Expired Engine at Tremblant

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chrisrupnik
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Expired Engine at Tremblant

Post by chrisrupnik » Wed Oct 10, 2018 9:35 am

Unfortunately, this engine expired at the track at Mont Tremblant,
Newly built. Had about 30 minutes of running prior to the first session, which unfortunately finished early due to running out of fuel. After refueling ran it again and no obvious problems.

Ran it for 1/2 a lap and under 5000 rpm and overheated with white steam from the exhaust, and a melted #4 piston as you can see here on the exhaust side. Head gasket obviously toasted.

No bent valves.

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friedman
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Re: Expired Engine at Tremblant

Post by friedman » Thu Oct 11, 2018 8:31 am

Is that a crack in the piston at the bottom of the left side valve pocket?
Carl in Virginia
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86 Bertone
77 X1/9
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chrisrupnik
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Re: Expired Engine at Tremblant

Post by chrisrupnik » Thu Oct 11, 2018 2:56 pm

I looked at it again, and in fact looks like it is melted material that just happens to be arc shaped.
fp55scca
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Re: Expired Engine at Tremblant

Post by fp55scca » Thu Oct 11, 2018 8:42 pm

--Chris, a wider view of all four pistons, and a similar view of the head and head-gasket would be helpful.

--Did you do anything new in this re-build? Different pistons/valves, etc.?

--Did you note temperatures and pressures prior to observing the white steam from exhaust?

--If you are lucky, looks like the block, crank and rods can be salvaged. Depending on pistons, you may just need one piston.
Jim Scurria
Norfolk, VA

1972 Fiat 124 Spider
1971 Spider - SCCA FP-24
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chrisrupnik
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Re: Expired Engine at Tremblant

Post by chrisrupnik » Fri Oct 12, 2018 11:28 am

The other three pistons look perfect. The #4 cylinder bore is scratched - see here.

The temperature gauge did rise above 90 c degrees before i shut the car down, so an overheat did occur.

Here is a picture of the head gasket.
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engineerted
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Re: Expired Engine at Tremblant

Post by engineerted » Fri Oct 12, 2018 2:06 pm

WOW !!! looks like #4 went lean, thus causing pre-ignition at piston crown edge. This over heated the block/head near that area, thus causing the gasket to fail. What CR, fuel octane and total ignition were you running? I also look for a possible air leak in the intake/carb.

When pre-ignition starts it will burn through almost anything very quickly.

What clearance are you running, piston crown to cylinder head?
1978 124 steet car
1974 124 EProd race car
Farmington Hills, MI
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chrisrupnik
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Re: Expired Engine at Tremblant

Post by chrisrupnik » Fri Oct 12, 2018 5:22 pm

10.1:1 compression and 94 octane fuel was used.
I do not know the other measurements though.

This should have worked :lol:
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SimcaBertone66
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Re: Expired Engine at Tremblant

Post by SimcaBertone66 » Mon Oct 15, 2018 1:54 pm

Hum, got a "theory" … engine is "specked" @ 10.1 to 1 CR.. theory part .. it's actually higher and the 94 ain't cutting it …. this is a newly built engine .. correct … ? just raced for the first time... with 94 octane unleaded... I think it was denoting straight away and just pushed it into an overheating condition … using a electric water temp sender... or an maybe more accurate mechanical... 194 F or 90 C water temp at time of the patient dying ? … Anyway, sorry for your loss.... RIP … BTW what's plan A thru ? to get the girl up and running again ?
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SimcaBertone66
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Re: Expired Engine at Tremblant

Post by SimcaBertone66 » Mon Oct 15, 2018 1:56 pm

Another theory … will running a race engine "out of fuel" cause a too lean condition as lowering fuel pressure follows diminishing fuel flow ??
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engineerted
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Re: Expired Engine at Tremblant

Post by engineerted » Mon Oct 15, 2018 3:18 pm

Since we are throwing theories out there, did you keep the heater heater hose connection? Heater removed but connect the hose to the water pump via. the coolant tap between cylinders 3&4? I find that this provides a more uniform temp across all cylinders VS. blocking this off. Blocked off could have caused a hot spot at cylinder #4 supporting the detonation.

I always run 110 octane with my 13cr 2l motor. High G forces and carburetors don't always mix well, same thing for fuel pickups. If you are pumping air you are most likely leaning out the fuel mixture.
1978 124 steet car
1974 124 EProd race car
Farmington Hills, MI
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