Duratec in detail

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David
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Re: Duratec in detail

Post by David » Tue Apr 19, 2016 11:18 pm

The weekend saw the first SLS of the year and the first time the car was used in anger. I was a little nervous about all the new bits and different tyres (new 1B list) for this year, but once I settled down it slowly started to come together. The warm-up and practice sessions went without any issues and, I must say, I quite enjoyed the qualifying.

Watch on YouTube

It was an extremely cold day, and without the supersoft compounds, the single lap final time was never going to be great, and a low 56 was about as good as I could have hoped for at my sort of skill level.

Watch on YouTube

That gave 3rd in class and 6th overall - with a field of 60 cars this year, that was about where I thought I'd be.

On the plus side, the speed trap put the car top of class

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Re: Duratec in detail

Post by BigD » Wed Apr 20, 2016 8:38 am

Good results. What tyres did you use this year and last year?

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Re: Duratec in detail

Post by David » Wed Apr 20, 2016 9:09 am

Last year I was using Kumho V70 in super soft compound and they started to work almost immediately, certainly within a lap - perfect for light Caterham. But they're nolonger a 1B tyre, so I'm using toyo R888 and they're not available in any soft compounds for my sizes. They're OK, just struggling to get any heat into them.
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Re: Duratec in detail

Post by tut » Wed Apr 20, 2016 9:52 am

More to come I am sure Dave.

Is the speed trap at the end of the Pit Straight? Looks as if your speed was 115, but Fiona and Adam were 118 and 120.

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Re: Duratec in detail

Post by David » Wed Apr 20, 2016 10:08 am

tut wrote:More to come I am sure Dave.

Is the speed trap at the end of the Pit Straight? Looks as if your speed was 115, but Fiona and Adam were 118 and 120.

tut
That's sector 3 which is back straight just before the baking zone - I do worse there due to aero drag limiting the Caterham . The table is in the order of the start line speed (next column), which is at the timing hut at the pit entrance. It's felt that best reflects power-to-weight.
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Re: Duratec in detail

Post by Dominic » Wed Apr 20, 2016 10:19 am

David wrote:
tut wrote:More to come I am sure Dave.

Is the speed trap at the end of the Pit Straight? Looks as if your speed was 115, but Fiona and Adam were 118 and 120.

tut
That's sector 3 which is back straight just before the baking zone - I do worse there due to aero drag limiting the Caterham . The table is in the order of the start line speed (next column), which is at the timing hut at the pit entrance. It's felt that best reflects power-to-weight.
I suspect that it will best represent P-T-W at that point as you have the climb from the hairpin, which is a slow corner. P-T-W will show up more from slow speeds, and uphill. ... IMHO
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Re: Duratec in detail

Post by Dominic » Wed Apr 20, 2016 10:19 am

Great vids BTW David! :thumbsup Car and driver going well. 8)
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Re: Duratec in detail

Post by KennyT » Thu Apr 21, 2016 10:31 pm

Very interesting thread David, particularly like the paddle shift mod, sounds like it is working well.

Looking at the videos I am interested by your very shallow line in to the hairpin, is there theory behind that?
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Re: Duratec in detail

Post by robin » Fri Apr 22, 2016 7:58 am

Hi David,

Just watched the lap - sounds awesome and fast too.

Your slide in the hairpin probably cost you a couple of mph up the start finish straight on your warm up lap - I wonder whether in your warm up lap you should go around the outside of the hairpin as you're not against the clock, you're just trying to get maximum exit speed!

I think where you're going to find the most improvement in lap times is in the braking zones - of course I have no idea sitting here in my kitchen, but it feels like there's scope for braking later/more aggressively! Easier said than done though, especially when you have just one lap to get it right :-)

Thanks for posting the laps - keep them coming!

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Re: Duratec in detail

Post by David » Fri Apr 22, 2016 9:56 am

KennyT wrote:Very interesting thread David, particularly like the paddle shift mod, sounds like it is working well.

Looking at the videos I am interested by your very shallow line in to the hairpin, is there theory behind that?
The tight line is something that I developed over the last year. Basically, the shorter distance is a bigger advantage than the faster speed of the wider line. I think it is peculiar to the Caterham as it's ability to turn quickly and accelerate is so good. The image below (hope it works) shows it in the delta - worth about 1/3 sec on the final lap and a little less if you go the whole straight (I'm green - blue & red are impreza's) .

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Last edited by David on Fri Apr 22, 2016 6:35 pm, edited 3 times in total.
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Re: Duratec in detail

Post by David » Fri Apr 22, 2016 10:04 am

robin wrote:Hi David,


Your slide in the hairpin probably cost you a couple of mph up the start finish straight on your warm up lap - I wonder whether in your warm up lap you should go around the outside of the hairpin as you're not against the clock, you're just trying to get maximum exit speed!

I think where you're going to find the most improvement in lap times is in the braking zones - of course I have no idea sitting here in my kitchen, but it feels like there's scope for braking later/more aggressively! Easier said than done though, especially when you have just one lap to get it right :-)

Robin
You're right of course about the braking, Robin - there's probably a winning time in there on that alone. Just my skill level needs a little work.

The hairpin was a compromise, not because you are wrong, just that it was very dirty and I went a little tighter to get more grip after some experimentation earlier in the warm-up.
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Re: Duratec in detail

Post by robin » Fri Apr 22, 2016 8:24 pm

And you heated the rear tyres :-)
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Re: Duratec in detail

Post by David » Tue Jul 19, 2016 8:43 am

Time for an update :)

The paddleshift has settled down quickly, but, I must admit it, it took me a little longer to feel totally comfortable with it. It is intuitive but I still look for the gear stick at times.

The only technical issue I have had was with the throttle blipper. In wet weather it filled up with water and corroded inside, got stiff, and it eventually broke the mount. I therefore moved it to the peddle box end of the cable, which in fairness to Geartronics, is where they recommended.

Image



A new throttle spring was also added to reduce a tendency to 'Kangaroo' as TB springs were not really up to the job. The roller barrels didn't do this but the pick-up with the SBD bodies is so good that even light pressure on the throttle can cause an un-commanded response.

Image



But my results at round 2 & of the SLS were somewhat mediocre. Lap times where not that bad and any gains with the paddle shift where offset by the loss of the sticky Kumhos this year - at least that was my excuse.

Blair McConachie's Caterham had clearly made some strides forward, despite the tyres, so a bit of soul searching was required. He was simply able to carry more speed. Now, a lot of that is just down to his level of skill, but I had a feeling there might be more to it, and the only real difference between the cars was the suspension.

So after round one of the SLS I took the decision to upgrade from the standard Bistiens. There are lots of shocks on offer - Nitron, and Quantum being popular. In the end I became interested in some development work Meteor Motorsport was doing with Penske to valve their 3 way 8760 series shock for the Caterham.

Image


Despite valiant efforts to get me a set made for SLS rounds 2 & 3, it wasn't to be. The first outing was on the June trackday, and they didn't disappoint.

Watch on YouTube

A PB on the first lap and a Vbox ideal lap in the low 54's is encouraging. But it was with the Kumhos, so maybe other factors there too. Just praying for some dry weather for the next round to find out how much of a difference they will make.



One other area that has become increasingly frustrating is fuel surge - particularly on the anticlockwise direction. I had a solution underway with ATL to make a bespoke tank for next season (delivery Autumn time) but while researching it I managed to snap the pipe of my standard Ford unit. So an interim solution was needed pretty quickly.

Image

A fairly standard approach with a Bosch 044 pump, 1 litre swirl pot and a lift pump. Still to test on track but hoping it will work without any problems.

Image

The lift pump was good fun to do, and I installed a dipstick for good measure while the tank was emptied.
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Re: Duratec in detail

Post by David » Wed Aug 17, 2016 1:35 pm

You can always go faster, but sometimes drawing a line is the sensible thing to do. I think I've reached that point, that's not to say I won't improve my PBs, but as far as the car is concerned, mission achieved.

Rory Butcher drove the car last month and did a low 53 second lap of Knockhill on his first hot lap. With less traffic, and a few more laps, I'm sure it would have been a low 52. Add some slicks (he was on road tyres) and it would be a 51's, or even in the 50's. That's up there with the best, certainly in the Caterham circles. And, with Rory's help, I lowered my own PB to a low 54 - by far the cheapest time I've found, and hopefully some more to come.

Enjoy Rory's lap and his appraisal of the car afterwards . . .

Watch on YouTube



So, for the time being, that brings to a close the project. There's still some work required to make the car as reliable and stable as possible for next year, and I'll maybe blog the Sadev rebuild, but basically I'm putting this thread to bed for a while.
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Re: Duratec in detail

Post by campbell » Wed Aug 17, 2016 2:02 pm

If you're bored, we've a Soapbox project to finish this week, David ;-)

Fabulous insight and hope you have enjoyed yourself. Such patience and attention to detail.

So. What's next...?
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