HP limit of the 800 CFI engine when RG Turbo'd?

LoudHandle · Jan 26, 2017

I ride Sea Level to about 7K' here and was pricing building a Watercraft based 1485. Polaris Watercraft cases, CrankShop 990 Twin cylinders and internals.
The 990 has to run on C-12. So with that as a given what will a Race gas 800 CFI put out for HP on C-12 at sea level? While maintaining reliability.

How drivable is a high horsepower RG Turbo? I hate the dreaded turbo throttle chop and their inability to recover under a load. The BB Triple would not have that issue.

The big bore Triple 1485 should yield more than 100 HP per cylinder. Mathematically ~309 HP.

The cost looks to be really steep for the BB triple watercraft build. So what is the turbo HP limit while maintaining reliability and at what cost?

Thanks

meathooker · Jan 26, 2017

My home made kit back in 08' (800cfi) ran 14lbs and it didn't skip a beat.

A buddies 600 race sled had an issue and he was running 18lbs - it ran amazing for half a day then blew the reeds out and stuck a cylinder.

I'd imagine with the new tuning capabilities and air to water Ic you could run 15-16lbs??

So how much HP does the 800 make at 14lbs? When I built it I figured it was 240-260 HP and it was a monster on the hill.

BILTIT · Jan 26, 2017

Sounds like a good candidate for a high compression low boost turbo that MH was talking about.

I know i LOVE my carls 910 in my short track at 1800-2200ft. I had even looked into putting it into my 11 rmk, i like it that much!

Its only rated at 168HP but the torque is amazing!

aj1180 · Jan 28, 2017

How much it can handle is really dependent on how much you are willing to spend beefing up the internals of the motor. I love the sound of a well tuned big bore triple but for the cash, id put a nytro turbo motor in with a head shim and make 300 plus hp without needing the high end fuel. There probably wouldn't be much weight difference between the watercraft triple and nytro motor. Heck I've seen turbo nytro for under 5k. You will spend way more than that on your big bore. Just some food for thought.

LoudHandle · Jan 28, 2017

aj1180 said:
How much it can handle is really dependent on how much you are willing to spend beefing up the internals of the motor. I love the sound of a well tuned big bore triple but for the cash, id put a nytro turbo motor in with a head shim and make 300 plus hp without needing the high end fuel. There probably wouldn't be much weight difference between the watercraft triple and nytro motor. Heck I've seen turbo nytro for under 5k. You will spend way more than that on your big bore. Just some food for thought.

Thanks! Interesting perspective, I likely won't do any of them unless I were to win the lottery.

Just a late night thought I had and thought others may be rattling around some variation too.

My goal as a snowmobiler has always been lightening / stiffening the chassis (while keeping and gaining strength) and making it work optimally, before upping the HP.

Which is the opposite of most weekend mechanics, who start with adding HP even when the stock sled could not be ridden due to chassis limitations with the stock HP.

Spaarky · Jan 29, 2017

LoudHandle said:
I ride Sea Level to about 7K' here and was pricing building a Watercraft based 1485. Polaris Watercraft cases, CrankShop 990 Twin cylinders and internals.
The 990 has to run on C-12. So with that as a given what will a Race gas 800 CFI put out for HP on C-12 at sea level? While maintaining reliability.

How drivable is a high horsepower RG Turbo? I hate the dreaded turbo throttle chop and their inability to recover under a load. The BB Triple would not have that issue.

The big bore Triple 1485 should yield more than 100 HP per cylinder. Mathematically ~309 HP.

The cost looks to be really steep for the BB triple watercraft build. So what is the turbo HP limit while maintaining reliability and at what cost?

Thanks

LH.... Nut up and turbo the 1485. :face-icon-small-sho

Typically you can figure 10 hp per lb of boost. That's pretty standard. There seems to be a break after 12-14 lbs. it just doesn't seem like you pick up as much. IMO after that 12-14lbs or so is when you start to run into reliability issues. Not necessarily the motor either. Split pipes... Things like that. Tell you what 14lbs on the mnt is a handful. Clutching can help you smooth out the boost, but it's a pretty big jolt when it fully kicks in.

Triples are nice but they are heavy.

I would have Turbotater build me a 910 and build a 10-12 lb turbo and be happy.

LoudHandle · Jan 29, 2017

Lottery ticket time! The Redneck Retirement Plan!

Spaarky said:
LH.... Nut up and turbo the 1485. :face-icon-small-sho

Typically you can figure 10 hp per lb of boost. That's pretty standard. There seems to be a break after 12-14 lbs. it just doesn't seem like you pick up as much. IMO after that 12-14lbs or so is when you start to run into reliability issues. Not necessarily the motor either. Split pipes... Things like that. Tell you what 14lbs on the mnt is a handful. Clutching can help you smooth out the boost, but it's a pretty big jolt when it fully kicks in.

Triples are nice but they are heavy.

I would have Turbotater build me a 910 and build a 10-12 lb turbo and be happy.

I'll start buying lottery tickets! :face-icon-small-coo

The 1485 would run an easy 15K (pre-turbo), Minimum of 20 Large with turbo, by the time I built the chassis (my way) probably pushing 40 large pretty hard. So come on Lottery!

Spaarky · Jan 29, 2017

LoudHandle said:
I'll start buying lottery tickets! :face-icon-small-coo

The 1485 would run an easy 15K (pre-turbo), Minimum of 20 Large with turbo, by the time I built the chassis (my way) probably pushing 40 large pretty hard. So come on Lottery!

I would just sell the double wide, live in a tent under a bridge And have a bad azz sled.

LoudHandle · Jan 29, 2017

Spaarky said:
I would just sell the double wide, live in a tent under a bridge And have a bad azz sled.

I'm damn near at Troll status now. :face-icon-small-sho

Thanks!

icr · Jan 30, 2017

A 1200cc watercraft triple can do 280hp and would be pretty economical.

A nytro motor is very close in weight to a 1200 triple but when you add on the oil tank, turbo, electronics, etc it gets heavier.

For the best power to weight ratio a big bore twin cylinder with a turbo would be my choice, Brad is doing an 1100 right now that should be around 350-400hp.

For lag free low octane hp a 1200 is hard to beat, but there is a weight penalty.

SNWMBL · Jan 30, 2017

Fwiw, Nytro motor is 112.2 lbs as pictured and with the oil drained.

05rmksteve · Jan 30, 2017

Should be able to build a watercraft based 1365 for 5- 6k. Using a 910 top end 800 crank with another rod pressed and a watercraft case. I've been tossing around the idea of putting 1 together since nobody wants to give me anything for my 910s.

LoudHandle · Jan 30, 2017

05rmksteve said:
Should be able to build a watercraft based 1365 for 5- 6k. Using a 910 top end 800 crank with another rod pressed and a watercraft case. I've been tossing around the idea of putting 1 together since nobody wants to give me anything for my 910s.

After the PAR run ability issues with their 910, that is not too surprising.

Stock parts do bring the price down a LONG ways. Not very cost effective to do a one off engine.

Crank Shop wants $5K+ just for the twin stroker crank; 76mm stroke (I was guessing / assuming 8K'ish for a triple version).

But as Spaarky put it, it would be a bad AZZ sled. Especially in one of my lightened chassis.

jhillam · Feb 1, 2017

I've asked the max 800 CFI HP question of Jim@dynotech and of boondocker. Jim related 300 hp is doable. Need lower compression heads (rktek) 2863 or 2871 turbo, larger fuel pump than stock, and good intercooling. Any hint of deto will destroy the CFI motor tuned much above 250 hp. Jim related pro-era cylinders are the ones wanted to make max boosted power as Axys and Dragon both have too much exhaust port timing.

Boondocker related that full mod Carl's cycles engined / boondocker turbo'd pros that ran in 2015 x games were in 300 hp territory.

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HP limit of the 800 CFI engine when RG Turbo'd?

LoudHandle

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