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just had the head and block skimmed
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cheers
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Tony
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simpson_eh wrote:just recently had a problem with my engine blowing smoke on cold start
simpson_eh wrote:traced it to the 1.2 mm hks headgasket
simpson_eh wrote:Down to the block not being skimmed first time
simpson_eh wrote:Down to the block not being skimmed first time around my own fault teach me won't it.
Went for a cometic 1.65mm gasket to bring it down a lot.After having a chat with someone
Any thicker and you are going to have an amount of charge between the piston and head that is going to give bad detonation.![]()
badgerbob wrote:Any thicker and you are going to have an amount of charge between the piston and head that is going to give bad detonation.![]()
Is this due to the quench of the pistons bud? wiseco state a maximum piston head to clearance of 30 thou(0.75mm)
simpson_eh wrote:now i really am confused,
the head and block was skimmed so i was told this gasket would bring the comp back down with those pistons
not cause me more probs
i hadfull blown chat with someone who said that was the way to do it due to the pistons, he was told what turbo and all the work that had gone into it and what power i was after,
was originally running a 1.2mm gasket with these pistons running 340bhp at 1.4bar with 335ftibmapped by ryan so was that gasket wrong?
bobhatton wrote:simpson_eh wrote:now i really am confused,
the head and block was skimmed so i was told this gasket would bring the comp back down with those pistons
not cause me more probs
i hadfull blown chat with someone who said that was the way to do it due to the pistons, he was told what turbo and all the work that had gone into it and what power i was after,
was originally running a 1.2mm gasket with these pistons running 340bhp at 1.4bar with 335ftibmapped by ryan so was that gasket wrong?
The stock head gasket is 1.2mm but that leaves an amount of charge between the piston and head, that is why you read so much about blown head gaskets and broken ring lands with the 3sgte engines.
You should never fit a thicker head gasket to try and change compression ratio.Machine the pistons or get new ones to lower the compression.
bobhatton wrote:If you drop your compression from say 9:1 to 8:1 you will lose 3% in power, and for any given boost you will have a larger charge in the cylinder, as there is more room, so that will give more power.
One of the most important settings in the engine and comes about by the head and piston design is the ignition timing advance.
Toyota will have spent a large amount of time getting this right and it should never be changed by much when setting up an engine.Unfortunately
most ECU tuners do not understand this and just retard the advance to get an engine to run with whatever fuel and boost they are presented with.
By retarding the timing the engine will lose up to 30% of its power, but as stated above lowering the compression will only lose 3%.
If an engine is detonating then the fuel octane needs to be higher or the compression lowered, not the ignition timing retarded.
Look what Toyota did when it changed to Rev 3, the boost went up and the compression ratio went down, 8.8:1 down to 8.5:1, does that not tell everyone something?
Now with pistons, you will find them in the USA at 8.5:1 and 9.0:1 off the shelve, that is because most people over there will run race fuel, its very cheap, but over here you will find pistons at 8.0:1 or even lower for some engine and that is because for racing we have to use road fuel and not race fuel.
simpson_eh wrote:The rev 1 and 3 gaskets are interchangable anyway, nether have full coolant passeges and both are semi blocked.
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So i just carry one set of gaskets for the 3sgte period
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If your 9.0:1 and you were saying about the power you wanted to run i would lower the CR to keep some longetivty in the block.the pistons are very high already but the thickest i sell is a 1.65mm for
£100.00 CR is based on a 1.4mm gasket anyway from JE and wiseco pistons.
So 1.65mm depending on your skimming amount would estimate into the 8.6-8.8:1 so back down to similar to standard
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Let me know if that is anygood to you
this i s the reply i had
hence i purchased 1.65mm