s1 rallye VS quaife gear kit

[Dave_P]

I've been told by more than one person that after fitting a c/r box to there race car the lap times haven't dropped at all.

Thats odd.

[sexy_gt]

Interesting

[axsaxoman]

then they are not driving right - ,--c/r on knockhill is at least 2secs a lap + lsd is another 2secs a lap on a saxo or ax n/a type of engine with same bhp over any std ma g/box ratios
boostedcars it may not hold true for the c/r ,but even more so for the dif

[sexy_gt]

Originally Posted by axsaxoman

then they are not driving right - ,--c/r on knockhill is at least 2secs a lap + lsd is another 2secs a lap on a saxo or ax n/a type of engine with same bhp over any std ma g/box ratios
boostedcars it may not hold true for the c/f ,but even more so for the dif

and thats on a short lap! so over a lap that will take 2 minutes do you expect 4 seconds off?

[KamRacing]

depends how many times you have to change gear!

[dannygti]

I'd say it would really depend on the engine of how much time is saved.
Standard'ish engine would still have a half decent broad range of power, so close ratios wouldn't give massive advantage

[raunchz]

Surely the c/r kit will be most beneficial on a windy'ish track where you accelerate through the gears a lot.

In comparison, on a long open track it wouldn't be a huge advantage?

[axsaxoman]

Originally Posted by sexy_gt

and thats on a short lap! so over a lap that will take 2 minutes do you expect 4 seconds off?

It does not work lke that
depends how long the straights are and how many corners etc ,etc .
even at silverstone a stdish engine saxo vts will never get to rev limter in fifth on the longest straight --so its over geared
If you cannot get very close to rev limter on longest straight in highest gear then you must loose time .
touring car with 300bhp+ 6 gears at knockhill only gear for around 135mph ,so ifyou can,t use higher gearing with 300 bhp+ 8000rpm what chance do you have with 150bhp and a 7250 lmter of getting to 142mph--none .
and most of you will be wanting to use 7500-8000rpm --that makes a top speed of 156mph @8k and thats not even taking into account the std gear ratios have big gaps which will make for flat spots in the acceleration ,
our ax race car at730kgs was geared for 118mph@8k with 128bhp@wheels --we never got more than 7400rpm in fifth ever on knockhill --
lowering overall gearing has the effect of giving more bhp@wheels .
the ideal gearing is you change at maybe 250rpm over maxbhp and the next gear shouldrop the rpm to just bfore where max torque is produced
so you are alwat accelerating between max torque +max bhp
you can debate this as much as you want - the bottom line is you should gear a car to suit the longest straight -ideally just on the rev limter as you hit the brake pedal at the 100 or 75 yard board for the corner

[sexy_gt]

john this is my power graph,

[axsaxoman]

looking at graph ,which looks a bit strange -- 5000-7000k would be the rpm range ffrom one gear to the next change at 7k and if gearing is right would comeback to about 5k,but with flat curve at top you could say change at 6600-you don,t have any more power further up,so its jsut wasting time as acceleration will be slowing

[sexy_gt]

Originally Posted by axsaxoman

looking at graph ,which looks a bit strange -- 5000-7000k would be the rpm range ffrom one gear to the next change at 7k and if gearing is right would comeback to about 5k,but with flat curve at top you could say change at 6600-you don,t have any more power further up,so its jsut wasting time as acceleration will be slowing

the flat line, any ideas john? the cams was timed on rollers to give most power. springs worn/lifters?

[Dave_P]

Originally Posted by axsaxoman

then they are not driving right

Well i cant comment on that, one of the cars races at Knockhill and is leading its class but the engine has a good spread of power/torque and isn't peaky at all.

I do find it hard to believe its not quicker but the times are the same.

[axsaxoman]

Originally Posted by sexy_gt

the flat line, any ideas john? the cams was timed on rollers to give most power. springs worn/lifters?

could be -something is wrong

[sexy_gt]

Originally Posted by axsaxoman

could be -something is wrong

would it be ok to rebuild head with new parts, having marked where the cams are set now and refit, take back to same dyno and expect much more better result?

[sexy_gt]

i have a perfectly good s1 box now, worth fitting a quaife diff in or sell on and get quaife gear kit for the vts box i have now?

[dannygti]

id say get the gear kit..

they make track work much more enjoyable as well as improve times.

[sexy_gt]

Originally Posted by dannygti

id say get the gear kit..

they make track work much more enjoyable as well as improve times.

cheers for input.

im confused as to if the quaife gear kit is going to be worth the extra money over the s1 box i have sitting here. ive driven a breathed vts with the s1 box on and it felt great, i just cant imagine how or where the quaife could and would improve. could you explain to me please?

[dannygti]

well the simple matter of it is, it wouldnt be a massive gain with your engine in its current spec. when an engine becomes peakier it requires the gear ratios to keep it in the good stuff, but your engine isnt so peaky so it wouldnt drop out of the good stuff as much.
however, say if you choose the wrong gear the close ratios wouldnt be as bad as a normal gearbox..

also, having a great gearbox makes an average engine seem strong. however a great engine will seem poor without a great box.

[axsaxoman]

you won,t choose the wrong ratios as the quiafe set is near perfect for an n/a car
its very simple drop your gearing by 20% and you will have 20% more torque at wheels at same rpm .
you have asked this so many times --do the maths you know where max torque of engine is and max power ,when you change up you should change at an rpm that means the engine drops back to around max torque --
you just can not do that with ANY std pug /cit g/box ratios