I want to bore over the block that im using for the alltrac engine. I was thinking .20 over. But I was thinking why not go all the way and do .40 over? Would that make the cylinder walls to thin for turbo. And if I were to do this would I still be able to but in an aftermarket head gasket like the HKS steel head gasket? But with a turbo your don't want to over bore do you?
where did this post come from? lol. there is no difference in head gaskets for boring over. but i would stay mild with a 20 over and some aries pistons. mabye weisco or cp but not je.
I dont know alot about about turbo's but I wouldn't unless its a NA car. But don't take my word lol, as mentioned I dont know alot (basically anything about turbo's) The reason I wouldnt is I think it would put too much stress on the engine, where as in NA the stress is gradual not a BAM like turbo.
why not just bore the head and leave the block alone, this way you have more torque on the streets and not have to worry about over powering.
a good 20 over bore will not hurt a damn thing but allow a little more air to be moved which is good. i don't think the 20 over pistons are corrected for compression so that means it'll drop the compression a little and that's good for turbos. means more boost safely. i would not go 40 over as this will make the walls a little thin IMO. for those NA guys. turbos are not a simple mathmatical power adder. the more NA power you make the more turbo power you make. now there are a ton of things to consider and calculate in but the one thing to remember is that getting all the mechanical power out possible means that you'll be pushing a lot more power at the other end with the same boost. basic equation: (boost pressure in BAR +1.0)base HP = crank output example, my car intake and exhaust, porting work yadda yadda base power about 175 boost equals 1 bar (14.7 psi) plug these numbers in you get (1+1)175 = 350 crank + nitrous now take the same equation with base HP of 150 (1+1)150 = 300 crank big difference with no boost change now i used 1 BAR for simplicity in math. it's not as simple as doubling the number. take stock alltrac 8 psi. 8/14.7= 0.544 (0.544+1)150 = 231.63 crank so the base number is off a little so lets reverse the equation to a known good number of 200 USDM 1st gen 3sgte (0.544+1)x = 200 x = 130 thus meaning on a stock alltrac motor the ratio of 1psi to HP yeilds a gain of 8.75 hp. so the base alltrac at a boost of 1 bar in this method would yeild a crank hp number of 14.7*8.75 = 128.62 + 130 = 258.62 crank which would yeild around 200 AWHP. if we use the other equation with the know good base number and back to 1 bar of boost we get 260hp. pretty damn close.
