Regular gas in WRX

[Hallraker]

That defeats the whole purpose of having paid the extra $$$ for the turbo
model in the first place.......

lol... That was kind of my point.

I knew a guy back in High School who had a Mustang. Nice car for the times,
but he insisted on putting these cheap ass tires on it. His rationale was
that, he was going to burn through them so fast, why not just get cheap
ones? I tried and failed to explain to him that paying more for better
tires was going to give him better grip and likely better wear as well.

-Matt

 

[y_p_w]

lol... That was kind of my point.

I knew a guy back in High School who had a Mustang. Nice car for the times,
but he insisted on putting these cheap ass tires on it. His rationale was
that, he was going to burn through them so fast, why not just get cheap
ones? I tried and failed to explain to him that paying more for better
tires was going to give him better grip and likely better wear as well.

Don't know about this. I don't know about when you were in HS, but
truly high performance tires with high wear ratings seems to be a
recent thing (for the most part).

I've noticed that a lot of cheapie tires also tend to be the ones with
harder, less-grippy rubber that tends to wear longer. It's ironic
that the more expensive high performance tires don't last. So one might
end up with a tire that costs twice as much and wears half as long.
That being said, there seem to be some really high performance tires
now that have treadwear ratings from 280 up to 400.

As an aside, when I was in to get my tire patched at a Firestone shop, I
was checking out their Indy car tire display (one new and one used). At
room temps, the rubber on those things was rock hard. I've been told
they have to be warmed up before the rubber softens up and grips hard.
I suppose those tires should get hot enough at 200 MPH. Someone said
that drivers starting a race drive side to side before the green flag
to get the tires warmed up.

 

[Jim Stewart]

Don't know about this. I don't know about when you were in HS, but
truly high performance tires with high wear ratings seems to be a
recent thing (for the most part).

I've noticed that a lot of cheapie tires also tend to be the ones with
harder, less-grippy rubber that tends to wear longer. It's ironic
that the more expensive high performance tires don't last. So one might
end up with a tire that costs twice as much and wears half as long.
That being said, there seem to be some really high performance tires
now that have treadwear ratings from 280 up to 400.

I can't speak for cars, but I used to ride a motorcycle
daily. The tires that were are true delight to run were
very soft and sticky and lasted about a year. And costed
about $150 each.

 

[Steve Jones]

I suppose those tires should get hot enough at 200 MPH. Someone said
that drivers starting a race drive side to side before the green flag
to get the tires warmed up.

I believe they also use tire wraps that warm the tires up. Basically an
electric blanket for the tires when the car is just sitting there.

Steve

 

[Cam Penner]

Ah, but the HS student wasn't wearing the tires out through
driving. He was burning them off with smoke shows. No
point in putting high performance tires on if you're just
going to roast them off.

I can't speak for cars, but I used to ride a motorcycle
daily. The tires that were are true delight to run were
very soft and sticky and lasted about a year. And costed
about $150 each.

A year for a motorcycle tire isn't doing too bad. The good
ones to run (street - non-race tires) last 3000-5000 miles.
And yeah - $150-$250 per tire isn't out of the question.
Bikes love good tires, and they eat them up and spit them
out.

 

[Henry Paul]

I know, I know. I couldn't resist.

Maybe he figured he was going to do a lot of showing off and peeling rubber
then? Why not get nice used tires instead of cheap new ones? Just a thought.

 

[Henry Paul]

Oh ok! I have seen that before the races start. I always thought they were
just being goofy.

 

[Henry Paul]

That's true. I bought an old jeep a few years ago that had a brand new set
of Yokohama Geolander tires on it. They were worn almost bald after 2
summers only. I did notice that they handled pretty well also. They are a
really good off-road tire.

 

[CompUser]

Oh ok! I have seen that before the races start. I always thought they were
just being goofy.

Nope. Those tires will even tend to "flat spot"
when they get a caution flag and are still
rolling. You'll see em doing it then too.

 

[T]

1) The compression ratio is typically lower with a turbo'ed engine than
in an equivalent normally aspirated engine.

Yes but the compression applied by the Turbo of Charger makes for
higher than normal pressures in the cylinders. The reason the piston
chambers are backed off to a lower base compression value is just
because of the higher net compression when under 'boost'.

It makes no sense to run lower octane gas because a turbo'd motor has
lower base compression.

2) The octane demands will be lower at high elevations. The fuel
available in many high elevation areas contains lower octane fuel.
I wouldn't use it unless I knew I was going to be there for a
while.

I have no experience w/ this and will accept it on the face of things.

3) Nothing can physically alter the "compression ratio" (which is
fixed), although the boost from the turbo does raise the pressure
(which some call compression).

Point being that you will need a higher octane (less likely to
preignite due to heat/ high compression) in a turbo motor.


TBerk

 

[T]

And for "predetonation", I got in serious doo-doo with a nitpicky
guy who said that there was no such word, and that it was grammatically
incorrect.

(Getting off topic).

The language is meant to serve, not be catered to.

Communication is key and if what you meant to convey is predetonation
then that is what you meant.

Use it enough and it become a 'real' word. ;])


TBerk

 

[y_p_w]

And for "predetonation", I got in serious doo-doo with a nitpicky
guy who said that there was no such word, and that it was grammatically
incorrect.

(Getting off topic).

The language is meant to serve, not be catered to.

Communication is key and if what you meant to convey is predetonation
then that is what you meant.

Use it enough and it become a 'real' word. ;])

I found several of the threads that generated so much discussion:

<http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&[email protected]>
<http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&[email protected]>
<http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&[email protected]>

 

[y_p_w]

Yes but the compression applied by the Turbo of Charger makes for higher
than normal pressures in the cylinders. The reason the piston chambers
are backed off to a lower base compression value is just because of the
higher net compression when under 'boost'.

Yes. However - I'm just saying that "compression ratio" refers to
the physical dimensions (max combustion chamber volume : min chamber
volume), and can't be altered by ambient conditions.

It makes no sense to run lower octane gas because a turbo'd motor has
lower base compression.

I never said that. I realize that forced induction raises the
pressures, and makes the nasty stuff (detonation/preignition)
more likely as a result.

I have no experience w/ this and will accept it on the face of things.

I've seen reports that regular/mid/premium in Colorado is typically
85/87/91. I remember an old '82 Olds Cutlass Cierra manual. It
said that a 2 octane point reduction would be acceptable at certain
altitudes (i.e. Denver). Check out the following article:

Point being that you will need a higher octane (less likely to preignite
due to heat/ high compression) in a turbo motor.

Again - I was only stating that the "compression ratio" is a fixed
number determined by the physical dimensions of the engine. The
compression ratio of my 2004 WRX is 8.0:1, which is the same whether
I'm driving in Denver or San Francisco.

 

[Byron]

Again - I was only stating that the "compression ratio" is a fixed

number determined by the physical dimensions of the engine. The
compression ratio of my 2004 WRX is 8.0:1, which is the same whether
I'm driving in Denver or San Francisco.

You terminology for compression ratio is correct. What I had meant to
say (even though I'm pretty sure you understood me the first time) is
that the ultimate cylinder pressure at TDC-compression and the amount of
oxygen molecules in the charge for a turbocharged car is essentially
unchanged by altitude.

Normally aspirated cars, when they can't get as much air into a cylinder
because the ambient pressure is reduced by altitude or temperature, can
often burn lower octane fuel successfully. There is just less oxygen
(and all other gasses) per cubic foot of air and that helps resist
detonation and preignition. But when a turbo is introduced, the engine
can then force feed the same number of molecules into the cylinder
because it has a bit of extra capacity - compressed air that would have
been passed out of the waste gate at sea level is sent directly to the
cylinder.

So when I was only able to find 90 octane between Oklahoma and New
Mexico when my WRX 2.0 turbo was fully loaded with a trailer, I was
rather apprehensive. I never felt or heard any knocking, but I bet my
knock sensor and ignition timing reduction equipment got a good workout.

 

[Dan]

The long and short of it. When a car is turbocharged higher octane fuel
keeps the engine from going BOOM!!!!!

 

[FNO]

The long and short of it. When a car is turbocharged higher octane fuel
keeps the engine from going BOOM!!!!!

Your brother is not likely familiar with forced-induction cars. For a
normally-aspirated car tuned for 87 octane, no increase in performance will
be noticeable. But, for any forced-induction car (turbocharged or
supercharged), the power gains are realized by compressing the air on the
intake. You need higher octane; full stop!

 

[NitroTrike]

I agree. One thing you dont want to happen under boost, is detonation
(pinging). THATS A BAD THING. Also the computer will "learn" timing curves
(among other things) to different fuels. If your ever in a pinch and the only
thing available is "mr econogas regular", then it will just run like hell, as
the computer will be retarding the timing and cutting back the boost to
compensate for the knocking (pinging). Nurse the car to a REAL gas station and
pump her full of super, and let it re-learn everything again. Good luck!

 

[Jim Stewart]

I agree. One thing you dont want to happen under boost, is detonation
(pinging). THATS A BAD THING. Also the computer will "learn" timing curves
(among other things) to different fuels. If your ever in a pinch and the only
thing available is "mr econogas regular", then it will just run like hell, as
the computer will be retarding the timing and cutting back the boost to
compensate for the knocking (pinging). Nurse the car to a REAL gas station and
pump her full of super, and let it re-learn everything again. Good luck!

Nitro,

Please learn how to inline-post so we know what
you're talking about. We can't see the message
that you're replying too unless you preserve the
relevant parts and put your reply at the bottom.

 

[busterb]

The long and short of it. When a car is turbocharged higher octane fuel
keeps the engine from going BOOM!!!!!

TOTAL CROCK OF BS!!!!! No carmaker would sell an engine that will be
damaged by regular gas. Otherwise their warranty claims would be
unbelievable. Yes the performance MAY suffer slightly but not enough
for most people to notice. Case in point- 2001 VW Passat 1.8 T.
"Requires " premium but has used only 87 octane for 125000 miles. Many
problems with vehicle due to VW "quality" but none that could be
attributed to lower octane. Run whatever gas you want.

 

[Ignignokt]

TOTAL CROCK OF BS!!!!! No carmaker would sell an engine that will be
damaged by regular gas. Otherwise their warranty claims would be
unbelievable. Yes the performance MAY suffer slightly but not enough
for most people to notice. Case in point- 2001 VW Passat 1.8 T.
"Requires " premium but has used only 87 octane for 125000 miles. Many
problems with vehicle due to VW "quality" but none that could be
attributed to lower octane. Run whatever gas you want.

Well... OK. Run whatever gas you want. But knowing what pre-ignition and
detonation are and knowing what they do to an engine and knowing that higher
octane helps prevent these things -- leads *me* to the conclusion that
running low octane in an engine designed for premium is a Really Bad Idea
(tm). I won't go so far as to say that "busterb" got lucky, but... Well,
scratch that: I'm going to say that "busterb" got lucky. Do a couple
Google searches on "detonation" and "pre-ignition" and decide for yourself
whether you want to do this to your engine. And bear in mind that knock
sensors can't *predict* engine knock, only *react* to it. They *limit* the
damage that prolonged knock would cause, they don't *prevent* that damage
entirely.

As for the "no carmaker would sell an engine that will be damaged by regular
gas [because of the expensive warranty claims]" remark: Keep in mind this
implies that the engine only need last as long as the warranty. Any forced
induction of an engine can lead to accelerated engine wear if not handled
properly. And by "handled properly" I'm not just referring to the hardware
changes, but to proper use, like running the proper type of fuel and
observing proper warm-up and cool-down of the engine. Which is why dealers
won't honor warranty claims on boost-enhanced cars: They have no way of
knowing whether the added boost was "handled properly." So it seems likely
to me that the manufacturers design their engines so that in the worst-case
scenario -- where a moron owner runs 87 octane gasahol in his STi for its
entire life, never warms up the engine before slamming the boost all the way
to the waste gate, and frequently shuts the engine off right after a string
of quarter mile runs without letting it cool down -- the knock sensors and
other design features will keep the engine alive long enough that in most
cases the engine will outlive its warranty. So like I wrote at the top:
Run whatever gas you want. It all comes down to whether you want to take
care of your car -- something "busterb" doesn't seem particularly interested
in bothering with.

Just my two-cents.

- Greg Reed