Author: pumaracing.co.uk

Introduction to DIY ECU Remapping If you’re looking for a DIY guide on how to remap an ECU yourself, you’ve come to the right place. This subject can be quite difficult and even frustrating if you’re not aware of what you are doing. If you’re looking for a professional opinion about what you should do, find someone who knows what they’re talking about and is experienced in this particular area. Otherwise, you’ll probably end up doing something that either costs you a lot of money or doesn’t work at all. The last thing you want is to waste time and…

Introduction to Rolling Road Testing and Power Measurement Issues I’ve written more about rolling roads and dynos than just about anything else on this web site. It shouldn’t be hard to guess that one of the things I really dislike is the nonsense flywheel power figures that get bandied around in the car magazines and by tuning firms based on rolling road tests where only the wheel bhp figure was really measured with any accuracy. Plenty of people have expressed a view to me that it doesn’t really matter whether the figures are accurate or not as long as they…

The Fundamental Principle of Engine Power The single biggest factor that determines an engine’s ultimate power potential is the total inlet valve area. Not all cylinder head designs have the same flow efficiency for a given valve area though and it is the flow potential rather than the valve area itself that really determines the power potential but valve area is much easier to measure and provides an ideal starting point for further analysis. There is no point however in having big valves if the port shape or other factors restrict the flow. To discuss this further it is best…

Ask a selection of people this question and one of the first things that will spring to mind is engine size. After all, big engines tend to produce more power than small ones. The second article on Power and Torque lists some data for standard road engines. It should be apparent that there is quite a big spread in the amount of power per litre that the engines on the lists produce. What Determines An Engine Power Even allowing for them having 2 valves per cylinder or 4 valves per cylinder doesn’t help much. The spread of outputs is from only 45…

There is in fact no way of directly measuring power – all types of dynamometer measure torque and then power is calculated from the formula we saw in the previous articles – BHP = Torque (ft/lbs) x rpm/5252. This basic equation is the cornerstone of all engine design and development work. Two main methods of measuring power are used in the automotive industry – (1) measurement at the crankshaft of the engine or (2) measurement at the driving wheels. We’ll look at both of these separately. Engine Dynamometers If we want to know the power of the engine alone then…

Introduction To round off the articles on power and torque, here is a real example of how the coast down losses from an actual car were measured on a rolling road dyno. Some time ago I asked a colleague to run a series of tests for me on their rollers. What we needed was a car with a reasonably well quantifiable flywheel bhp and one that we could run in any gear without getting wheelspin on the rollers. This ruled out modified cars that had not been on an engine dyno and anything with too much power. Some time later…

Introduction and Basic Principles From the preceding three articles on evaluating an engine’s power potential it should be clear that you can never have too much inlet valve area. It directly determines power potential – every 10% increase in inlet valve area gives a 10% increase in power potential. However, in many engines there is a trade-off between inlet and exhaust valve size. By making one smaller you can increase the size of the other. Equally this is not always the case. Sometimes a larger inlet valve will hit the bore wall long before it interferes with the exhaust valve…

The Peugeot TU series of engines was fitted to most of the smaller Citroen and Peugeot cars in capacities from 1124cc to 1587cc. The basic design has an overhead cam running inside bores in the cylinder head and opening the valves via rockers. Valve clearance is set by manual adjustment of a screw and locknut. Early engines had an aluminium block with wet liners like the XU and later engines had a cast iron block. There are in fact a staggering number of slightly different variants of the engine all with their own engine code which makes sourcing parts a…

The 205 was Peugeot’s attempt to really see off the other hot hatches such as the XR2/3 and Golf Gti. The power output is very high compared to other engines of the time and was a result of Peugeot paying a lot of attention to engine design detail. The legacy of this high output is that it is not as simple to improve the power as with other engines that are in a lower state of tune as standard. A great many modified engines that both I and colleagues in the trade see, have LESS power than standard and the…

The Ford Pinto engine seems to have been around for ever and its strengths and weaknesses ought to be well known by now. For what is basically a very simple engine design there are complexities, especially in the valve train, that mean that many tuned engines don’t realise anything like their full potential. Made over the years in 1.3, 1.6, 1.8 and 2 litre capacities, it is mainly the 2 litre that is of interest for tuning purposes. Anyone with a smaller engine would do well to fit a 2 litre as a first step – they are plentiful enough…