MikeR
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| posted on 9/9/08 at 07:16 PM |
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I disagree with what you're saying based on a conversation with NS Dev last night in his garage. He spanners for a caterham race team at
weekends. The data logger on that showed the car doing around 135 - 140 on 200ish bhp.
Not sure what you call winding up to speed, but i'd have thought if you can get there on a track thats fast enough.
(nb i may have miss quoted / miss understood what was said last night but i'm pretty sure of the conversation)
quote:
Originally posted by JimSpencer
quote:
Originally posted by alistairolsen
so i suppose you could say Im using this thread to guage diff selection,
Right that makes more sense.
A really quick seven will do 140 ish, if it's got a superb engine in it, the other side of 300bhp good..
250 will see you nudge 130
200 around 120 ish
And I'm working on getting to that speed reasonably quickly, not "winding up to them eventually" sort of speeds.
Assuming you're running a box with an 'overdrive' 5th or 4th giving you the normal 0.87 / 0.88 ratio in top, you'll want diff
ratios of:-
3.7
4.1
4.4
..ish, for the power range's above
Based on the normal 185/60/13 or 195/45/15 tyres.
If what you're doing doesn't fit into that let us know the power it's going to have and the gearbox ratio's and it's a
simple job to work out the axle ratio needed.
HTH
[Edited on 9/9/08 by JimSpencer]
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Volvorsport
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| posted on 9/9/08 at 07:22 PM |
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youll need the highest possible gear ratio in first that you can pull away with , light cars with high power dont need as much torque multiplication
.
so 2.2:1 is used in some close ratio 4 speeds , and it also depends onyour rear diff , so that means starting in second if as mentioned before your
using std gearing from the donor or thereabouts .
my volvo gearing is about 29mph in first !!
www.dbsmotorsport.co.uk
getting dirty under a bus
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TOO BADD
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| posted on 9/9/08 at 07:36 PM |
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Assuming gear change at 6800.....
Ist 46
2nd 70
3rd 98
4th 112
5th 138
225 50 15 Toyo R888
My redline is set at 8000 so my figures are
54
83
115
132
163 !!!???
200bhp with unknown torque and will spin from start to 7500 ( 50 ish )in first without dropping the clutch and with a little more in second and
sometime a waggle in third.
All controllable..... 
BGH close ratio and 3.92 LSD
[Edited on 9/9/08 by TOO BADD]
[Edited on 9/9/08 by TOO BADD]
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the_fbi
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| posted on 9/9/08 at 08:09 PM |
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quote:
Originally posted by alistairolsen
surely anyone who actually drives their car will know this intrinsically! for instance my old corsa:
@6800
1st - 35
2nd - 60
3rd - 90
4th - 125
5th - 150 ish (never revved it out, was a bit over 3k at 70.)
car had 150bhp and 150ftlbs of torque thru the front wheels.
wheelspin was possible int he dry, but very controllable and easy to avoid even int he wet.
Ratios were very well placed for road use, never had the car on track.
Presuming this was an 20XE with an F18w or F28 its possible.
Take a while to get up there, but it would get there.
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JimSpencer
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| posted on 9/9/08 at 08:58 PM |
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quote:
Originally posted by MikeR
I disagree with what you're saying based on a conversation with NS Dev last night in his garage. He spanners for a caterham race team at
weekends. The data logger on that showed the car doing around 135 - 140 on 200ish bhp.
Not sure what you call winding up to speed, but i'd have thought if you can get there on a track thats fast enough.
Hi
I was using the speed trap on Aintree back straight, i.e. - it's the quickest place we go.. around 1/3 mile last corner (a fast one too) to
speed trap - good bench mark for a reasonable track day car.
So thought it would make a good example.
Somewhere a bit bigger would see more - as would holding the foot planted and let it wind up, as would different tyres - wind direction and teams
knowing what they're doing etc etc
- but either way what a Seven is about - it's the abilty to hurtle out of a corner up to a good speed quickly... and then stop before the next
bend..
so we're mot a million miles away either way..
Aintree on Saturday was:-
175bhp = 114
240 = 125
300+ = 135
Known cars (striker, Westfield, Dax - in that order) & recorded via MST timing.
[Edited on 9/9/08 by JimSpencer]
[Edited on 9/9/08 by JimSpencer]
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alistairolsen
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| posted on 10/9/08 at 07:04 AM |
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Paul (notts) cheers fella! sounds promising.
Turbo ben - mx5 based locost with a volvo T5 engine.
The FBI, it was an r reg corsa 1.2 complete with the LS badging and everything on a late dispak xe, F20, equal length shafts, 288mm brakes, decent
tyres and no extra weight. Cost me £600 to build with new bearrings, clutch, cambelt etc and made an entertaining commuter for a year. Did 15k in it
and sold it on for 1300 quid
quote:
Originally posted by TOO BADD
Assuming gear change at 6800.....
Ist 46
2nd 70
3rd 98
4th 112
5th 138
225 50 15 Toyo R888
My redline is set at 8000 so my figures are
54
83
115
132
163 !!!???
200bhp with unknown torque and will spin from start to 7500 ( 50 ish )in first without dropping the clutch and with a little more in second and
sometime a waggle in third.
All controllable.....
BGH close ratio and 3.92 LSD
[Edited on 9/9/08 by TOO BADD]
[Edited on 9/9/08 by TOO BADD]
Thank you! Kinda what i expected.
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NS Dev
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| posted on 10/9/08 at 12:02 PM |
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Ok,
Vauxhall XE 2.0 16v
Normally Aspirated
204 hp @6400 rpm
168 lbft torque (can''t remember what revs at)
Yokohama A048R tyres, medium compound, 195 x 60 R14
Std type 9 gearbox from 1.6 4 cyl sierra
3.62:1 LSD diff from sierra XR4x4
Car weight = 540kg
My limiter is 7500revs so not sure on speeds but ballpark 40mph 1st, 70mph 2nd, 90mph 3rd, never looked in 4th and 5th, certainly over 110 in both.
In terms of traction...
here's my shouty bit!!!
THERE MUST BE SOME REALLY CRAPPLIY SET UP CARS ON THIS FORUM!!!!
IN DRY CONDITIONS I have NOOO problems with wheelspin in ANY gear other than first. It will take full throttle in any gear, and just grips and goes,
with a touch of slither in first and second gears, but not what you would call "wheelspin", just wheelslip and a bit of squirm.
That's using 140 lb/inch rear springs, which i know are much softer than most on here run, and probably explains the increased grip.
Wheelspin is not a problem, and another 30hp would be sensibly useable.
0-60 is currently around 4 secs, (3.8 best)
1/4 mile on datron gear is 11.9 secs, but that wasn't on a dragstrip so may or may not be dead accurate.
[Edited on 10/9/08 by NS Dev]
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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alistairolsen
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| posted on 10/9/08 at 12:53 PM |
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cheers for taking the time to type that
sounds pretty promising!
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jeffw
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| posted on 10/9/08 at 05:28 PM |
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[Edited on 10/9/08 by jeffw]
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smart51
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| posted on 10/9/08 at 08:10 PM |
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quote:
Originally posted by JimSpencer
A really quick seven will do 140 ish, if it's got a superb engine in it, the other side of 300bhp good..
250 will see you nudge 130
200 around 120 ish
[Edited on 9/9/08 by JimSpencer]
No, this is way off. I've had 120 out of my car at 11,750 RPM (the red line in top). A dyno plot of my engine shows 152 BHP at 10,000 but only
100 BHP at the red line. 100 BHP is good for an indicated 120 MPH. I don't have a windscreen screen BTW.
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NS Dev
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| posted on 10/9/08 at 08:27 PM |
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The caterham C400 superlight racer that I spanner on pulls 144 mph at snetterton.
That has 220hp and 8000 rpm
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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MikeR
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| posted on 10/9/08 at 08:51 PM |
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damn, i thought it was 140 to 145 but thought i should err on the side of caution.
And i was 20bhp out  well i was tired.
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JimSpencer
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| posted on 10/9/08 at 09:12 PM |
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quote:
Originally posted by smart51
quote:
Originally posted by JimSpencer
A really quick seven will do 140 ish, if it's got a superb engine in it, the other side of 300bhp good..
250 will see you nudge 130
200 around 120 ish
[Edited on 9/9/08 by JimSpencer]
No, this is way off. I've had 120 out of my car at 11,750 RPM (the red line in top). A dyno plot of my engine shows 152 BHP at 10,000 but only
100 BHP at the red line. 100 BHP is good for an indicated 120 MPH. I don't have a windscreen screen BTW.
No its spot on - as its actual speeds by actual cars properly recorded.. see the posts above clarifying, what was just an example, > but folks
can't seem to accept an example they want specifics..
It was just used to a set context - which was 1/3rd mile after beachers bend at Aintree -
Which is all incidenal to the point anyway
But the removal of the screen makes a big difference as it would too for the Caterham - thing is we Have to run screens in sprints..
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JimSpencer
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| posted on 10/9/08 at 09:53 PM |
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quote:
Originally posted by NS Dev
IN DRY CONDITIONS I have NOOO problems with wheelspin in ANY gear other than first. It will take full throttle in any gear, and just grips and goes,
with a touch of slither in first and second gears, but not what you would call "wheelspin", just wheelslip and a bit of squirm.
That's using 140 lb/inch rear springs, which i know are much softer than most on here run, and probably explains the increased grip.
Wheelspin is not a problem, and another 30hp would be sensibly useable.
[Edited on 10/9/08 by NS Dev]
Was wondering about this - likewise for me too, can't understand how wheelspin is even an issue - and that's on 1A's, use B's
and other than a brisk start wouldn't see it at all.
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C10CoryM
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| posted on 10/9/08 at 10:56 PM |
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quote:
Originally posted by JimSpencer
can't understand how wheelspin is even an issue
Any idea how much torque you have?
Torque is what gets wheelspin. NSdevs 205hp is great, but the 165ft/lbs is really not that much (although not sure you need more for a light car).
Compare that to the torque of a V8 and you can see why tire spin is an issue.
My car is not complete yet but specs are:
Supercharged V6. 240bhp, 280ft/lbs torque 6000rpm redline.
3.08 LSD differential
23" tires (225/45r15) RA1 or R888
1st: 45mph
2nd: 70mph
3rd: 100mph
4th: 140mph
5th: 180mph
No idea when it will run out of power but I am willing to bet this is the first car I won't have the balls the run to top speed.  I am also
willing to bet I will have little to no traction below 40mph.
Cheers.
"Our watchword evermore shall be: The Maple Leaf Forever!"
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JimSpencer
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| posted on 11/9/08 at 08:20 AM |
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Hi
Certainly you're talking a lot of torque at 280lb ft, and I do think you might have hit your own nail on the head with the'do you need
more than the 165lb ft' - probably not..
But it would be rude not to have a go wouldn't it ?
You'll certainly need to get the right tyres on it, and make sure the supension is soft enough and nicely damped. Lots of folk (me included) ran
or run these cars way too hard.
I ended up running the car on 275F / 200R at one point and it was just plain useless. Had the error of my ways explained to me and the rates are now
roughly 2/3rds of that at the front and just over half rear - much better, much nicer to drive & quicker too.
(& MUCH quicker in the wet..)
Be interested to see how you find it when it's up and running.
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alistairolsen
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| posted on 11/9/08 at 09:17 AM |
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interesting what you say about stiffness, I was chatting to BobC about this the other day and he runs very soft springing and reckons the car handles
excellently. I suppose the ideal is getting the rear of the car to hunker down as you apply power, and squat properly onlaunch, but without applying
too much dynamic camber.
The point about torque is of course also true, and the tyres will have a certain torque limit they can sustain grip below given a certain surface.
obviously the higher the overall gearing, the less torque at the wheels however.....
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C10CoryM
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| posted on 12/9/08 at 02:31 AM |
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quote:
Originally posted by JimSpencer
But it would be rude not to have a go wouldn't it ?
Bingo!
The silly thing is that for $60 I can buy a smaller supercharger pulley and get about 275bhp and 300ft/lbs.
I have a live axle with an adjustable 3-link. IIRC I can dial in about 110% antisquat with it in its most agressive position. So I *should* be able
to get some traction. Not sure how well it will corner that way though.
Ive already learned my soft spring lesson on my last car. I turned my camaro into a road racer when I really needed a rally car. Meaning I was too
stiff, too low, and not enough wheel travel. I am waiting until I have final weight before ordering my shocks/springs.
Alistair, you may want to look into antisquat. You may squatting works different than it would seem. The IRS guys who drag race here tend to run
very stiff in the rear to keep the tires square to the ground.
Cheers.
"Our watchword evermore shall be: The Maple Leaf Forever!"
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bj928
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| posted on 24/10/08 at 04:35 PM |
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my viento is gear for 61 in first,
rev limit 6000
axle ratio = 2.73 (stock mustang gt 8.8)
1st = 61
2nd = 92
3rd = 126
4th = 163
5th = 221
6th = 327
6th @ 1000rpm = 54 mph
rear tyres are toyo 888, 295 30 18
running a viper v10 (gen 3) with stock 6 speed manual with remapped ecu, power estimates
550 hp +
575 Ib/ft +
car should weigh in at about 800kg
a good site for gear ratio calculations is http://www.f-body.org/gears/ , i use it all the time
[Edited on 24/10/08 by bj928]
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Antnicuk
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| posted on 29/10/08 at 02:08 AM |
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my stylus weighs about 650kg-700 kg, dynoed last week with 330 ftlbs and 320 bhp. 8k red line but turbo runs out of puff at 7 at the moment.
Stock Mazda RX7 gearbox which has quite a long first gear. Atlas diff with 3.09 f/d.
not sure of individual gear speeds but at 70mph i'm doing just under 2300 rpm in 5th. 3rd takes me over 100. Stock mazda diff is 4.1 and the
stock car does 160 mph with only 200 bhp and 200 ftlbs
Not sure about the comments on wheel spinning equals crap set up although i know they are linked. I spin the wheels all the way through 3rd with
ACB10's on the back and lots of squat, which leads me on to my next question....
I need to reduce the amount of travel my suspension has, i am already at 250 lbs rears and it still squats too much under power. I know the squat
helps me get traction but its hindering my tyre choice and ride height as i have to have it high with narrower tyres to stop the tyres rubbing the
arches.
what can i do to run less suspension travel other than put rock hard springs? i'm new to this suspension business and need to tame this
torque!
600 BHP per ton, Stylus Brought back from the dead! Turbo Rotary Powered!
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