Car Guese

KONI Sport and FSD (Frequency Selective Damping)

During a typical mile of travel down the road, the damper will move in (compression) and out (rebound) millions of times. Break that mile into one second of travel, and the number of times the damper moves (stroke) defines the operating frequency (Hertz, Hz). Controlling body roll entering a corner induces relatively few strokes of the damper (low frequency), while chattering over broken pavement at highway speed results in a much higher quantity (high frequency) of very short strokes. Knowing this, damper frequency can also be used to tune handling and ride quality. Vehicle body roll control needed to aid handling occurs at a frequency of around 1Hz. Ride impact harshness is felt when damper frequency reaches approximately 10Hz.

Hit a bump without dampers, and the suspension would continue to bounce up and down uncontrollably like a bobble head doll. The damper's job is to reduce the size and/or speed of the suspension movement, preventing the never-ending bobble head scenario. We've all seen that older car going down a smooth highway with one of the rear tires visibly vibrating up and down very rapidly, which is caused by a worn-out damper that is no longer controlling the movement of the suspension. The lack of damper control allows the suspension to move uncontrolled.

The piston moving back and forth through the oil inside the damper creates the resistance needed to control (dampen) the suspension movement. How much resistance (force) develops for a given movement is determined by internal valves that control the flow of oil. Based on the force, the valves open or close to self adjust to each bump or any vehicle body roll. All dampers do this; but KONI's FSD units add a second valve system that responds to the damper's operating frequency, allowing ride and handling to be tuned more independently than with conventional dampers.

KONI's design theory for tuning dampers uses the compression (in) force to dictate the amount of axle movement and is directly linked to handling like steering response, road holding, etc. The rebound (out) force is used to control body movements (side-to-side body roll and/or pitch fore and aft) and is also directly linked to ride comfort.

KONI's traditional user-adjustable yellow sport dampers most applications have a fixed setting for the compression rate, but allow the user to manually adjust the amount of rebound control to tune the balance between ride comfort and handling. The FSD dampers also have a fixed compression setting, but instead of allowing the user to manually adjust the rebound, the internals of the FSD dampers automatically adjust the rate and shape of the force curve (when plotted on a graph) on the fly, responding immediately to the frequency of the damper’s movement. The unique secondary valve used inside the FSD units is engineered to provide large amounts of force to control vehicle body movement at relatively low frequencies, while generating less force at the higher frequencies that affect ride quality.

Once you have built your new motor, or fitted any tuning parts you will NEED to visit a good automotive Dynamometer or rolling road. If you don't you will never be able to set up your engine properly. A good dynamometer allows you to use a gas analyser while under load so you can see the real air fuel mixture at all RPM's while driving.

Rather than discuss the subject on this site it is better if you go to my Automotive Dynamometer pages, as I used to build them! (Below)

Non Turbo Cars

Heard a boy racer telling his mate the other day "just fitted a chip to my xxxxx car (non turbo) yesterday, and its loads faster!". Well that is just NOT possible.

I asked him how and he didn't know, but said it was about 20mph faster flat out! Now since it takes 4x the power to go twice as fast, that equates to a simply huge power increase! So he was obviously lying...

First of all, a noticeable increase in power is simply not possible with a naturally aspirated car (no turbo) by fitting a "chip" or having it "chipped". As we said in the first few pages engines breath air. If you do not increase this flow somehow it cannot make more power than it already is doing! That chip simply tells the fuel system how much is the CORRECT amount of fuel to add! The manufacturers stock settings are usually optimum for peak power. It also controls the Ignition timing, but again the stock settings will be about perfect for full power. It is only possible to get tiny gains in "drivability" rather than more real power.

t is possible to gain a few percent here and there at different rpm's and throttle plate positions, because the manufacturers tailor the fuel map to give optimum economy, smoothness and low emissions. But these gains are pretty small. They "may" result in better drivability, but definitely not enough extra power to notice!

Turbo Cars

It is possible however to chip a turbo car for more power in many cases. The max boost level is often controlled by the engine management system. So in this case reprogramming, or rather remapping the ECU or chip can bring power increases. Be careful though because the manufacturers set these things as they are often for good reasons - usually reliability!

By allowing the turbo to make higher boost the engine gets more air and therefore can make more power, often considerably more.

By "conventional engine tuning" we mean internal engine work. Not Turbocharging, Supercharging, Nitrous Oxide Injection, etc. No "bolt on power" modifications. but tuning the internals to give better airflow.

Getting more power from a standard car engine by conventional tuning means is at best difficult. (we will ignore standard turbocharged cars for the moment). The only way is to increase the airflow drawn through the engine. There are lots of ways to do this and it all involves a lot of work and money! For example:

• Bigger side draft carbs or throttle bodies

• Bigger engine bores / pistons (machined to increase capacity)

• Bigger engine stroke (offset ground machined crankpins and shorter connecting rods)

• better tubular exhaust manifolds and system

• better port shape in the head (ported head)

• Bigger inlet and exhaust valves fitted with specially shaped valve seats

• Higher compression ratio

• longer duration and higher lift camshaft

• forged pistons (for strength)

• stronger connecting rods to cope with higher RPM's

• uprated oil pump/system to help engine reliability at higher RPM's

• Crank / Connecting rod lightening, balancing, strengthening etc to cope with higher RPM's than standard engine

Depending on what you are trying to achieve you may need to do all of the above or just some! A fully tuned and "built" race engine is seriously expensive, loud, and unsuitable for road car use. It has bad driving characteristics, uneven idle, little low rpm power etc. And it is usually short lived as it has to be revved hard to get to any useful power. Obviously then it is best to start with the biggest engine variant of your model of car to begin with! This way you may not need to tune it at all to get the same power! If you do tune it it will not need as extensive modification to achieve the desired power so will be more user friendly.

Conventional tuning has low limits on how much power you can expect too. Its easy to get a few horsepower more, but very difficult to get any big power increases. And the cost of power goes up and up as more power is wanted...

Unless you have a good reason to use "conventional tuning" rather than fitting a bigger engine, or a turbocharger or Nitrous injection then these are probably better options for road use.

First we need to understand the differences between the two common road fuels we all use, and a few "race" fuels.

1st we have all those "additives" that claim to improve power, and torque, improve "smoothness" emissions, and mileage! Sometimes by 25 percent! But they cannot, or will not tell you how! Well get real! They are a CON!

2nd we have "octane boosters" SOME of these work well. Look for tests and recommendations, or just use proper high octane fuels in the first place!

3rd we have "upper cylinder lubricants" such as Redex etc. Well in a road car they may not hurt. In a highly stressed race engine running on the borderline of detonation, it might just be enough to kill it! You see oils radically lower the total cylinders Octane So be careful!

4th Methanol. This can if added in small amounts increase octane. But it may make the total fuel mixture weaker so again be careful!

Then there are the lead replacement additives. These may or may not work, some definitely don't. They are designed to replace the lead that some engines like to stop valve/head seating problems in pre unleaded fuel days! Don't confuse lead and Octane. Lead is for lubrication. Octane is a measure of the fuels ant knock properties. Although lead happens to increase octane a little too!

A little known fact...

In the UK leaded pump fuel if you can get it when mixed with super unleaded gives a higher octane than either alone! Because both use different additives to increase octane that work less effectively the higher the concentration

On the other hand, if you have just spent a fortune building a "big valve" race engine with lightened and balanced internals etc it would be stupid to fit a standard camshaft, as most of your hard work would be wasted! Like everything in life it has to be a balance. So its best to know what you are looking for and plan for that! Its no use just putting a few go faster bits on your car and hoping! That does not just apply to camshafts but to the complete engine. All the bits need to be matched and work together! You must have a plan before you start.

Cams types can be described (very general guide) :

a) Stock - smooth, long lasting, good emissions, good economy, good low down power for smooth easy driving in traffic. The main manufacturers are not stupid! Think carefully before you decide on a "race" cam. Power falls away at higher RPM's.

b) Towing, mild, or whatever - these will give good economy and will work much like the manufacturers stock cams. Standard lift and duration Usually expected top give more torque than stock ones at low RPMs Smooth tick over.

c) Fast road camshaft - Usually works OK with stock head/valves and a good free flow exhaust system, and bigger better multi carbs. These will give a higher RPM peak power than stock and usually at the expense of some low down power. Remember that low down power is where you spend the most time in a road car. Usually a touch more lift and duration (about 260 / 270 degrees) Slightly lumpy idle in some cases. Gas flowed head and bigger valves helps if you can afford to do it, but generally not essential.

d) Sport Cam / Very fast road - Not a sensible choice for road use, unless the car is also a race car and you can suffer a bit! Very lumpy idle on some engines, not smooth or powerful at lower 25 percent of RPM range. Peak power typically 1000 RPM higher than stock camshaft, big valves, ported head, free flow exhaust, multi carb or big throttle body, needed really to take advantage. Probably 20 percent more peak power than stock cam would give if the engine is as described. Lots of overlap, so high emissions likely. free flowing exhaust essential. 280 to 290 degrees, usually more than stock lift.

c) Race... Speaks for itself. in a road car far too much! To work, you need to have a totally "built" motor, with strong bits to stand much higher RPM than stock. And good head, big valves, open big bore exhaust (loud) and good free flowing induction system. High compression ratio needed as there is less time to "trap" the gasses. Much power! At high rpm only. Think "Bike engine"!

d) Turbo or Nitrous Cams - These have stock (ish) intake timing, but less overlap, and high lift long duration exhaust timing, to get rid of all the extra gasses.

There are LOTS of aftermarket Camshaft manufacturers to choose from. Companies such as:

Kent, Piper, Crower, Holbay, MTS, ISKY, MAHLE, Comp Cams, Crane, Edelbrock, Erson, H.O., Indian Adventures, Iskandarian, Lunati, Speed-Pro, Summit, Ultradyne, Systrand , Schrick Camshafts, Wolverine, Lazer Cams to name just a few!

The short answer here is that LPG or Propane fuel has a higher detonation limit so makes a better fuel for tuning than pump petroleum does.

It allows either more turbo boost, or higher compression ratios, or more nitrous to be used before detonation of fuel stops play!

In short, if you want power its a great idea!

copyright : tuning.wanadoo.co.uk

Supercharging your car makes more power by forcing more air into your engine just like an Exhaust driven Turbocharger does.

This allows you to burn more fuel.

The difference is that the compressor is driven directly by the engine rather than the exhaust gasses. The one shown is a VW VR6 Motor with an aftermarket low boost "supercharger" fitted.

In this case it is actually a centrifugal compressor just like a Turbocharger uses, but driven by an auxiliary drive belt.

Most superchargers are "screw" types, and positive displacement like the one on the left.

The VR6 one at the top of the page is unusual in that it uses a turbocharger type centrifugal compressor instead.

The Supercharger has a few disadvantages over a turbocharger, in that it takes power to drive the compressor directly from the engine. This is then lost or wasted. A turbocharger on the other hand uses waste exhaust gasses to drive the compressor so is more efficient.

But the supercharger has advantages too! There is no lag! Boost is always available, no matter what. With a turbocharger you have to wait until the engine starts to produce enough exhaust gas to spin up the turbo to give you some boost.

For ultimate BHP, like a top fuel dragster with 5000bhp supercharging is the only option! They accelerate from zero to 300 MPH in 4 seconds. A turbo would still be winding up!

copyright :tuning.wanadoo.co.uk