Advanced Hemi 212cc Predator Build

[bob58o]

You'll have to excuse me. I am sick in the head.

 

[Jrgunn5150]

Vaseline and alcohol, looks like a party!

 

[chancer]

And a syringe!!!

 

[Poboy kartman]

OH WAIT! Maybe this IS a FreeRunner thread after all!

 

[bob58o]

If you can see in the picture, with this plug...
It needs to be rotated about 180 degrees to fire nearest the exhaust valve.
Do indexing washers do anything besides lower compression?
If I do use 100 octane, should I use that AR3910X plug that Poboy dislikes so much? I thought I read something like "unless using racing fuel" but my memory is not the greatestest.

 

[Jrgunn5150]

If you can see in the picture, with this plug...
It needs to be rotated about 180 degrees to fire nearest the exhaust valve.
Do indexing washers do anything besides lower compression?
If I do use 100 octane, should I use that AR3910X plug that Poboy dislikes so much? I thought I read something like "unless using racing fuel" but my memory is not the greatestest.

Indexing a plug puts the spark facing the intake charge, and allows for a cleaner boom when thing's go bang.

Will it matter on a 1 cylinder making 15hp or so? I doubt it.

 

[bob58o]

Indexing a plug puts the spark facing the intake charge, and allows for a cleaner boom when thing's go bang.

Will it matter on a 1 cylinder making 15hp or so? I doubt it.

OK thanks, for some reason I though it was supposed to face the other valve.

I probably won't mess with it.

 

[Jrgunn5150]

OK thanks, for some reason I though it was supposed to face the other valve.

I probably won't mess with it.

I was somewhat unclear. Usually they wind up facing the cylinder wall, the goal is to turn it around to face the center of the combustion chamber.

For most engines that means they wind up facing the exhaust valve.

 

[bob58o]

Maybe a colder than stock plug?
Too Cold is Better than too Hot of a Plug?
Modified engines generally require a colder plug?
https://www.youtube.com/watch?v=ST_qXTwlDI4
http://www.enginebuildermag.com/2011/05/understanding-spark-plug-heat-range/
Basic Heat Range Guidelines
• Supercharging/turbocharging: Forced induction leads to increased cylinder pressure and temperature, which could lead to detonation. Depending on the exact application, you’ll need to go with a significantly colder heat range (faster heat transfer) over stock.

• Nitrous oxide: The high cylinder temperatures caused by nitrous usually requires a colder heat range over the stock plug.

• Methanol: Since it has a higher octane level than standard gasoline, methanol delivers more complete combustion. As a result, you’ll need a colder plug to transfer more heat from the combustion chamber.

• Increased compression ratio: Higher compression ratios mean higher cylinder pressure and temperature. Once again, you’ll need a colder heat range to rapidly transfer all that extra heat to the cooling system.

• Air/fuel mixture modifications: Lean air/fuel mixtures raise the operating temperature, along with the plug tip temperature, possibly causing knock or pre-ignition. Use a colder heat range for leaner air/fuel mixtures. Rich air/fuel mixtures can cause the plug temperature to dip, allowing carbon deposits to build up on the tip. Use a hotter heat range for rich air/fuel mixtures.

• Advanced ignition timing: In general, advanced ignition timing will raise the spark plug temperature. In fact, NGK estimates an increase of 70° to 100° for every 10° advance in ignition timing. For this reason, you may need to go with a colder heat range to prevent knock or pre-ignition.

• Prolonged acceleration/high speed driving: Frequent and drawn-out acceleration and high-rpm driving raises combustion temperatures and generally requires a colder heat range.

–Tech Tip courtesy of Summit Racing

 

[Jrgunn5150]

That is all correct, I have no idea what the stock plug is though. If I were you, I would start three steps colder than stock.

 

[Poboy kartman]

I was somewhat unclear. Usually they wind up facing the cylinder wall, the goal is to turn it around to face the center of the combustion chamber.

For most engines that means they wind up facing the exhaust valve.

No...you have to look at it this way...the fuel charge you are trying to ignite is coming from the intake valve.....now...a plug with the electrode facing AWAY from it is blocking that charge from reaching the area the spark is happening...(it has to GO AROUND it!!!!)

Soooo...whether it's one cylinder or 16...there IS a benefit and it's consistent whether 1 hp or 1000... more consistent "light off" = more power....

And yes...now you can see how the worst position can hurt....therefore how the best will be with that gap pointed straight at the center of that intake valve.....and anything inbetween will have varying degrees of improvement.

EDIT: And while its true that the center of the combustion chamber is also good....consider this....like I said...that's where the charge is coming from....so no matter how good the mix....how good the swirl...if there is ANYPLACE the charge is likely to be "stagnant" or slightly more concentrated....where would it be?

 

[Jrgunn5150]

No...you have to look at it this way...the fuel charge you are trying to ignite is coming from the intake valve.....now...a plug with the electrode facing AWAY from it is blocking that charge from reaching the area the spark is happening...(it has to GO AROUND it!!!!)

Soooo...whether it's one cylinder or 16...there IS a benefit and it's consistent whether 1 hp or 1000... more consistent "light off" = more power....

And yes...now you can see how the worst position can hurt....therefore how the best will be with that gap pointed straight at the center of that intake valve.....and anything inbetween will have varying degrees of improvement.

I agree it's an improvement. But it's typically an improvement of about 2%. So 2% of 500, is somewhat significant, at 10hp. But 2% of 15, is .3. So if it's worth it to you or not is your call. Bob did pioneer the GAB principal of Kart building lol.

 

[bob58o]

Stock Plug is BP5ES heat rating 5 (for honda gx).

Autolite doesn't even give AR3910X a heat rating except for "Racing".
Some places call it a 3.
Other say for compression of 11:1 - 14:1.

I hope that plug will be ok? Plus 4 electrodes so indexing is easy, but I know some people don't like that design.

 

[Jrgunn5150]

Stock Plug is BP5ES heat rating 5 (for honda gx).

Autolite doesn't even give AR3910X a heat rating except for "Racing".
Some places call it a 3.
Other say for compression of 11:1 - 14:1.

I hope that plug will be ok? Plus 4 electrodes so indexing is easy, but I know some people don't like that design.

I'm not familiar with that plug, but it's interesting because typically Autolite uses the last digit as the heat range, so a 23 is a 3, 25 is a 5, etc.

It sounds like it's pretty close if the information you have found is accurate. I tend to err on the side of caution with plugs on more extreme engines.

 

[bob58o]

I agree it's an improvement. But it's typically an improvement of about 2%. So 2% of 500, is somewhat significant, at 10hp. But 2% of 15, is .3. So if it's worth it to you or not is your call. Bob did pioneer the GAB principal of Kart building lol.

Most of the things I have done are 2% mods. They all add up. Milling the head will probably only yield 5%? tops. 20 pages of port and polish = maybe 2%? Thinner gasket and longer connecting rod = 2%?.
Spark Plug = 2%?. Ignition Timing = 2%?. Jettng = 2%?

I really don't know what to expect from the above, but with only GAB at my disposal and no PAFR stunts like forced induction or NOS (AT THIS POINT), It has to be the little things that add up right?

The biggest gains, I'm expecting, will come from the Cam, Carb, Air Filter and Exhaust.

 

[chancer]

Definitely index the plug. You are right all the little things add up. And of all the things this will be the easiest. So why not.
GAB NATION!!!!!!!

 

[Jrgunn5150]

Definitely index the plug. You are right all the little things add up. And of all the things this will be the easiest. So why not.
GAB NATION!!!!!!!

That was my thought, I was surprised when you initially decided not to lol.

 

[Poboy kartman]

If the women can't find you handsome...they should at least find you GAB!

Hmmmm....New third party? (Or maybe replace one?) Like instead of the GOP...the GAB? I might have to run on that platform for Pres!

 

[Jrgunn5150]

You have my vote, I support the GAB cause and values.

 

[Poboy kartman]

You have my vote, I support the GAB cause and values.

And to keep up with American political tradition....if elected....my first official act will be to betray all my political promises and PAFR!