How can i get more horsepower out of my toyota avalon 2004

Perhaps the OP would prefer a human analogy to his/her car situation.

Can you force a late middle-aged man to run faster?
Yes, you could give him a big dose of amphetamines.

Will that endanger his health and very likely shorten his life span?
Again… yes.

In other words, trying to extract more power from the existing almost two decade-old engine could work… in the short term. In the long term, it will only hasten the death of that car.

yeah, trade it in for a Hellcat…


Trade it in for a 2021 Avalon, 301 hp.

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We’re not dyno testing. I’m calculating the increase in power put out by the engine given a certain amount of boost. Doubling the air pressure from 14.7 PSIa to 29.4 PSIa doesn’t double the power. It produces a little bit over double. Just like cutting the pressure in half to 7.35 PSIa doesn’t make half power, it is more like 1/3 or 1/4. At 3.675 PSIa the engine might stall or produce 0 HP.

There is always a small safety factor or over design in a professionally engineered machine. The account for the MAP or MAF sensor being at the edge of the tolerance or dirty. So I bet 1 PSIg of boost wouldn’t exceed the limits of the computer or sensors. 3 PSIg might though.

Engines can gain power with age due to carbon build up and higher compression! Bearings in engines wear out with use, not with age. It’s no different than a 1 year old car with 100k miles on it.

edit: added PSIa/g

By my textbooks, you are calculating it incorrectly.


All you people here are completely missing the point. A 2004 Avalon is a powerful car in stock condition, and should satisfy even the most performance-oriented drivers. People have become too hungry for obscene amounts of horsepower, when the bigger concern should be to have a car which delivers reasonable performance, fuel economy, and reliability, while keeping costs down.

Personally, I have been satisfied driving economy cars with NA 4-cylinder engines. The performance is adequate for my needs and driving preferences, and the low fuel consumption is great for my budget.

To put the OP’s question into perspective, I remember when my family had a 1998 Toyota Camry CE with the 4-cylinder engine and automatic transmission. I thought it was a very fast car with excellent performance and handling.

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Agreed on this point.

I had a Dodge Challenger with the 5.7L Hemi V8, somewhere around 375HP. I now have a Mazda 3 with the 2.0L engine, maybe 150HP. I’m fully aware a V8 differs a lot from an inline 4 cylinder… but the Mazda is very peppy and fun to drive. I suspect it’s at least 1000 pounds or more lighter than the Challenger, too, so it doesn’t “need” as much engine power to move. The 40+ MPG is a huge bonus too.

So it’s not always about having the most horsepower. Unless you’re wanting to brag to your buddies, of course… but they probably have Jeeps with lift kits and LED light bars they never use…

Not the OP’s question. They want more power. Do they need it? Nope.


Heres an update on you guys am a keep it stock and trade it in for a hellcat🤣


However, younger drivers–whose driving skills are an unknown to us, along with their repair budget–might think otherwise, even if it’s not realistic for them.

With all due respect to the OP, he/she probably thinks that he/she “needs” more power. In the real world–complete with auto accidents and insurance claims–I ask… Does he/she really “need” it?

A little over double??? 29 psi of boost takes a 200 HP engine to over 590 HP… with supporting fuel /ignition management

That (7.35 psi of boost) is 50% more boost to give you 300 HP over 200 HP…

The little Honda’s specialty built K-24 engines are making over 1000 HP out of a 2.4L normally stock 200 HP engine by boosting it 60 PSI… again with supporting fuel/ignition management…

I don’t know what ur smokin’ but perhaps we should all partake. An AVALON satisfying even the most performance-oriented drivers?? I know people who would never ride any amusement park ride, it’s too much for them. I also know others that will get on rides I would never even consider riding. I wouldn’t think of telling those people they don’t need to ride that hair raising rollercoaster, they should be perfectly satisfied riding the one I think is plenty thrilling…

Have you ever driven a Corvette?? Or any (actually serious) performance car?


An Avalon is grampa’s car. It is fast enough, durable and reliable as heck, handles OK, rides nice and is a very competent sedan.

It is neither fast nor sporty. But it was never intended to be that.


@Rpereina_186852, the best way to accomplish your goal is to sell your Avalon and buy a car that meets your desires. The Avalon never will even though it’s a good car in its class.


Some peoples need for speed is on a whole different playing field… Some people are happy with a slow and low lead sled cruiser, some people want a 10 second street car, you absolutely can not compare the 2 by saying both would be happy in the same vehicle…

My daily driver is a stock Vibe/Matrix 5 speed and even though it is fun to drive, it is no where quick enough… My hot rod is surprising quick for a N/A engine that looks mostly stock… And it is NOWHERE quick enough for me…

So no I would never be salified in a stock 2004 Avalon, would I drive it and leave it stock? Yes, would I always wish it had way more power? Yes!!!

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Nahh. There’s a reason Avalons are called the Japanese Buick. They’re silky smooth, quiet, but absolutely not performance oriented. Certainly not powerful, by modern day standards.

They are lovely cars though.


I’m using PSIa not PSIg. I realize most car people talk about all pressures in gauge pressure, or PSIg, which is what the pressure gauge shows. So it’s confusing. But gauge pressure can’t be used to make accurate calculations. The engine doesn’t care what the atmospheric pressure is. The manifold absolute pressure (PSIa) is what matters.

29 PSIg of boost at sea level is 43.7 PSIa! Just over 3 times the normal pressure in a NA engine.