Drying out the Duratec

[David]

I ordered a a dry sump from Caterham Cars last year but it didn't turn up until June and, as the job seemed quite daunting, I've been putting it off. But the time has come for it to be done, so I thought I'd share the experience with you

Does the Duratec need a dry sump? Well, general opinion is that the Raceline wet sump (the one the R400 comes fitted with) is good enough for road tyres. But I found the long brake in to the hairpin at KH did challenge the system - it was OK if you kept it clean, but get it wrong or spin and oil pressure drops.


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This shows the problem. It is the ECU download of 'lowest seen oil pressure'. When the car was new it followed the grey line but as the number of trackdays increased it recorded more low pressure events. Caterham have suggested a check/swap of big end bearing and I hope to give the engine a once over for wear/damage and also fix a noisy tappet.



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The bits . . . . .
It is an internal, two stage chain driven scavenge pump made by Titan to the Cosworth design and it uses OE pressure pump. Caterham now use the single pump Raceline unit that replaces the OE unit. It is probably more reliable (less parts) but being smaller, must have a smaller capacity.

I'll post progress/disasters/failures over the next few weeks.

David

[r055]

[David]

Progress report day 1

The car looked like this . . . .

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But now it's like this. . . . . .

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A day stripping out the ancillaries and the engine came out easily.

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It was then off with the gearbox and, in true Haynes tradition, I fabricated a tool to lock the flywheel

The pulley bolt was next. There's no key on the Duratec and it just uses two friction washers and a very tight bolt. And it was tight - all my weight on a 2 foot bar didn't shift it. Plan B, use the air gun, and off it came.

Couldn't resist a look inside so we quickly ran off the timing cover . . . . . .

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and then the sump . . . . . . .

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An interesting feature in this picture are the oil galleries that guide the oil returning from the head and keep it clear of the crank - part of the features that increase the efficiency of the engine. But they are not ’G’ friendly and can make the running oil capacity high.

More over the weekend

[BiggestNizzy]

I love these threads

[mwmackenzie]

Very clean lump! Keep the updates coming

[David]

Day 2

The loosened pulley bolt meant the camshafts are no longer locked to the crank. As there is no key, you can’t rotate the engine without risk of hitting the valves. I wanted to look at the big ends so there was no other option but to remove the cams.


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The reason for the noisy tappet became clear but I’ll leave that for a later post.



On to the big ends.


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This is a CPT (Caterham Power Train) branded engine built by Ford at their factory. On the bottom end I was expecting it to be essentially standard but I was pleased to see ARP bolts and I did expect after-market up-rated bearings.

Well, off with the caps! . . . . and out with the shells!



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. . . . . after a quick check of the part numbers they were standard OE ford.



Clearly the bearings were scored (a new one in the picture is for comparision), but they weren’t worn – as you can still see from the horizontal machine marks. I suppose this is typical of a momentary breakdown of the oil film, and what I was expecting. The crank was perfect.



The caps also told a story of getting very hot


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I’ve wiped most of it off in the photo, but there was burnt oil behind the shell which suggests they where approaching their temperature limits. The eagle eyed among you will have notice that the mating surfaces look like a broken surface – and you would be right! The Duratec rods are forged in one piece and then sheared. It is a clever system that makes them cheaper to make and also makes a stronger ‘keyed’ joint.



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And the joint when on the rod




More on the big ends to come . . . . .

[tut]

As we all know, we have some talented guys on here.

Even for us limited upgrade it numpties, its great to see posts like this.

tut

[Jacobite]

Intresting and informative as well as a good read
thanks for sharing
cheers Hamish

[David]

I am not an expert on bearings but the Duratec got me googling. What was interesting me was why the bearing seemed to be under size - the Ford bearings had a 2.5 mm gap on each side of the bearing. To make matters worse, the new replacement ACL bearings were even narrower. A check of the Ford spec revealed that both were in spec.



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When the shell was in place on the crank it began to make sense


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The gap makes a groove and as the diagram shows . . . . .




. . . the hydrodynamic pressure goes negative and sucks the oil back in to the bearing.

Anyway, more google trivia . . . . .

Modern bearings are good and, at high rpm, the biggest loads are inertial and not combustion. This means more BHP does not necessarily require bigger bearings and the load bearing capacity is mainly determine by how well the hydrodynamic pressure is maintained. And finally, the hydrodynamic pressure is not related oil pump pressure but is generated by the shear velocity of the surfaces, quantity and the viscosity of the oil.

. . . . . . sorry


ARP bolts next . . . .

[David]

ARP Rod bolts are beautifully engineered.


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Their catalogue is well worth a look if bolts are your thing. http://www.arp-bolts.com/Catalog/Catalog.html

With the new ACL heavy duty shells in place it was time to bolt the caps down. My engine came with ARP bolts fitted, but I decided to replace them new as I wanted to start a log for each bolt. ARP recommends you keep a record of the length and measure them at each rebuild. Any increase beyond .001 inches will indicate they have been over stressed.

The polished fillet under the head to reduce stress and failure.



A stretch gauge is the recommended method when tightening ARP bolts. I didn’t have one (and there is restricted access with the Duratec cradle anyway) so I used the second method – a torque wrench. You torque them up to 40 ftlbs and then loosen them off (three times) with the ARP assembly grease on the threads and under the head.

Being American, the heads are 7/16” bi-hex and I calibrated my torque wrench before I started.

The ‘snug torque and angle tightening method’ that Ford recommend should only be used for OE bolts as it is specific to the materials used and will change with higher spec bolts.

Big ends done, onto the sump . . .

[Shug]

Coulda sworn I'd posted this before, but maybe I didn't hit submit...

Great thread - love this level of detail and really good images. Must note to use a decent camera the next time I decide to document a hair-brained scheme of mine.

[David]

Coulda sworn I'd posted this before, but maybe I didn't hit submit...

Great thread - love this level of detail and really good images. Must note to use a decent camera the next time I decide to document a hair-brained scheme of mine.

Apologies - you probably have I'm just posting things as I do them.

[Shug]

Coulda sworn I'd posted this before, but maybe I didn't hit submit...

Great thread - love this level of detail and really good images. Must note to use a decent camera the next time I decide to document a hair-brained scheme of mine.

Apologies - you probably have I'm just posting things as I do them.

No, mate, I meant I thought I'd posted my comment before

[Ferg]

great stuff, loving the detail.

The engine looks massive in pics considering what it came out of!

[graeme]

The Duratec rods are forged in one piece and then sheared. It is a clever system that makes them cheaper to make and also makes a stronger ‘keyed’ joint.

Very

I learned a new thing today. Thank you!