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

I have a fully stock toyota avalon 2004 and was wondering if theres anything i could do to add more power to it.

Yes there is. Proper service will help restore the 200 hp or so it was built with. Air filter, new spark plugs and keeping up with oil and timing belt changes depending on mileage and/or time. This 19 year old should be on its 3rd timing belt.

Getting more power would take a large pile of money… much more than the car is worth.

Ignore cold air intakes, they make noise not power. Same for performance exhaust.


Thanks for the reply really appreciate it. And what about an e85 conversion kit, would it be a bad idea?:thinking:

Has barley passed the 100k mark miles

Here’s an idea.

Be happy with the perfectly good, well cared for car that you have.

Stop worrying about making it “better”. As long as the car gets you from A to B, that’s all you need. Any money you put into “upgrades” will be money wasted in the long term.


E85 won’t do much for power on an unmodified engine but it will kill your mileage. You will lose about 25 to 30% of your economy… so 30 mpg to about 22 mpg. Your fuel pump and injectors may not be able to provide the 20 to 30% more extra fuel E85 requires.

On a 100k mile car, it may cause fuel system problems because it will find the weak points.


Follow the advice Mustangman provided in his first response.
If you want a performance car, save your money until you can trade in your Avalon for a performance car.
As far as E85, expensive conversion, only “complete” kit I could find was $1200 for parts, and that did not include a listing for the Avalon.


Spending that much money (+ labor costs) on modifying a 19 year old car doesn’t seem like a practical use of one’s financial resources. Instead of using the money in that manner, I think that the OP would be better-served by setting aside cash for repairs and/or buying the next vehicle.

No matter how reliable Toyotas are, with 2 decades of wear and tear there will inevitably be needed repairs coming up, and using this money for repairs–instead of something like an E85 conversion or other power-boosting modifications–would be much more practical.

Exactly, plus any significant HP increase would likely need suspension upgrades.

Why would E85 conversion yield any significant hp? Only if a turbo was involved, seems to me.

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Additionally, the almost 2 decade-old transmission might not take kindly to a significant increase in engine output.


There can be some small gains from the cooling effect of more fuel from E85. Spark advance can also add some hp IF the ecu allows it. Big if.

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Forced air induction. Right now it is 14.7 PSI. Figure 3.7 PSI is 0 HP. 14.7 200 HP.

14.7 - 3.7 = 11.

Add 2 PSI of boost from an electric motor air pump kit.

11 + 2 = 13

200 * 13 / 11 = 236 HP

Use premium gasoline. Have 236 HP with no pinging.

So a supercharger. But many of those aren’t legit. Which one are you referring to?

And you don’t need E85 to do this.


E85 main benefit for performance is it’s 105 octane rating and cooler intake charge, that is great for high compression engines and forced induction engines as it raises the resistance to denotation/knock…
Basically it is a waste of money unless you are running a race engine on the street… lol

You can add about 8-9ish pounds of boost and get 50% more HP for $$$$ and you will have a 300 HP vs a 200 HP engine, but then you will start finding ALL the weak links in the driveline such as trans and axles (and many other things), plus reducing the life span of the engine…

If you want to play you are gonna have to pay…

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I am guessing he is talking about adding a leaf blower?? lol


Yup! In addition to the trans and the axles, I really wonder how the 2 decade-old main bearings would take to that type of power increase.



The equation should be (14.7+2 psi)/14.7 psi X 200 hp = 227 hp

From where? I’ve seen a number of videos with dyno tests that prove these devices make NO horsepower at all.

Additionally, why do you think the MAP sensor will work at positive boost? And why do you think the ECU can understand positive boost and adjust fuel delivery accordingly? Seems like you could go very lean (if these things actually worked) before the O2 sensor corrected.

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Like these guys tested:

It says you already posted this link. But they had big success in their video.

If the pump has less air flow than the engine requires, then it will actually reduce power!

At some point as the manifold pressure dops the internal losses will consume all the energy that the engine puts out. Rev an engine to its peak torque RPM with no load on it and measure the manifold pressure if possible. That lost energy should not be considered when calculating the added power from adding boost.

I think Toyota went to MAF when they added VVT-i. It should go a little above the maximum range even with MAP. 1 PSI over at 15.7 PSI would work even with MAP engines I think. That’s why I said 2 PSI boost. 5 PSI boost would probably exceed the range of the sensor or software as you say. I would think MAF would have more range beyond what is normally seen in a stock engine compared to MAP.

What lost energy? Dyno testing is done at WOT. The losses are already considered in the measured output. The added pressure (or reduced pressure if at high altitude) is a direct add (or reduction) in the engine’s output. Your “method” gives a larger HP number than my method. By your logic, your number should be smaller.

Research ICE “Correction Factors” for air pressure and temperature.

Now this method does not include the additional losses from drag on the alternator from an electric turbo nor the temperature rise from compressing the air. Probably close enough since the boost is so low and because the battery will supply the bulk of the power to be replenished by the alternator later.

So this is just a guess?