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Now, I know I know

V-twin are torquey in their stock form.

My curiosity lies in the fact that I4 makers always concentrate on high hp number @ 14-16K rpm.
why don't they tune the bikes to make more torque in the lower rpm range.

Could one re-cam an I4 to make more torque? giving up some of that power up high?

the essence in my question is my undeniable love for the triumph daytona 600 and 650. I only rode the 600, and loved everthing except........you guessed it...the low end or lack there of.

how could you make an I4 a torquey motor?

no I am not swapping a v-twin in there. hahaha

Q
 

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Changing the sprockets supposedly can help accelertaion. I dont know off hand if going to more teeth or less teeth will make it quicker on acceleration. But at the same time it will lessen the amount of top end speed.
 

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Putting different sprockets on as in less teeth on the front sprocket and more teeth on the back won't make the bike "more" torquey, it will allow the bike to rev higher at lower speeds, making it feel more torquey. You will lose top end, if that bothers you.
 

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QfactorSV said:
Now, I know I know

V-twin are torquey in their stock form.

My curiosity lies in the fact that I4 makers always concentrate on high hp number @ 14-16K rpm.
why don't they tune the bikes to make more torque in the lower rpm range.

Could one re-cam an I4 to make more torque? giving up some of that power up high?

the essence in my question is my undeniable love for the triumph daytona 600 and 650. I only rode the 600, and loved everthing except........you guessed it...the low end or lack there of.

how could you make an I4 a torquey motor?

no I am not swapping a v-twin in there. hahaha

Q
Fundamentally speaking it would be difficult to produce the same kind of torque figures lower in the rev range with a similar sized I4 that with a V-twin. If you think of comparing a 1000cc twin with a 1000cc 4. Each of the cylinders (pistons too ) of the twin displaces 500ccs. Now each time these move they can exert a much greater rotational force which is torque than each of the 250cc pistons of the 4. But these larger pistons dont allow the engine to rev as high as the 4 with its small pistons. So the 4 ends up making just as much torque though at rpms that the twin possibly can't even reach.

This is very rudimentary and does not take into account many variables. But it's almost impossible for a 600 4 to make as much torque as a 650 twin low down in the powerband(of course the 4 will make almost as much peak torque as the twin, but higher up in the rev range)
 

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raise compression.
 

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Hall Monitor
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Simple to do:

1) Decrease the bore-to-stroke ratio, making for smaller-diameter pistons with a longer stroke.

2) Shrink the valves down (you'll need to anyway because of 1) ). While you're at it, choke down the intake port diameters. All of this will act to increase port velocity at lower rpms, leading to better cylinder filling at lower rpms.

3) Smaller diameter carbs as well.

4) Re-profile the cams for lower lift, longer duration, and less overlap.

All of these will shift the power down lower in the rev range. They also act directly against the multi-cylinder engine's primary advantage of better breathing (more valve area per displacement).

Kind of like truning a Ferrari into a low rider. It can be done, but not really the best application.

Bill
 

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QfactorSV said:
Now, I know I know

V-twin are torquey in their stock form.

My curiosity lies in the fact that I4 makers always concentrate on high hp number @ 14-16K rpm.
why don't they tune the bikes to make more torque in the lower rpm range.

Could one re-cam an I4 to make more torque? giving up some of that power up high?

the essence in my question is my undeniable love for the triumph daytona 600 and 650. I only rode the 600, and loved everthing except........you guessed it...the low end or lack there of.

how could you make an I4 a torquey motor?

no I am not swapping a v-twin in there. hahaha

Q
Dude, just adjust your love to the new Triumph Daytona 675 Triple.

http://www.triumph.co.uk/uk/3932.aspx

Check the torque on that bad boy.
 

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I don't like riding my triumph as much as I thought I would. It would make a great second bike though. I just wish I could afford two bikes. :(
 

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put a 72 tooth sprocket on the back ;D
 

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Current supersport inline fours are oriented towards racing. Drivability (and torque) at low rpms is sacrificed for top end. Even then - in the meat of their powerband, current I4's make virtually identical torque to an SV650 (~48 ft/lbs).

In order to get more power you typically increase displacement. Simple, cheap - easy. For racing - you can't do this. It's 600ccs or 1000ccs. Since they can't change displacement - they do the only other thing they can. They spin the motor harder and harder. This requires a larger bore, shorter stroke - which is the exact wrong recipe for low-end torque.

You CAN make an inline more torquey down low. Not like a twin is out-of-the-box. The twin inherently has torque - longer stroke, more leverage, bigger power strokes (bigger BANGS) = torque.
 

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make it more cc's how many twins have the torque of a busa ? maybe a couple that are 500 cc bigger like the vtx1800
 

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orangegilly said:
Dude, just adjust your love to the new Triumph Daytona 675 Triple.

http://www.triumph.co.uk/uk/3932.aspx

Check the torque on that bad boy.
72Nm (53ft.lbf) at 11,750 rpm

still pretty high up the rev range aint it ;D

considering its peak power is just under 1k higher "125PS (123bhp) at 12,500 rpm"
 
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Cams are an easy fix. More A/F mix in the in the cylinder - open quicker, sooner and stay open longer. All depends on the profile. It's never going to feel torque heavy on the bottom, it is an I4, but you can improve it.
 

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turboLT said:
after a turbo upgrade in my cage I could pass people in 5th like they were standing still...with an I4
Depending on the size of the turbo and tuning you could end up with a less "torquey" motor. I understand hp = (torque * rpm) / 5252 but when many people say "torquey" they mean low end power. Lag and waiting for spool up usually means different.
 

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If Q's original question related to "feel" or "around town driveability" I would second (or third) the sprocket swap.  While it does not increase torque, it does make the available torque more usable at common rpms.  I am sure everyone knows this, just wanted to add my vote to it making a real difference in feel.  Cheap and adjustable, too.
 
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