125 replies to this topic

[chris_uk]

This is about as much durability teating they did. "Testing at a given power level concluded when the engine could survive a series of 8-10 full-power dyno "Sprints" from peak torque through maximum power in 50 rpm steps, concluding with at least six seconds at full power, for a total of at least 20 very hard seconds. GM Racing successively verified that the Ecotec survived happily at 200, 225 and 250 hp over numerous dyno pulls" Whether thats good enough for track use im not sure. It also goes on tp say that at 4400rpm at 283bhp all 4 rods went whoch i believe was quite close to joes 276bhp? When his went.. The big question is.... Did they block off the pcv or not!

[Bargi]

As above, when you read that article you found it was about lasting X times at the drag strip. Having said that I think for even those that track their cars going 400bhp the liners would be fine looking at the results. There's other limiting factors bound to pop up before then.

[FLD]

I've been reading around liners recently to find out about this.  The problem seems to be cylinder pressures at high power lift the head slightly.  An MLS gasket will continue to seal but with the raised head the cylinders are unsupported at the top and so can move around.  This is what causes the failure in most cases.  There are a number of solutions.... Darton liners have a location ring around the top but machining the block for these removes a lot of strength from the block and there are examples of the block splitting into two.  Some strength is added back to the block by adding an inch of block fill to the bottom.  You can use a thicker liner which increases the rigidity of the cylinder slightly.  There's the ZZP deck plate which is used with the stock sleeves but this is costly and when GM tried a deck plate they were cracking blocks.  The Gen 3 block has cast in support at the top and is rated to 800 bhp by GM.  You can use the copper gasket / fire ring approach which ties cylinder to head.  I was going this route but I've found getting the rings machined in is freekin' expensive.  All of these options tackle the symptom.  Clamping the head down harder would obviously render the solutions unnecessary.  I have a set of ARP studs but I believe many people use 1/2 inch studs and re-tap the block.  I'm not sure if you can use a long bolt and go right through to the mains on this engine.  Having ranted on about the problem being the head lifting, the liners themselves are pretty poor.  In my searches around and about t'interweb I've come across liners cracking resulting in catastrophic failure which makes it difficult to define the problem.

[Exmantaa]

I've been reading around liners recently to find out about this.  The problem seems to be cylinder pressures at high power lift the head slightly.  An MLS gasket will continue to seal but with the raised head the cylinders are unsupported at the top and so can move around.  This is what causes the failure in most cases.  There are a number of solutions.... Darton liners have a location ring around the top but machining the block for these removes a lot of strength from the block and there are examples of the block splitting into two.  Some strength is added back to the block by adding an inch of block fill to the bottom.  You can use a thicker liner which increases the rigidity of the cylinder slightly.  There's the ZZP deck plate which is used with the stock sleeves but this is costly and when GM tried a deck plate they were cracking blocks.  The Gen 3 block has cast in support at the top and is rated to 800 bhp by GM.  You can use the copper gasket / fire ring approach which ties cylinder to head.  I was going this route but I've found getting the rings machined in is freekin' expensive.  All of these options tackle the symptom.  Clamping the head down harder would obviously render the solutions unnecessary.  I have a set of ARP studs but I believe many people use 1/2 inch studs and re-tap the block.  I'm not sure if you can use a long bolt and go right through to the mains on this engine.  Having ranted on about the problem being the head lifting, the liners themselves are pretty poor.  In my searches around and about t'interweb I've come across liners cracking resulting in catastrophic failure which makes it difficult to define the problem.

 

Not many (of US roadcars) that I know of have re-tapped the engine for bigger size ARP headstuds. I think you will be more than fine just using the stock size. Or are you planning a secret >450HP monster turbo engine in your VX?

 

(I'm still on the stock stretch headbolts and no issues yet with the Harrop 2.0)

[FLD]

Nah, no mad plans.  I had planned on using the copper gasket to make the most of the location effect of the fire rings but I was quoted 600 plus vat to machine the hed / block for them.  I guess I'll be using an MLS one if I can't figure it out.  I could machine them in myself but I really don't fancy that job.

[Exmantaa]

I really wouldn't bother for a modest ~350BHP supercharged engine. Use the stock MLS gasket and if you fancy some ARP headbolts. Done.