Car question: how to increase performance without forced induction?

I just bought a new car after driving an old junker for 9 years. It’s got decent acceleration, but I’d really like it a little better than decent.

I know turbocharging and supercharging are good ways to increase acceleration, but I think that might be a little overboard for me-- I’m not a tuner. I know next to nothing about cars, and the little I do know about super/turbo systems is that they’re expensive and complicated. If something went wrong, I wouldn’t have the slightest clue what to do about it, and it’d probably destroy my engine before I got it fixed. Besides that, I’m not trying to race it or show off; this is strictly for my own personal enjoyment. I’m just looking for some low-maintenance modifications that won’t kill my gas mileage but will make a noticeable difference in performance.

Any ideas, dopers?

(And my apologies if this is more of an IMHO question; I really don’t know how subjective these things are.)

We’re gonna needs specifics on the type of car.

Note: If it’s an import, like a Civic, ignore those that come in and claim you can’t make them go fast.

Waiting for more info…

While waiting for more specifics on year make and model, I would just like to note that such mods will in some cases void your factory warranty if found out.

Case in point customer comes in and complains his AC is inop. Tech checks out the car under warranty. After several hours tech discovers that the climate control module is not receiving the OK to start the compressor from the engine control module. He also notices that the engine seems a bit peppier than normal. Customer is called and asked if he has a modified control unit. No is the reply. Technician calls for technical assistance from the factory. Technical specialist comes out and goes over the system with technician. No other faults found. TS looks at the software in the ECU and discovers that it is non-factory stuff.
Customer is presented with a bill for 6 hours of labor, and warranty is voided on the engine and driveline.
Bottom line is you bump the horse power using non-factory parts, you assume the risk if it breaks.

I thought the warranty was only invalidated if it can be proved by the dealer that the mod caused the failure? In this case, that’s true, but not in all.

The modder’s mantra should be, “Return to stock before bringing your car back to the dealer!”

Either that, or wait until your warranty is out before modding your car.

Damage can be cumulative, and if you read the warranty that comes with your car, the car maker reserves the right to do this. The car maker can’t void parts of the warranty that are not affected by the mod. For example, the car maker could not void the warranty on the power train if you installed a different radio. But since the factory engineers spent plenty of time figuring out exactly how much power out put from the engine the transmission and axles can take, they are with in their rights to void the powertrain warranty if you install a hot control unit.
This is known as the sucks to be you clause.

Eliminate weight: Leave your spare tire at home. Take out the back seat. Clean out your glovebox and trunk. Replace your hood with carbon fiber. Take out the radio.

Change tire size: Smaller diameter means better acceleration, worse gas mileage. Larger diameter means better gas mileage (on the freeway), worse acceleration.

Cold air intake, headers, performance exhaust, and a performance “chip” would be a few things you could do for between $200 and $600 each.

If you enjoy having money in your pocket and a car that runs and has a warranty, you should really steer clear of this course of action entirely.

Intake and exhaust aren’t very intrusive and could give you 10 or 15 more horsepower and will only make it more efficient in daily driving. High-flow catalytic converters could help too.

But OP, you need to post what year and model car you have.

2007 Scion tC.

I’m planning on researching carefully before I do anything, of course, but more than likely I’ll be getting all my parts from Toyota Racing Development and having them installed by professionals. AFAIK, this doesn’t void the warranty.

Can’t read & respond individually right now (leaving work), but thank you for all your responses so far! I’ll check them when I get home and get back with y’all soon.

If you live in an area with a lot of standing water, you may want to avoid installing a cold air intake.

In general, chipping is usually the easiest way to improve performance on the cheap.

Intake and exhaust then, definitely. Stay with the Toyota stuff if you’re worried about your warranty. Keep in mind this will make your car louder, and it might drone at highway speeds. But since engines are basically a big air pump this will help it breathe easier.

Put a lot of stickers on it. Automatic 25 horsepower increase.

That’s not always true. I read somewhere (I think it was here) that someone had put smaller tires in their car and it resulted in the car kicking into overdrive sooner and thus getting better mileage.

FWIW if you change the tire size and do not recalibrate the speedo, none of your MPG numbers will be correct.

OK, so aside from “don’t do anything,” the resounding advice seems to be cold air intake, exhaust, headers, and a performance chip. If I installed all of these, what kind of performance improvement could I expect?

(Also, if anyone would care to explain what each of these things do, that would be swell. If not, I can google, but I like dopers’ simple/concise explanations. :p)

I forgot to mention before that it’s a 4-speed automatic. I know that limits my options, but as I said, I’m really not looking to burn up the roads; just want a little more pep.


An Automatic? That’s probably going to negate the vast majority of the things you try to do, as the shifting is all automated for efficiency rather than power.

There are a ton and a half of Scion clubs (my mother and her boyfriend are in one) out there that are supported by Toyota. If you look for some of their fora, I’m sure you’ll find some more specific input.

That being said, the Nopi online catalog has a lot of cosmetic type stuff for your car… lights and such.

The following are uber-simplistic descriptions of each for the ultra-lay person:

Cold air intake - draws air from outside the engine bay; cooler air is more dense, which means more oxygen reaches the combustion chamber. An intake may actually improve your mileage while improving performance, and makes a better sound. Possible drawbacks include getting water into the intake if you mount it too low and drive through a puddle.

(Aftermarket) exhaust/headers - decreases back pressure in the exhaust system which allows the engine to get rid of waste gases faster (and therefore produce more of them). Headers are individual exhaust ports for each cylinder, which allows faster flow than a manifold (one big pipe for all cylinders). Possible drawbacks include lots of noise and possibly issues with your catalytic converter.

Chip - the ECM is the microchip that tells the engine “what to do”, ie. what fuel/air mixture to use at a given throttle position, load and engine speed. “Chipping” means replacing or remapping the ECM so it tells the engine to use a richer fuel/air mixture. This essentially releases the engine’s “untapped power”, ie. the power that isn’t produced because the engine is tuned to stay within certain volume and mileage ranges. The drawback is it will certainly increase your fuel consumption.

I suspect that the maximum sensible increase in power from doing all of the above is about 40-50 hp. With a chip, you can theoretically increase maximum power to almost any number, but certainly anything over a 30% increase is going to make things wear out/break sooner - particularly the transmission.

Note that for straight-line acceleration you can shift into “1”, “2” and then drive manually - and you can may be able to have the shift patterns remapped if/when you get the car chipped.