QLDMIKE your dads Nissan GU front facing scoop on his 87 Rangie not making any difference to his engine performance experiance or worsening it with dust etc seems to support my thoughts on this subject.

If you read my post carefully you will see it is not about about ramming air (dust and water etc) into the engine bay but all about removing heated air out of the engine bay.

I reakon if your Dad reversed his Nissan GU scoop so it was pointing backwards and it was at least located half way between screen and bonnet front then IMHO I think his performance results would have been very different.