remapping a car

Former Member

Anyone had their car chipped? If so did it make much difference?

Former Member

Depends on the car. If it's forced induction(turbo/supercharged), then you'll usually see very noticeable gains. If it's naturally-aspirated, then it can still make a difference, but it's usually quite subtle. They tend to run a tighter ignition map, and the fuelling is tweaked for efficiency(power and economy) over emissions.

You can potentially make 25%+ on a turbocharged car - but keep in mind that the more power you make, the closer to the edge the components in the car will run. You increase boost, and the turbocharger will be operating nearer to full-boost(higher RPM) than the vehicle manufacturer intended, which can shorten the lifespan - especially if the car still uses transient overboost, which temporarily allows the turbo to spin outside of the design parameters. It can also drastically increase the temperature of the turbocharger, which may well be why the manufacturer lowered the output in the first place - can the engine cool the oil adequately? Is it likely to struggle to get a perfect oil supply when working hard, but being chucked around a corner?

You also increase the stress on other parts - piston crowns run hotter, and are more likely to see detonation(very bad). Manifolds run hotter, injectors work harder, big ends have to deal with more force than standard.

On the other side of things, you have an increased load going through the clutch, gearbox, differential, CV joints, and tyres.

Some cars are produced well below their rated power output - I can't remember if it's still the case, but BMW motorbikes producing 100bhp were built and tested at 150bhp, and then downgraded to give better reliability. The same goes for their car engines - the 2.5 and 2.8 were hugely strangled by the inlet manifold, to keep power down. My Mondeo - if I swapped out the inlet manifolds and throttle body, I'd see close to 20bhp with no other changes...

With a naturally aspirated car, the chances are you'll see more gains if you find what's actually restricting the engine. A tweaked ECU will - generally - offer a more ideal running of the engine, but it can only go so far if the lump is mechanically restrained and incapable of reaching its peak.

Sorry if that was a bit long...

Former Member

You also legally need to inform your insurance company, who may increase the premium by the same percentage as the gain you see.

Former Member

what about those drop in air filters? The oiled ones that replace the paper ones? Are they any good?

Former Member

Can make a slight difference, but TBH we're talking a couple of horsepower at most on the majority of cars. Often, people slap on cone filters, but end up with nasty heatsoak as they chuck away the standard airbox, and the associated air feed. I've always stuck with standard filters, to be honest.

Former Member

whats heatsoak?

Former Member

Cold air is denser, and more power can be made from a given quantity. Warm air becomes thinner, and has the opposite effect. When people fit cones, they often lose the air feed from outside the car as they do away with the airbox, so they're always drawing in warmer air from around the engine bay. It's not so noticeable when on the move, and often the larger surface are of the filter outweighs the loss of cool air flow. But when in traffic, it can make a huge difference, even to the point of promoting stalling when you start trying to pull off.

Heatsoak is when the air in the engine bay increases in temperature, and adversely affects the performance of the engine. You'll find it on most cars, but it's often worse when things are messed with.

Former Member

Find a forum which has your car i.e. fiatforum.com ukfiestanetwork.co.uk

and post the same question on there. Might be also a good idea to look on the net for 'modifying' your car.

You will receive more answers than on here!