Torque on a restricted SV

As you all know, I bleedin' love my SV. Yea, its got 33 bhp and a god-awfull looking topbox (bloody handy though) but it gets me everywhere and I love the handling and the engine.

And on the subject of engine, I was wondering if anyone had a dyno output of their restricted bike, showing a curve for the torque; or, failing that, if anyone has an idea of what torque a restricted SV would be producing?

I was just curious as to the drop in torque in my restricted bike, compared to that of a full power machine.

Anyone got a rough idea?

Matt

Originally Posted by alpinestarhero

I was just curious as to the drop in torque in my restricted bike, compared to that of a full power machine.

Anyone got a rough idea?

Well I have know idea on the curve as I've never had it on a dyno, however I can tell you that after just de-restricting mine 3 weeks ago, the drop is tremendous as now I have to really hang on in the midrange and it just keep pullin from there.

Greg

send me a chip and i will find out

I wouldn't of thought the bottom end of the torque would be that different. You'd still be pretty much just as quick as a full power bike off the line.

The midrange, maybe a difference, I dunno.

The top-end on a restricted bike probably wouldn't be there at all, but you probably already knew that.

power= torque x engine revs. So peak torque will be very low in the rev range. when you getting it unrestricted?

[Stu]

Looking at my Dyno chart, it hits 33hp at a smidge over 5000 revs, so I guess it would be the same up to there, then the torque would have to fall off as the revs go up?

I see, I see...it all makes sense now. I did realise that at lower RPM's the bike would suffer less since the required amount of air isnt as much i.e. theres enough air getting passed the restrictors to make the power at those low revs.

Stu - sounds about right, tails off exponentially after 5000 rpm (least, it feels like it)

And baph....yea, i did realise a distinct lack of power

Matt

Originally Posted by Baph

I wouldn't of thought the bottom end of the torque would be that different. You'd still be pretty much just as quick as a full power bike off the line.

If it behaves like other restricted intake systems on larger motors, you probably have higher torque numbers in the lower rpm band than the same motor without the restriction. (That's just experience with v8's of the small and big block varieties...it probably holds true of all motors breathing through less than optimum sized intake runners.)

Originally Posted by alpinestarhero

I see, I see...it all makes sense now. I did realise that at lower RPM's the bike would suffer less since the required amount of air isnt as much i.e. theres enough air getting passed the restrictors to make the power at those low revs.

Stu - sounds about right, tails off exponentially after 5000 rpm (least, it feels like it)

And baph....yea, i did realise a distinct lack of power

Matt

Mine is good up to about 7K then tails off, 3rd and above and she'll slowly creep up to about 9K or so - Not that I'm complaining cause thats fast enough for me at the moment!

one of you guys should get a dyno and post the charts so we can see the power trend