Hey guys, whats the max i can mill a vvti head? have a customer's vvti engine that we had to mill the head down .020 on it and the machine shop scared my partner into thinking it will have piston to valve contact.

Anybody know?

 

You are probably going to want to use a TT headgasket now and in the future to account for that.
Don't forget to factor in the possibility of the head being decked before also, which is why I suggest just measuring it out which is easy.
The GE head is basically a GTE head with a .030 recess in the chambers, so technically you can remove all of the recess in the chamber, but that space should be re-accounted for with a TT headgasket generally speaking to keep the squish close to the same and not dangerously low. so the answer is you can prob take off whatever recess there is on the vvti head if there is any on there but you will have to spec out the vvti recess and piston deck height to make sure you have at least a .032 squish I believe. since the GE gasket is .01 compressed you will likely want to use a TT gasket when removing more than that amount from he head which is .05 compressed.

you can see in this picture how they shaved it so there is no recess in the chamber anymore.
this is a ge non vvti head shaved .025-.027


Had a BHG and was milled ~.027 and I can't really say for sure if it would or not hit the pistons with a GE gasket but it would still have too low of a squish either way (.01 ge gasket plus head recess .003 and deck height ~0 is all less than .015 for me, much less than min recommended .032) and also will raise the compression some and I didn't want to go over 10:1.
So I put the TT gasket on which is about 1 mm or .040 more than the stock ge gasket and that would give me just a little bit lower compression than stock and retaining a healthy squish. still haven't started it but I have turned it over manually and it seems fine.

on a vvti I am not sure what the stock recess is but the stock squish should be similar or a little lower. try and measure the recess and if the vvti HG is the same as a non vvti headgasket the headgasket adds in .010 compressed so just add that and vvti deck height (non vvti is basically 0) and you should be above .032 really.
If the customer is considering turbo or anything like that sell them on the TT gasket and there will def be no problems and safer for boost and reg pump gas. If they are going for max compression or boost with E85, then to know for sure with the GE gasket if it will hit you will have to slap the head on and check it by hand so you don't destroy the top end but it may interfere, at the least it will be very close but I wouldn't recommend it because of the squish.

this thread has some good info and also says what will hit the head, its not vvti but you can just measure the recess and deck height will prob be 0 like a non-vvti but I don't know for sure.
http://www.supraforums.com/forum/sho...ght=shave+head

"The GE combustion chamber is virtually a GTE chamber with a .030” recess machined at bore diameter. When you add the GE head gasket, .010” compressed, you get about .045” (1.14mm) piston to cylinder head clearance. With the GTE (no recess) the head gasket is .050”compressed and you get about .055” (1.4mm) piston to cylinder head clearance.
It is generally accepted that .032”(.8mm) is the minimum safe piston to cyl head clearance.
It is also generally accepted that when the piston to cyl head clearance exceeds .060”(1.5mm) the squish effect is severely diminished.
So, if you use a GE head gasket and a GTE head, .015”(.37mm) clearance, THE PISTON WILL HIT THE HEAD.
If you use a GTE head gasket and a GE head (NA/T) you end up with .085”(2.15mm) clearance and a less than effective squish.
The GE HG volume is 1.51cc & the GTE HG volume is 7.55cc a difference of 6.04cc"

on another note for na-t you can also conclude that a GE head with the recess removed and a GTe headgasket lowers the compression to mid to higher 9's while keeping a perfect squish.. around .060. Just matters what you care more about compression or squish many have the normal ge head with gte headgasket with .085 squish and don't have any issues.

 

Did the math on it and shaving 0.95mm off the 2jzge cylinder head and using GTE head gasket puts you at the same compression ratio as stock.
I'm building a 2jzge vvti for boost with E85. Going this route will allow me to maintain compression ratio but have a better head gasket. Also allows me to get GTE forged pistons and know they'll accurately reflect their advertised compression ratio somewhat and have proper squish.
Only thing I haven't been able to find is whether the GTE head is shorter by 1mm compared to the GE head in their factory uncut height, would be interesting to know.

 

Just a thought....might be possible to use GTE head gasket with 2jzge head keeping the combustion chamber recess and 3sgte pistons as they have a 1mm higher compression height and lower dish volume. They use the same size valves so valve reliefs would fit too.

 

I don't have experience with pistons that come above deck height, not sure what else that could lead to but doesn't seem worth the piston change.
I would spend the time and money on the proper arp bolts and hardware throughout the block, and alter the head after you choose the head gasket.

I am not sure how people are doing on big power and the ge headgasket specifically with e85.
Probably not as popular of an option but with e85 it could hold together just fine with the stock headgasket, really it is hard to say.
I am not sure if you would blow the ge headgasket first or bend a rod if you have a solid tune, but I don't have much experience with it but haven't heard people blowing them either.
The gte headgasket is well proven but you don't hear of as many setups on the stock ge hg which would really only have a chance on e85.

 

Doesn't seem to be an issue in most circles of engine building. I might just try it...

 

I still don't think it's worth it unless you are talking about a vvti block with weak rods and pistons, then it makes sense cause you have to go in there anyways.
But a ge non-vvti block already has the good pistons and rods, opening it up just makes more issues that can go wrong and you wont be adding any power holding potential there.
It would be neat though, so you would get some points for that. If you do it let us know how it goes, you might need to clean up the cylinder wall at the top cause there is usually a ridge from the stock piston.

 

Yeah this would be on a vvti block. I would build it with non vvti rods and 3sgte pistons and definitely clean up the cylinders.

 

Well on a vvti block that does sound interesting then, good luck keep us posted.