AMR500 Blowup - Questions

[666Beetle]

Alright, so the story goes. Bought this car with the motor already built. Not foreign to these motors but still getting a grasp on an AMR500 build. Drove the car 3 hrs home, bad idea I know. I believe the car got hot, gear side of the amr500 was reading 220f ish.

Drove it a few times after and boom goes the dynamite. Locked up. Realized the supercharger was super hard to turn, shavings in oil, so out came the motor. Come to find this piece of metal slapping in the cylinders. Luckily I missed a valve and the cylinder looked fine. My guess is, something came loose in this charger and shot it into the cylinder. But wtf is this? A set screw for one of the scoops inside the charger?

This has caused very low confidence with these chargers and im trying to rebuild that confidence so I can enjoy the car. New supercharger is in and running okay but the paint in bubbling on the gear side of the charger. I usually get readings around 200F. 3:1 ratio so spinning around 15k at 5k. Dont go past that much. Is that too hot?

So to recap:

Is it getting too hot right now or is that cheap paint from china just bubbling? I havent seen readings over 200ish.

Thoughts about adding a steel mesh screen after the charger to avoid this in the future. Curious on others thoughts of this? Or did I have a perfect storm scenario?

Does anyone have any ideas about what this foreign object could be?

[Alstrup]

These chargers are generally fine. That one apparently had an issue. It also looks like it is geared rather agressively for the larger than stock displacement. (Loooks to be a 1914, with a copper head gasket ) That contributes to elevated temperatures on longer cruises. The draw through set up can´t cool the charge enough.
If you want to continue with a charger I suggest you reduce the speed on the charger a tad and maybe do a little work on the intake side in order to maintain the performance level.
Whether you can save those heads with a clean up cut is hard to determine from the photo.
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[666Beetle]

Appreciate the reply. Running a 53mm pulley up top giving around 6psi. Was thinking of throwing a 75mm in and seeing if that allows for better cooling. Main concern is this does have a CB Black Box and i'm no tuner with the nearest hours away.

I think I got myself into a bit of a mess. Give me mechanical stuff, im fine. I like early cars to avoid tunes, yet here we are. Lol

I grinded the top head down and slapped everything back in and is actually running very well BUT startup seems to be rough. I think my timing is off just a tad but AFR is reading ok.

Either way, appreciate the insight.

[PatJr]

I don't have one of these, I was just looking into putting one on my van.
I think I read that the upper limit on the charger is 12,000 rpm
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[vwracerdave]

If you're asking about oil temps than no 220*F is not too hot. Above 235*F is when you start to panic on oil temps.

There are a few threads that go into more detail about oil temps.
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[666Beetle]

[rayjay]

It would be cool to have some fan blades on the SC pulley blowing air across the gearbox.

[vwracerdave]

[Rob Combs]

You might be able to knock some temperature out of the intake by adding a water injection spray nozzle between the carb and the supercharger. If you can rig up a system to only spray at or beyond "x" temperature, that seems like it would be ideal.

What do you have plumbed into the manifold between the carb and the supercharger inlet (two AN fittings and hoses seen screwed to the manifold)? Are you flowing something through there to add heat or to remove heat?

Maybe I missed something, but that FOD is disturbing. Have you identified exactly where it came from? Is it from an internal part of the failed supercharger? I don't recall seeing anything internal in mine that looks like it could create this...

[EVfun]

[666Beetle]

[666Beetle]

[666Beetle]

[rosevillain]

There's an oil cooler/ intake charge heater between the carb and the blower? Seems like warming the intake charge would be a bad idea?

[NJ John]

I thought the superchargers sold on Amazon are problematic?
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[666Beetle]

[Rob Combs]

Torben mentioned above that the draw-through system cannot keep the temps down over time when turning the charger at that pulley ratio, especially into what appears to be a 1914, which is theoretically a little large an engine for an AMR 500. In my opinion, you're complicating that problem by introducing a liquid to air heat exchanger into the intake path, wherein you're removing heat from the oil. Whatever heat you're removing from the oil is inevitably making its way into the intake path.

One of our members and contributors, Clonebug, has a lot of experience with forced induction on these engines and has a really good idea what they will and will not take before we start breaking stuff. He has noted at least once, but maybe a few times, that 130 F intake air temp is the tipping point where it gets nearly impossible to keep detonation under control. Draw through is helping to keep your IAT in check, but if you're already at or slightly beyond its limits, I think adding the oil cooler system you've got might actually be a detriment, even if it turns out it's not the root cause of your current situation. If your supercharger case is nearing 200 F, you might be right on the line or over it.

Please let us know how that teardown goes.

[nsracing]

So this is how you massage a head - chunks of something dancing around.

There has to be a better way to screen for foreign objects before they get to the chambers if running odd things about the intakes.

From looks of it seem to be new heads too.

[mark tucker]

when you get it fixed and the crap out of it put a intercooler on it!!! theres not that expensive and there are some small factory ones that are very nice.

[oprn]

I wonder if the purpose of heating the base of the carb is to prevent chunks of carb ice from entering and damaging the supercharger? Would not a piece of window screen do a better job?

200*F on the supercharger case would indicate to me that the air charge temperature is even higher to heat the case that much. Unless the heat was coming from a seized bearing, that is the only other possible heat source.

I agree that the fan is slipping badly with such a tiny contact area on the pulley. The fact that the generator light does not come on only indicates that the alternator/fan has not stopped turning completely!
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