Well, my race car doesn't have hardened seats, but since the cylinders are
horizontally opposed, I don't worry about the seats dropping out no matter
what. ;)
Seriously, as the owner of a '76 TR6, I looked into it at one time and had a
chat with one of the reps from Mobil who came to the SCCA National
convention a few years ago. Here's what he said:
Bottom line: Don't worry about it.
Slightly longer version: The whole hardened valve seat thing was a great way
for a bunch of folks to make money on the switch from leaded to unleaded.
The lead was handy in the early days of engines, but was pretty much
unnecessary after WWII due to improvements in metallurgy and machining. Your
valves are far better, lead or no lead at 100k miles than those made prewar
at any point in their life.
So I put whatever is available in my race cars and non catalytic cars.
Street car gets unleaded to keep the cat alive. Doesn't seem to make much
difference.
On that note has anyone seen dyno results on the same engine with different
fuels? A matrix of HP vs leaded/unleaded by octane would be interesting.
On Wed, Jul 29, 2009 at 5:13 PM, Jim <britbits@netzero.com> wrote:
> While I'm in a regroup/research mode, what's the feeling on leaded vs
> unleaded in TRs, Spitfires more specifically.
>
> I started driving as leaded was being phased out, and there have been many
> variations on the urban legends regarding using unleaded in cars designed
> prior to the 1970s.
>
> One concept I've seen has it that using a tank or two of leaded in the
> "pickling" phase of a new engine is enough to add lead to the valve seats,
> good at least for a street car run on unleaded.
>
> Hardened exhaust seats are good for a street car but can potentially drop
> out of the head on a race car, causing other problems :O
>
> Obviously, if you're running leaded fuel then it's not an issue.
>
> Anyone running unleaded willing to share their experiences?
>
>
> Just trying to improve the ride.
>
>
>
> Cheers,
>
> Jim
> Dallas
> Spitfires.. And other toys
>
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