how do I go faster with nitro I need to jump across the bridge at eth end of a level and it never works iwthout nitro and the nitro doens't work

I82 I presume?

As memory serves you need to hit the nitro early enough that it burns out just before take-off.

Consider using a SuCCLeR (if available) for an extra boost.

It's also possible the vehicle you are using isn't fast enough even with the nitro - you may need to grab a pre-positioned car on the level.

It's I76 and I think it's the level right after the dream level