AMR 500 supercharger build

[advinnie]

Hi all, I’m after some advice please. I have a 1600 Vw beetle that I am slowing collecting all the parts to supercharge it using a AMR 500 charger. I have a 123 distributor that I can program and I believe that I need to reduce timing for every 1psi of boost down to 24° BTDC , is this correct?

Also there is no relief valve on this charger so does that mean that if I’m cruising along at 3500rpm will the engine still be under boost ?

Now I have a boost gauge fitted the the manifold but where on a Weber DCOE carb do I take a vacuum/boost signal for for the distributor advance and retard system?

Cheers all

[V8Nate]

Hi all, I’m after some advice please. I have a 1600 Vw beetle that I am slowing collecting all the parts to supercharge it using a AMR 500 charger. I have a 123 distributor that I can program and I believe that I need to reduce timing for every 1psi of boost down to 24° BTDC , is this correct?

Also there is no relief valve on this charger so does that mean that if I’m cruising along at 3500rpm will the engine still be under boost ?

Now I have a boost gauge fitted the the manifold but where on a Weber DCOE carb do I take a vacuum/boost signal for for the distributor advance and retard system?

Cheers all

That distributor should work well, I would tap a port into the intake after the supercharger. If you try and plumb it into the carb you will never see boost pressure

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[V8Nate]

As far as retarding the timing every motor is different, dropping it down to 24 degrees under boost would be a safe bet. When I built my amr500 1641 I used a vacuum advance/retard canister from a saab and I timed it to 30 degrees max advance. I'm wanting to say under the 4 lbs of boost I was running it only pulled 2-3 degrees

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[advinnie]

Hi all and thanks for the reply’s. So I have figured out that the 123 distributor can be plumbed into the manifold and that I will have to set the distributor to ignore the vacuum reading at idle otherwise the distributor will sense the high vacuum and advance the timing.

The other question I have is this., when at a cruising rpm will the supercharger still be producing boost or not?
If not I can’t understand why not cause I can not to a relief valve. Can someone please explain to me why it will not be proving boost please

[V8Nate]

It probably won't, it's kind of dependant on how you drive it honestly. It's a pretty small s/c to be honest. When you are driving you can accelerate and not even be in boost but if you push harder on the loud pedal here comes the boost and power. It's awesome really!

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[advinnie]

Nice set up. How much boost are you getting and how do it drive? Any carb icing issues?
My current 1600 has a pair of dells and was wondering how much more power will I see with a supercharger over twin carbs?

I’m also gathering parts for a basic 1914cc engine but I think the supercharger would be to small on this size engine what do you think?

[V8Nate]

Nice set up. How much boost are you getting and how do it drive? Any carb icing issues?
My current 1600 has a pair of dells and was wondering how much more power will I see with a supercharger over twin carbs?

I’m also gathering parts for a basic 1914cc engine but I think the supercharger would be to small on this size engine what do you think?

Thank you. With that pulley setup it was around 4 psi. It's going to make a huge difference compared to the dells. That motor was literally slapped together with trash parts that I was never going to use again(with the exception of new stock style Chinese heads with single high rev springs) mix and matched out of balance rods, scored crank, stock used cam, I can't remember but I'm pretty sure it had stock rocker arms and shafts, a couple jb welded head and case studs ect.

It did have some icing when I ran a single kadron 40/44 on it but I made a plexiglass box i called the tower of power it kept just enough heat in to keep it from icing. I never could get the single kad to lean out enough on cruise so I went back to my original design with a Rochester 1 barrel off a chevy straight 6. It was getting in the 20's mpg and I had it jetted to 12 flat on the afr gauge at wot. It was actually a great draw thru carb. There's a guy on YouTube that has a red bug with a 1914 I believe with a amr500. It will be on the small side but if you don't ask to much of it it will work, you ask for more boost and it'll become a heat pump. I only have a few videos of my 1641 with the s/c but you can check it out if you'd like my channel is v8n8t

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[V8Nate]

That picture with the iced carb was after I was cruising down the highway and let off the gas but it kept going like cruise control I shut it of and the ice melted in a few minutes then back on the road I went. With it so far away from the heat of the engine and being outside of the body during the winter it simply just became frozen. The plexiglass box fixed that

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[Alexander_Monday]

The other question I have is this., when at a cruising rpm will the supercharger still be producing boost or not?
If not I can’t understand why not cause I can not to a relief valve. Can someone please explain to me why it will not be proving boost please

A supercharger without a bypass valve will increase pressure, but throttle position will determine whether or not it creates "boost" since the common use of the word boost is above atmospheric pressure. If the inlet to the supercharger is under vacuum there are only so many air molecules to pack together. Open up the throttle and you are allowing more air in to compress. At some point (if the compressor is large enough in relation to the engine) the amount of air into the supercharger and it's ability to compress it based on the efficiency of the supercharger and rpm it is turning will create boost.

The downside to not having a bypass valve is it is always increasing the temperature of the air. With superchargers that are larger compared to the engine size this will heat up the supercharger too much. With a 500cc supercharger will not be a practical problem with a VW engine. A supercharger closer to 1/2 the size of the engine does, but is mitigated a lot if it is a draw through due to the cooling effect of the fuel because the fuel has a much larger mass than the air.

[V8Nate]

The other question I have is this., when at a cruising rpm will the supercharger still be producing boost or not?
If not I can’t understand why not cause I can not to a relief valve. Can someone please explain to me why it will not be proving boost please

A supercharger without a bypass valve will increase pressure, but throttle position will determine whether or not it creates "boost" since the common use of the word boost is above atmospheric pressure. If the inlet to the supercharger is under high vacuum there are only so many air molecules to pack together. Open up the throttle and you are allowing more air in to compress. At some point (if the compressor is large enough in relation to the engine) the amount of air into the supercharger and it's ability to compress it based on efficiency of the supercharger and rpm it is turning will create boost.

The downside to not having a bypass valve is it is always increasing the temperature of the air. With superchargers that are larger compared to the engine size this will heat up the supercharger too much. With a 500cc supercharger will not be a practical problem with a VW engine. A supercharger closer to 1/2 the size of the engine does, but is mitigated a lot if it is a draw through due to the cooling effect of the fuel because the fuel has a much larger mass than the air.

Perfectly said!

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[Alexander_Monday]

The other question I have is this., when at a cruising rpm will the supercharger still be producing boost or not?
If not I can’t understand why not cause I can not to a relief valve. Can someone please explain to me why it will not be proving boost please

A supercharger without a bypass valve will increase pressure, but throttle position will determine whether or not it creates "boost" since the common use of the word boost is above atmospheric pressure. If the inlet to the supercharger is under high vacuum there are only so many air molecules to pack together. Open up the throttle and you are allowing more air in to compress. At some point (if the compressor is large enough in relation to the engine) the amount of air into the supercharger and it's ability to compress it based on efficiency of the supercharger and rpm it is turning will create boost.

The downside to not having a bypass valve is it is always increasing the temperature of the air. With superchargers that are larger compared to the engine size this will heat up the supercharger too much. With a 500cc supercharger will not be a practical problem with a VW engine. A supercharger closer to 1/2 the size of the engine does, but is mitigated a lot if it is a draw through due to the cooling effect of the fuel because the fuel has a much larger mass than the air.

Perfectly said!

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Just summarizing what Corky Bell said.
I would highly recommend "Supercharged! Design, Testing and Installation of Supercharger Systems" by Corky Bell to anyone wanting to dig into the technical details of supercharging.

[advinnie]

Everyone thank you so much for your help
I have one last question for now that is I need some oil for the charger can anyone suggest what to go for please

[Clonebug]

I'm pretty sure thedubshop.net has oil available for those blowers.....along with pulley's and brackets if you need them.

[advinnie]

Brace bar, shut I’ve not thought about that

[advinnie]

Well it’s in and fitted. Still got to fit the hose clamps , accelerator cable and tune the carb but it starts and it runs