Klaus

iTrader: (1)

Yes you definitely need to run 91 in your SC- that goes back to the point about compression and the gasoline's autoignition temperature. 91 octane has a higher autoignition temperature than 87, therefore it is safer under the various conditions that a high compression engine such as the 1uz and 2jz has. The Boyle's law reference refers to the principle that as you compress a gas it's temperature increases. The ONLY difference between 87 and 91 is the resistance to detonation (high autoignition temp)

So for instance putting c16 race gas in a bone stock car that requires 91 will have no benefit. If you're running an 8:5:1 economy engine that requires 87 octane, again no benefit to running 91 octane.

1WILLY1

iTrader: (9)

Im not trying to be an argument starter here or be difficult but are you sure there are NO benefits to using 91 octane fuel in a car that doesnt necesarrily need it.

Doesnt it burn cleaner-----leave less residue-------isnt it better overall for your engine.

Are you telling me that a car ran on strictly 91 octane for ten years would not be better off than a car ran on stricly 87 for ten years.........

masagsxr

Also the point I was trying to make when Klaus responded about gas. I do just put 87 on my Nissan Titan tho.. That thing is $80 to fill up (28 gallon at fully empty, lights up at around 22-23 gallon so I fill it about that much which cost about 70-80 bucks)

Specaiist

iTrader: (3)

Hey Klaus, I have to correct you on this point. My 1998 SC400 DOES specify what type of plug to use. It clearly states that plugs are to be replaced with "iridium" plugs.. Other than that I'm with you.

Here are the pics to back up my claim:

This is a pic of the drivers side valve cover, just below the coil.

Klaus

iTrader: (1)

Haha no ****? Alright so I stand corrected on that point

Specaiist

iTrader: (3)

So the "fact" is, Iridium plugs are the way to go for us SC owners... Although we can still debate what brand/type is "better"

imDementeD

iTrader: (7)

i think hes strictly talking performance..since that was main topic..do the best spark plugs add anything performance wise

as far as gas goes..it definitely depends..if the engine does only call for 87..then itll run best on that..its meant to burn 87..
as far as cleanliness..idk but i do know back when i had my waverunner that called for 87..i ran 93 for a while until i talked to a pro rider friend of mine..and he said use whats suggested it will get you the most hp out of the water craft..so i started using 87 and sure enough the ski was noticeably faster with 87 vs 93 (2005 gp1300r)..and i raced plenty of other 1300's and walked all of them..from 04s to 06s..all thought i had something done but it was bone stock...

1WILLY1

iTrader: (9)

Thanks imdemented

And thanks everyone-----this was a good thread-----I learned a little bit of info here.

1WILLY1

iTrader: (9)

And lol klaus

Dont worry were not going to rub your face in it lol

Thanks man

TechGreek

iTrader: (4)

Iridium/Platinum plugs do NOT spark off any better of a spark. They have a finer electrode but a much longer lasting material.

I put the NGK Iridum in my SC300 and haven't had any issue. It's just so I don't have to replace my plugs but every 60k miles.