Cosworth Pistons / Block
Part of the Furniture
Joined: Jun 2005
Posts: 156
Likes: 1
From: Australia
If Im not mistake the piston sits proud of the block 0.50mm on a stock engine. The important thing is that you should have at least 0.7mm between the piston and Cyl head meaning that the head gasket thickness (compressed) should be 1.2mm +.
Too many posts.. I need a life!!
Joined: Jul 2007
Posts: 581
Likes: 1
From: Kiev, Ukraine
1.piston sits above of the block at maximum 0.50mm on a stock engine.
2.YB0611 Gr.A head gasket thickness (compressed) 1.3mm.
Thanks.
Virgin
Joined: Nov 2009
Posts: 5
Likes: 0
From: Chelmsford
Standard Pinto Ford gasket is 1.63mm 0.065" compressed
Pistons on a standard Pinto are 0.5mm lower than the block deck on average but can range to 0.38mm
127mm rods 41.65 piston pin to piston top height = 168.65
Cosworth rods 128.5mm
40.5 pin to piston top = 168.5 I conclude the cosworth piston is 0.15mm lower down the bore,0.65 the lower compression of the Cosworth engine achieved by a bowl in the piston.
Standard gasket I think is 1.3mm 0.051"
0.75mm piston top to head face is safe to 7500rpm and will give good squish, 0.9 probably safer to 8000+.
If you are running a Turbo Cosworth you don't want the pistons protruding the block, if you are running a normally aspirated Cosworth you need pistons with a crown.
If you are building a Pinto with a 205 block, deck the block to get the pistons level or if you are going for it, 0.15mm protruding with a 1mm gasket (0.040").
Pistons on a standard Pinto are 0.5mm lower than the block deck on average but can range to 0.38mm
127mm rods 41.65 piston pin to piston top height = 168.65
Cosworth rods 128.5mm
40.5 pin to piston top = 168.5 I conclude the cosworth piston is 0.15mm lower down the bore,0.65 the lower compression of the Cosworth engine achieved by a bowl in the piston.
Standard gasket I think is 1.3mm 0.051"
0.75mm piston top to head face is safe to 7500rpm and will give good squish, 0.9 probably safer to 8000+.
If you are running a Turbo Cosworth you don't want the pistons protruding the block, if you are running a normally aspirated Cosworth you need pistons with a crown.
If you are building a Pinto with a 205 block, deck the block to get the pistons level or if you are going for it, 0.15mm protruding with a 1mm gasket (0.040").
Too many posts.. I need a life!!
Joined: Jul 2007
Posts: 581
Likes: 1
From: Kiev, Ukraine
thanks for reply.
I want to use this pistons for rebuild:
COSWORTH YB WISECO PISTONS 91.5 mm (BORE SIZE)
COMPRESSION HEIGHT 40.87mm
BOWL VOLUME 20.2cc :
COMPRESSION RATIO 8 : 1
I think dimension of this piston totally the same with 4wd mahle pistons. So, seems 40.87 pin to piston top height at std mahle piston...
But I am sure, piston is not lower down the bore, it above the block is around 0.5mm(not sure) at std YB engine. If I will use 1.3mm gasket(YB0611 Gr.A), seems 0.8mm piston top to head face... But not sure, need PF members help and confirmation. ))
Because I need to get CR 8 : 1. Will use 2wd head 138.4mm thickness.
I want to use this pistons for rebuild:
COSWORTH YB WISECO PISTONS 91.5 mm (BORE SIZE)
COMPRESSION HEIGHT 40.87mm
BOWL VOLUME 20.2cc :
COMPRESSION RATIO 8 : 1
I think dimension of this piston totally the same with 4wd mahle pistons. So, seems 40.87 pin to piston top height at std mahle piston...
But I am sure, piston is not lower down the bore, it above the block is around 0.5mm(not sure) at std YB engine. If I will use 1.3mm gasket(YB0611 Gr.A), seems 0.8mm piston top to head face... But not sure, need PF members help and confirmation. ))
Because I need to get CR 8 : 1. Will use 2wd head 138.4mm thickness.
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