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Testing HP without dyno

I want to know if it is possible to measure my horsepower without using a Dyno. I have a 91 Honda accord 2.2L sedan. I don’t know if it helps but I am capable of weighing the car accurately and measuring the time accurately from 0-60. Any way to make a formula to measure the HP from these measurements or any other way without spending $$$. we all know how tight cash can be these days.

This is only as accurate as the timing equipment. You’ll never get as accurate as you will with a dyno.

Not trying to get very accurate just within 10 hp or so to tell if the mods i have made are effective compared to the cash i have spent. I have spent 150 on parts and made some Mods based on theory some that i have never seen anyone else do. At least not for as cheap as i have. I believe that you can do Mods cheap if you put enough hours into them to make sure they are safe and effective.

By the way thank you for the link. It seems like you cracked this problem!

10 hp or so is very accurate, you’ll see more difference than that between two different brands of dynos. You’ll get a rough estimate, and it should give you an idea whether the mods are helping or not.

Rather than timing the car from 0 to 6o, I would time from 30 to 60 just because the results would most likely be more repeatable. If you time from zero, you are measuring your tire’s traction as much as the engines power.

The concept is pretty simple. How much kinetic energy did the car gain per unit of time?
Ke = mass X velocity squared / 2
Let’s say your car has a mass of 1000 kilograms and the engine takes it from 10 meters per second to 20 meters per second in 5 seconds.

Kinetic energy at 20 meters per second = 1000 x 20 X 20 / 2 = 200,000 joules
Kinetic energy at 10 meters per secone = 1000 x 10 x 10 / 2 = 50,000 joules

200,000 joules - 50,000 joules = 150,000 joules of energy gained.
150,000 joules / 5 seconds = 30,000 joules of energy gained per second or 30,000 watts of power or 30 kilowatts.

multiply kilowatts by 1.34 to get horsepower.

If you do not know the HP before the modifications then how do you know the mods have even done anything at all?
If you’re going to be basing this on the post modification figure against the factory stated HP figure then you may be in for a big disappointment. Those factory numbers are on a new vehicle and are often fudged a bit.

A dyno machine has also broken a lot of hearts when the numbers are not what someone thought they would be after sinking a fortune into an engine.
Sometimes at car shows a dyno will be present for car owners to guess their HP and then verify it with a dyno run. About 90% of the car owners guess wrong by guessing way high.

What baseline measures of performance did you establish before you modified the motor? Lap times at a race track? 0 to 60 time? 1/4 mile time and speed at the end of the distance? If you have base measurements, repeat them and see if there is improvement.

If you have 10% improvement over your baseline performance, you might “roughly” estimate a 10% increase in HP and/or a 10% increase in torque.

Most mods are never well documented. The driver feels a difference which could be real or imagined. There is a definate placebo effect to justify the money and time invested which tends to overstate effects of many modifications.

Dynos also ignore loud exhausts and window decals.

As mentioned those are small, incremental measurements to be accurate enough using those methods. $$ are an issue for many people but here’s one option that is more accurate, you own it and can use it anytime (versus dyno time) and it’s relatively cheap. Plus you get lots more info than a simple dyno run. Maybe someone else following this thread in the future will be interested as well-

Most of the time a free-flowing loud exhause will offer more power than an exhaust system that was made with low noise levels in mind. Granted these days the gains are small on most cars. But there’s a reason you never see racecars with mufflers (except were it’s mandated)

I’m thinking the 30 to 60 measurement plus a coast-down measurement 60 to 30 to factor in rolling and aerodynamic losses could be pretty accurate.

The most accurate, truthful device to measure performance gains is a drag strip. Dyno gains do not always translate into actual performance gains in the real world. Get some runs in to establish a baseline, make your mods, and run it again. You’ll have your answers.

If using a drag strip, go by terminal speed, not by elapsed time. Elapsed time is too dependent on driver skill and what happens in the first 100 ft of the run. The terminal speed is much more repeatable.

That’s why I suggested a 30 to 60 time instead of a 0 to 60 time. A 30 to 60 time is much more repeatable and measures the performance of the engine, not the launching skill of the driver.

What are the mods?

Remember these mods are meant to be cheap and easy for someone with some auto experience and little money. First and foremost i replaces the factory intake and exhaust with K&N and thrush turbo (I HATE the big round “fart cams”) I then ran a filtered tube from my intake to my hood scoop to bring in cooler air. I upped the idle for better takeoff being sure that i didn’t lose traction. I got smaller tires for better acceleration. I put in some decent dual spark spark plugs. Cleaned the fuel injectors and modified them to give it slightly more fuel. Took the engine block to a machine shop and got the cylinders a little wider and bought bigger cylinders. Started using high octane now with the bigger cylinders. And last but not least i put in an extremely fine water/methanol mister to cool the fuel as it is combusted. AND NO THERE IS NO DANGER OF HYDRO LOCKING MY ENGINE. The mist is so fine that it instantly turns to steam when combustion occurs and is harmlessly ejected from my exhaust. Sorry for the caps but people always tell me I’m going to ruin my car but Ive been running water injection for years and never had that problem.

PS please no replies that say get a Turbo because i want a unique little ricer that is high performance without just throwing a turbo and some NOS in there.

All of those mods you mention, including what is apparently a bored engine block, can possibly contribute a small amount of horsepower but it won’t be earth shattering.

Water injection will not harm an engine if used in moderation but it’s not designed to run all of the time. Water or coolant in the combustion chambers is corrosive to aluminum.

My gut feeling is that if you put this engine on a dyno and get some real world numbers you may be in for a bit of a shock; and some disappointment. A dyno run is not that expensive in my opinion and around here 60 bucks gets you 2 dyno pulls. One initial pull, time allowed for some tweaking, and then a repeat.
How much horsepower do you guesstimate your engine puts out right now?