Spark Plugs

[deefred]

Better to leave the indexing out as a possible factor when doing the comparison.

[Micah / AF1 Racing]

Actually to make a fair test both sets of plugs MUST be of very similar index value.

[DanV990]

What would happen if you ran one DCPR8E and one DCPR9E in each cylinder? Could it hurt the engine? Would it be of any benefit for aggressive street use where it takes a while driving along sedately to get to the fun, but once you get to the fun all hell breaks loose? And if it would be of benefit which plug should go in the central location and which one at the outer edge?

[kzmille]

Has anyone ever had any problems with the 9's specified by aprilia? I never have. In fact my original plugs went 17,000 miles. My air cooled BMW's from the early seventies through the mid eighties came with 8's and that's what I always used. This was a 7200 rpm engine with a 9.5:1 compression ratio. Don't you think the V60 at 10,500 rpm and 11.4:1 might need one step cooler?

[oscar fish]

Not to beat a dead horse here but you may find some useful information on this thread from an NGK engineer that addresses the material issue, indexing, and temperature. http://forums.nasioc.com/forums/show....php?t=2346681

[Andr3]

Not to beat a dead horse here but you may find some useful information on this thread from an NGK engineer that addresses the material issue, indexing, and temperature. http://forums.nasioc.com/forums/show....php?t=2346681

good read, cheers man. Kinda sounds like NGK forbids him to tell the people how much more there is to gain from that... off to the garage indexing and gapping!

[AmareAprilia]

Has anyone ever had any problems with the 9's specified by aprilia? I never have. In fact my original plugs went 17,000 miles. My air cooled BMW's from the early seventies through the mid eighties came with 8's and that's what I always used. This was a 7200 rpm engine with a 9.5:1 compression ratio. Don't you think the V60 at 10,500 rpm and 11.4:1 might need one step cooler?

Aprilia specifies the 8's as well, in the RSV Mille SL owner's manual. Of course it's the same engine, but I guess since the Falco was a street focused Mille, they have the alternate heat range specified.
http://www.serviceaprilia.com/public...p?l=SL%20Mille

[kzmille]

That's funny. Given that, you might expect a similar recommendation for the even more mildly tuned Futura and Caponord but in the two owners manuals I downloaded the only plug specified is the 9.

[Eskimo]

What would happen if you ran one DCPR8E and one DCPR9E in each cylinder? Could it hurt the engine? Would it be of any benefit for aggressive street use where it takes a while driving along sedately to get to the fun, but once you get to the fun all hell breaks loose? And if it would be of benefit which plug should go in the central location and which one at the outer edge?

You think too much..

[liquidspace]

The fact that manufactures specify a particular type and temperature plug would lead me to believe there's more to then just a spark? So, I'm going with it does matter.

[Micah / AF1 Racing]

I use 8 heat range on street bikes because they stay cleaner over thousands of miles and do not increase a detonation tendency UNLESS they get really hot like under the stress of track use or a long high speed pass, even then as long as the motor is above 4k rpm it is really hard to get detonation even on the dual spark motors UNLESS you are running the FP1413 eProm, which has a lot of ignition lead low in the rev range. I use 9 heat range in trackday and racing motors of the V990 origin as that sort of use is correct for the heat range of the plug. The reason the older BMW airheads will tolerate 8's in most cases is that air cooling automatically raises plug temp by about 100F degrees. That said on the last high comp airhead boxer I did with dual plugs I ended up using 7 heat range and a LOT less ignition lead than one would expect to get the motor to sing in harmony.

In the Land Speed Aprilia even under 13 psi boost, nitrous and water/methanol systems still uses 9 heat range plugs. We brought 10's and 11's last time with us tot he track but never had a reason to run them since the 9's were looking perfect every pass including the 200mph pass!

[oscar fish]

Regarding plug heat ranges from the link I posted above I quote:

"When it comes to heat range, it is all about temperature of the surface of the spark plug ceramic. You want a plug that is not too hot or too cold. If it's too hot, the surface of the plug could cause autoignition, or pre-ignition, which is bad juju. Basically, instead of combustion occurring under controlled conditions by the ECU, ignition can occur uncontrolled, and destroy an engine. There is no way, currently, for the ECU to detect this, so you have to make sure you use a cold enough plug. Now, a plug that is too cold could increase the chance of carbon fouling. Carbon is a by product of combustion, just stick your finger in your exhaust pipe, and you will see carbon. If the plug stays too cold, carbon will accumulate on the spark plug, and since it is conductive, carbon can cause misfiring.

Theoretically, heat range could have an effect on performance, but if it does, it's so small that even we can't measure it with our $1,000,000 test equipment. When we talk about performance of a plug and all the things that affect performance, heat rating is ignored. There is, however, an effect on spark plug wear if the center electrode is cooler, but this is only seen during high speed, high load, OEM durability tests.

So, if you are racing your engine, and all it sees is WOT, run the coldest you can. If you have a stock, or modified street machine, stick to the stock heat rating, or one heat rating colder. If you have a heavily modified setup, you have to consult your tuner. There are so many things that can change in a tune, it's impossible to know what's going on.

Based on my experience with OEM engines, if you started running race gas (100 octane or higher), I would go two heat ratings colder, just to be safe."

[Micah / AF1 Racing]

So question Oscar, typically higher octane fuels burn at a lower temperature in terms of flame front, I know for instance AvGas at 100 octane burns cooler than pump gas at 87 octance, and also that 93 octane pump gas has a little less energy potential than 87 octane in MOST cases. I agree with most of what you posted from that link but see heat rating to be a little more important. I feel the plug is not hot enough if an only slightly "over rich" or slightly richer than stoich mixture leaves deposits on the insulator. Not trying to start an argument and being a big enough fan of NGK plugs that I have most of their catalog committed to memory. Running colder plugs than are needed in most cases just leads to premature replacment of the spark plugs due to fouling and in modern bikes where it might just take, hours, to swap a set of plugs I consider it to be a bit cautious. I know DCPR8E plugs are safe in street ridden V990's, over 30k miles on my personal V990's with zero issues related to the heat range are proof enough for me if not most folks. I do say this with the caveat though that for track use I would use the 9 heat range plug ESPECIALLY in the dual spark head version of the V990.

Oscar it sounds to me like you work in a very interesting environment and are probably a welcome addition to the forum. If you are doing heavy life cycle testing on car engines I can see the point in going from a 5 or 6 heat range up to the 7-8 heat range.

[oscar fish]

Micah,
First, let me clarify that this is not my research but I am quoting that of an NGK engineer that participates on an automotive forum I am a member of that pertains to forced induction Subarus. I am by training an archaeologist and biologist so take that for what it is worth. My work is interesting most times. I don't view this dialogue as an argument but as an exchange of knowledge.
Secondly, as i interpret what his research shows particularly as it applies to the OP's question and a following comment regarding the value of platinum, iridium vs. nickel (copper) plugs for street use is that for normal use it is an issue of not of performance (power) gained or lost but of the durability of the plug and the protection against pre-ingition and the potential for engine damage that may occur. If the choice for the OP is to run the recommended plugs or a hotter plugs he risks pre-ignition. If he were to choose cooler range of plugs he may experience possibly fouling plugs sooner as you pointed out. However, by using the recommended... plug no harm no foul. Sorry Micah I couldn't resist the pun. As to how far he can deviate up or down the temperature range from Aprilia's recommendation I would defer to your experience as I believe you when you state that the DCPR8E is safe to run i just don't understand why not run the recommended plug for street us on pump gas unless you are consistently fouling this plug.
Thanks for the discussion.

Greg

[Micah / AF1 Racing]

Back before good EPROMs and Power Commander equipped and fine tuned bikes they were fouling a lot...less of an issue now for sure since 90% of early Aprilia's have been modified by this late date.

Interestig background. I am from a pretty strong Peleo background so maybe that is what I was picking up on?