something in addition to a light ev mode.
 

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Gen2 insight probably has lean-burn disabled, just like the Gen1 civichybrid has its lean-burn disabled in California (SULEV variant). The capability is there but not turned on.

And 6-8 HP is really small. I have a model airplane that is rated 1.2 HP at full throttle. Hard to imagine you could move an entire car with just 6 or 7 model airplane engines.
 

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Thanks Peter,
Any chance of test fitting and torquing a couple of off the shelf NGK iridium LFR5AIX-11. and Autolite 4469
as suggested in eq1 post on fitting.
Savings would be substantial compared to sourcing from Cdn Honda dealerships!
If you send me some free possibly.
 

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If you send me some free possibly.
Not to worry, I've changed my mind after considering the long service life of the iridium spark plugs in general and will go with the original Honda indexed spark plugs as per my post in the other concurrent spark thread : "Replacing Spark Plugs".
False economy possibly can result if there's even a 1% loss of economy over the mileage span involved with wrongly indexed plugs if HP equates to fuel consumption.
 

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Discussion Starter #20
Right, all fitted. I haven't seen many other pics on here, so I thought I'd do a quick photo guide on how to change plugs, for those who want it try this themselves.

Firstly, it is possible to see the index mark by only taking the plastic cover off the engine. However, if its covered in oily dirt, you won't. You'll probably need a torch too. Alternatively, just follow the following steps up to after removing a coilpack.



Now, to ensure I could tell where the electrode was ending up, I drew a line in permanent marker in my extension bar (turns out I only needed the one bar).



The tools I used are all here. The drill has a 10mm hex socket, and the wrench is a 17mm. Needle nose pliers make it easier to remove the coilpack plugs could be done by hand though.



Right, to the car, after removing the plastic cover, the bolt at the back right needs removing to remove the coil lead holder. 17mm socket to loose, then unscrew.

Once off, disconnect the coil packs from their leads using needle pliers.

 
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