Dudes. I drove 18 hrs yesterday to get o Denver. Now my truck is DOG slow

Drove the same situation a few years ago in CO. Amazing place. My 2008 F250 6.4L twin turbo powerstroke... tuned.. basic intake exhaust egr deleted and few intercooler tubes upgraded. With just 3 people and a couple bicycles and I was nervous as hell driving all those steep grades uphill and high elevation. Temps just kept getting higher for exhaust and engine... Felt like a slug haha. Truck was starving for air. Not much to do I couldn't imagine my lil runner doing it and expecting any more than how you stated the power being. An my truck dyno'd in NY low alt. at 575HP roughly to the wheels haha.

Take the air out of your lungs like that and its a real pain to run jump or pedal the same you do with more air. My runner struggles just on silly little hills on highway around here without flooring it.
 
ColoRig said:
I think the key is to relax and take in the awesomeness of Colorado and enjoy the slower pace of mountain life :)
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Exactly perfect - pull into one of the legal wacky tabacky joints and relax but don't forget to follow all the CO rules while doing that. Luck! :cowboy:
 
ColoRig said:
I think the key is to relax and take in the awesomeness of Colorado and enjoy the slower pace of mountain life :)
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Sounds like a deal breaker when your normal motto when driving is

1316595744_clarkson-power.jpg
 
02SE said:
The higher you go in elevation, the less Octane the engine needs. The Octane rating refers solely to the AKI (anti-knock index) of a particular gasoline.

That's why Regular (which is what a stock 3rd gen is designed to run on) is 87 r+m/2 Octane at lower elevations. While at high elevation, Regular is 85 r+m/2 Octane.

Less air pressure at high altitude, means less cylinder pressure in the combustion chamber. With less cylinder pressure, there is less chance of pre-ignition (knock).

If the engine isn't experiencing knock on Regular gasoline, Ie: the computer isn't sensing knock, and retarding the ignition timing in response to knock, using a gasoline with a higher Octane rating will do nothing for the engine. You will just be wasting your money on higher octane gas.
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so at a mile high, running 85 is the same as running 87 at sea level?
 
amalik said:
so at a mile high, running 85 is the same as running 87 at sea level?
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From an anti-knock perspective, which is all the Octane rating is, yes.

Knocking, pre-ignition, auto-ignition, self-ignition, pinging, are all names for what is essentially an uncontrolled explosion in the combustion chamber.

The Octane rating is not an indicator of the energy content in the fuel. It is only a measure of the fuels tendency to burn in a controlled fashion, instead of exploding in an uncontrolled fashion.
 
Yeah, Colorado Native speaking here.

1) Running premium isn't going to do crap. You are wasting your money on an engine without the compression ratio to take advantage of the extra octane. You will actually make less HP and no, your mileage will not magically increase by 1-10 MPG.

2) Your ECU sensors (yes, on a 3rd gen) are constantly sending signals to the ECU to adjust for changes in ambient temp, altitude, barometric pressure and a host of other things. Unplugging the negative battery cable, pulling the ECU fuse, etc.. to "reset" the ECU is bovine excrement. ;-)

3) You did not say (or I missed it) how much of a load you had in your 4Runner. I can tell you my 2002 (with just two passengers and ski equipment) would hold 65 in third gear on Floyd Hill all day long but the 3.4 is working hard to keep all that weight moving up a 7% grade. If you are flooring it in 2nd gear to maintain 65 mph your air filter is junk, your plugs are junk or your cat convertor is junk. Or all three.

I never beat my vehicles up so I just let it do 65 and didn't try to make it do 80. (Off the record my sportbike will easily do 140 up Floyd Hill as would my Carerra 4). Don't ask, I won't give details. LOL

Every vehicle I have ever owned (and there have been some very high HP vehicles in that group) - you will notice the lack of oxygen the higher you go. It becomes math at a point - HP (or shall I say excess HP) and weight.

Start with your air filter. When did you change it last? That is HUGE in Colorado at altitude. You need a LOT of air coming in.
 
TheDurk said:
It's also a Federal offense to put avgas in road-use vehicle, as you are skipping paying the gas tax. Race cars are ok.
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Pretty sure Avgas has lead it in, or at least it used to.

My dad is a private pilot, and had some left over Avgas. A friend of his decided to run it in his car. It was a long time ago, but it destroyed either his O2 sensor or his catalytic converter. Can't remember which it was.
 
Weird, I lived in denver and my 98 Tacoma never had a problem in the mountains. It was a manual, but i don't know if that really made much of a difference.
 
02SE said:
From an anti-knock perspective, which is all the Octane rating is, yes.

Knocking, pre-ignition, auto-ignition, self-ignition, pinging, are all names for what is essentially an uncontrolled explosion in the combustion chamber.

The Octane rating is not an indicator of the energy content in the fuel. It is only a measure of the fuels tendency to burn in a controlled fashion, instead of exploding in an uncontrolled fashion.
Click to expand...

Oh wow. So the extra octane in forced induction or a better compression engine creating more power has less to do with the higher octane/fuel and more to do with the difference in the engine itself? In that case, sounds like 91+ simply prevents knocking?
 
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Colorado Native here too and my 3rd Gen. makes the trip from Denver to Vail about 70 times per year (for past 18years)... never had a problem, usually cant hold her back. Runs best east bound up and through the tunnel for some reason. Maybe a bit sluggish if I have it loaded up with buddies and equip.
 
KJ303 said:
Colorado Native here too and my 3rd Gen. makes the trip from Denver to Vail about 70 times per year (for past 18years)... never had a problem, usually cant hold her back. Runs best east bound up and through the tunnel for some reason. Maybe a bit sluggish if I have it loaded up with buddies and equip.
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70X a year!? wow. Do you have a cabin out there?
 
amalik said:
Oh wow. So the extra octane in forced induction or a better compression engine creating more power has less to do with the higher octane/fuel and more to do with the difference in the engine itself? In that case, sounds like 91+ simply prevents knocking?
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Exactly. Higher octane burns slower, helping to prevent detonation in high compression or forced induction engines. That's all it does. However, in normal engines designed for regular, it does give more money to the oil companies.
 
On the subject of octane

Are the 4runner JDM ECU equivalents tuned for a higher octane?
I know on the Toyota MR2 they were.

Just curious.
 
98OzarksRunner said:
Exactly. Higher octane burns slower, helping to prevent detonation in high compression or forced induction engines. That's all it does. However, in normal engines designed for regular, it does give more money to the oil companies.
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In terms of pump gas for street legal vehicles, saying that higher octane gas burns slower, has some validity. For pump gas and the engines that are designed to run on it, it's better to say that the higher Octane gas simply resists premature ignition better than a comparable but lower Octane gas.

In reality there are so many variables in gasoline blends, especially racing gas blends, that we would need to know the specific gravity of a particular fuel in question, to have an idea of how quickly it burns.
 
scrap metal said:
On the subject of octane

Are the 4runner JDM ECU equivalents tuned for a higher octane?
I know on the Toyota MR2 they were.

Just curious.
Click to expand...

Japan uses the RON (Research Octane Number) Octane rating system.

In the USA, and some other Countries, the (R+M)/2 (Research Octane Number + Motor Octane Number divided by 2) Octane rating system is used.

There are variables, but the difference between those two different Octane rating systems in terms of the Octane number, is approx. 6

So a Japan (RON) rating of 98 Octane, would equate to a USA (R+M)/2 rating of approx. 92 Octane.

So if an MR2 specs 98 (RON) in Japan, and 92 (R+M)/2 in the USA, then we know their octane requirement spec is the same.
 
There is a big difference between E85 and regular 87. The higher alcohol content of E85 offers considerably less potential energy per gallon than regular 87.

But above 87 is also a waste of money on an engine that isn't performance tuned to take advantage of the higher octane.

Just stick with good old regular. And get your ass back to Chicago where it's flat! Low 50's here all week!
 
Yes way less potential power per gallon which is why us e85 guys have to add up too 30% more fuel just to get good afr's. But once you get the fuel system setup and enough delivery the stuff never detonates. Makes tuning fun since your usually tuning too knock. But once you have e85 your tuning to what your motor can handle. Which can be scary. LOL.

To the OP like stated, keep the reg in there, save your money. Im used to the dog slow feeling up here. Supercharger helps get some of that lost PSI in the high altitude.
 
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