DupermanDave

I have been doing some searching on various HP increase mods for the 22re. The biggest suggestions are to get headers and a new cam from engnbldr.

I have 2 questions regarding each. How do headers work scientifically? How do headers increase horsepower in the engine? I always thought it was because the headers allowed the exhaust gases to flow away from the engine more efficiently than standard exhaust. I also saw a post abecedarian said to stick with stock exhaust. How do headers work, and why isnt stock exhaust good enough? I'm sure stock is pretty efficient, as toyota wouldnt waste development time to do a half decent job building an engine.

second question relates to the cam. how does the cam allow for more power? Does it increase air intake to mix with the fuel?

What are the mechanics behind each device?

yoterr

well headers like you said flow better, its not that a toyota one doesent do the job just now that your getting a cam your going to be moving more air and thus more exhaust flow, and a cam holds the intake valve open longer, thus sucking in more air and fuel=more HP and coupled with a header ur going to see a pretty nice improvement, now this is just lamens terms im sure some 1 will chime in with better terminology

DupermanDave

Lamens is fine. I'm just curious as to how all this works. I'm looking at some HP upgrades in the future, and rather than stick them in and know they work, I'd much rather know why and how they work. I'm curious like that. I'm always trying to learn.

thook

Yoterr said it well enough. All your doing with the cam (or any other upgrade to the combustion process) is increase the capacity for air to spark to fuel potential. Increase cylinder bore even and you have more displacement/more volume for air and greater explosion. The header allows for the greater heat generated from increasing combustion to escape more readily so heat/exhaust doesn't back up (so to speak) and kill this combustion potential. It's kinda like smothering a fire somewhat, otherwise. Plus, the extra heat is harder on the valves.

yoterr

better to want to learn than throwing money at stuff, doesent allways work

xzyragon

i do believe that headers work by allowing the exhaust to escape easier, increasing flow.

From what i've heard others say, you don't really increase the HP of the engine but really only "unlock" the HP that's already there. In all honesty, its a 22re we are talkin about, and if you really wanted more HP, get a bigger engine, or a turboed one. My dad's 1.8 turbo in his jetta kicks ass

DupermanDave

Now if a header allows air to flow out faster and in greater amounts, won't dual exhaust pipes with a larger diameter do the same thing?

GenXr

You don't need dual exhaust on a 4 cylinder engine. A single exhaust up to 2.5" diameter running from a header and free flowing cat & muffler will improve throttle response significantly. If nothing else it should help your gas mileage a little.

I'm running the Downey intake and exhaust system on an otherwise stock vehicle. 1. It's louder, 2. It's more peppy, 3. It's louder, and 4. I get better gas mileage. Did I mention it runs a little louder? There are trade offs for every mod you do.

abecedarian

I saw my name so I've got nothing to say.

No, seriously, I don't think I said to 'stick with the stock exhaust' but may have said something along the lines that Toyota went with a Tri-Y exhaust setup for the factory exhaust and it works well, giving decent low-end torque and high-rpm horsepower.

For all intents and purposes, Toyota 'dumbed down' the setup to give a decent all-around setup suitable for playing around and doing some work. Seriously though, Toyota trucks are envied in many circles due to their grunt, power and reliability, right? Some trucks may make more power but they break more often... etcetera.

But anything you do to the engine is going to have you giving up something for another.

You can't really get more torque or more horsepower withoug giving up something. More HP will usually cost you torque, in the form of a more narrow torque band, meaning you'll have less torque than you used to at certain RPMs. Likewise, a low-rpm stump puller needs more torque so you'll give up peak HP. For comparison, old army jeeps had a peak HP of about 35, compared to the 22re's peak of around 100... and those jeeps were nearly unstoppable. They didn't have a very high torque peak either (nowhere near the 22re's peak) but also had lower gears to compensate. To get higher peak HP and torque ratings usually means they happen in more narrow RPM ranges (maybe at the cost of top speed, like the army jeeps).

Sometimes that's the difference between a 'streetable' engine and a 'race' engine. And what I mean is that a 22re optimized for peak power at 5200 rpm will likely not have enough power at 1500 rpm to make the engine capable of operating on the street, comfortably- you'd be slipping the clutch and revving high to take off from stop signs.

Now I'm not saying you can't get more power out of the beast because it is possible, and headers and cams are the easiest, most reliable ways to do so... without sacrificing the longevity of the engine. I could also say you could get as much power from bumping the compression ratio to 10:1 as you would from headers and a cam but... now you're inside the engine.

Headers, properly designed, allow scavenging- the pulse from one cylinder draws the exhaust out of another, much like blowing over a straw sucks soda up the straw. Cams change when and how much air/fuel and exhaust enters and leaves the engine. One complements the other. And a cam and header designed to work together can make for what is an all-around better engine. But then that comes down to driving habits.

thook

Nice post. <<tip, tip>>

DupermanDave

That's a well explained answer. Thanks. But on standard exhaust manifolds, isnt this affect still in play?

abecedarian

Our manifolds are 4>2 in the upper and 2>1 in the downpipe, in effect a factory tri-y header. But it's not perfectly designed. It works well on a stock truck but there's room for improvement. For one, it has to last (at least as long as the warranty). So a less-than-perfect system gives them some fudge-room.
Keep in mind Toyota had to sell a design that works well with engines of varying stages of wear so it had to last. A 'perfect' header might work well on a new engine but may not work so well on an engine with 50K miles due to changes in compression (from wear for instance). Many variables are involved as are the different owners' attention to maintenance- I mean how many people actually get in there and adjust the valves when they're supposed to... since the 22re just keeps going? It's literally one of the few engines that abuse and neglect doesn't really hurt much.