Why does it seem the guys on No Prep Kings are switching from dual to single turbo?
 

I've recently noticed the trend and just wondered why the switch? Seems the fastest guys with turbos are making the switch this past season, and I just wondered what the thought process is for the changeover?

Single turbo car do not have to add weight to their car. Dual turbo has to be a certain weight. Dual is better. Easier to spool and can make more power.

Yup as 73 TRANSAM stated, there was a rule change in 2018 that gave a weight advantage to single turbo cars. There were a few takers on that including Larry Larson and Birdman.

Birdman was struggling (along with a lot of people) up at Bandimere last season when I went for the race. Larry's pickup was dialed in fairly well. It was interesting to see the setup at work. Pretty soft in the first 330' but boy did that thing frickin move once that massive turbo got going.

The show only shows you the actual round match-ups, but if you make it out to one of the NPK events, there's a lot more that is typically going on. For the Bandimere race, although Doc, Larry Larson and Monza went out either first round or fairly early, they were still able to compete in the Big Tire invitational throughout the weekend, which had a 10,000 purse. So you got to see these cars running fairly consistently on track, even after they had been eliminated from the weekend's bracket.

Being a complete novice at turbo race cars I thought that a dual setup would spool quicker too. I wasn't aware of the rule change. That puts it into perspective, Larson does seem to have it figured out, Finney seems to be struggling.

Larry Larson is running 136mm and Birdman is running way too big from the way it looks. I remember him saying it is a one off 154mm turbo. Those are huge compressor wheels.