Monday, March 19, 2012

Hybrid turbos

One great way to easily uprate and improve a turbocharged engine is with the aid of a hybrid turbo. Sometimes it is quite hard to fit a larger turbo to an engine, the most notable reason being the lack of space available. Add to this the complexity of fitting a larger unit into the exhaust manifold and relocating the oil feed and air intake piping. So you can see that there is a lot to recommend getting different turbo internals in a standard turbo housing as this becomes a bolt in upgrade.




Turbos are simple double ended propellers or impellers. The size, angle and shape of these will greatly affect the performance characteristics of the engine. By adjusting the profile of the exhaust impeller you can encourage early spooling or focus instead on producing a wider power band.
Turbo housings can often be flowed, that is smoothed out and opened up a little allowing a greater throughput of air and this also allows the use of larger internals.  Common applications include taking a large turbos internals and fitting these to a smaller unit. The smaller turbo is still externally the same as the OEM turbo and can therefore be bolted straight in place.

Another option is that completely custom made internals are fitted to your turbo. Due to the high rotational speeds it is essential that the internal components of a turbo be balanced pushing the job of hybridising outside of the scope of most DIYers.
Look at the engines existing power band and decide where you want the power to come in and how much more power you want. A hybrid turbo specialist can then work out which profiles to use in your turbo.
The trouble is that you can’t usually have it all. Whilst there is a certain degree of improvement available over the standard OEM turbo you need to select where you want the power to be.
A larger power figure will often mean later spooling and more lag and lowering the spool up time will usually be at the expense of top end power.
Variable geometry turbos are great for this reason as they are adjusted depending on engine speed and load. Sadly it adds another layer of complexity to the manufacturers of hybrid turbos.
So work out carefully what your needs are and have a chat with your local Turbo specialist to decide on an appropriate solution.

Car tuning - turbo engine

When deciding on a power train which should you go for? I will admit to being a little biased towards turbos. Here is my take on Turbo Engines.
The sheer exhileration and excitement you get as the turbo kicks in is something that sticks with you for a long time.


I will concede that due to lag the turbo does not produce much power low down. Even the mighty Mitusbishi EVO suffers from terrible lag low down in the power range. Instead of this getting you down view it as a car with a split personality. In heavy traffic it is civil and economical but if you are overtaking or enjoying a thrash there is a monster waiting to be unleashed.
 Nearly all turbo engines are built to withstand more pressure in the combustion process. Most cars with turbos (yes even diesels) can be remapped to release loads more power. A remap is a simple reprogram of the cars computer which controls the wastegate, fuelling and thereby the amount of fuel/air that can be burnt. A remap will cost a few hundred pounds but will typically give another 30% of reliable power to your car.

After this modification there are loads more, if you strip down the engine and get it gas flowed and ported, strengthen the rods,pistons and crank and get it balanced you can look at doubling the power output of the engine. (Some cars can cope with 100% more power without an extensive rebuild although reliability may suffer.
A turbo upgrade will also yield substantial power gains, so look out for an OEM (standard case with uprated internals) or after market (bigger housing requiring minor modifications to the cars exhaust, wastegate and air intake housing diameters.) A ball bearing turbo will spool up quicker. Smaller turbos reduce the problem with lag. A twin turbo setup with a boost controller will control the sheer power and manage the delivery to a more progressive level again minimising lag. Large turbo conversions will make bigger power figures but tend to suffer more from lag at the lower end of the rev range.