How does tunning work?

[quyen]

I have noticed that it is possible to tune an engine to produce different amount of power (e.g. Standard M5 engine 400bhp, Tuned M5 engine in Ascari 500bhp). How does this work and what are the advantages and disadvantages of tuning for more power?

Edited by quyen on Friday 25th April 08:14

[Ordinary Bloke]

quyen said:

I have noticed that it is possible to tune a engine to produce different amount of power (e.g. Standard M5 engine 400bhp, Tuned M5 Engine in Ascari 500bhp). How does this work and what are the advantages and disadvantages of tunning for more power?

Tunning? I guess you mean tuning?

You can get more power from your engine. It may increase the cost of your insurance. It may reduce the life of your engine. It may make your car more difficult to drive. It may use more petrol/diesel. HTH

[phumy]

quyen said:

I have noticed that it is possible to tune a engine to produce different amount of power (e.g. Standard M5 engine 400bhp, Tuned M5 Engine in Ascari 500bhp). How does this work and what are the advantages and disadvantages of tunning for more power?

Suggest google or buy an engine tuning book, the subject is vast.

[fatjon]

It's about getting more air through the engine. If you get more air through you can burn more fuel and get more power. Typically this will involve better airflow into the engine by improving the air filters and the ports on the cylinder head. You can also change the length of valve opening time and overlap between inlet and exhaust valves and improve the exhaust manifolds and system. Of course on modern cars this all means you have to modify the engine management program in most cases to really see the benefit. This is the theory at its most simplistic but it is a real science and a good book will fill in the details, for example tuning the lengths of the pipes to get resonance at the right RPM and the advanced aspects of port and cylider head design.

Jon

[quyen]

Thanks Jon for the succint answer. I guess I should have guessed that from basic physics (no such thing as free energy). However, I have always been intrigued as to why when an engine can achieve 500bhp, a company like BMW only put it out at 400bhp. Must be something to do with the cost of tuning it up to that spec I suppose?

[Richair]

How does the earth rotate? How was the galaxy formed? How does neuclear fisson work?

All questions of simelar magnetude and complexity. There is no simple answer and this is a vast subject; so called 'chip' tuning being very one small area.

However, being as it seems you're specifically refering to the 'electronics' of tuning, or mapping here it is in a nutshell:

The ECU for a modern fuel injected car controls many aspects of an engine, but the main two variables are fuel (i.e. how much fuel and air there is in the cylinders) and ignition (when and how long there is a spark).

The ECU adjusts the ratio of fuel to air to an ideal ratio for the given condions (e.g. air temp, loading, rpm, exhaust gas O2 etc). The ratio will depend on the loadings and throttle opening; accelration requires a slightly richer mix of fuel to air and at cruise the engine will go 'lean' to conserve fuel.

The time the spark plug fires is also adjusted to make best power for the given fuel type (higher ron is more resistent to knock/detonation), air temp and loading. Basically, more spark 'advance' (i.e earlier in the cycle) results in more power. But to much advance and detonation will occur (very bad) which will damage the engine) So the ECU is constantly calculating how much advance is required.

To do all of the above, the ECU has a set of 'maps' which is basically a load of graphs/tables/numbers for fuel and spark for any given condition. When an engine is 'mapped' the graphs are changed so that the ECU will adjust the fuel and spark for any given situation differently than it was before being changed.. (if that makes sense!)

Obviously that is just the tip of the iceberg and there is A LOT more to it than that. If you want to learn more, i suggest spending a few hours/weeks/months reading up on the web

Rich

[Mr2Mike]

quyen said:

Thanks Jon for the succint answer. I guess I should have guessed that from basic physics (no such thing as free energy). However, I have always been intrigued as to why when an engine can achieve 500bhp, a company like BMW only put it out at 400bhp. Must be something to do with the cost of tuning it up to that spec I suppose?

1) BWM sell many thousands of cars, and they don't want to have to replace lots of engines under warranty. The engines state of tune is such that failures in the warranty period will be very small.

2) BMW have to comply to some very strict emissions regulations, some of the methods for lowering emissions hurt power output, and engines in a lower state of tune tend to have better emissions anyway.

[Snake the Sniper]

May I suggest you buy David Vizard's book on tuning the A series (mini) engine. It will teach you loads about tuning engines. Then get a book by Corky Bell on turbo charging. Those two will tell you all you ever wanted to know about tuning, and probably more than you ever really cared about! For more modern ECU stuff, you're on your own there. I just see them as little carbs and dizzy's in a box.

[Richair]

Forgot to mention; if you are that inclined to learn about modern tuning, read one of A Graham Bell's books. 'Four Storke Perormance Tuning' is a great read. If you're as sad as me, once you pick it up, you won't put it down!

Also, another rule of tumb with any kind of tuning; anything you do or change will have drawbacks elsewhere and I mean ANYTHING! It may be financial, or it may affect the life/strength of another component. But it is always a case of weighing up benefits and disbenefites....

[Ordinary Bloke]

quyen said:

Thanks Jon for the succint answer. I guess I should have guessed that from basic physics (no such thing as free energy). However, I have always been intrigued as to why when an engine can achieve 500bhp, a company like BMW only put it out at 400bhp. Must be something to do with the cost of tuning it up to that spec I suppose?

That was succint, mine was more succint-er than his!!!

Tuning: You can get more power from your engine. It may increase the cost of your insurance. It may reduce the life of your engine. It may make your car more difficult to drive. It may use more petrol/diesel.

[Mattt]

Richair said:

Forgot to mention; if you are that inclined to learn about modern tuning, read one of A Graham Bell's books. 'Four Storke Perormance Tuning' is a great read. If you're as sad as me, once you pick it up, you won't put it down!

I took it on holiday once with me, along with 'Forced Induction Performance Tuning'

[Ordinary Bloke]

Mattt said:

Richair said:

Forgot to mention; if you are that inclined to learn about modern tuning, read one of A Graham Bell's books. 'Four Storke Perormance Tuning' is a great read. If you're as sad as me, once you pick it up, you won't put it down!

I took it on holiday once with me, along with 'Forced Induction Performance Tuning'

Four Stork Tunning? Is that the bird, or the margarine?

David Vizard's books are all good, the Ford SOHC and Mini one's are full of useful info. He explains, in everyday language, how to do Turbo/Blown engines with Nitrous Oxide...

Edited by Ordinary Bloke on Friday 25th April 23:40

[buggalugs]

quyen said:

Thanks Jon for the succint answer. I guess I should have guessed that from basic physics (no such thing as free energy). However, I have always been intrigued as to why when an engine can achieve 500bhp, a company like BMW only put it out at 400bhp. Must be something to do with the cost of tuning it up to that spec I suppose?

Its about compromise, BMW are after a ballance of low end, top end, smoothness, low noise and long life in harsh conditions - other people have different priorities!

[fatjon]

Ordinary Bloke said:

quyen said:

Thanks Jon for the succint answer. I guess I should have guessed that from basic physics (no such thing as free energy). However, I have always been intrigued as to why when an engine can achieve 500bhp, a company like BMW only put it out at 400bhp. Must be something to do with the cost of tuning it up to that spec I suppose?

That was succint, mine was more succint-er than his!!!

Tuning: You can get more power from your engine. It may increase the cost of your insurance. It may reduce the life of your engine. It may make your car more difficult to drive. It may use more petrol/diesel.

It may have been succinct but did not really address the question of "how does it work". I think anyone with most of a braincell knows if you tune your engine it may guzzle fuel, not last as long and your insurance company will rape you but none of those points address what I guess was a someone trying to learn a little about the physics of autombile engine tuning.

I second (third) the suggestion about books by David Vizard, he knows his stuff and has the right balance between the laymans explanation and the nitty gritty science aspects.

Jon

[Ordinary Bloke]

We're going to have to call it a draw because you didn't answer the second part of his question, the advantages and disadvantages

[fatjon]

Agreed :-)