How much extra power

[Paulo uk]

I have a trex 700 with an os 91szh pumped engine. I have the chance to put a 91hz non pumped in for not much money and I wondered how much extra power the newer model of engine will give me?


Cheers,


Paul

[Si Goodchild]

I can't help with your specific question, but I do know someone who's after an engine like yours so please bear me in mind if you sell the old unit.

[Rotorhead]

The HZ is rated at 3.4 BHP and the SZ is rated at 3.3 according to OS, so not much difference.

It will probably benefit from it though as the HZ is supposed to be a lot smoother than the SZ, though I cant qualify that with personal experience, I never had an SZ myself.

But whether thats worth the outlay for a new motor at this time is really the question, does it really need replacing?

[Paulo uk]

The HZ is rated at 3.4 BHP and the SZ is rated at 3.3 according to OS, so not much difference.

It will probably benefit from it though as the HZ is supposed to be a lot smoother than the SZ, though I cant qualify that with personal experience, I never had an SZ myself.

But whether thats worth the outlay for a new motor at this time is really the question, does it really need replacing?

Thats very interesting 0.1 of bhp! It makes me wonder if its worth me spending the extra money. Sometimes I wonder if we often get the wool pulled over our eyes in this hobby?

Paul

[GIZMO750]

Hi Paul
I have 2 Trex 700's one with an SZ and Viper 2 plug head and the other with an HZR. The HZR gives better fuelling over the whole range and has a lot less vibrations than the SZ. Not a lot to choose between them on power.
I think you will love the HZ it just seems to pull better.

Giz.

[moonmanflyer]

The HZ defo runs smoother and better fueling through the whole tank range as the sz, but no real difference in power.
If you want a power increase go for a YS

[Eckchaz]

The only difference between the OS's are fuel supply and less vibes compared to old models with next to nothing on power gain.. Like james mentioned.. you have to look at YS and Hatori pipe to get extra power

HZ-H - new heatsink, better crank, piston over SZ to reduce vibes 3.4bhp

HZ-PS - As above & improved bigger pump over predecessor 3.5bhp

HZ-R - As HZ-H and a regulator like the YS to gaurantee steady fuel supply during 3D - 3.4bhp