B7 vs. B8 on 06 superjet

[Idok]

was looking at a buddy's 06 SJ this weekend and noticed the factory stickers calling for B7's...



now, i (as well as the rest of the crew) was under the impression that were supposed to be running 8's...





best I can figure is that it has to do with high compression and advanced timing....but have they always been rated @ 7's for stock???

 

[Big Kahuna]

Stock runs a hotter plug

 

[WaHoo_1]

I have a stocker 04 for that calls for B7hs as well... think that pretty much typical as far as I know.

 

[oxnard111]

My stock 97 pipe has a sticker saying B7HS. But I have been running BR8HS since I think the head has been milled. (Did a compression check after buying it used and I have about 172 in each cylinder)

Since this topic comes up so much, someone should write up a little tech article about the nature of spark plugs and put in the Tech Article Section. Who's up for it?

 

[yamaslut]

Stock runs a hotter plug

why is that the case????? I guess it doesn't make sense to me

 

[Idok]

why is that the case????? I guess it doesn't make sense to me

sure it does...

think about it..


stock:
stock timing
lower octane fuel rec'd
stock compression

mod:
higher compression
higher octane
advance timing

it should take less heat for the plug to fire off the fuel on the mod application vs. the stock......IM guessing detonation woudl occur with the hotter plug in mod application..

at least thats how it plays out in my mind.....

 

[sflsurfrider]

i was always lead to believe that you always want to go with the stock plug recommendation even on a modded boat.

 

[oxnard111]

sure it does...

think about it..


stock:
stock timing
lower octane fuel rec'd
stock compression

mod:
higher compression
higher octane
advance timing

it should take less heat for the plug to fire off the fuel on the mod application vs. the stock......IM guessing detonation woudl occur with the hotter plug in mod application..

at least thats how it plays out in my mind.....

I was gonna write something like but you beat me to it.

i was always lead to believe that you always want to go with the stock plug recommendation even on a modded boat.

If anything your not going to hurt the ski by going with colder plug

 

[hangtime]

I was gonna write something like but you beat me to it.



If anything your not going to hurt the ski by going with colder plug

Stock is hotter not colder

 

[oxnard111]

i was always lead to believe that you always want to go with the stock plug recommendation even on a modded boat.

Stock is hotter not colder

I realize that hangtime, I was refering to slfsurfrider's comment above. He said he was lead to believe that you should go with stock plugs on a modded boat (hotter plugs) and I replied with my comment that even if you put a colder plug in, it is not going to hurt the engine. You might experience damage if your boat recommended a colder plug and you purposly put in a hotter plug, but just maybe depending on your setup.

 

[Ollie Rastabean]

The temperature of the spark plug's firing end must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is called "Thermal Performance", and is
determined by the heat range selected.



http://www.ngksparkplugs.com/techinfo/spark_plugs/techtips.asp?nav=31000&country=US

 

[Ollie Rastabean]

NGK nomenclature breakdown:

http://www.ngksparkplugs.com/techinfo/spark_plugs/partnumberkey.pdf

 

[Ollie Rastabean]

I was gonna write something like but you beat me to it.



If anything your not going to hurt the ski by going with colder plug

Agreed. But, you have to be hot enough to prevent fouling.

-O

 

[Ollie Rastabean]

nice find ollie.. i run 9's in all my modified motors... theory being:

A colder heat range is necessary when the engine is modified for performance, subjected to heavy loads, or is run at a high rpm for a significant period of time. Colder spark plugs remove heat quicker, reducing the chance of pre-ignition/detonation. Failure to use a cooler heat range in a modified application can lead to spark plug failure and severe engine damage.

:biggrin:

Where is Edwin. This must be someone else?!?!?!


I have always run 8's. But, that being said. It would not hurt for me to try out a set of 9's to see if I foul them out. I get 200 PSI on the gauge on my motor + run pump gas. Have not found any deto yet. But, the motor is really starting to wake up now and I need increase my checkups to make sure I do not have any probs.

-O

 

[Ollie Rastabean]

as in +/- 200psi with static advance and an msd enhancer? poor mans overignition/overcompression compensation??? :sneaky:

You got to it before I did.

I also run the MSD. No static advance though.

I was not happy with the 200 PSI. But, I was sick of buying domes + thought I would give it a shot.

-O

 

[oxnard111]

Agreed. But, you have to be hot enough to prevent fouling.

-O

Agreed also, but I don't consider fouling a plug "damaging" your engine, which was what I was refereing to in my previous posts

 

[Ollie Rastabean]

10-4

 

[masterblaster]

ive always had better luck with 7s,my motors are around 180 psi,no advance,93oct,they never run hott with these plugs,7s last longer,cause less misses and fouling,and eat water for lunch without crapping out and needing to be pulled umteen times if ya get water in your motor,I recommend keeping a set of these around to get your motor going again after ya get some water in it,even if ya dont run them after.

 

[Idok]

ive always had better luck with 7s,my motors are around 180 psi,no advance,93oct,they never run hott with these plugs,7s last longer,cause less misses and fouling,and eat water for lunch without crapping out and needing to be pulled umteen times if ya get water in your motor,I recommend keeping a set of these around to get your motor going again after ya get some water in it,even if ya dont run them after.

definatly agree with that........thats a trick we learned at vilano about a year ago or so.....

a sunk boat shold be revived with #7's....it will get running MUCH faster, and with the help of a primer it can be done on the 1st or 2nd plug change :bigeyes:

 

[Idok]

thats a good trick to know.. i'm gonna try that out next time it happens to one of us.. i dont see how this trick would work, but i'll take your word for it and give it a go..

i would think a wet plug is a wet plug is a wet plug... isnt it???? or because the electrode retains more heat than a 8 or 9, it keeps the temp in the combustion chamber a little higher, helping to ignite the mixture a little easier? what is the theory there?

tellin' ya man...this is THE trick that will make you :highhorse: on the beach.....about a month ago my hood popped loose, and we dragged the red boat in bouncing off the bottom...took about 45 mins for the tow :bigeyes: (the whole time I kept thinking about skywalker)..

took her to the beach, put in a set of #7's.....butti continuously pumped the primer and it fired off first time :bigeyes: a second plug change with some ether (still pumping the primer) fired it off and she ran....

2 plug changes, and back on the water in 5 minutes...


normally, without using either one of those tricks you are looking at minimum a dozen plug changes.....hell, ive seen it take 30-40 changes..