We often get asked why we recommend 205/30 and 180/30 instead of 205/80 and 238/80 when towing heavy or when you want quicker spool up. That is because bigger injectors/nozzles are less efficient at lower rpms and actually tend to spool turbos slower.
People argue against this all the time... but it never plays out in real life. Larger nozzles will spool slower and run less efficient down low. If you run lower rpms under high load you will see benefits from the smaller nozzles. In truth... too small is also bad, but the point is that bigger is not always better.
Here is a dyno graph from today. same truck, same tuner, only thing changed was going from 205/30 to 238/80.
It may not look like much but 60-100tq more under 2100rpms can make a big difference to someone who tows a lot and does not like going down the road at 2500rpms. Now... even the owner of this truck said after swapping injectors he feels so much more power with less throttle input. That is true, because nearly 300% more fuel will be injected at the same throttle input... so it takes less throttle input to make the same power and makes the pedal feel more responsive. But under max load the bigger nozzles fell short at the lower rpms no matter how hard we tried. Now higher rpms saw huge power increases... which is to be expected.
But the point of this post is just to point out there is a trade off when it comes to low end vs top end when it comes to turbos and injectors and where you will get the best power/efficiency/spool up/towing
