is tunnig after mods necessary?

Dan Z Man

so, i've been lookin around the internet in general for a while now, and i've come across a lot of things regarding valves when it comes to running a free flowing exhaust, or say someone is running open header or down-pipe or something..a lot of people say stuff like "have fun destroying your valves" or "wow lets just destroy the motor while you're at it"

so my question is, for those that either get headers, or test pipes, or HFC's or something regarding a free flowing exhaust, and without a tune, or even with a tune..does it really hurt the engine that bad?? like idk, it doesn't make sense to me, a ton of people do exhaust on their cars and what not and not really a lot of them have a problem "killing the valves" or whatever..can anyone shed any light on this??

also, say i do intake, exhaust and get no tune, you say it could run either rich or lean.. my question is, can it run too lean/rich and damage the car??

Cmike2780

It won't necessarily "hurt" your engine by installing bolt on's. The on board computer can compensate to some degree, but limited by what Nissan has it calibrated for. Having a tune done basically tells the computer that the part you upgraded was like that from the factory. In a sense, the performance gains from the upgrade is limited by the stock tune and can't exceed those values set from the factory.

Chances of an intake or exhaust damaging your engine without a tune is unlikely so long as it was installed properly. The changes aren't enough to really throw off the computer. Add a turbo or supercharger for example, and the scenario changes greatly, where the computer doesn't "understand" where the massive amount of extra air is coming from. The farther you go away from what the stock tune values are set for, the more you risk damaging your engine. Bolt-on's alone are well within the stock tune limits, but not optimized for those parts.

Hope that helps.

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