Gernby

iTrader: (1)

Most manufacturers pick spark plugs that will work "okay" in every climate. They will be hot enough to prevent fouling in extremely cold climates even with short driving cycles, and the ECU will just pull timing and enrichen the fuel mixture in hot climates when the ECU detects knock. If you live in a hot climate, then running a colder spark plug will allow more aggressive fuel and ignition tuning.

In my S2000, running a plug that was 1 step colder caused the ECU to advance timing by about 10%.

is4fsr

I was at a local parts store last week and I was talking to the store manager about regular vs premium gas and high perfomance cars. He said only HIGH performance cars such as muscle cars ie Vette, Shelby, Camaro, need premium gasoline. All others including high end or performance luxury cars such as Lexus, Infinity, BMW 3 series, Acura, etc will "run well on regular unleaded gas" and "running them on premium is a waste of money". Anyone care to comment on this one. Even my trusted mechanic tells me it should be ok to use reg gas on my IS. I guess the key here is SHOULD BE OKAY but i still use premium .

jimmyjazz

IMO our engines have too much compresion to run on regular. I know gas is getting high but premium is "only" 10 cents more per gallon. Thats just $1.50 for 15 gallons.

Gernby

iTrader: (1)

Both guys are making assumptions about the engines. It doesn't matter what kind of car you are talking about. If the engine has a high output per liter, it will probably require high octane fuel. Keep in mind that the IS350 makes more power per liter than any of the "HIGH performance cars" that you mentioned above.

lobuxracer

iTrader: (2)

Sparkplug heat range is entirely unaffected by climate in water-cooled engines. The only thing that the sparkplug does with heat range is keep from fouling and keep from causing detonation from acting like a glowplug.

Average cylinder temperature is what determines heat range. Cooling system performance is critical to this, and average load is also critical to this. If you are running significantly harder than design spec, then you might benefit from a step colder. More often than not, running a step colder on an unmodified street vehicle used for daily transportation only makes the plugs foul.

Also, advancing timing is not necessarily an indicator of better performance. Without some supporting information, arbitrarily saying more timing is better is just wrong. There is only one thing that matters for timing - when (in crank degrees) does the peak pressure occur? Anything else is either BS or academic.

Gernby

iTrader: (1)

I ran my colder spark plugs for years in my S2000, and I never had any fouling during the summer, but I did sometimes have fouling in the winter if I did several short drives. This was not a percieved issue at all. The first time it happened, I pulled the plugs, they were heavily fouled, so I gave the car a long, hard drive to clean them up. This happened only a few times during the winter.

I'm also certain the advanced timing was a benefit, or I'm sure the stock ECU wouldn't have advanced it in the first place. I measured this via OBDII on 2 otherwise identical S2000s, so I don't see why there's any reason to question this...

nabbun

WTF????

Your premium is only 10 cents above regular???

most gas stations around North Jersey have regular at (around) 2.90 and premium at (around) 3.05!!!!!!

and don't get me started about crossing the border into new york, I feel bad for them . . .

is4fsr

Here in SoCal it's 20-25 cents difference and our regular unleaded starts at $3.40ish.Chevron around the corner reg $3.48 and super unleaded $3.69.

CoasterG

iTrader: (1)

In central Florida right now Premium (93 octane) is running about 31-35 cents higher than regular - regular is about 3.04 and premium is ranging from 3.35 to 3.39.

And that jump only happened in the past 2 days, was running about 15 cents cheaper previously.

Anyways back to the topic at hand, on the spark plugs are there any colder plugs available for the IS350? We never see truly cold temps here and with summer here basically I'd love to see if there's a difference.

jimmyjazz

Here it's 10 cents between each grade. We usuall have 86, 88 and 90 Some Chevrons have 91 all 7-11's (Fina) have 92. I was refering to the mid grade and Premium. You can only buy86,88, 90 Shelland the super90 costs 5 cents more than 91 Chevron!

lobuxracer

iTrader: (2)

It's not questioning. What you are saying is your engine was pulling timing all the time until you put colder plugs in it. So you were getting detonation all the time and the ECU was correcting for it by retarding timing.

I've noticed what seems to be a misconception many times about ignition timing. The ECM does not advance timing until knock is detected. It tries to run the value provided in the look up table based on rpm, coolant temperature and load. If the knock sensors detect knock, the ECM retards timing to protect the engine. Both power and economy suffer when this happens. However, if you run race gas, the ECM will not continue to advance the timing beyond the values in the look up table.

Your comment about fouling the plugs severely very clearly indicates they were too cold all the time. They were marginally better in summer. Just enough to keep from fouling, but not hot enough at all in winter.

You could have solved this problem by changing your coolant to water ratio very easily. What your results indicate is the engine's cooling system was not running efficiently. The simplest and easiest way to remedy this is to change the ratio to more water and less antifreeze. This will make the head run cooler immediately and will reduce your octane requirements by as much as 2 points. I've been running 80% distilled water and 20% Toyota red coolant with Red Line Water Wetter for more than 8 years for exactly this reason. Colder plugs will not solve the problem, they are only a band aid.

There is one caveat to this. If you track your car, you may very well benefit from running one heat range colder. But the reason this works is because your average heat load at a track event is far higher than you will ever see on the street. If I did this for a track day, I'd put the regular plugs back in the car as soon as I got home.

Gernby

iTrader: (1)

That is what I was trying to say. My friend's S2000 with the stock plugs was running with retarded timing, and mine wasn't.

I agree with this completely, and wasn't trying to imply otherwise.

I still disagree with this. I think the colder plugs were just perfect. I didn't have any of the complaints that so many other S2000 owners had in the summer. The times that I fouled the plugs were very special situations where the car was driven very short distances on icy roads at 15 MPH to the convenience store and back. Any plug will foul if it isn't allowed to reach its self-cleaning temperature.

I did this too, and it did make a significant improvement. I also used a higher pressure radiator cap and lower temp thermostat and fan switch. I believe this was part of the reason why my plugs fouled those couple times.

Gernby

iTrader: (1)

Where in Texas are you? All the gas stations I've been to in Texas have been selling 93 octane for years.

jimmyjazz

Lubbock, 3200ft alt, and like I said, you have to try to find 91/92. Two Chevron's and all 7-11's, everyone else only has 90 for super.

ngogsr

iTrader: (1)

yup dont bother using race gas , because it will probably not make a difference unless tuned. wonder if lexus will develop a car using e85.....that would be nice high octance/cheaper =)

i havent bought c16 in awhile , but the lastime i bought some it was $10 gal