Which 4 stroke motor?

[m1kflyingtiger]

I'm looking at doing a 4 stroke turbo in the pro chassis. I was leaning twards a polaris/weber 750 fst motor, but There's a nytro motor going in one on the member builds forum that the guy is looking at producing the motor mounts which would make it a lot simpler of a swap.

The part I'm still wondering about is what's the best 4 stroke motor under boost for a sled? Size is a concern as I'd like to keep the structural integrity of the cast aluminum bulkhead, but I'm looking for a good, reliable 220-250 hp on 90 oct non-ethanol pump fuel at sea level.

Am I pretty much limited to the nytro, fst, or proclimb 1100t motors with those goals and the conditions we run in?

And can you run a turbo 4 stroke at a steady throttle such as a trail ride or will I have to constantly keep an eye on everything if I'm not WOT like I had to with my 2 stroke turbo?

Thanks in advance

 

[BigFish BC]

the nytro with a head shim will make 220hp no prob on 91 oct & very reliable would need about 10-12lbs boost.the nytro motor is the best of the 3 listed by a bunch & is lighter than the 1100 by about 20- 30lbs .when trail riding with the nytro you dont have to watch gauges you wont be on boost much so it will run like the stock motor with no issues.oh the poo 750 will not make 220 at sea level without some race fuel not even close power wise to a nytro motor.

 

[kinger9]

Physically the apex motor is smaller then the nytro, it will make 250 all day long on 91 pee. Lots cheaper and some will argue much better then the nytro. About 8lbs heavier though then nytro because of gear reduction.

 

[tjc]

Physically the apex motor is smaller then the nytro, it will make 250 all day long on 91 pee. Lots cheaper and some will argue much better then the nytro. About 8lbs heavier though then nytro because of gear reduction.

are you positive on this? I would have never guessed that is possible. even width wise?

 

[Octanee]

hmm could be true on the apex motor size, either way they are a what, 1000CC or 1200CC motors, so whether its a 3 cyl or 4 cyl the surface area of the overall cc ends up being the same, so i could see the apex being a bit more...

and the apex with head shim does like 270 hp on 91 pump, nytro is 240

 

[BigFish BC]

Physically the apex motor is smaller then the nytro, it will make 250 all day long on 91 pee. Lots cheaper and some will argue much better then the nytro. About 8lbs heavier though then nytro because of gear reduction.

the only way its smaller is in width 1050cc 3cylinder ,1000 4cylinder so the nytro cylinders are bigger.the apex motor is longer & a touch deeper

 

[1100]

Would the 1200 doo engine not be easier to fit with the forward exiting exhaust?

 

[HANDSOME]

I have an fst with the 2012 reflash which in dynotech was good for 194 hp on pump gas with every failsafe imaginable. When my intercooler temps are too high it backs the timing off.Good on gas too.

 

[kinger9]

This is taken from a guy that measured both motors side by side " Comparing both engines with a tape measure as well as possible with them mounted in snowmobiles the four cylinder takes less space than the triple. The total width from the back of the clutch to the outside of the magneto housing is too close to call. The triple valve cover is two inches thicker from front to back, but the biggest difference is how much taller the triple is as a result of the longer stroke, longer rods, taller cylinders and high mounted crank. That thing is huge."