suprafan72 Posted July 5, 2007 Share Posted July 5, 2007 Can anyway enlighten me what the benefits of uprated exhaust (standard size) and inlet valves are over OEM stock ones? Quote Link to comment Share on other sites More sharing options...
JohnA Posted July 5, 2007 Share Posted July 5, 2007 'uprated' in what way? Before focusing on hazy and immeasurable 'benefits' here are some practical questions: Will they expand and behave in exactly the same way as the stock ones? Will they need lapping to seat properly and then re-shim? Will they weigh less or more? (inertia can be a problem at high revs) Will you find out the hard way the answer to any such issue? Questions, questions... Quote Link to comment Share on other sites More sharing options...
suprafan72 Posted July 5, 2007 Author Share Posted July 5, 2007 'uprated' in what way? Before focusing on hazy and immeasurable 'benefits' here are some practical questions: Will they expand and behave in exactly the same way as the stock ones? Will they need lapping to seat properly and then re-shim? Will they weigh less or more? (inertia can be a problem at high revs) Will you find out the hard way the answer to any such issue? Questions, questions... Jesus you know how to make my head hurt in the morning don't you:d Surely if the exhaust and inlet valves are stock size a re-shim wouldn't need to happend? I would of thought less?... Yes agreed intertia may be an issue.. but i'd of thoght a stock rpm limit would be more adequate? Quote Link to comment Share on other sites More sharing options...
JohnA Posted July 5, 2007 Share Posted July 5, 2007 Jesus you know how to make my head hurt in the morning don't you:d I gave you the long version. Would you prefer a yes/no? Surely if the exhaust and inlet valves are stock size a re-shim wouldn't need to happend? we're talking fractions of a mm here. Would you risk burnt valves? I would of thought less?... Yes agreed intertia may be an issue.. but i'd of thoght a stock rpm limit would be more adequate? adequate for what? The whole assembly has been designed along specific parameters, with assumptions of a specific kind of use. Changing one link of the chain creates a different balance. Not necessarily what you want. For example, for whatever new operating needs you have, will the stock valve springs play ball? ...and if you fit stronger, 'uprated' springs, what will the lifespan of the camlobes be afterwards? Think of this: You've got a ladder at the back of the garden. You cut off and swap a couple of steps with 'uprated' ones. Is the whole ladder now uprated? Without looking closer at the new design, it could be that the ladder overall is now more prone to fall apart, or topple over (or whatever). You get the picture. Quote Link to comment Share on other sites More sharing options...
gaz1 Posted July 5, 2007 Share Posted July 5, 2007 I gave you the long version. Would you prefer a yes/no? we're talking fractions of a mm here. Would you risk burnt valves? adequate for what? The whole assembly has been designed along specific parameters, with assumptions of a specific kind of use. Changing one link of the chain creates a different balance. Not necessarily what you want. For example, for whatever new operating needs you have, will the stock valve springs play ball? ...and if you fit stronger, 'uprated' springs, what will the lifespan of the camlobes be afterwards? Think of this: You've got a ladder at the back of the garden. You cut off and swap a couple of steps with 'uprated' ones. Is the whole ladder now uprated? Without looking closer at the new design, it could be that the ladder overall is now more prone to fall apart, or topple over (or whatever). You get the picture. you in one of them moods john:D ladders bejesus:D Quote Link to comment Share on other sites More sharing options...
Ian C Posted July 5, 2007 Share Posted July 5, 2007 If you change the valves you'll have to reshim them, the whole point of shimming is to take up tolerances in the valvetrain. Benefits of "uprated" stock sized valves running a stock rev limit? I'll go out on a limb and say "None" unless you are the person selling said "uprated" valves, in which case it's "£". How are they "uprated" then? -Ian Quote Link to comment Share on other sites More sharing options...
JohnA Posted July 5, 2007 Share Posted July 5, 2007 you in one of them moods john:D ladders bejesus:D OK, then, I'll give you the short'n'sweet version, that of the aftermarket manufacturer who will charge you a fortune for their titanium/unobtainium wonders: Better driveability and up to 10% more torque Happy now? Quote Link to comment Share on other sites More sharing options...
suprafan72 Posted July 5, 2007 Author Share Posted July 5, 2007 I wish i never asked LOL Quote Link to comment Share on other sites More sharing options...
Ian C Posted July 5, 2007 Share Posted July 5, 2007 I think you've got your answer then -Ian Quote Link to comment Share on other sites More sharing options...
JohnA Posted July 5, 2007 Share Posted July 5, 2007 I wish i never aksed LOL Hopefully you are now a tad wiser. Questioning terms like :'uprated' Demanding clarifications and tangible, measurable benefits under your operating conditions. Otherwise they just uprate someone else's bank account:d This stands for all sorts of 'mods', not just valves. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 5, 2007 Share Posted July 5, 2007 Stock inlets are fine, if you can find someone trustworthy that offers exhausts in a better material than the stock ones, they may be worth considering. If you are chasing every last BHP buying none stock valves with better head shapes and thinner stems will add airflow, but may not be as reliable, long term. Same with running multi angle narrow seats, you may get a bit more air flow, but the seats will wear faster, meaning more frequent strip downs and re shimming, blah blah. You could fit Colsibro bronze guides and get some better heat transfer and wear properties, again, it's really race engine stuff. Getting custom valves made is possible, but VERY expensive. Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 5, 2007 Share Posted July 5, 2007 Are the stock exhaust valves sodium filled or not? If everything else is stock, or near to stock I can't see the point in upgrading the valves. In fact I can't see the point in trying to upgrade them unless you are going to run very hot or very fast (RPM wise). Even then, upping the rev limit is probably more cheaply done through stiffer valve springs (at the expense of some cam / tappet wear). I'm not having a pop but TBH I can't see the point of uprating anything unless you know how they are uprated. I'd like to see that word banned from this forum. Quote Link to comment Share on other sites More sharing options...
JohnA Posted July 5, 2007 Share Posted July 5, 2007 ... I'd like to see that word banned from this forum. He he, maybe Branners can take a note for the next forum upgrade:d Quote Link to comment Share on other sites More sharing options...
suprafan72 Posted July 5, 2007 Author Share Posted July 5, 2007 HAhahahahahha what are you guys like!!!! I will ommit "uprated" from my vocab. Quote Link to comment Share on other sites More sharing options...
dandan Posted July 5, 2007 Share Posted July 5, 2007 While we're on the subject of valves does anyone know: What are the stock inlets and exhausts made of? As Digsy said - are the exhausts sodium filled? Are the stems plated? What are the stock guides made of? Does anyone know what the tuners like PHR supply in their "built" heads/long blocks? (Personally I normally run one piece stainless steel valves in Beryllium Copper guides) Quote Link to comment Share on other sites More sharing options...
dandan Posted July 6, 2007 Share Posted July 6, 2007 Anybody? Quote Link to comment Share on other sites More sharing options...
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