Tag Info

Hot answers tagged

14

tl;dr: They do. It's just harder to tell how much. The longer answer is that they do and that effective compression is failing you as an approximation for actual effects. Think about detonation (AKA premature ignition of the fuel-air mixture). Normally we consider two causes: compression (the change in the space enclosed by the cylinder as the piston ...


11

tl;dr: No. This sort of vehicle dynamics question best addressed by Racing Car Vehicle Dynamics What follows is a basic discussion at the high school physics level. As you will see from the reference text, high school physics is insufficient to statically model the complete vehicle system. A dynamic model is required to agree with easily obtainable ...


8

The problem is, the crossfire isn't just high compression, I believe its supercharged as well. Forced induction motors like octane - the high pressure, high compression, and most importantly high combustion temperatures make you more prone to detonation. There are enough electronics in the engine (knock sensor for one) to realize that something is amiss ...


7

Firstly, the comments made by others are correct. The power used by each of the components listed will vary on a component by component basis and even on an installation by installation basis. The power used by each component will also vary depending on the speed that it is running at. Also the number and type of components will vary from car to car. With ...


5

Performance exhaust pipes increase power by getting the exhaust gas out of the engine faster. It does this by eliminating the restiction by using larger pipes or less sound absorbing/reflecting material. An analogy is the aerator on the faucet it slows down the output or flow out of the pipe similar to a muffler. Gas mileage is improved by getting more of ...


5

On my most recent car before my current car, I put in a K&N air filter. I believe I saw a minor improvement in horsepower, but it could also have been the placebo effect. As to your questions: You can save money with a K&N as long as the following are true: You clean/oil the filter at the recommended intervals You don't live in an excessively ...


4

One of the reasons that a turbo setup with the equivalent effective compression is more forgiving of low octane gas than than a static compression setup is that you're not at that compression ratio all the time. Take that honda, for example. At 9:1 static ratio, you can run 87 octane all day as long as you don't push any boost at it. When you do start ...


4

NOTE: the below assumes that you aren't talking about ECU-controlled cars that explicitly pull timing intentionally at high revs. In the spirit of checking the easy answers, you should check the map in the ECU. If you're looking for measurable factors, there are two critical items that might trigger detonation and, therefore, convince the engine to pull ...


3

I wouldn't rule out a bad MAF so quickly - there was a generation of VW and AUDI MAFs that slowly went south without any indication from the ECU that they were doing so and IIRC the ECU managed to compensate for the dying MAF for a while. Also, if the ECU thinks you might be boosting at 15psi and using a conventional gauge suggests you're boost 7psi, you ...


3

I am looking @ Page 96 of 1999 Toyota Avalon Owner's Manual. This page shows Dash buttons with labels & some nore. This is what written on that page for ECT. "PWR" (Power) mode for powerful acceleration ECT PWR "PWR" mode indicator light on the instrument panel shows the driving pattern selector button is in "PWR" mode.


3

this sounds just like a clogged fuel filter to me. The car starts fine because the fuel has had time to percolate through the clogged filter but once that fuel is used up the engine starts starving for fuel because the flow through the filter is not great enough to run normally. Since it occurs randomly it will be hard to test this. But I would try ...


3

This is one of those eternal debates that have very few definite answers. My view is: Try lower octane gas, if you notice either knocking or decreased performance then you should stick with the higher octane fuel. Try midgrade first, then if everything is good, try regular. My mother had a Mazda Miata that recommended Midgrade but would run fine on ...


3

Factory turbocharged cars typically run very little timing on the top end (high RPM/high load) - so what you're seeing via logger may most likely be correct. Additionally to further confound the issue the factory also tunes A/F to a very conservatively rich value @ WOT. Those two factors alone will make a car feel "soft" at higher RPMs. That's part of the ...


3

Doing incremental upgrades is a very wise move - not only does it spread the costs, but it also gives you a much better idea of the effect of each change you make. For mountain driving (and, in fact, for any situation), the first things I would look at are the brakes and tyres. The tyres are vital, as they're the only things keeping you on the road! The ...


2

In addition to good answer by @Bob: There are some tricks that can be used to ease the problem: A knock sensor for detecting premature detonations (and adjusting boost pressure). E.g. Saab APC allows safe use of lower octane fuels. Injecting water to cool the combustion chambers (instead of excessive fuel) Per cylinder exthaust thermometers (and ...


2

Speaking to the asker: From page 158 of the 2005 Crossfire Owner's Manual: "DaimlerChrysler Corporation requires the use of 91 octane or higher premium fuel to minimize the potential for engine damage." Spend the extra $4 per fill-up and get the 91 octane. Speaking to the question itself: Without specifics, and without defining "high" and "high ...


2

... I'm curious about if such fuel is safe to use in your typical stock engine on a passenger car If they've added lead, no. I suspect that it's very unlikely that anyone is selling leaded gas at a common access pump (at the race track, maybe). If no lead, then it's quite likely fine but a waste of money for most cars and drivers. Cars (especially ...


2

Have a read of this question on the benefits of premium fuel and this one on what you should choose for your car, as it all depends on your engine and its tuning - a high compression engine can usefully use higher octane petrol, but a lower compression engine will just run badly (or fail to run). Conversely, some higher compression engines can downtune in ...


2

A lot of performance Japanese cars are tuned for higher octane fuels from the factory, and will often pink badly on anything less than 97. I suspect the "Racing Fuel" will have other additives as well. If your car is tuned for 93 it would probably still run on 100, but certainly won't run well. (out of interest, what ratings are "regular" and "mid" - here we ...


2

The higher the octane, the less power per gram the gasoline contains. Use the lowest octane your car needs. expanding on my answer: It's safe...ish to use on stock engines. The fuel burns cooler and may clog your catalytic converter. You certainly won't see any better power or mileage from it, unless you're tuned for 100 octane. It's sold solely for ...


2

What does it do? (better performance [and how so?]? better mileage? cooler sounds?) It depends. One of the goals of a performance exhaust is usually to create a tuned system: A tuned exhaust system is an exhaust system for an internal combustion engine which improves its efficiency by using precise geometry to reflect the pressure waves from ...


2

The quickest way is probably to phone a Seat dealer and ask. Usually recalls are "Any vehicle with a VIN in the range X to Y" - so all you need to do is find that range and make sure the car you're looking at isn't in it... The VOSA Database also has a list of all official recalls on UK market cars or parts, and doesn't list any for a 2008 Leon.


2

Assuming this isn't a daily driver, make sure it is legal locally to burn and start with small doses (2% mix) then add a little more every fill until it doesn't run properly. Then come back and tell us how it went! :) Also, this may foul plugs, ruin O2 sensors and lead to high carbon build-up, but all in the name of progress right?


2

The Ford will definitely be cheaper to run. Partly because, as you say, it is a more common car, and so parts are more readily available, but also because the Subaru has the flat-four 'boxer' engine, which is commonly known for being a pig to work on, as almost everything is inaccessible with the engine in the car... The Subaru will also cost more in fuel ...


2

Is there a noticeable difference in handling due to the added weight of steel wheels? (seems to be 5-10 lbs more per wheel, ignore the salt and potholes for now) (scaling safety and performance) Yes. Assuming that your steel wheels are heavier than your alloy wheels (which might or might not be true), you'll be facing an increase in unsprung weight ...


2

Bob cross makes some good points, however, I would offer the following opinions: Winter tires don't have the dry grip that summer tires do. Your "high performance" handling will be limited with your winter tires on. Therefore, I wouldn't be too concerned about the incremental difference in handling due to the difference in unsprung weight between steel and ...


2

The obvious (though not necessarily right) answer is no, the rules don't make the cars safer if ballast is allowed. But I would add that that doesn't mean the guys at Red Bull will deliberately make a car unsafe. If they kill their star driver, they won't win any more races. Materials are lighter than ever and engineers have the benefit of experience, but ...


2

Before you go fast, you need to be able to slow down. That means better brakes and tires and possibly uprated suspension components (springs and shocks). And strut braces if you don't mind shortening the life of your tires. With that out of the way, as far as making the car go faster, I always work from back to front, meaning I make sure that the things ...


2

Preface I ended up doing a fair bit of thinking and research on this, so I figure I may as well write up what I found. Thanks all those who responded, particularly BobCross. In the end though, I wanted an answer that went beyond calling a car a mystery box on balloons - I asked this question because I actually want to understand it. Intro - Tires Given ...


2

You have a lot of big questions here, so will try to answer them for you, but be ready for the diatribe of the century ;-) There is a simple rule when talking about power/torque output which goes: There is no replacement for displacement. If you increase the size of the four cylinder (through whatever method) to match the size of the six cylinder, you will ...



Only top voted, non community-wiki answers of a minimum length are eligible