Custom/Hybrid Pump size Vs engine/boat size? Bigger is better? any equation or formel for this?

[Christian_83]

I've been wondering for quite some time now about this, and wanna see if i can get some answers.
For many years, people have been using 144mm pumps designed for a 650cc and 701 engine, then people started upgrading engines and making the skis lighter, some stepped up to 144 mags, some people even 148mm mag and a few running "secret spec pumps" now
My question is, would there be some power/extra thrust hidden, in lets say a 155mm pump, maybe even at complete pump setup from er GP 1300.
I gues the engineers have made some calculations about engine power vs pump size, to provide X thrust. My point is, some of these high performance billet engine produce more power than these couches, and uses smaller pumps.
Is there any equation for this or?

 

[D-Roc]

771cc turning my 155 pump with a tbm pump stuffer. Rips!

 

[Christian_83]

Yeah D-Roc, i have read your thread. How is the diffrence with the 155mm pump? Saw the video, its it only a 771cc? It launches you pretty bad light weight top deck?

 

[D-Roc]

It's hard to describe the difference. You gotta ride a 155 pumped ski to feel how different the power gets put down. It's a major difference from my 144. It took a bit to dial in but I would not be running it if it wasn't better than a 144. I happened to bust my fx140 steer nozzle and until I get it fixed, went back to a bored gp1100 steer nozzle. That alone makes my ski looser. My skat reduction nozzle does not have the straightening fins so the jet blast is twisting out and spreads wide. With the fx140 steer nozzle the jet blast has much less twist and spread making the ski a lot more predictable and stable. Just some food for thought if your going the way of the big pump.