Bowmans Mod Shop

anybody ever wondered what the real capacity of a prom is in watts?

well i was playing with a prom tonight...
and i know everyone knows i use dale resistors now for a heat load...no guessing and no...it is supposed to be 80 watts thing.
i put mine under a meter and measure actuall amp draw and voltage..i can figure wattage close...very close now

well i made up 3 loads or i should say 2 load blocks with one being adjustable..that i can run one or 2 87.78 watt resistors.

i ran a 404 prom at 77.34 watts of heat load...did great -47c
bumped it up to 87.78 watts...got -44c...and the next step i had to go was 175.56 watts...and guys a prom cannt handle that.....:(

that is alot of heat..

just something i was playing with tonight...

and the only diff was i was making sure the evap got full contact.unlike a cpu..where it may have a 100 watt output...only so much can go though that small core die.

just something i am playing with...

They claim it will handle up to 200w.:rolleyes:

I wonder if they mean it will dissapate 200 watts to ambient?

almost forgot..i know everyone wants pics..

here is what i use...

and i have a bunch of those large resistors i had to buy them in bulk to get what i wanted.

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Originally posted by TheDude
They claim it will handle up to 200w.:rolleyes:

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yea i would like to know how they caculate that...?

proberly some form differant than i am thinking of...

they have some way thay came up with that figure..i am sure of that...just not sure how.proberly some test they came up with.

o i forgot,,i have a another brand new unmoded prom here..i will try and run the same test on it this week to see how far it drops.

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i ran a 404 prom at 77.34 watts of heat load...did great -47c
bumped it up to 87.78 watts...got -44c...and the next step i had to go was 175.56 watts...and guys a prom cannt handle that.....

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Ummmmm... Well, that's not quite right. It can handle it, but at what temperature?

In other words: It can handle 77.34 watts @ -47C. It can handle 87.78 watts @ -44C. It can handle 175.56 watts @ ___C.

And that's with the current cap tube, tuning, and ambient conditions. A cap tube system is tuned for a specific load under specific conditions. It will not perform as well under any other conditions.

At the very least, you should tweak the refrigerant charge for each test load for a fair comparison.

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Originally posted by Gary Lloyd
Ummmmm... Well, that's not quite right. It can handle it, but at what temperature?

In other words: It can handle 77.34 watts @ -47C. It can handle 67.78 watts @ -44C. It can handle 175.56 watts @ ___C. And that's with the current cap tube, tuning, and ambient conditions.

A cap tube system is tuned for a specific load under specific conditions. It will not perform as well under any other conditions.

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Thats why I think they mean it can bring 200 watts to ambient temp.

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Originally posted by Gary Lloyd
Ummmmm... Well, that's not quite right. It can handle it, but at what temperature?

In other words: It can handle 77.34 watts @ -47C. It can handle 67.78 watts @ -44C. It can handle 175.56 watts @ ___C.

And that's with the current cap tube, tuning, and ambient conditions. A cap tube system is tuned for a specific load under specific conditions. It will not perform as well under any other conditions.

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well yep,thats what happens when you tune for a specific heat load...

but i never let the prom keep going she was over 15c and steady rising...so i stopped it.

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but i never let the prom keep going she was over 15c and steady rising...so i stopped it.

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Sounds like the evaporator was starved. Probably if you had added a little refrigerant, it would have come right back down.

that evap head looks awesome!

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Originally posted by Gary Lloyd
Sounds like the evaporator was starved. Probably if you had added a little refrigerant, it would have come right back down.

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now you know me better than that....i already tried to add some...it wont budge...

which tells me the evap was starving for refrigerant....but if i tune it for heavy loads which no one sees,the evap temps are higher and you have flooding problems...to the compressor...

as you know it is all a balancing act...give and take...

how much can you take from here and give to there.

but then again we are back to the problem of cap tubes....they have some great qualities,,but lack flexability of heat load range..

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now you know me better than that....

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Yep, lost my head... LOL

Everything is balances and trade-offs. :D

The cap tube is a wonderful invention. There are better ways to control refrigerant flow, but all of them are more complex, more expensive, and less dependable. Whatsmore, a device which allows more refrigerant flow requires more refrigerant and more condenser capacity.

Sooner or later, someone will try running evaporators in series, using a TXV, and this may be the answer.

BOWMAN & BAKER....I have only one thing to say to you two,,,,,,,,,
SWEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEET!!!!!! !
:worship: :D

crap those blocks are awesome!

well as i stay really busy this time of year,,,short days.
but i just got in some items i thought may draw some attention.

evaps,evaps,evaps,evaps,and covers.

plus a sweet little 226watt tec unit..which i am going to make a peltiers cooled cascade prometia.trick will be keep it small without going outside of the factory prometia case.
this is garys idea.....so i have a scape goat...LOL.

got some machining to do to make the heat exchanger fit.

OOOh whats those evap covers made of?

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plus a sweet little 226watt tec unit..which i am going to make a peltiers cooled cascade prometia.trick will be keep it small without going outside of the factory prometia case.
this is garys idea.....so i have a scape goat...LOL.

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I can't wait to see how it works. :D

I am hoping we can drop the SCT below ambient. Until then, we are just subcooling. If we can condense in the neighborhood of 32F/0C, we could switch to R410A using the stock prommie cap tube, with no other mods. Well, maybe an oil separator.

I can't find a pressure/temperature chart for R410A that goes into the really low temps, but I'm thinking we might hit about -80C, or maybe even lower.

WHoa this thread rocks, im gonan read all 35 pages now. Be back in a couple of hours lol :)

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Originally posted by Gary Lloyd
I can't wait to see how it works. :D

I am hoping we can drop the SCT below ambient. Until then, we are just subcooling. If we can condense in the neighborhood of 32F/0C, we could switch to R410A using the stock prommie cap tube, with no other mods. Well, maybe an oil separator.

I can't find a pressure/temperature chart for R410A that goes into the really low temps, but I'm thinking we might hit about -80C, or maybe even lower.

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well thats first mod ....install heat exchanger first...and hope for the best.:D

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well thats first mod ....install heat exchanger first...and hope for the best.

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I agree. I wouldn't install a separator unless/until I see oil problems. It may not be needed.

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Originally posted by Gary Lloyd
I agree. I wouldn't install a separator unless/until I see oil problems. It may not be needed.

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yea but thinking about it..i will need a oil sep proberly..already have oil troubles on my triple..but i live with it since it doesnt run but a few hours a week anymore...

a very small oil sep..wont be too hard to do..just have to run cap tubing to the compressor to regulate the oil return...

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yea but thinking about it..i will need a oil sep proberly..already have oil troubles on my triple..but i live with it since it doesnt run but a few hours a week anymore...

a very small oil sep..wont be too hard to do..just have to run cap tubing to the compressor to regulate the oil return...

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You might want to check out these sites. Helical oil separators are over 99% efficient.

http://www.henrytech.com/techtips_pdfs/HT-TT4.pdf

http://www.schlosser-moller.no/tekni...vakontroll.pdf

bowman is ghetto moddin p!mp!