Kawasaki Sportsbike Riders Club - Australia - Online Forum

Dan,

you make things so smiple.

Buy a ZX10 or ZX12 and you will be ok.

Good thinking 99.

icebreaker wrote:Has anyone notices that BOTH Ian's are very technical.
...snip...

Now as for my Layman's say on the maters...
The engines rev range, and level of torque, is what I look at if I were to SC or Turbo.. And where you want the power to be...
No point getting a SC in a car if you like to Redline it all the time.
And no point putting a SC on if it doesn't have much bottom end to run it..
So i guess with Bikes, being so high rev'ing, which allows the exhaust pressure to build up, a Turbo would be the Ideal way to go.
Dan

me...??? technical...??? probably...
never really thought about it....
and Dan, you are probably right too.....
thinking about it...I am technical because of the way I got my mechanical knowledge....
Apart from a Welders Certificate (from the local TAFE) I have no mechanical training (I have a Bachelor of Business and a postgraduate degree in Computer Science...neither of which imparts ANY mechanical knowledge!)
so, unlike most. I got mine by trial and error...and then checked the manual when something went wrong!
the practice PRECEEDED the theory...not really the way you are meant to do it....
and the errors I made and the work done to fix things, means I am self taught I guess .....
built modified and repaired....
more engines, diffs, transmissions, brake and suspension systems than I care to remember (and that applies to both cars and bikes)
even built a few complete cars from scratch....
take a burnout out or written off shell..and away you go....

and re the applications..you mentioned above....
No point getting a SC in a car if you like to Redline it all the time.
hmmm...tell the drag racers....
funnily enuff, turbocharging has never been a big hit in drag racing

And no point putting a SC on if it doesn't have much bottom end to run it..
hmmm...not sure about that either....superchargers start compressing air from the time, you turn one over...no lag with a supercharger
(unlike Turbos that require what...? 3000 engine rpm before they start forced induction)

Smitty1955 wrote: and re the applications..you mentioned above....
No point getting a SC in a car if you like to Redline it all the time.
hmmm...tell the drag racers....
funnily enuff, turbocharging has never been a big hit in drag racing

And no point putting a SC on if it doesn't have much bottom end to run it..
hmmm...not sure about that either....superchargers start compressing air from the time, you turn one over...no lag with a supercharger
(unlike Turbos that require what...? 3000 engine rpm before they start forced induction)

Fair enough i guess...
It all comes down to the application..

And where you feel the engine lacks the grunt..

With my old 18R and 18RGE, I always wanted a SC, because it lacked realy torque down low but came into it's own from 4,000RPM+... Which meant you had to keep the engine up in the rev's to ensure you had power in hand... providing you thought you were about to need it..

But alot of other people would believe that a turbo would be better suited, and I'm sure if i wanted ALOT more power, and prob a not so reliable set up it would be... So I guess in my case, it would also depend on how far you want to go..

*shrugs*

aaaah Dan....
now you are getting into the very interesting area of camshafts
and their design of lift and timing....

by 18R and RGE..we are talking 4cyl Toyota engines of what????
1600cc or 2000cc capacity with a single overhead camshaft????
yes???
ok....
smallish internal combustion engines lack torque (by design and capacity)
and torque is what makes you move...NOT horsepower!
but you can partially substitute torque with horsepower at hi engine revolutions....
so what do some car and bike makers do.....?
make small engines rev....
(note..lack of torque is NOT a problem with a 351 Falcon engine.... )
so
you design these small engines to rev.... and so make horsepower
at higher revolutions than a large capacity engine
and you do the camshaft timing and lift to suit....

an engine that you want to rev(apart from generally being of a shortstroke design) ...
will generally have a camshaft with a higher lift and a longer dwell (valve open) duration
and that engine will make LESS torque at low revs...
but...
yes
you can stick in a cam that makes MORE torque at low revs
(Falcon Taxi drivers do this all the time....yep, its called a taxi cam!)
coz you want the engine to make most of its torque at 2500rpm
not 4500 rpm!
and so
we have cams for Supercharged engines and DIFFERENT cams for turbocharged engines....
so
tell ya camshaft grinder that you want the cam for a SC engine and it will perform from say 1800 rpm up to 5500 and prolly make most torque at 3000rpm
a turbo engine should start at 3000rpm and go to 6500rpm
and make most of its torque output at 5800rpm
note- very different....
and those 2 different engine characteristics..
then lead to different tranmission choices (auto vs manual) and gearing (low vs high)
but thats another story....


cheers

is that right.

18R is a SOHC, 18RG is the DOHC (8 Valve)

icebreaker wrote:18R is a SOHC, 18RG is the DOHC (8 Valve)

ta...
makes no diff to my post though...just curious...
and I am not going to touch valves sizing and volumetrics
enuff technical stuff...................for today.....

at the end of the day, belt driven centrifugal superchargers still cant put out much more boost than a turbocharger without the use of an intercooler, and a half decent intercooler should be able to cool the charge back to near ambient temps even with crazy boost, and fitment of an intercooler is not a problem on a bike as has been proven time and time again


dan thats a bit of a generalisation there with "turbos for top end, supers for down low" ... somebody go tell an XR6T owner that his motor makes less low down torque than a gen3 and he'll laugh at you with good cause

and your big $$$ twin screw blowers make crazy boost down low (some have to use a bypass valve down real low to prevent pinging i think?) and still rev out pretty good


but to say that turbos always hit with a violent *KABAM!* is also an unfair generalisation .... all depends on the turbo ... a T04 on a 13B rotary will usually have a crazy hard hit at about 4000rpm i think ....where as a T28 on a SR20 has a seriously linear torque delivery... a twin screw blower could certainly have a violent powerband to begin with (unwanted wheelspin?)

it all depends on how the turbine and compressor are matched up, A/R ratio's and stuff... do it right and there will only be a soggy spot down low that you should avoid like the plague and the rest will be very useable power


turbos arnt exactly free HP, sure they dont take power directly from the crank but they do make an engine have to breathe a lot harder just to get its exhaust gas out ...

the exhausts most all turbocharged bikes use are just a 6-8" section of pipe to direct the gasses through the fairing not sure how legal they are, but i wouldnt be supprised if it wasnt a great deal louder than most N/A bikes with loud pipes



as for turbos in drag racing, they are really big in the states at the moment... on NHRA drag racing on foxtel you see plenty of SBC 400ci's running a huge single turbo and putting out 5 second 1/4 miles 2250hp

ps make sure you take out any overlap if your gonna play around with cam timings if your serious about forced induction

SocialSecurity wrote:ps make sure you take out any overlap if your gonna play around with cam timings if your serious about forced induction

absolutely....
otherwise..the intake charge....goes straight out the zorst port!
and the resulting bang (combustion) is little indeed!!!

thought we weren't gunna get technical.....

and...while we are at it....
somebody go tell an XR6T owner that his motor makes less low down torque than a gen3 and he'll laugh at you with good cause

this is an interesting one (and this coming from someone with a LS1 GenIII (manual)
the facts...
the XR6T has a fairly linear and FLAT torque graph..which is good...
(but its gearing...box and diff are not optimal though...total gearing in 1st is too high to properly use it..off the line)
the GenIII has a torque graph that is bananas...very weird & strange
nothing at idle...rising up at 1800 rpm the dipping again then going off the scale at 3500 and staying there....
which is why an auto works well with the GenIII!!!

the XR6T torque graph is caused by the turbo setup with the right engine compression ratio and it runs outta puff a bit over 5000rpm but who cares...
the GenIII if kept over 3500 will run away from just about anything
but where can you do that...'cept the track or freeway?
btw
the cause of the GenIII's behavior is partly to do with its camshaft specs
(all top end) but is also caused by its inlet manifold....
oh..here we go again....
a very short inlet tract....reduces torque
(we all knew that , didn't we ...???? )

oh...
and the reason an SS runs away from an XR6t (but not by much) is...
weight......
the Ford is a lard arse....about 120kg more than the Holden



cheerio

my point is, peak torque starts at 2000rpm on the xr6t's motor, goes against common perceptions of turbos


lol ive collected a few scalps while riding my cbr250, recently a VY SS as well as a BA XR8

id be happy with this power band

I'd like to hear Robs thoughts on the XR6 vs the SS

i know which i prefer

http://www.airpowersystems.com.au/falcon/phase_iii.htm