Rod to piston oil spray

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vcg
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Rod to piston oil spray

Post by vcg » Thu May 01, 2008 12:20 am

Guy, will you GC/Cunningham rods work on 131 2.0Lt without oil jets fitted to the block? Looking at the pictures of your rods I see no oil spray holes towards the pistons. Integrale and Tipo blocks had oiljets and no oil holes in the rods, if I remember right. What happens with 131 that doesn't have oil jets? Thanks,
Vassilis
124 BS1, 124 BC1, 131 Racing, E Type 4.2 SII, XJ-S 3.6

Guy Croft
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Re: Rod to piston oil spray

Post by Guy Croft » Thu May 01, 2008 7:38 am

The GC rods have bleed slots in the rod cheek that provide oil for bore lubrication. This is a proven way of doing it and I copied it years ago from Abarth Gp4 037 rods. In addition GC race pistons have dual pin oiler drillings to take care of the pin/rod bush lubrication. In fact I have actually run the TC engine without any kind of bleed or spray bore lubrication, splash and vapour seemed to do the job well enough though that is a long way from saying I recommend the practice!

On engines with oil sprays one can reasonably assume that they have the additional function of controlled spray lubrication of the piston underside region for cooling and enhanced ring-wetting/bore lubrication on cold start to reduce start-up emissions of HC. Their ability to prevent 'knock' (detonation) at really dangerous levels (sufficient to hole pistons/damage heads/blow gaskets) is however, in my experience, zero, and moreover I have a reliable report from a race engine builder well-known to me that they reduce measurably reduce power output and thus I would not use them on a competition engine unless pressure-charged at boost of 15psi or higher. And I would be using them solely as a means of keeping the piston temperature down and preventing degradation of the alloy material per-se. All materials lose strength as temperature rises and so if you wanted to make a reasoned case for using them on an engine you really would have to have data-logged in-cylinder temperature records to demonstrate that need. F1 engines use them and at 300bhp per liter I figure you'd need them too.

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tmvolumex
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Cunningham rods

Post by tmvolumex » Sun Sep 28, 2014 7:47 pm

Guy,
How much clearancing in a Fiat / Lancia block do 2 liter Cunningham rods require?
Is the rod length the same as stock or are custom pistons required to use them?
Thanks,
Tom
GC_31

Guy Croft
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Re: Rod to piston oil spray

Post by Guy Croft » Mon Sep 29, 2014 11:36 am

Direct interchange Tom,

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Piotrek125p
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Re: Rod to piston oil spray

Post by Piotrek125p » Sat Jun 11, 2016 11:44 am

GC, could you tell me how depth should be a bleed hole in rod cheek ? It should be up to bearing edge or shallow/deeper ?

In my opinion it should up to edge or slightly deeper, but it is not supported by my experience, only conjectures.

I marked on this photo this holes.
Gc vs std piston & rod (3).JPG
GC Cunnigham rod.
Gc vs std piston & rod (3).JPG (234.03 KiB) Viewed 1236 times
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Re: Rod to piston oil spray

Post by Guy Croft » Sat Jun 11, 2016 6:32 pm

well, buy a set and you'll find out won't you Piotr?

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Re: Rod to piston oil spray

Post by Piotrek125p » Sat Jun 11, 2016 6:46 pm

Too much for my budget. Maybe in future.
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Re: Rod to piston oil spray

Post by Guy Croft » Sat Jun 11, 2016 6:53 pm

yes they all say that..

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Piotrek125p
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Re: Rod to piston oil spray

Post by Piotrek125p » Sun Jun 12, 2016 2:49 pm

This is a way that Ford make this groove on a rod cheek.
20160612_112145.jpg
20160612_112145.jpg (31.8 KiB) Viewed 1190 times
Today discover from a laboratory about engines on Lodz University of Technology :)
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Re: Rod to piston oil spray

Post by Guy Croft » Sun Jun 12, 2016 3:00 pm

probably been reading my forum...

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Piotrek125p
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Re: Rod to piston oil spray

Post by Piotrek125p » Sun Jun 12, 2016 3:24 pm

No doubt, we all should take a lessons from the best and we are doing it here, dear GC.
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