2uzfe broken exhaust valves scenario

[thalj]

i have broken alot of 2uzfe valves in my twin turbo setup and cannot fix this problem. the longest valves which ever made it were the vvti valves which made it only for 7 month, and its always the exhaust valves.

im making about 700whp at 1.5 bar on dyno dynamics. with my twin turbo billet turbonetic setup and ttc performance camshaft [email protected], .356 lift and ttc single springs. the valves diameter is stock and the guides are stock, should i upgrade to oversize valves ?

im looking at paul drag car 4.7 liter hes reving 10k rpm with stock valves on the 1uzfe heads. what could be the solution for my problem ?

 

[99RedSC]

One possibility is that the stock valves have 44.5 degree face angle and the valve seat is 45 degrees. A ring contact won't conduct heat effectively, which is very important for keeping the exhaust valves cool. Try a 45 degree grind on the valves.

 

[XR8tt]

Check if 2JGTE valves fit ??
Valve issues could be in tune ??
Too rich and retarded is safe for engine..
But temps get very high on exhaust side..
Fatter tune at peak torque and drop off AFR's
slightly at higher rpm , maybe ??
Maybe better valve springs if std ??

 

[ash]

i have broken alot of 2uzfe valves in my twin turbo setup and cannot fix this problem. the longest valves which ever made it were the vvti valves which made it only for 7 month, and its always the exhaust valves.

im making about 700whp at 1.5 bar on dyno dynamics. with my twin turbo billet turbonetic setup and ttc performance camshaft [email protected], .356 lift and ttc single springs. the valves diameter is stock and the guides are stock, should i upgrade to oversize valves ?

im looking at paul drag car 4.7 liter hes reving 10k rpm with stock valves on the 1uzfe heads. what could be the solution for my problem ?

What do the valve collets look like?
The groove in the valve stem?
Installed pressure?
Take the head and valve to a head guy, he will tell you straight away by looking at parts...

 

[rms]

How much valve/ piston and Inlet/Exhaust valve clearance do you have at TDC overlap ???????

How much lift does the cam have at TDC overlap ?????

Too much heat melts valve heads - mechanical contact with pistons breaks valve stems.

 

[XR8tt]

Could be valve float too ?? So many variables ! It's not intitirley the power level .. Must do damage to rest of engine ! How steep are the cam rate lift ? Back to the drawing board, there's some mismatch going on!!