Let's talk exhaust valves (uprated)
Turbo Mini Forums

I've screwed something in my valve-train over the weekend - tons of smoke on a hard over-run and a short plume at start-up.

I've always said i'll get rid of the Sodium cooled ex. valves next time I have some head-work done. So I need to source some valves. I'm going to go for 30mm as I'm not wanting to push the exhaust insert too far.

So, one-piece valves it is - but how do I identify whether I'm getting pukka one-piece valves? I also desire to continue running iron valve guides - so what options have I got?

Cheers,
D

I was thinking about this a while ago, I know I have stainless valves, but not sure if there are one piece. But do you really need one piece valves on an engine not reving over 6.5k?

Edited by Jimster on 5th Jul, 2005.

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rimflow not 1 piece?

if you dont rev it why do you want one piece?

or is heat the big issue your worried about?

Alex

AlexF

i am with wolfie with this one
i would use the rimfow valves dave

i have heard bad reports on stainless one peice valves and the sodium valves on turbos but NEVER ! owt on the rimflows.

my oppinion buddy

I'd use Minispares one piece valves if the head would have bronze guides. As Dave states he will be using iron guides, I'd go with the rimflos as well.
Using one piece valves is not JUST because the heads don't fall off, but also weight reduction and flow increase. The original A+ valves are of very good quality, but they dont flow near as good as a decent set of one piece valves not matter how much back-cut they are.

Also, valves are dirt cheap.

Finally Dave.. I can understand the desire to run iron guides as they wear much better, but they are much worse in transferring heat right?? Mayve bronze alloy ones should be the choice still?

yep i would use the bronze guides dave as heat transfer (apparently) is better plus they last longer than iron guides on big lift cams and 1.5 rockers.

as for valves ive used rimflows for years with no probs but as you no ive only started into the turbo scene but im currently running rimflows at the moment with no probs.

always looking for them bigger bunches of bannanas

I always find that bronze guides wear better than iron, but the bronze ones kill valves. In my book, guides are cheaper than valves. This is why I use iron guides as much as I can...

If using bronze guides, the valves wear.
If using iron guides the guides wear.

Come to think of it, I've never used Rimflo ( or other chromed stemmed valves) and iron guides. Maybe this is the best wearing combination?????

could be right vegard ive never had wear probs using rimflows with bronze guides

always looking for them bigger bunches of bannanas

I've never understood the big claims behind the head dissipation between the stem and the guide material to be honest...

For a start, the stem is not in total contact with the guide (like if it were a press-fit) - so there is a reduction in the effectivness of moving heat from one to the other due to the air-gap.
Next - the thermal conductivity of the iron guide is anything up to 81 W/mK (assuming pure iron) but probably more like 70-75W/mK. The figures quoted for Bronze is 64W/mK, whilst the Manganese alloyed is anything in the 46-139W/mK range - so let's call it 70W/mK for the manganes bronze guide... Thats hardly a huge difference now is it? Especiually is you consider pure aluminium is 204W/mK and aluminum alloys anything in the 70-240W/mK range...

You also have such a (comparativly) small area to actually pass the heat through - so will you actually notice the difference? I doubt it. Going to a larger stem (as in the metro turbo exhaust valve) will help - slightly...
I reckon the greatest gains can be found in simply running a wider seat on the exhaust... You are getting a firm contact with the cylinder head - and actually over quite a large area if you do the math.

I need to make a descision soon! Rimflows are looking good at this time.

i think they say because you can run a tighter running tolerance for bronze guides thats why the dispence heat more efficianlty. but like every thing else dave what happens in pratice may not be what is supose to happens in theory.

but i will say from personal experiance is that when i was using a 276 cam with 1.5 roller tip rockers my iron guides were jacobed after 1000 miles, i would sit at the lights in stowmarket facing down hill and you couldnt see behind the car it was that bad.

soon as i swapped to bronze guides they lasted for about 3 years before replacing was necssary.

but like every thing TD try what you recon and see what happens thats what ive done.


look what the great mr vizard and other so called a series tuners that 1380 was crap for turboing well mr jukka has done with supurb sucsses, t3tone has done even better using a 276 which alot of people said it wouldnt work, and guess what a lot of top engine builders like avon bar, minispeed are now doing 1380 turbo engines.

the proof is always in the pudding and not just in the custard. lol

always looking for them bigger bunches of bannanas

Im using rimflow inlets and have kept the rimflow exhaust valves as i may fit them in the future. Be handy to regain some top end if i loose any when i fit a set of 1.3 rockers.

I say go for the rimflows dave, im sure jukka has used these for many years.

-MINI CLUBMAN 1380 TURBO-

G&S valves make valves for many of the mini people up to f1 , depending on how much you want to spend per valve , check their web site for tech material info manufacture and choices , or paul Ivey at specialised valves , who make rimflows ,
guides colisbro or menite (iron /graphite0 are the hi perf guide bronze and iron

Edited by stuart gurr - vmaxscart on 18th Jul, 2005.

Stuart to you know the website addy for G&S?

Team Racing

http://www.gsvalves.co.uk/

Metro turbo weekend driver,Mini turbo in the making again!

didn't look very had did I

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