Cold Air Horsepower

[homeyclaus]

While there is of course an effect of air density in regards to a 4Runner's aerodynamic (or lack thereof) drag coefficient, I think the values would be very minimal. It's been a long time since I messed with fluid mechanics but I would think the altitudes required to really change something for a passenger vehicle are unobtainable unless they are an airplane. If you want to investigate you could look up density altitude (DA) graphs.

Let's add humidity into the equation! Yay!

And Harper, "someone" should dyno their 1GR-FE engine after three tanks of running on super petrol, and see if our 4Runners ended up with the same ignition maps as the Prado overseas. If I had written that code, I'd advance the timing until i get a pre-iginition signal from the knock sensor and then back it a quarter degree or less. Calculate timing map vs. throttle position. Repeat every 100 milliseconds.

 

[Lolrax]

Try it with a Turbo! My Subaru used to become a beast when it was spooling up really cold air.

 

[adam2562]

i wonder how long before we see a NOS'd 4runner hahahahaha

 

[flyrv9]

So, looking at 1Engineer's charts - HP goes down as Temp goes up and HP goes down as Altitude goes up. How about the fact that temp decreases with an increase in altitude i.e. lapse rate. Standard lapse rate is = to 3 degrees F drop per 1000' increase in altitude. Seems to me this would be a wash for altitudes under 10,000' for normally aspirated engines and would be similar to density altitude effects experienced by aircraft. I go higher, the air gets thinner (less dense) but cooler. However, if you're at a high altitude on a hot day you're screwed performance wise. That's why high altitude airports have longer runways and why airports close when it gets very hot.

 

[1engineer]

So, looking at 1Engineer's charts - HP goes down as Temp goes up and HP goes down as Altitude goes up. How about the fact that temp decreases with an increase in altitude i.e. lapse rate. Standard lapse rate is = to 3 degrees F drop per 1000' increase in altitude. Seems to me this would be a wash for altitudes under 10,000' for normally aspirated engines and would be similar to density altitude effects experienced by aircraft. I go higher, the air gets thinner (less dense) but cooler. However, if you're at a high altitude on a hot day you're screwed performance wise. That's why high altitude airports have longer runways and why airports close when it gets very hot.

In a perfect world you would still lose some HP at altitude even with the standard deviations of temp/altitude. High and low pressure areas take care of that though lol.

 

[flyrv9]

Agreed. There are also other sources of loss to consider. Heat generated by the engine, miles on the engine, etc.

 

[1000MPH]

As the temperature decreases so does the speed of sound.
So you're that much closer to driving your 4Runner at Mach One.lane:

 

[flyrv9]

It's an airspeed - groundspeed thing. You can be making 100KTS into a 40KT headwind and be only making 60 over the ground. Not all that uncommon for low speed small planes to make negative ground speed i.e. fly backwards!

 

[1engineer]

So there's a current thread on "How to spend $1,000.00 to get a few extra horsepower." That's not the name of the thread but it's the gist. I thought I would bring this thread back so some could see that "horsepower" is not equal all the time, and how I gained 20 hp in one day for the price of a tank of gas lol.

 

[Intruder]

So there's a current thread on "How to spend $1,000.00 to get a few extra horsepower." That's not the name of the thread but it's the gist.

Is it the LED headlight bulb thread? I knew I should've ordered a set of those...

 

[eddiebx]

Looks like you're better off spending that 1000 bucks on gas to drive to somewhere will lower elevation and/or cooler temperatures. The HP gains would be phenomenal, and scientifically proven! :violin:

 

[scanny]

So there's a current thread on "How to spend $1,000.00 to get a few extra horsepower." That's not the name of the thread but it's the gist. I thought I would bring this thread back so some could see that "horsepower" is not equal all the time, and how I gained 20 hp in one day for the price of a tank of gas lol.

Yes and winter is coming, those graphs look linear so I'm afraid to think how much HP I'll have when it hits -22F : )

 

[Lolrax]

So there's a current thread on "How to spend $1,000.00 to get a few extra horsepower." That's not the name of the thread but it's the gist. I thought I would bring this thread back so some could see that "horsepower" is not equal all the time, and how I gained 20 hp in one day for the price of a tank of gas lol.

Here is my answer to that thread

 

[1engineer]

I pulled this thread up for an answer to somebody and thought I would bump it back to see if any of the new guys want to take a look. 1st post has the info.

 

[Supraformance]

Cold air = tightly packed O2 molecules = more thorough combustion

 

[SouthernSS]

speaking of extra power and the fact that TRD has been dragging their heels on releasing the supercharger for the 5th gen...I've been eyeing a small turbo to build full boost before 2000rpm. It would probably run out of its efficiency band before redline, but then again, I'm not racing it in the 1/4 mile.

Im just totally underwhelmed with its torque even in 4 low. Granted, I'm coming from an AMG supercharged V8 but DANG this thing is gutless.

Whatcha think? Doable? For less than 5k? I'm thinking the ECU would be able to handle up to 7psi or so safely without adding anything other than a manifold/turbo/boost controller.

 

[1engineer]

speaking of extra power and the fact that TRD has been dragging their heels on releasing the supercharger for the 5th gen...I've been eyeing a small turbo to build full boost before 2000rpm. It would probably run out of its efficiency band before redline, but then again, I'm not racing it in the 1/4 mile.

Im just totally underwhelmed with its torque even in 4 low. Granted, I'm coming from an AMG supercharged V8 but DANG this thing is gutless.

Whatcha think? Doable? For less than 5k? I'm thinking the ECU would be able to handle up to 7psi or so safely without adding anything other than a manifold/turbo/boost controller.

What exactly do you expect from this vehicle as far as performance? It runs the 0-60 times as fast or faster than many vehicles in its class and even out of it's class. In 4 low it will spin in the dirt, mud and rock and even pavement and we both know that max torque is achieved right before the tires break loose. If you compare apples to apples then the 4Runner is right there. You would be much better off re gearing if you really want to spend mon...I mean increase torque. I am sure you will put at least 285's on too so the re gearing makes much more sense than a performance adder that will probably light up your dash due to the ECU being locked up tighter than a drum but hey, go for it and let us know!

 

[bimrunner]

What exactly do you expect from this vehicle as far as performance? It runs the 0-60 times as fast or faster than many vehicles in its class and even out of it's class. In 4 low it will spin in the dirt, mud and rock and even pavement and we both know that max torque is achieved right before the tires break loose. If you compare apples to apples then the 4Runner is right there. You would be much better off re gearing if you really want to spend mon...I mean increase torque. I am sure you will put at least 285's on too so the re gearing makes much more sense than a performance adder that will probably light up your dash due to the ECU being locked up tighter than a drum but hey, go for it and let us know!

This.

 

[SouthernSS]

well, its already got 285's on it which is why Im already looking to spend more mon...I mean, increase torque. Im not a huge fan of regearing because I do a lot of highway driving and long range towing. I dont expect much but I would like to be able to merge onto the interstate without having to smash the accelerator through the floor.

I see Bimrunner is running 4.56 gears. What type of rpms are you seeing at 70mph or so? and how is your mpg?


EDIT: for towing regearing would probably help. It is my daily driver though so I've still got to consider gas mileage and you and I both know that a turbo is the most efficient method of adding power.

 

[Narkhelek]

My 4R was way under torqued even in 4L with 33" on. Re-gearing was a major upgrade as all who have done it can attest to. I would not blame anyone for wanting more power from the stock conservative gearing and shift points.