Page created: 2-Dec-06
|Technical: Discovery I|
I've always shied away from larger intercoolers in the past, mainly on the basis that their position compromises engine cooling by blocking the main radiator. Whilst this is probably not too much of a problem in this country (at least until global warming does for us), it can be in warmer places and when the vehicle is under a higher load such as when heavily loaded or towing. However, having come to the conclusion that I'd like at least a bit more power, I looked at the possibilities a bit more seriously.
A number of companies now manufacture replacement intercoolers that occupy the same space as the original but offer greater efficiency by way of increased area of the cooling fins and better air flow characteristics. Whilst these types of intercooler can't match the performance of the larger full width versions, they do retain the integrity of the engine cooling system and still provide a useful power increase, which seemed the ideal compromise for my needs.
After a little research I decided to go for the intercooler offered by Allisport. This was partly because they have a good reputation for quality and partly because they offer free fitting and fueling adjustments as part of the package.
I took a trip to their workshop near Ross-on-Wye and had one of their intercoolers fitted along with new silicon turbo hoses, which are supposed to be more robust and longer lasting than the original rubber ones. I also asked them to remove the EGR valve once and for all, whilst they were at it. As part of the install, the turbo boost was checked by temporarily plumbing in a boost gauge and taking the vehicle for a quick blast up the road. It was found to be around 14psi, which increased to 15psi (1 bar) after the work was done and this was pronounced to be ok. The fuelling was increased slightly, to take advantage of the increased air flow, by turning the diaphragm in the top of the fuel pump a quarter turn and the smoke screw was adjusted a little bit. I was advised that it might smoke quite a bit for 500 miles or so whilst the old gunk is cleared from the system by the greater airflow, and this did indeed appear to be the case. It still smokes a bit more under load than it did before but I'll leave it a while longer before fiddling with it any more.
Other than that, I'm pretty impressed with the results. It hasn't transformed it into a sports car but I never expected it would as I've gone for a relatively mild tune in the grand scheme of things. However, I keep finding myself arriving at roundabouts at a faster speed than I expected and corners that used to need second can now be handled in third. Now that I've gotten used to it a bit, it's the latter change that's the big benefit. It now pulls smoothly from so much lower down the rev range - pootling around at 35mph in 5th and then accelerating smoothly is no problem - which makes it much more flexible and relaxed to drive. In fact, my main reason for wanting this upgrade was to improve the towing ability and on the evidence so far I'm sure it's going to make a big difference.
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