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Big Valves

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103 replies to this topic


  • Pitcrew
  • 4,308 posts
Joined: 21 Oct 2003
  • Location:Nr Truro, Cornwall
Some builders/sellers love big valves, because it makes sense in simple terms to increase sizes, increase flow and hence power. The work and parts involved is nicely chargeable, the business case is strong.
What really makes good engines it moderate, considered choices in all areas, pragmatic sizing of things like valves, bores etc and having it all matched and set up really well.

Repeating myself, but there's alot more background and testing to my point than you'll ever know... the standard valve sizes are more than adequate for all but the most extreme engines. You're more likely to make your build worse than better, by increasing the valve sizes.

Edited by Sandy, 21 September 2011 - 05:42 AM.


  • Pitcrew
  • 5,584 posts
Joined: 15 Nov 2003
  • Name:Peter Taylor
  • Location:Sydney, Australia

anyone know whats the best size valves to use for big valve 2.0 mi16/s16 head that i want to build and what car they from??

I know of an engine builder who bought a set of 36.4mm valves from my supplier and turned them down to 35.5mm as he didn't want the hassles of shrouding. Like Sandy said......................


  • Drivers
  • 371 posts
Joined: 20 Sep 2011
  • Location:Exeter
well i was looking today at work in our valve book and the 2.0 hdi runs 35.6 x 6.0 x 107.1 and stardard 34.6 x 7.0 x 106.4 inlets i was thinking would a bit easier to fit and got a hole hdi engine at work doing nothing, would need more valves and to change valve guides to 6.0mm

also got catcams inlet cam and vernier pulley at work, would port and polish the head same time while it was off to

what you reckon??

and would be running with superchip ECU, uprated fuel reg (4 bar) and gti6 inlet manifold which is already in my 205

cheers GUYS (:


  • Drivers
  • 161 posts
Joined: 22 Jun 2010
  • Name:Štef
  • Location:Rijeka, Croatia
Well hell, go for it! And do report back how it goes, will you? :)