83.00mm forged piston ring gap size? *Help*

[Gray]

Hi all,

I am in the process of building an engine for my r26... The machine shop has bored and honed the block, but have asked me to double check the ring gap size as they seem too big in their opinion.

I am using Supertech low compression pistons: http://www.engine-dynamics.com/Products/Product.asp?id=104811

Going by the calculations given on the paper work the gap works out to:

Top Ring: 0.018" / 0.4565mm

Second Ring: 0.021" / 0.5395

For the oil control rings it states 'They should have a minimum gap between 0.35 - 1.00mm' (this seems quite a large tolerance to work with?!)

Any help much appreciated,

Kieran

 

[Coops Mk1]

afaik the oil control will have a larger tolerance as all it does is scrape the bore and as it rotates with each stroke it clears 99% of the area so no worries. the compression rings have a set gap as they seal the bore for the power stroke so no wiggle room

 

[Gray]

afaik the oil control will have a larger tolerance as all it does is scrape the bore and as it rotates with each stroke it clears 99% of the area so no worries. the compression rings have a set gap as they seal the bore for the power stroke so no wiggle room

I need numbers man!

 

[Coops Mk1]

my point was those numbers provided seem reasonable to me

 

[Gray]

I spoke to Engine Dynamics (the pistons supplier) today and they have recommended the below spec:

Top ring: 0.35mm – 0.40mm

Second ring: 0.42mm – 0.45mm

Oil ring: minimum gap of 0.35mm

A fair bit smaller than what the piston paperwork recommends to work with, but they are meant to be guidelines only

 

[Fred@BTM]

even that sounds wrong, call me

Engine Dynamics buy them from the same place i do

 

[Gray]

even that sounds wrong, call me

Engine Dynamics buy them from the same place i do

Doh, only just seen this!

Too late, they've been gapped now too small, too big?

 

[DTM Cars Ltd]

ED spec is what i near enough do and sound fine.

Andy