How to tune-up a secondhand car?

[cheesehead]

On an episode of Top Gear, one of the presenters took an old Renault and, via rather a lot of elbow grease, managed to boost output from around ~160HP to within a few of the 210HP claimed from when the car was new. I think he listed a new air filter, new injectors, and a new intake manifold (do intake manifolds wear out? Or was the new one an upgrade of some sort?) as the key ingredients. I'm going to be buying a secondhand Subaru sometime in the near future, and I'd like to screw as much horsepower out of the engine as I can without spending a lot of money or impacting the reliability or fuel economy.

 

[coxmaster]

Generally this is how it works.

Power Increase == Reliability and Fuel Economy Decrease

 

[exdeath]

Best bet, if you want cheap and easy and noticeable gains, is to start with a platform which already has forced induction and/or an established modding/tuning community. Then basic mods like boost controller, wastegate, intercooler, intake, exhaust, and fuel tuning will give you 50-100+ RWHP easily.

Otherwise you are just going to end up wasting a lot of money with half ass self fabricated parts or parts that the engine is ill equipped to handle. Do your research in advance and pick a good platform, otherwise you could dead end your performance potential as soon as you buy the car. Some engines just flat out suck in their initial design and have zero room for upgrades (eg: Chevy 305, Toyota 2.2L 5S, etc).

That said Subarus are a very good platform for tuning/modding if it's a turbo car or if it's a WRX/STI.

 

[Bignate603]

Change all fluids (may not get you that much power, but it's just a good idea), spark plugs, injector cleaning (you'll most likely need a mechanic to do that), change the air filter for a brand new one (Get OEM or a good OEM style one, most performance ones aren't worth much).

Stuff like this will help get it back to closer to how it was when it was new but won't really make it better than new. To do that you'll impact reliability, fuel economy, your wallet, or most likely all three.

 

[TehMac]

that Top Gear test (I remember it) is flawed because they have this ridiculous concept that "horsepowers disappear" over the years.
They dyno tested their car to prove it, but what the dorks didn't realize that with an automatic trans, power to the wheels was something like 147-167 WHEEL hp, which they compared with the factory rating of 210 bhp. When they "got it back to its factory condition," after tuning the shit out of it, they were disappointed when their dyno test "only" gave them 210 whp, not realizing that flywheel horsepower is much more.

Frankly, the show knows fuckall about the technical aspects of cars (Clarkson has even admitted this several times). They deliberately skewed the GT 500's power rating, making it seem like it was a farce because it had 447 whp, and not "500 hp" which it had, just made it at the flywheel.

Not a show to base any consumer advice on, but very amusing and entertaining...when it's any good.

 

[TehMac]

Also, the concept of saying modified cars are useless and using a Renault Caravan failing to catch an Evo X is laughable, but I think that's dry British humor for you.

The fact that Clarkson drove an Evo in Season 13 that got 0-60 in 3.7 tells you something about the abilities of a well-modded car.

 

[jlee]

that Top Gear test (I remember it) is flawed because they have this ridiculous concept that "horsepowers disappear" over the years.

I'm not saying that their whole testing concept was flawless or anything, but I have a hard time believing a 20yo car with a couple hundred thousand miles on it is going to make the same power it did when it was new. Things do get tired eventually.

 

[HarryLui]

Fast, cheap, reliable

Pick two

 

[Eli]

Generally this is how it works.

Power Increase == Reliability and Fuel Economy Decrease

Uh, no.. not when you're talking about a simple tuneup.

In fact, a tuneup should increase engine life...

Air filter and plugs will probably be the biggest things that could affect power.

 

[cheesehead]

Frankly, the show knows fuckall about the technical aspects of cars (Clarkson has even admitted this several times). They deliberately skewed the GT 500's power rating, making it seem like it was a farce because it had 447 whp, and not "500 hp" which it had, just made it at the flywheel.

James May is actually one of those sorts of geeks who not only understands the difference between BHP and WHP, but how it's possible to calculate drivetrain losses using the rotational intertia of the rolling road. (He even brought it up on the show.)

On the subject of automotive modding, they do, for the most part, have a point: For the cost of all the tuning and add-ons required for a significant horsepower boost, you could've bought a better car secondhand. There are some notable exceptions - specifically anything with an LS-series V8 or the Subaru WRX - but for the majority of people, who own things like Renault Clios, Civics, and Foci, there's not a whole lot of point. Sure, you can weasel 420BHP out of a Civic and do some impressive things with the suspension, but for all the money you've spent, you could've bought a rather nice secondhand M3.

Generally this is how it works.

Power Increase == Reliability and Fuel Economy Decrease

The thing is that I'm not looking for a power increase - I'm just looking for the ~160HP the car came with from the factory.

 

[HarryLui]

Oil, oil filter, air filter, clean the intake track, clean the throttle body, coolant, plugs, wires, cap, rotor, transmission oil, seafoam the engine, new catalytic converter (upgrade the entire exhaust if you want)

 

[cheesehead]

Oil, oil filter, air filter, clean the intake track, clean the throttle body, coolant, plugs, wires, cap, rotor, transmission oil, seafoam the engine, new catalytic converter (upgrade the entire exhaust if you want)

I've been looking into the procedure for the oil and various filters, but I'm not sure about how to go about cleaning the intake track and/or throttle bodies. Also, what do you mean about the cap and rotor? And what happens to old catalytic converters?

 

[Eli]

I've been looking into the procedure for the oil and various filters, but I'm not sure about how to go about cleaning the intake track and/or throttle bodies. Also, what do you mean about the cap and rotor? And what happens to old catalytic converters?

I don't think any car made in the last 15 years still uses a distributor(cap and rotor).. lol

To really clean the intake manifold and TB, you would have to remove those parts and use a little elbow grease.

If you need to "look into the procedure" for an oil change, this may not be for you.

 

[exdeath]

I don't think any car made in the last 15 years still uses a distributor(cap and rotor).. lol

15 years ago is 1995. Plenty of cars still have distributors.

 

[Eli]

Like?

 

[jlee]

Like?

MR2, Supra, etc. comes to mind.

 

[Bignate603]

Like?

My '97 Cherokee uses a cap and rotor.

 

[Eli]

Ahh.. Yeah, I guess... Was thinking that coilpacks became the norm by then. So when did the cap/rotor finally disappear? By 2000?

 

[cheesehead]

If you need to "look into the procedure" for an oil change, this may not be for you.

1. I'm not much of an auto mechanic, and figured I ought to make sure I was doing everything properly. Subaru engines can be a little weird, in part due to the opposed cylinder pattern.

2. Finding the oil filter can be a ah heck if you don't know where it is.

I'm still a bit unsure about the seafoam stuff - it seems that to get the most use out of it, you remove the catalytic converter before use and clean (or replace) the spark plugs and O2 sensor afterwards. In addition, if run through the oil system, you want to change the oil ASAP. That said, it seems that I'll be doing all of these things anyway - the net cost for new oil, new plugs, and replacement air and oil filters is under $100, and the rest of it just seems to be variations on "Remove, clean, replace."

 

[CraigRT]

15 years ago is 1995. Plenty of cars still have distributors.

I can't think of any around 1995.
my '88 had a distributor.. my 96 has coilpacks.

 

[Bignate603]

1. I'm not much of an auto mechanic, and figured I ought to make sure I was doing everything properly. Subaru engines can be a little weird, in part due to the opposed cylinder pattern.

2. Finding the oil filter can be a ah heck if you don't know where it is.

I'm still a bit unsure about the seafoam stuff - it seems that to get the most use out of it, you remove the catalytic converter before use and clean (or replace) the spark plugs and O2 sensor afterwards. In addition, if run through the oil system, you want to change the oil ASAP. That said, it seems that I'll be doing all of these things anyway - the net cost for new oil, new plugs, and replacement air and oil filters is under $100, and the rest of it just seems to be variations on "Remove, clean, replace."

If you don't know how to change your oil go get a manual for your car (Haynes or Chilton are the ones I see the most of). It will tell you exactly where everything is.

 

[HarryLui]

I've been looking into the procedure for the oil and various filters, but I'm not sure about how to go about cleaning the intake track and/or throttle bodies. Also, what do you mean about the cap and rotor? And what happens to old catalytic converters?

Take all the intake pipings out and use carb cleaner and a rag to clean all the oil/dust/grease out.

Old catalytic converter can clogged up and rob your power by making a restriction in your exhaust system.

Also, change all your vacuum lines, PCV valve, and whatever that are worn out and need replacing.

 

[PlasmaBomb]

On an episode of Top Gear, one of the presenters took an old Renault and, via rather a lot of elbow grease, managed to boost output from around ~160HP to within a few of the 210HP claimed from when the car was new. I think he listed a new air filter, new injectors, and a new intake manifold (do intake manifolds wear out? Or was the new one an upgrade of some sort?) as the key ingredients. I'm going to be buying a secondhand Subaru sometime in the near future, and I'd like to screw as much horsepower out of the engine as I can without spending a lot of money or impacting the reliability or fuel economy.

From memory it was just "clean the intake", the episode is on youtube...

Basically over time the intake can get some gunk in it (due to EGR etc.), which lowers its efficiency. Less efficiency means less airflow, and that means less power. Similarly the injectors can get gummed up, reducing efficiency. Basically all they did was return it to factory spec and power output.