Hi everyone, I'm new to the forum I actually joined to share my experience, and see if someone can explain the tech behind it.
So I have a Fiat Punto t-jet, (am from eastern Europe so please excuse my language) I modified the pipes to and from the airbox. And got the car remapped. These engines have a small turbo so they spool early. In stock form it had a high ridge in the torque curve early around 2000 rpm, than tapered down a bit till de horse power came in at 4000 rpm. With the remap this high point in torque became even worse.
I started to live with it, but after I modified the airbox, took out the restrictive inlet and outlet, the torpue comes much later and is smoother.
And I really dont understand why. So basically I would like to understand why...
Sorry for the long read everybody.

 

Welcome to the forum. So the tune made the turbo come on stronger and when you modified the intake afterward the turbo came in later? Was the modified intake on when it was tuned?

 

The tune made the torque peak come even earlier, around 2000 rpm it went from 160Nm to 200 and max from 200 to 270 Nm.

Actually the lower half of the airbox was already modified, there was a smallish and varying diameter elliptic pipe routing air in the box. Removing that gave better throttle response so I concluded its restrictive.
I bored the lower part of the box and routed a 3inch plastic pipe. This made me feel as if the turbo has to work less to achieve max boost.
I had no more time before the remap so that is how it was remapped.
I frequently found my self lifting off the throttle as the torque was too strong in city driving.

The upper half of the airbox had a 2 inch pipe collecting air and routing it in the turbos 3inch hose. It had a sharp step in it so I thought that might be for sound wave bouncing.. To make the box silent.. I replaced this with a straight 3inch pipe.
I expected even earlier boost. But the opposite happend with the second mod.
The torque starts to build around 3000 and now pulls strong till 6000 rpm

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If this happened on an NA engine it would be nothing strange. Power band moves higher with less restriction.