Cams, V8's vs high rpm streetbikes.
05-27-2004, 09:03 AM
#1
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Cams, V8's vs high rpm streetbikes. I've got an odd question.
Why is it my Japenese streetbike can pull cleanly from 2,000 to 10,500 rpm... while an American V8 with a healthy cam has a relatively very narrow powerband, and poor driveability down low?
..."long block" differences aside - assume both motors can easily sustain 11,000rpm.
Say my truck motor peaks at 6,500. It's safe to say I gave up a lot of extreme lowend power for that.
My streetbike peaks right around 10,000 - yet I have very little lope, excellent lowend driveability, and I can lug 6th gear from 1,800 rpms at 20mph.
What gives?
Why is it my Japenese streetbike can pull cleanly from 2,000 to 10,500 rpm... while an American V8 with a healthy cam has a relatively very narrow powerband, and poor driveability down low?
..."long block" differences aside - assume both motors can easily sustain 11,000rpm.
Say my truck motor peaks at 6,500. It's safe to say I gave up a lot of extreme lowend power for that.
My streetbike peaks right around 10,000 - yet I have very little lope, excellent lowend driveability, and I can lug 6th gear from 1,800 rpms at 20mph.
What gives?
05-27-2004, 09:08 AM
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ALso, I'm working on digging up cam specs for my bike.
It's a '00 Yamaha R1. 1-liter motor, 125hp at the wheel.
My truck, comparitively, should have 750hp at the wheels - drivetrain differences aside.
It's a '00 Yamaha R1. 1-liter motor, 125hp at the wheel.
My truck, comparitively, should have 750hp at the wheels - drivetrain differences aside.
05-27-2004, 09:43 AM
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In comparing the two types of motors, it is important to consider the actual power being produced at the various RPM ranges. Your street bike may pull cleanly to 10K + RPM and you mention you can "lug" it around town at 1800rpm. If you have dyno charts for this bike, you will most likely see a particular range the power really comes on and it is most likely from 5K or so to redline.
A typical American V8 is typically designed for torque down low, giving way to high RPM capability. In comparison, Ferrari has released several V8 or higher number cylinder engines that pull cleanly to 9K rpm levels and F1 motors pull into the very high teen's x thousand RPMs. I believe the V12 in the Enzo pulls almost 10K RPM and can be lugged in the low RPM range, but it wants to run higher like your bike.
The new LS2 motor was explained in terms that engineers like to use and would be good for comparison on your part. 90% of the peak torque is available in the LS2 motor from 1800rpm to redline. If you where to chart your bike you would find a much different range where the power was availabe at a 90% figure.
Todd
A typical American V8 is typically designed for torque down low, giving way to high RPM capability. In comparison, Ferrari has released several V8 or higher number cylinder engines that pull cleanly to 9K rpm levels and F1 motors pull into the very high teen's x thousand RPMs. I believe the V12 in the Enzo pulls almost 10K RPM and can be lugged in the low RPM range, but it wants to run higher like your bike.
The new LS2 motor was explained in terms that engineers like to use and would be good for comparison on your part. 90% of the peak torque is available in the LS2 motor from 1800rpm to redline. If you where to chart your bike you would find a much different range where the power was availabe at a 90% figure.
Todd
05-27-2004, 10:13 AM
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The couple of dyno's I've done with the bike show a glass-smooth 40-degree rise in rpm vs horsepower. I'll try to get one scanned in tonight.
Here is one of a bone stock '02 and '04. (They're comparing the recammed '04 motors to the old style '98-02 cams) bike dyno...
My '00 motor is like a big electric motor - notice the long flat torque curve.
It just seems odd that V8's have such a large comprimise in driveability, while these little things idle fine at 900rpm and can spin serious rpm's.
I do make sense out of your 90% figure... I'm no good at math, or I'd try to figure out 90% of the '02's graphs above. It seems as though the motor is healthy (going by torque) by 2,500 - and it can make good power all the way up to 11,500.
Here is one of a bone stock '02 and '04. (They're comparing the recammed '04 motors to the old style '98-02 cams) bike dyno...
My '00 motor is like a big electric motor - notice the long flat torque curve.
It just seems odd that V8's have such a large comprimise in driveability, while these little things idle fine at 900rpm and can spin serious rpm's.
I do make sense out of your 90% figure... I'm no good at math, or I'd try to figure out 90% of the '02's graphs above. It seems as though the motor is healthy (going by torque) by 2,500 - and it can make good power all the way up to 11,500.
05-27-2004, 10:21 AM
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Are we forgetting something, WEIGHT! Put that 1.0 liter motor behind 3600# vehicle and tell me about drivability in 6th gear @ 20MPH. 
Your not comparing apples to apples. 1.0 Liter VS 5.7 Liter. Inline VS a V motor.
Those B18C Honda motors dyno graphs look just a an inline motorcyle motor in regards to dyno HP, RPM, and drivability. The reason the graphs do not look the same is b/c a larger displacement motor like the LS1 makes torque right in the low rpms and carries it all the way, but an inline like a 4cyl honda engine with Vtec comes it hard at like 4K rpm and carries the HP and TQ up aggresivly in 45 degree like your motorcycle.
V8's have a lot of rotating mass comparied to an inline 1.0 liter engine. You could spin a V8 motor up that high look at nascar motor tach's when they race.
Your not comparing apples to apples. 1.0 Liter VS 5.7 Liter. Inline VS a V motor.
Those B18C Honda motors dyno graphs look just a an inline motorcyle motor in regards to dyno HP, RPM, and drivability. The reason the graphs do not look the same is b/c a larger displacement motor like the LS1 makes torque right in the low rpms and carries it all the way, but an inline like a 4cyl honda engine with Vtec comes it hard at like 4K rpm and carries the HP and TQ up aggresivly in 45 degree like your motorcycle.
V8's have a lot of rotating mass comparied to an inline 1.0 liter engine. You could spin a V8 motor up that high look at nascar motor tach's when they race.
Last edited by m1key99WS6; 05-27-2004 at 10:29 AM.
05-27-2004, 10:27 AM
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Besides the weight difference,mechanical difference in the way power is transfered,
small engines are more efficient. your not really comparing apples to apples here.
push the weight up to avg car power to weight ratios and see how they do.
i am NOT saying v8's better, just work in a different environment.
small engines are more efficient. your not really comparing apples to apples here.
push the weight up to avg car power to weight ratios and see how they do.
i am NOT saying v8's better, just work in a different environment.
05-27-2004, 10:28 AM
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Yeah, I definitely realize the weight issue.
Scaling the '02 dyno above up 6 times (1.0L vs 6.0L) - I'd have a cam in my truck that would make 270ft/lbs at 2.5K, 360ft/lbs at 4K, and 420ft/lbs at 7K.
As a completely random LS1 example, compare the numbers to this healthy motor...
EDIT:
Okay, I forgot about the drivetrain differences above.
Engine to engine, I DO see the V8 making more torqe now. I was in the framset before that they were still very anemic compared to these high strung inline fours.
Scaling the '02 dyno above up 6 times (1.0L vs 6.0L) - I'd have a cam in my truck that would make 270ft/lbs at 2.5K, 360ft/lbs at 4K, and 420ft/lbs at 7K.
As a completely random LS1 example, compare the numbers to this healthy motor...
EDIT:
Okay, I forgot about the drivetrain differences above.
Engine to engine, I DO see the V8 making more torqe now. I was in the framset before that they were still very anemic compared to these high strung inline fours.
Last edited by marc_w; 05-27-2004 at 10:46 AM.
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05-27-2004, 10:34 AM
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Okay, the weight of the rotating masses is something I didn't thoroughly think over... 
On that note though, what are F1 cars running, something like 4.0 V8's? (granted they have pneumatically actuated valves and all... )
On that note though, what are F1 cars running, something like 4.0 V8's? (granted they have pneumatically actuated valves and all... )
05-27-2004, 10:38 AM
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Originally Posted by OWENMUSTANG
Your not comparing apples to apples.
HEY you beat me to the punch line
HEY you beat me to the punch line
Even if we take the vehicle and intended use out of the equasion?
05-27-2004, 10:50 AM
#11
rotating assembly weight, lack of tq needed to move a light bike, and most importantly - exotic valvetrane and a VERY VERY favorable bore to stroke ratio. something no one has touched on. the piston speed for a 10K rpm bike is no where near a 10K rpm piston speed of a stock bore and stroke ls1 motor. also very few bikes turn 100K miles - how many ls1 cars do? vast majority of them.
designers could easily design a motor to turn 10K rpms. look at the NHRA classes of sbc destroked and launch at 8K rpms and shift to 10K - they sound like weedwaker motors. but they are also packaged with big gearig and enourmous stall convertors. they would get beat by a stock ls1 car on the street given the same driveline.
designers could easily design a motor to turn 10K rpms. look at the NHRA classes of sbc destroked and launch at 8K rpms and shift to 10K - they sound like weedwaker motors. but they are also packaged with big gearig and enourmous stall convertors. they would get beat by a stock ls1 car on the street given the same driveline.
05-27-2004, 11:01 AM
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Okay, you cleared that up for me pretty good John. I never thought about bore/stroke ratios.
The whole gist of this thread was the comment I made under an edit:
"Engine to engine, I DO see the V8 making more torque now. I was in the framset before that they were still very anemic compared to these high strung inline fours."
Thanks everyone!
The whole gist of this thread was the comment I made under an edit:
"Engine to engine, I DO see the V8 making more torque now. I was in the framset before that they were still very anemic compared to these high strung inline fours."
Thanks everyone!
05-27-2004, 11:35 AM
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The main reason a street bike motor can pull so many RPMs safely is because they have an incredible short stroke. For instance I have a ZX6R, and the displacement of all 4 pistons it equal to my dads Buell 1200, and its a V twin. The buell motor feels more like a car, while my bike revs to the moon.
