Un saludo y espero que sirva de algo a alguien
Engine - Fuel Systems
This section is basically to cover the products that are not covered specifically by others and that are related, eg carbs, management etc.
Parts that comes to mind are fuel regulators and power boost valves.
Firstly power boost valves, we have tried several and not found any to be that good in operation but more more importantly do not seem to last long before failing, maybe this is becuase of the adjustable nature of most of these units. We find the changing of the fuel pressure regulator for a higher pressure unit to be a far better solution to give the desired effect, probably due to its "sealed unit" style stopping people messing about with it.
Fuel Pressure Regulators
I am specifically talking about those fitted to TU engines that fit in the end of the fuel rail, which covers most multipoint injection units, although the principal works for any ECU controlled engine.
For those that do not know what it is. The fuel pump on all injection cars can pump up to between 6 and 10 bar of fuel pressure, but the system only wants a constant 3.5 bar, so the pressure has to be regulated to give an even 3.5 no matter what. Some may say, why not get the pump to just produce 3.5 bar, this does not work, as the pump will fluctuate in the pressure it delivers, especially as it gets old and because it has to force the fuel through the fuel filter, so to over come these factors the pressure is deliberately made a lot higher and regulated just before the injection process.
So why fit a higher pressure unit, and how does it work. Assuming the higher pressure unit was fitted on a car that did not have an ECU controlled lambda unit, it would mean the engine would be fed with an over rich mixture, which may give a performance benefit, maybe not, if the engine was not tuned to handle the extra fuelling.
The reason fitting a higher pressure regulator (4.5 bar) on the TU engines gives a performance benefit, is because of the lambda unit. Let me explain. On the old cars with a carburettor, when you put your foot down on the accelerator it actuated an "accelerator pump", this basically squirted a lot of extra fuel in to give a burst of extra power, it only operated as you pressed the throttle down, once down it stopped operating, to have it keep putting fuel in would have reduced power as the engine could not burn it. This same situation works when you fit the 4.5 bar regulator but operated by the lambda unit.
Perhaps a bit about what the lambda unit does is appropriate. This unit sits in the exhaust manifold and sniffs the exhaust gas, if the gas is too rich it sends a signal to the ECU to weaken the mixture and if too weak, tells it to richen it up and so keeps a balance to give none poluting exhaust gasses.
So when you fit the 4.5 bar regulator the richness is increased guay up and gives your engine a big boost in BHP as you are accelerating (over rich mixture very good for rapid acceleration of the engie rpm but not good for constant speeds) but the lambda unit sees the over rich mixture and gets the ECU to screw out the excess fuel. This takes quite a few seconds to achieve but by the time the mixture is back to normal the acceleration period is most likely over.
Also putting in one of these units over comes a particular problem that a lot of 16 valve units have, this usually happens on older units that have done some mleage and shows up as a low idle speed and sometimes the engine stalling.
The reason for this is that the fuel system is not 100% and the lamba unit is screwiing out more fuel than it should as you take your foot off the gas and come to a standstill, by having this higher pressure regulator in, the richness stays up long enough for the idle circuit to take over.
The great thing about this unit for TU series engines is that the new unit is identical in everyway to the original, apart from the pressure and so is an easy job to replace the original.
Injectors & Fittings
We carry a lot of fuel parts like uprated injectors, injector fuel line and electrical fitting kits for same, just ask.
Throttle Bodies
There are several manufactuers of throttle bodies, the 2 that we deal with are Weber and Jenvey. Most people considering throttle bodies are doing so because they want to fit mulitple units, for those involved with competition formulas that insist on only one, we can supply very large single units.
So why fit mulitple throttle bodies. The purpose is to allow unrestricted flow of air to the cylinders, which is often a problem with standard inlet manifolds, plenum chambers when searching for maximum bhp. Having said this too many people jump to the conclusion that this what is holding their car back and want a throttle body kit. There is no point fiting throttle bodies on standard engine or on one that is only mildly tuned, as unless you have a high lift cam, head work, performance manifold and exhaust system, etc your engine will not be able to use the extra capacity of air you are throwing at it. Sure it will go better but the money for a throttle body kit would give more power if you used it for the above mentioned parts, the only big benefit would be the fantastic sound that only throttle bodies give. It must be remebered when going for throttle bodies, the vast amount of other parts needed to fit them, the parts usually needed besides the throttle bodies themselfs are, inlet manifold, fuel rail, adaptors for trumpets, trumpets, air box, filter, throttle switch, linkage etc. For a rough guide most throttle body kits cost over £1000 plus fitting, plus you will need some form of programable management and the cost of programing time on the dyno.
Most relativley highly tuned engines do need throttle bodies, an example is the British Touring Car Championship, they are forced to use 1 single 64 mm throttle body and they still get over 280 bhp. I am noy trying to put anyone off the idea of multiple throttle bodies , just trying to make you aware that this is not be all and end all of serious tuning. Another example is the full race Saxo VTS engine we built for a racing series in Taiwan, this engine made 150 bhp at the wheels, OK a lot of money was spent to get this and would have been a lot cheaper to get this power by not doing certian things and using mulitple throttle bodies. The reason I mention this is that many people are worried about insurance and the fact the insurance engineer will be able to see the engine has been mwage tuned if he sees throttle bodies on it, whereas you can stiil have an enigne that looks reasonalbly standard from the outside and give good power on the standard throttle body.
So what is a throttle body set up worth over the standard single unit. Assuming the engine has been well sorted first, 15 bhp is usually the extra gained, on a basically standard engine, probably about 5 to 7 bhp. These comments are based on saxo engines, some engines have terrible inlet manifolds and plenum chambers, the Vauxhall Corsa 16 valve being one where far more could be expected.
Asuming you have decided to go for a mulitple throttle body set up, which throttle body do you specify. The best we have seen are the weber and Jenvey units and recently we have been favouring Jenvey more, as they do a far greater range of sizes and fitting applications, particularly short bodied units, which are a must when fitting to a front wheel drive car that has the induction system pointing to the bulkhead. The reason I mention this is that just fitting a throttle body kit on any car, is only going to work well if certain rules are followed. The three main things you must achieve are an inlet length (from cylinder head to the end of the trumpets) of at least 15 inches, as if this is not achieved, all the power will be at very high revs and a reduction in low speed power. Secondly, it is no good having a system that makes the trumpets nearer than 2 inches away from the bulkhead as this will restrict air flow and finally it is no good sucking hot air from the back of the engine, so unless you can fit an unrestricted air box that draws air from the front of the car you are wasting your time. If you were to fit a throttle body kit that does not achieve all these functions it is doubtful it will be of much if any advantage over the single one it replaces.
The above reasons is why we use Jenvey throttle bodies on our saxo kit, no other throttle bodies were short enough to allow a worthwhile system to be fitted. All the above reasons hold good for any make or model of car.
If you are contemplating going for throttle bodies remember biggest is not best, our above Saxo kit uses only 40 mm units (shown above), if you go too big the air speed is slowed down and you only get good cylinder filling at very high rpm, which means no low down power and the extra you get at the top is very small, whereas you loose a great deal below this. Most engines need good power from say 4000 rpm to 7000 rpm, what is the point of getting another 5 bhp at 7000 rpm and loosing between 35 and 15 between 4000 and 6000 rpm. To prove the point of how you do not need big throttle bodies the cross sectional area of the British Touring Car engines using the 64 mm single unit is 32 sq, cms, whereas 4 singles at 40 mm are equal to 12.5 x 4 = 50 sq cms, So the saxo on 40's has one and half times as much air capacity as a BTC engine.
