Nomad TT

Me to im lovin this

Brian-PA

I was admonished for not being more specific with what happens to the air after it passed through the turbo.

The compressed air from the turbo is sent into the combustion chamber where it is mixed with fuel and burned. Then it exits via the exhaust system.

I assumed that anyone who read the post would conjecture that the air was used in the combustion process. Yes, I know I should have not assumed and I should have been more specific. So, no I did not mean that the turbo actually was the complete process in the cycle.

Sheesh, I will preview my post next time.

Brian

Kenny

Re: Enlighten Us Then with your Knowledge, & mention specifics....

peterl

The Toyota Camry V6 (1991) is a non-interfering design - can't hit the valves. The Honda design (valve crimping) is not common for mass market cars. I wouldn't do this without understanding your engine. Mine(at the time) and my wife's (she had a Corolla) both are "safe" on a belt break - basically a bad misfire followed by a stall.

Check your car - my Camry would have been fine - and that was from the engine manual and the dealer.

Peter

Bollinger

Basically a turbo charger uses the power remaining in the exhaust gases to compress incoming air.

As exhaust gases exit the manifold, they push in a set of air vanes (like fan blades) which spins a shaft. This shaft then spins another set of vanes in an impeller (see below) which compresses the (engines) incoming air.

This forces more air through the engine. Now you simply have to add more fuel also, and your engine acts much as if it were a larger engine. It is similar to increasing displacement, except for turbo lag. Lag can be minimized, but not removed. A belt or gear driven supercharger has no lag, and doesn't have to use an impeller, so it doesn't have a need for an intercooler.

Using an impeller in a turbocharger makes it force in a lot of air efficiently, but also causes it to compress the air instead of just moving more of it. This causes the air to heat up. An intercooler removes much of this heat, at the cost of a little more lag and more plumbing. A roots-type supercharger just forces more air in, without compressing it.

An impeller works by bringing in the air (in this case) near the spindle, and then centrifugal force forces the air out to the edge of the spindle, where it piles up against the turbo housing. The compression and the rotation of the spindle also forces the air out of the exhaust port of the turbo. This exhaust port is not related to the engine exhaust, as it actually leads to the engine intake manifold.

Turbocharging doesn't have much downside if the engine is designed for it. Aside from minor lag problems, the only real problems are created by the incredibly high rates that the turbos spin at (up to 100,000RPM). You need to make sure it is well lubricated and the bearings cooled to endure this treatment. Ideally, you would continue lubrication and cooling after the car is turned off, until the turbo spins down (which can be 10-15 seconds or more). Audi continues the cooling, which is the more important, but doesn't continue the lubrication. Lets hope they know what they are doing, and that cooling only is enough.

Bollinger

Although they are marketed as such. What they mean is full-time available, automatically activated. This is like the Audi TT/S3. Or an automatic Subaru. Or a Honda CR-V, Volvo, or BMW X5.

Many cars/SUVs are only RWD (or FWD) until the rears slip, then the fronts are shunted in. The reasons for this are mechanical simplicity, weight, and cost.

This has a downside. When you have variable low-traction surfaces, the car (SUV) can jitter and slide around as the center diff locks and unlocks. Also, the delay can be annoying. If you are slipping on a turn, the rears will slip outwards, creating oversteer until the center diff locks up. This can cause short moments of alarm since you appear to be entering a spin.

So why not punch that 4WD HI button and go full-time? Well, because that locks up the center diff and will cause driveline binding on grippy surfaces.

I spent a week out of my A6 and in an Explorer and I have to say it was not a good experience. The slow activation of the AWD was alarming, and since I was driving on variable surfaces I couldn't go to true full 4WD.

Plus, locking the center diff ensures that at least one tire has to slip when you turn, no matter what surface you are on. Is this really something you want? To axiomatically lose at least 1/4 of your traction during turns when you turned on 4WD to get more traction in the first place!

I simply felt trapped between the capable, but flawed 4WD HI mode, and the herky-jerky of the part-time auto mode. I'll take the more capable Quattro IV system, or the systems available on the Mercedes ML, Land Rover Disco II, and the optional higher end (Quadra Drive?) available on the Grand Cherokee.

Bollinger

Coil over plugs is the ignition system you refer to. This shortens the high voltage path and makes the plug wires much less important.

It is definitely the wave of the future, as it gives more precise spark which helps with emissions. I don't know if Audi has it or not.

Basically, the system moves the ignition coil from one centralized location to one at each spark plug. This costs money, as you have to have multiple coils.

These kinds of things are great, but nothing to make a purchase decision on. GM made the last big advance (actually, several) in ignition by going to distributorless in 1986. BMW didn't start until much later (early 90's, I believe). Last I checked, Honda still hadn't switched the Civic over (1995 was last time I looked).

Now, I ask you, is a 1995 Civic a car with a bad engine? Even though it was at least two major advances behind in ignition, the car is as solid as a rock.

Wando

force, compress they are one and the same and it is the compressing of the air that heats it up, so even a supercharged engine would benefit from an intercooler, and you say having an intercooler decreases lag but you are wrong again! if you increase intercooler size on a turbo engine then you increase the ammount of lag as more air has to be compressed to pressurize the inlet system, so if you had no intercooler you would have a bit less lag, but less power so the power gained makes it worthwhile.

Regards
John