What Engine Tuners Don't Tell You

PART 1

First and foremost let me define...
An Engine Tuner is a person who does the adjustment, modification, addition and alteration to the internal combustion engine components (software or/and hardware)to alter its performance, to change the engine output characteristic (torque curve vs rpm, hence horsepower), fuel economy, durability (or any combination of those).

It is a norm for any engine tuner to tell you what will be the expected improvement in maximum torque and maximum horse power after the what so called tuning is done for your car engine. Probably you believe it after taking a short spin when your car had been successfully tuned...

You are so happy when a gentle tap is applied on the accelerator pedal the car seems to be flying... and you tell the whole world without knowing your car engine will be out of breath before reaching the new record breaking top speed.... then you became frustrated!

For instance, an n.a diesel engine car also behaves like that. A diesel engine of the same capacity even has higher maximum torque than petrol powered engine. But how come a car powered by n.a diesel engine is so sluggish in century acceleration and 400m standing? However, a turbo diesel engine has a totally different story.

Now, there are something that some engine tuners don't tell you. While a few are pro enough letting you know some..., if not all. I'm not paid to make any recommendation but you will be able to decide what's not and where not to go to tune-up your car.

Before I proceed, probably you need to refer back to your old school book to find out the relationship between TORQUE, RPM and HORSE POWER then come back. I'll wait.
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PART 2

Most people are confused about the relationship between POWER and TORQUE. We often heard engine tuners ask customers:

"U mau improve HORSEPOWER atau TORQUE aah?" in a tone which strongly suggests that these 'experts' believe power and torque are somehow mutually exclusive.

In fact, the opposite is true, and you should be clear on these facts:

Horsepower is dependent on TORQUE and RPM. Torque and RPM are the MEASURED quantities while HORSEPOWER is CALCULATED from the product of torque, RPM and a constant figure. For time being forget about the 'constant figure' . What you should know now is:

HORSEPOWER is proportional to TORQUE x RPM inclusively (but the horsepower is not necessarily proportional to torque or rpm exclusively)

Remember that, torque and horse power do not work together. Horse power is a result of the the torque applied at specified rpm.

Got this? Good. Now think for a moment... what makes a car to accelerate? Torque or Horsepower?

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PART 3

In my studies I categorize torque curves in three difference types. Each type has its own application, one of them may suit ur driving style. I'll explain later.

The following are different type of torque vs rpm charts and the calculated horsepower in p.u values. (Taking maximum torque and horsepower as 100%).

Type 1: Low-Rev (narrow) Power Band


Type 2: Mid Range (wide) Power Band


Type 3: Hi-rev (narrow) Power Band

BTW, our Peugeot 308Turbo torque is Type 2 . Relatively wide power band at moderate engine rpm. AL4 transmission is good enough. In tiptronic mode, in 3rd gear the car can accelerate aggressively from 70km/hr to 145km/hr and still has enough torque to ultimately reach 160km/hr w/o shifting up. On 4th it can pull away easily from cucukers behind you from 90km/hr to 190km/hr before the engine is out of breath and lifeless after touching a few km/hr above 200.

Pls take note... even though some n.a cars with bigger engine capacity which accelerate at slower pace below 190km/hr still be able to accelerate all the way beyond our stock 308 top speed... don't play play with them above 190km/hr... unless we tune up our car in such a way the torque curve is extended further into the redline, hence increasing maximum horse power!

You need a suitable tuning kit and remapping... w/o even increasing maximum torque too much. The key word is EXTENDING the useful torque curve further into the red zone!

Ada tuner boleh bikin ini macam kaa?

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PART 4
When a close-ratio or 6- or 7-speed transmission needed?

A car having six-speed and even seven-speed transmission can not be legitimately called "close-ratio" for performance driving. Probably it is not better than a car equipped with a standard 4- or 5-speed. It actually has extra high overdrive gears for leisure and economic hi-way cruising.

However if it keeps the top gear ratio about the same as in a comparable 4- or 5-speed transmission, and rather distributes more closely spaced ratios among the lower gears, then YES it has a 'closer-ratio' transmissions so to speak.

For instance a 5-speed transmission can be a close ratio too as shown below:
... the 5-speed stock transmission is actually a 4-speed with an over drive.

When do u need a close-ratio transmission?
The answer is when you got dyno chart as shown in Type 1 and Type 3 in PART 3 where power band is relatively narrow.

What is the significant of Type1 and Type 3 and where to use?
Ask you tuner for the answers.

So do not simply upgrade and lanyak ur car w/o knowing how it is going to perform and whether the power band ngam or not with the existing transmission . Otherwise u will be a born looser even before the red lights are off....

'HAPPY MOTORING'