Titanium exhaust valves

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by Big Steve, Nov 6, 2018.

  1. Big Steve

    Big Steve Member

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    Blown BBC 25-30LBS of boost with XR1 blower in TD. Currently have Ti intakes and SS exhaust valves. Would it be worth the money to make the switch to TI exh valves? What are the positives and any negatives of making the change?

    Car has run in the 6.0x at almost 230 so I am going to have to slow it down to make the new 6.10 index but want to run it soft down low and run 230 plus up top and was wondering if a lighter valve would help
     
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  2. BEDNAR1320

    BEDNAR1320 Member

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    *crickets*
     
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  3. Neil Morley

    Neil Morley Member

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    What kind of rpm are you turning this combination to?
     
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  4. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    Titanium valves are going to save you money in the long run. The stainless valves are obviously quite a bit heavier so that puts a strain on all the parts trying to control that valve. It's going to be a lot harder on the seat as well.

    I'm not a BBC guy, but I would think the added strain would be hard on the rocker assembly. I know that can be a weak spot on some combos trying to pull the threads out of the head.

    There's a lot of things you can get away with but at that performance level, the odds will eventually catch up with you.
     
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  5. Big Steve

    Big Steve Member

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    Shifting around 8300 thru the traps at about 8000.

    Will,
    As far as pulling the studs out on a BBC, I dont think its as much a weight thing as it is opening the exhaust valve against the boost.

    The weight savings is an added benefit but I was wondering if the Ti valve will handle the heat better.
    I have already been told that Inconel valves would have to be made special, no one stocks the size needed for my Profiler heads so I either stay with SS or spend the coin for TI
     
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  6. rb0804

    rb0804 Member

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    It’s opening the exhaust valve against the combustion pressure. As we make the camshaft profiles on wider lobe centers it opens the exhaust valve sooner, which gives us an earlier start on clearing the cylinder of spent gases from the previous cycle so we can get a good clean mixture on the next stroke. Titanium doesn’t transfer heat real well and will need a copper alloy seat to assist in the heat transfer process. The seats job in addition to sealing off the combustion chamber is transfer some combustion heat into the head from the valve so that the valve can live at a reasonable temperature and do it’s thing. The more RPM and camshaft duration that we run, the less time the valve is on the seat transferring heat. Too much heat and we get into valve sealing and valve job issues, amoung other issues like tuliped valves and eventually dropped valves.

    The copper beryllium seats are toxic to machine, but they now have some less toxic alternatives. If you don’t already have some type of copper alloy seat, factor that into the price to switch as well. An inconel valve is pretty heavy, but deals with heat well. That is primarily a turbo deal where back pressure in the exhaust can cause issues (titanium works well in most turbo applications). Really, 8,000-8,300 isn’t terrible rpm to be pulling with a big Chevy.
     
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