Technical Composition of valve guides?
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Technical Composition of valve guides?
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Thanks!
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Just out of curiosity really and to broaden my knowledge, what are inconel valves? Also why can't you have stainless with iron, seizing issues?
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Just ran a magnet over it. The valve seats and stem guides are magnetic. Don't ask what specific material!
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Graham, we had this argument on MSN, and i cba googling 
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Inconel is -- it says here -- a 625 steel originally developed for jet engines with a high nickel and chromium content and some molybdenum. Said to maintain its strength and durability at temperatures in excess of 1800F. Double the yeild strength of 321 stainless, maybe 50% more tensile. I'd only heard of it the other day as a valve material when I found it specced for a 800bhp Scooby by Cosworth motor. But as well as the cost, there may be other downsides.
Seizing, lubrication and wear issues with stainless and iron, so phosphor bronze is probably the way to go.
When I have a valve in my hand I'll go and visit the Alfa folk -- if I'm lucky there will be a sodium filled stainless valve from a 4 valve head that can be machined to fit.
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I've seen inconel in the exhaust heat shielding for Colin McRae's focus..
http://www.darchem.co.uk/products/insulation/automotive.stm
http://www.darchem.co.uk/products/insulation/automotive.stm
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The other place it's relatively common is in exhaust manifolds (the extreme upstream part) of turbo manifolds.
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Tell that to an Alfa engineer!
But no, it's for Imola Blue, terroriser of BMWs, humbler of Alfas, 120bhp turbo 1100 Cinq (looking for 140bhp+) :yum: .
You can get the existing valve guides sleeved with phosphor bronze, pretty cheap and extremely reliable.
Pete
Pete
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Having new guides machined up and popped in shouldn't be a problem. I'd do it myself, but the oven isn't big enough!
with respect to the alfa engineer he might be right, BUT i am speaking from exsperience and on my 1310 turbo project i use steel guides and road quality velves with no problems, the only backdraw of not using ss is that the valves need lapping a bit more often, i know people with 280 brake only using phos bronze guides and ss valves, oh ye another down fall of sodium filled valves are they are two peice so can come apart, most 214ss valves are 1 piece
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It's -- arguably -- overkill, but not by too much if at all. Even the 105 bhp Uno Turbo used sodium filled stainless exhaust valves (and IIRC, water injection). It's true that they fall apart, but the only example I'm aware of where that was commonplace was the Ferrari Dino which had bigger valves and revved appreciably higher. Many turbo folk believe that Scoobies -- which use "road" exhaust valves -- are woefully underspecced in that respect, and the Scoobie has much the same specific power output as Blue has now.
Of course, the idea is to get the heat out of the valves as quickly as possible to help keep detonation at bay.
Vauxhall Redtop XE has got sodium filled valves as well, they come with 150ish brake from the factory and I've seen em pushing nearly 250 without falling apart.
well i see that you are talking about cars that are made some 10 to 20 years ago, they are a bit out of date, technology has got past the problem some what, and putting water injection into a car only producing 105 brake is a bodge, much better ways of sorting out detenation problems then squirting water down an engine. for a start if its for a turbo motor just make the exhaust valve seat a bit wider will make no difference to performace and way out ways the cost of buying very exspansive valves, 20 qiud a pop i think they are and thats without guides. anyway its up to you just much better things to spend money on then some fancy thing you can talk to you mates about down the pub. if the japs didnt think sodium filled valves wernt needed then i would go with it there not stupid, better then most of us at r and d
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Well, lack of stupidity is not a racial characteristic
. When Cosworth developed the Scoobie mill, they specified Inconel............ and I still think the Integrale is a better car!Water injection can be a good solution. You need more power, you need more boost. Detonation rears its destructive little head. You've specced everything to the max and run out of space for intercoolers and charge coolers. Where you gonna go? You can retard the ignition (but will loose power), you can increase the fuelling (but will run the risk of bore wash and then, petrol is expensive), or you can run water injection. Where you gonna go?
