at what point is head work needed

[mellonman]

just wondering when head work is needed, i hear alot of people now going upto over 600bhp with no head work and stock block, is this the norm or at what time head and internal work needed to be done?

and at what bar/boost early years boost was limited at 1.3 but now people are going 1.6 which is a big difference in the real world

[Chris Wilson]

Porting and fitting bigger valves is probably only worthwhile for a serious race type engine. It should only be entrusted to a chap that knows exactly what needs doing, and has the right gear. I remember helping Tony Licence out when he had the head done by cowboys and the valves didn't seat... A good porting job will be expensive. Fitting bigger valves similarly so. Personally I'd be tempted to fit bigger exhaust valves and leave the inlets stock, but I am NOT recommending you try this as it may not work with "normal" profile cams. What you must do is have all the guides checked for wear and fit new valve springs, as on most 2JZ engines these will now be tired. I see lots of expensive external mods added to an engine that's one step from the knacker's yard, and needs a full rebuild before adding boost or revs.

 

Adding boost effectively removes valve spring seat closing pressure. Think about it...

[mellonman]

Thanks chris

As always you make total sence.

[Chris Wilson]

Thanks chris

As always you make total sence.

 

Perhaps you could tell the wife....?