Apex vs Vector Max RPM

[schroon]

Why is the Vector so far behind in Rpm vs the Apex. It has a fair amount of hp. I would think it would spin at least in the 9000 rpm range.

 

[Oak Hill]

It has a longer stroke, more low end torq, turns less RPM and as a end result no gear reduction and less weight. Just my 2 cents.

 

[BigFoot]

The reason the Vector doesn't spin higher, and the reason the Apex has gear reduction on the output shaft is all because of clutching. CVTs, in the application like on snowmobiles really becomes inefficient above about 9000 rpm. The Vector motor, from what I understand, was really a blank-sheet design for snowmoblies. The top desired RPM range was taken into account and one of the specs they targeted. The Apex motor is still a decendant of the R1 bike motor, which can rev higher because of no CVT.

 

[schroon]

long stroke

I also drag race cars, and we use the longer stroke to spin higher RPM. This isn't true with the sleds??

 

[Red2003]

Actually you would use a SHORTER stroke to spin higher rpm. Thats exactly why the 4 holer can spin higher rpms. The bigger the stroke the farther the mass on the crankshaft is spinning from its center and therefore cannot withstand the higher rpm. Which is why a 8 or 10 cyl indy type (or F1) car is only two litre, but makes a thousand hp at 20,000 rpm. Very very short stroke. Man those Farrari's sound sweet though!!! Now a drag racer would probably want a longer stroke to get max torque, but would certainly give up rpm for it.

 

[schroon]

We use the longer strke to gain higher RPM, slows down piston speed and reduces rod angle. We use what we have in torque in higher RPM. We have a 433 inch hemi spinning at 10500 rpm. Thanks

 

[backonblack]

I think you have you stroke and piston speed backwards. For example,
if you have a 4 1/2" stroke crank and 2 1/4" stroke crank the piston on the 4 1/2" crank will have to travel twice as fast for 1 revolution if the crankshaft. Thats why pro stock motors run a short crank with a large bore, the large bore also helps unshroud the valve.
Thanks:Rick

 

[TT670]

We use the longer strke to gain higher RPM, slows down piston speed and reduces rod angle. We use what we have in torque in higher RPM. We have a 433 inch hemi spinning at 10500 rpm. Thanks

I think youve got your terminology confused. You slow down piston speed and reduce rod angle with a longer rod and a raised wrist pin location in the piston.. You increase the stroke of the crank to gain cubic inches and torque, while lowering the effective operating RPM.

 

[brianidaho]

We use the longer strke to gain higher RPM, slows down piston speed and reduces rod angle. We use what we have in torque in higher RPM. We have a 433 inch hemi spinning at 10500 rpm. Thanks

I think youve got your terminology confused. You slow down piston speed and reduce rod angle with a longer rod and a raised wrist pin location in the piston.. You increase the stroke of the crank to gain cubic inches and torque, while lowering the effective operating RPM.

You are confusing the difference between rod length and stroke. Increasing the rod length does exactly what you say, without changing the stroke of the motor. However, with the same rod, increasing stroke (assuming you can do so w/i interference) causes higher piston speeds. For high rpm motors of the same displacement you want short stroke, long rods and a bigger bore. Stroke is determined by the crankshaft throw, it's independant of the rod length.

 

[Red2003]

We use the longer strke to gain higher RPM, slows down piston speed and reduces rod angle. We use what we have in torque in higher RPM. We have a 433 inch hemi spinning at 10500 rpm. Thanks

I think youve got your terminology confused. You slow down piston speed and reduce rod angle with a longer rod and a raised wrist pin location in the piston.. You increase the stroke of the crank to gain cubic inches and torque, while lowering the effective operating RPM.

You are confusing the difference between rod length and stroke. Increasing the rod length does exactly what you say, without changing the stroke of the motor. However, with the same rod, increasing stroke (assuming you can do so w/i interference) causes higher piston speeds. For high rpm motors of the same displacement you want short stroke, long rods and a bigger bore. Stroke is determined by the crankshaft throw, it's independant of the rod length.

YUPPERS!!! That's what I was getting at, but you said it much better. Schroon, I think you've just been voted off the island, but we still love you Bro!!!

 

[Bob Miller]

The new Suzuki M109 V Twin Cruiser is a good example of a Short Stroke, Large Bore, High HP, High Torque design: Leave it to the Japanese!

Engine Features
1783cc, 4-valve DOHC, 54 degree, liquid-cooled, fuel injected V-twin engine designed for strong throttle response and quick acceleration
Massive 112mm bore and 90.5mm stroke utilizing huge 112mm forged aluminum alloy pistons with short skirts, and cut away sides riding on chrome moly steel connecting rods.

Producing 127 horsepower at 6,200 rpm, and 118 ft. pounds of torque at 3200 rpm, With the simply massive 112mm pistons blasting up and down their individual 90.5mm strokes, the engine will rev till to 7400 rpm before the limiter shuts things down. Maximum power is quoted at 6,200 rpm, but the bike still keeps pulling solidly till 7000 rpm if you need.