Crazy Eddie
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 posted on 6/2/08 at 01:56 PM |
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New 3.38 Diff can't decide if better or not??
Well I changed my 3.62 LSD in my 893 blade to a 3.38 LSD.
On the road it is much better when cruising naturally because of lower revs.
However at Oulton I think I actually went slower round the track.
Is this due to feel because I'm leaving it longer between gear changes or do you think it's because I need to drop an extra gear than
before to keep the car on the boil (so to speak)?
Also whilst I'm asking about track driving what rev renge to you lads try to keep the engines at. I noticed, when watching video back) at a
couple of corners the revs have dropped to 6000rpm and then took longer to accelerate.
Should I be aiming for 7000rpm minimum?
Cheers
Eddie 
www.EdwardsSchoolOfMotoring.co.uk
For online shopping that earns you money  : Ei42.com
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TimC
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| posted on 6/2/08 at 02:25 PM |
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I always thought the 3.62 was quite suited to the Blade.
At Oulton, pre-swap were you ever on the limiter in 6th? If not, your old diff will be quicker surely.
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smart51
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| posted on 6/2/08 at 02:36 PM |
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overall, your car is no quicker accelerating with the new diff or the old. In each gear, you'll accelerate faster with the old diff but you can
stay in each gear for longer with the new. They average out so on a timed 1/4 mile. I doubt it would make much difference.
6000 RPM is probably a bit low and you could probably take a lower gear and still have room to accelerate out of the corners.
The new diff will give you more top speed. Crucially, it will move the peak power of your engine to a higher road speed in top gear.
My R1 BEC with a 3.62 is very fast upto 100 but peak power in 6th is at 103 MPH. Once over this speed, both power and acceleration drop right off.
A 3.38 diff would move this up to 110 MPH. It would do 2 things for me. 1) stop the cars that I'd just overtaken, taking over me. 2) up my
top speed up the hill on Park Straight at Cadwell from about 108 to maybe 115 because I'd be closer to peak power.
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worX
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| posted on 6/2/08 at 03:01 PM |
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As said above, it depends on whether you've hit the limiter in 6th at Oulton!
Steve
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Andy B
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| posted on 6/2/08 at 06:53 PM |
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blade diff ratios
might be able to shed some more light on this one.
Having built John Cutmores Westy for the RGB series with 3.62 diff we initially thought it was spot on. However as he got more and more confidence in
the car and upped the corner speed he started to run out of gears too early. A change to the 3.38 saw quicker lap times and with the IRS RGB cars 3.38
is the norm, however on shorter circuits like Lydden there remains the argument for changing diff to 3.62 - if I could be bothered (which I cant!!)
The 3.54 used in the live axle seems to be a good compromise again but once again if corner speed is good this can rev out to early at the longer
circuits - back straight at Snett for instance.
Racing can be very confusing - initally we found ourselves going softer and softer on springs to give the driver confidence then he goes and screws
everything up by going faster and needing to go harder on spring. 3 years on and we are now back where we started on harder springs only difference
now is the car and driver are much faster and winning races
It does my head in sometimes!
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Crazy Eddie
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| posted on 6/2/08 at 07:44 PM |
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Cheers for help guys.
So basically I need to drive the car faster and stop being such a girl!
Back at Oulton on 29th Feb so I'll try knocking it down an extra gear from the norm and see how it goes
PS Hi Andy,
Reverse is spot on mate cheers again for all your help and work getting it installed.
Already saving up for the airbox Just need to buy the wife something first so she overlooks it 
www.EdwardsSchoolOfMotoring.co.uk
For online shopping that earns you money : Ei42.com
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