Duratec in detail

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David
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Re: Duratec in detail

Post by David » Thu Jun 29, 2017 8:38 pm

A four cylinder inline engine is always going to be a compromise when it comes to balance. But it is worth getting the static balance correct as an error from one end of the crank to the other will 'rock', or bend, the crank and that's bad for the main bearings and longevity of the engine.

With this engine (and it's extremely long stroke) I decided it was worth going to the extra effort of balancing it professionally.

So it was off to Midland Balancing Ltd to spend an interesting few hours in their workshop. It is in part of a working farm and not the place you'd expect find McLaren cranks by the dozen, nor the precision grinding of racing cranks for BTCC cars, but their reputation for quality work didn't seem to be affected by farming environment.


Image


Spinning up my crank on their balance rig was straightforward with no bob weights required on an inline 4 cylinder. It proved to be good out the box at 5 grams at 1 cm (less than 0.5 grams at the web), that was good figure! Even more satisfying was that it appeared to be the key-way that was causing the unbalance, and when we fitted the sprocket and pulley it got better. After some light grinding we got it down to 2-3 grams at 1 cm (about as low as we could measure reliably). Then the flywheel was fitted and a small adjustment made to bring it back to same balance.



Following that, the pistons rods, and pins where weighed and mixed and matched to find the best balance. In the end we achieved 0.1 gram between the set without removing material - a truly remarkable figure and praise should go to Omega and Robson for there ability to provide such good matching sets.


Image


Finally we used a rig with precision bearings to measure each end of the rods. All were within 0.5 grams and we felt that it was better to maintain the peened finish than adjust.

This is probably the best balanced set of parts I have ever achieved. Whether that is luck, or just everyone upping their game for this 'early' spec engine, I don't know.
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BigD
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Re: Duratec in detail

Post by BigD » Thu Jun 29, 2017 8:57 pm

Impressive amount of detail there.

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David
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Re: Duratec in detail

Post by David » Wed Aug 23, 2017 1:53 pm

With all the parts available, and balancing done, the assembly went ahead without problems. It's all covered in earlier posts, so I won't do it again. The engine started first time.

Watch on YouTube

So it was off to Northampton Motorsport for Troy to do his magic. Running it was totally uneventful and the mapping straight forward - basically more fuel needed everywhere.

Watch on YouTube

Watch on YouTube

Image|https://thumbsnap.com/azyfQHIE[/img]

The power runs were keep to conservative RPM levels and raised in stages to 7,500 RPM where we will leave it for the time being. We will go higher, but I want to get some track experience with it before risking the engine for the sake of a few more RPM. Despite the runs seeming a bit subdued (compared to the frantic 2L engine), it gave a healthy 294 BHP which was a shade above what I expected for this RPM. Torque was very good too, reaching over 90% of the theoretical maximum. So all working well and potential for getting over the 300 BHP.

The graphs are comparisons to the 2L engine.

Image|https://thumbsnap.com/WL6qJQel[/img]

Image|https://thumbsnap.com/qNhYjsca[/img]

So I'm pleased with the result but it's still work in progress with perhaps another session early next year to push things a little further.
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Re: Duratec in detail

Post by Sanjøy » Thu Aug 24, 2017 10:26 am

8)

Might want to make your laptop stand out of nomex.
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Re: Duratec in detail

Post by Dominic » Thu Aug 24, 2017 10:37 am

Great stuff David. Fascinating posts and updates and a real education... for me at least! 8)
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Re: Duratec in detail

Post by mckeann » Thu Aug 24, 2017 11:16 am

awesome, would love a shot of that. i've driven a 250bhp Honda type R caterham, and a 340 bhp V8 RST caterham aswell. The 340 bhp one had so much grunt that the revs became almost irrelevant as you just didnt have the traction to use it all.

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Re: Duratec in detail

Post by Sanjøy » Thu Aug 24, 2017 11:20 am

mckeann wrote:awesome, would love a shot of that. i've broken a 250bhp Honda type R caterham, and a 340 bhp V8 RST caterham aswell. The 340 bhp one had so much grunt that the revs became almost irrelevant as you just didnt have the traction to use it all.

Fixed that for you.
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Re: Duratec in detail

Post by David » Mon Aug 28, 2017 6:47 am

Well, the engine held together for the SLS . . .

Anti-clockwise

Watch on YouTube


Clockwise

Watch on YouTube

Much easier to drive it too.

So that concludes the story for the time being. . . who mentioned superchargers . . .
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Re: Duratec in detail

Post by Ferg » Tue Aug 29, 2017 1:55 pm

Congratulations on the PB. Must be what its all about after all. :)

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Re: Duratec in detail

Post by David » Mon Oct 16, 2017 9:21 pm

I've taken some time to put together a website to support the Duratec in Detail's Facebook page. For those of you not familiar with the page, it blogs my Duratec engine builds. The site is not intended to replace the Facebook page, but I hope it will provide an index-able resource for those interested in the Duratec.

http://duratecindetail.com/
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Re: Duratec in detail

Post by David » Mon Apr 29, 2019 9:31 pm

It is over a year since I last posted. That's not because there's been nothing happening, far from it, it was more that the engineering work on the engine came to a halt. It has proved to be reliable and the car went on to win the Super Lap Scotland Pro Class in 2018.

Image

. . . and times came down to 52 second laps.

Watch on YouTube

But the big development that year shifted to putting some 'aero' on the car. Firstly with a rear wing and a Caterham Lavante front wing. Later I made my own front wing, and with help from Simon McBeath, we developed the aero further. The success in SLS, and a similar success for another car Simon helped with in the Time Attack, resulted in the idea of an article in the Racecar Engineering magazine which was published over three months earlier this year (March April & May). https://www.facebook.com/RacecarEngineering/ The basis for the article was a session at the full size wind tunnel at MIRA.

Image


That was really good fun and you can read a PDF version of my story at

https://docs.google.com/document/d/1a7w ... sp=sharing

Image
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Re: Duratec in detail

Post by Mikie711 » Mon Apr 29, 2019 10:59 pm

My, my you have been a busy boy. All getting a bit serious now isn't it?
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Re: Duratec in detail

Post by graeme » Tue Apr 30, 2019 8:24 am

:shock: 8)

Outstanding!
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alicrozier
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Re: Duratec in detail

Post by alicrozier » Tue Apr 30, 2019 8:26 am

:thumbsup :D
Great read that David!
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Re: Duratec in detail

Post by IanD » Tue Apr 30, 2019 8:36 am

Really interesting to read the stuff about aero and what you can do within your means.
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