unfamilia 1,938 Posted January 20, 2014 I had stright lpg on my old datsun race car. ... it was pretty quick and cheap. 2min 23 fastest lap around phillip island out of a 1.6lt. Wondering how the iron heads react to straight lpg. Thinking of ditching petrol in it for straight lpg. My lpg guy reckons the later alloy heads were better on lpg (not the crappy first series alloy heads). Many iron heads on lpg round here? Share this post Link to post Share on other sites
Crazy2287 1,886 Posted January 20, 2014 Will need. To run upper cylinder lube unless u get stainless valve gear upgrade done. Share this post Link to post Share on other sites
gerg 10,871 Posted January 21, 2014 A bloke at work runs his XU1 on unleaded and runs flashlube in his petrol. No hardened valve seats and no dramas so far. I guess it depends on how much you're going to use it. Daily driver: use flashlube. Race car only: don't worry about it. If the valves wear out, time to do up the head anyway... At least you'll get some use out of it. Share this post Link to post Share on other sites
SJG351 6 Posted January 21, 2014 Alloys are supposed to dissipate heat better, so, you can increase the things that make power like compression,ignition,fuel etc.... How much more than an iron head i dont know? Share this post Link to post Share on other sites
Crazy2287 1,886 Posted January 21, 2014 There is that, but the crossflows suffer from a warped head a lot easier, Being the cast block and the alloy head expand a different rates. Cast is a lot less likely to warp in the event of a cooling issue. Though what we usually do to get around that is make sure the cooling system is A+ =P Share this post Link to post Share on other sites
gerg 10,871 Posted January 22, 2014 I reckon the best application for an iron head would be in a boat. Lots of hot/cold running and general punishment that alloys won't take. Share this post Link to post Share on other sites
bear351c 10,273 Posted January 22, 2014 A well seasoned head, say 150,000 kays of driving, will convert to LPG no probs. Its just if you overhaul the heads, you cut through the 'hard face' of the valve seat, exposing the soft castiron. Hence the old "running in" scenario we used to have with cast iron rings and such. Heat and pressure pounding on the valve seat, give it a hard face that is almost equivalent to the Stellite seats they install on Gas engines. Alloy heads already have Stellite valve seats installed, and Bronze valve guides, to handle ULP. You will need these IF you o/haul your iron heads. Flashlube is just there to add lube to the valve guides and seats. Your exhaust valves will glow red hot on LPG, around 850*C, and its bone dry. Share this post Link to post Share on other sites
