Would a higher octane gas help a car with header+s-pipe +intake. I understand it will not help on a stock tc engine. Thanks for any info.

 

No.

 

But a turbo can change the need for a higher octane? The richer condition of the addition of a header and intake will not?

 

No it wont.

 

You're just providing freer airflow, not changing the compression in any noticable way.

 

Unless your engine is knocking, you don't need it. Not including forced induction... And an intake doesn't count for that.

http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm

 

87 may be the minimum octane rating required, but according to Toyota all testing was done with 91+ (its right in the manual) . That may very well include testing the engine's power, although I don't know that for sure. Personally, I would use premium, especially with mods. What many people don't take into account is the fact the ECU will adjust for a lower octane rating to decrease the risk of knock (it has a knock sensor) which is likely to adversely affect power output. The only way to know for sure if it will make a difference for the tC, however, is to dyno a car running on 87, then on 91+, using the same car, same dyno, and preferable on the same day. Otherwise, we're just speculating either way.

 

So is it a knock sensor or a potential knock sensor?

 

i would stick to 87 for now. once you do a turbo or even the trd sc (if it ever comes out), i would go to a mid-grade or premium gas.

 

Yes, there is a knock sensor without a doubt. What is in doubt is if there is any knock on 87 octane, and the ECU makes adjustments to accommodate that. It could very well be that 87 runs fine, no problems, and the sensor is there as a safety precaution to account for other factors. I don't know for sure, we would need someone to test that.

 

How about you just get 89 and forget the whole debate? lol

 

That's what I use and I have an intake, header and s-pipe and my car is running just fine and no knocking.

 

oh gawd not this again.

OCTANE DOES NOT PROVIDE ANY PERFORMANCE BENEFITS AT ALL!

it is only a measurement of how easily the gasoline is to ignite and burn. running a gasoline that is higher then what your car is rated for or built for is just wasting money. don't buy into the marketing bs.

unless you're turbo or sc.. then forget about it. header/intake/spipe/exhaust.. etc.. won't require a higher octane.

 

We know what an octane rating is. What we are discussing is if, due to possible ECU adjustments, the tC would benefit from use of a higher octane, stock and/or with mods. Yes, a car can be designed for use with 87 and run fine, and see no benefits from higher octane. What's at debate here is whether or not the ECU in the 2AZ makes performance degrading adjustments when 87 is in use because it detects knock. To say higher octane does not provide any benefits at all on a car who's minimum rating is 87 is making a large generalized statement that's not always true. It depends on the car and how it was designed. It's been dyno proven on various other platforms that a bump in octane will show a increase in HP (a small %) due to the ECU making adjustments to make use of the lower volatility of the higher rating (I'll have to find some dyno test from SCC and others). This can include advancing ignition timing, changes in cam timing and the fuel maps. This isn't a 95 Dodge made for 87 we're talking about here with a low compression ratio an unchanging ignition timing. There are other factors involved, namely the ECU and its various sensors and the adjustments it makes.

 

so is it bad to run 92 octane on a tc? we only get 92 here

 

Im with you, people get so complicated in their little heads. "OH IM GONNA USE HIGHER OCTANE CAUSE I USE SIMPLE BOLT ON MODS!!!111"

Jesus, no it doesn provide more power, not it wont EVER make your car knock, so stop pretending to know something when you dont, and dont give false advice please.

 

turbo's don't change compression.

turbo's SOMETIMES require higher octane fuel to resist detonation.

turbo'd engines are better with lower compression (8.8:1 or so) but timing can also be used to safely keep the engine out of detonation.

you won't see a significant increase in power with premium fuel.

 

You wont see ANY increase in power, only time you will see it makes a difference is like everyone said with a turbo or higher compression, but since 99% of us out there dont have either, stick with the cheapest gas you can put in. On my old Turbo DSM i put medium gas and my **** started to knock all over the place, wouldnt go over 8psi when I usually ran it at 17, so yeah octane ratings are gold with turbos.

 

how do you know the timing isn't advanced when there is premium fuel?

 

Because running higher octane will not make the car run richer on our cars, at least not significantly enough. If your logic is correct, than adding those simple bolt ons would make the car run leaner and retard timing even moreso, when clearly this does not happen.