last yr my friends in the high country fell in love with 3071's on the 800 Cats and a few poo's.
On the low lands a 30 hot side for an 800 is just so much easier on fuel and cooler running you would never go back to a 28.
Here is where it gets a little confusing for most. Higher exhaust backpressure WILL offset a smaller compressor in power production.
What I have learned and published here on snowest is that larger compressors take away the need to use the turbine side to ( choke ) flow and increase the tuned waves efficiency even with a tiny tiny 66 size comp wheels, the 2860 is equal too that wheel.
when you up the comp wheel flow that drives up total airflow thru the engine in turn driving exh side pressure back up without limiting flow on the turbine side and reducing temps on the exhaust face of the piston.
response does NOT suffer and the window of boost is wider too. Would you rather have more contaminated charge in the return wave or less ? So you see the answer is simple once you try one you will understand.
an example like a 2860 /2871 working with a 4-6 psi over boost exhaust side in the 8-13 psi intake boost window would see lower fuel consumption and lower charge temps with a 3071 .64 ar and be even more powerful and responsive. the intake side window would jump to 18 psi or more and still be flowing enough on the turbine side to stay cleaner with less radicals sent back on that damn piston face..
We 2 stroke lovers have to live with the piston doing double duty to a 4 stroke. they only use the dome. we use the dome, the exhaust skirt and ring as well as the underside too... What were we thinking ?? lol
back in the day, I too thought that smaller was the way to go but after spending some time at Dynotech then going to the field and working on the tune it was clear. We always have more to learn than what we already think we know..The devil is in the details
I'm doing a 1000 rt flatland efi turbo for me !!! relocating the SDI injectors to cat throtttle bodies and adding 2 more for fun. it will have a 3582 .84 ar and run at 2 psi over boost up to 24 psi.. this will be a pumpgasser with e raves.
Next for me will be an 800 twisted kit on a cat with a 3076 . I ride at sea level close to the ocean and never see more than 2500 feet elevation. The sled has to survive with marginal cooling snow as we have icy flat groomed trails for days on end. I cant have 4 psi over in the pipe and cruise at 1/4 throttle for 30 miles with a 2860. We tried 3 yrs back with a 2871 and never made it past 10 miles without it showing dome edge errosion or sticking. that turbo had 3 psi over boost in the pipe at 8 psi boost .
the better the loose snow you have the cooler you run and the larger your window for safe operation.
fwiw I should also explain that I ONLY use 5 wt synth oil in the turbo ever. mud is not where its at with a ball bearing , cool clean low viscosity is better at washing heat off the bearing.
Gus
crazy bastage ?? I take offense too that. HE WHO climbs a straight up chute is the crazy bastage !! lol