Stage 3 impeller change

[DFW GP1800]

I have the full stage 3 back on my 17 gp1800 now with the 20psi riva wheel and their tune. The acceleration difference is insane but I only went from 77mph to 81 in 100 degree heat and a hot lake in north Texas. Obviously disappointed in the top speed and not sure why I can't get 85 plus. It went 81 in November last year with stock wheel with cooler weather and a fresh clutch. My question is what would you expect from changing from the 13/18 to the 13/21 solas impeller? I have both and the 13/18 is currently on it.

Thanks

Josh

[Adam4pt6]

What are your rpms at?

[DFW GP1800]

What are your rpms at?

I need to check them this week with the 20 psi wheel but with the oem and 8500 tune they were 8450.

[Adam4pt6]

8450 at 77?

[DFW GP1800]

8450 at 77?

Yes that is correct. The water is definitely hot right now along with outside temps and humidity but still... I went from 66 stock to 71 with stage 1plus. Then 76-77 with stage 2 in this same summer time condition. Then in late fall 80-81 with stage 2 and new clutch. So I picked up 4 mph with 20 psi wheel and a major difference in acceleration. Curious if the 13/21 wheel will help with top end and why my junk is so much slower than others on here with same setup. No one beats me at the lake so maybe my candoo GPS is off but I doubt it. I calibrated it and says 5mph everytime I start it like directions said

[FAMT]

Solas 13/18 and pitch to spin 9150...

[DFW GP1800]

Went out today with the map tuner and 9500 stage 3 tune. Was only turning 86-8700 rpms and 30psi which I guess is really 15.5psi and i have a 20psi wheel on. Obvious rpm issue so any advice on that? I dont have a lucky 13 cone so is it really needed to dial rpm's in or just a prop repitch?

[DFW GP1800]

I must also say the stator has about a dime size piece broke off from cavitation wear also. Second time that's happened but I dont see that killing 5-600 rpm. I noticed the stainless stator riva sells has more veins in it than oem aluminum one so it seems it would be off from the nozzle veins behind it.

[Adam4pt6]

Isn’t 15ish at 8700 a little low for that wheel? For comparison I’m at 13psi at 8400 on a stock wheel.

[DFW GP1800]

I have no idea. Hoping for some guidance on here about the low rpms with that 9500 tune. That alone is killing some boost.