I don’t see an issue in open tag. The Rok GP has 36hp.
A good place to start for comparing the old X30 to the new one would be to know what the RPM ceiling is for each one. (if it’s the same for both, then it makes straight comparisons of the other specs much more straight forward)
I’ve spent a bit of time finding out how different configurations of the same engine can make and deliver power. My own results backup the idea that it can be really misleading to look at a gross number like HP, because for a single speed kart especially, there’s going to be other numbers that are more important, particularly the tighter the track you run on. All other things being anywhere close to equal, the RPM ceiling that the coil is set for is by far the most important thing to know when comparing engines to each other. If one person has an engine that is rev limited to 15,000 and another has an engine that can rev to 17,000, even if that higher revving engine has a lot less horsepower they can make it keep up with you and possibly even beat you on tighter tracks by using a higher gear ratio. Much to my surprise, but also relief because it solved a mystery for me, I recently found out that top senior KA’s at my local track run an 8.2 gear ratio (equivalent to running 10/82 or 11/90 sprockets!) and because that package is capable of revving so high and my most local track is so tight the KA can lap nearly as quickly as ANY 125 single speed out there (in fact, because the KA is so much more popular around here, I have not found evidence of any 125’s that have actually beaten the best KA time that I know of, though I’m currently working on that after having remapped my ROK GP to rev to 17k - I just need to add about 5-6 teeth on the rear now).
Admittedly such a situation is an anomaly because most tracks aren’t so tight (the average speed at Prairie City for KA senior is somewhere around 45mph versus 55’ish mph for average outdoor track) and at higher speed tracks that the 125’s are more easily able to show their horsepower advantage and leave the 100cc engines behind, but it still goes to show that for single speed karts that it’s not all all about horsepower.
This, I think they were just matching the 37 HP to compete with the GP in open TaG classes.
This isn’t a ‘new X30’. IAME release engines like this every few years.
I can’t quantify the difference in lap time as I was running on a worn chassis and tyres, green track and sub-zero temps.
Though it is quite a lot faster, the difference in power is noticeable from 7k all the way to the redline. This is welcomed as I feel the X30 was a bit underwhelming in terms of power