Scocialized medical care in Canada, all I paid for were the crutches.

 

The reminds me of a great quote I read once - sorry I don't know who to attribute it to...

Cheers,
Hymee.

Now I can start posting again - after saving something good up for my 3000th

 

epitrochoid:

Just a note for purities sake: Torque is a moment not a force. It is a force acting on some moment arm. Could be a small force with a big arm or a big force with a small arm.


In the electric motor arena - the government is looking at electric drive systems for a number of new ground vehicles. These systems produce a tremendous amount of low end torque. However, since batteries can not be used for long term propulsive effort, there is still a requirement for a diesel, gas turbine, otto cycle system, rotary or some other type of prime mover that will then drive generators. These systems are not too far removed from the trains dragging stuff around the world.

Hymee,
Congratulations: 3000th post. Seems like it belonged in one of your own threads though. Sigh

 

Holy posts Batmanbastard, I never noticed your contribution has been going on that long. :D If you had a dime(US) for every post, you could buy yourself a shifter.

 

Thanks. It does have it's very own thread! go have a look at this: https://www.rx8club.com/series-i-tech-garage-22/hymees-3000th-post-something-special-instantaneous-fuel-consumption-51828/

Cheers,
Hymee.

 

right but, a moment is more of a "force" than horsepower, and since all the "arms" in our car are more or less a constant (spare gearing), all that changes is the force.

flat tq = linear acceleration

 

Turbine_pwr, That is the system the navy uses on ocean going tugs. THey have, at least on the one I saw, four big engines driving generators. Under low load, like not towing, they just run one engine. The big deal is that they have very fine adjustment of whatever power they need. This ship had one huge prop that turned slow. At least that is what was explained to me.

Thinking about it now I realize that they probably had cavitation if they applied to much power or tried to get to many rpm wwith a smaller prop.

One huge prop turning slowly will grab the water better. So to get it to turn while towing a destroyer they need the power. They can get the best RPM at all times if they can vary the power without raising the shaft speed because they had to raise engine speed that is conected to the shaft.

 

Richard,

Good points. But don't forget the gas turbine powered ships either. We have a number of engines that are providing motive power for various shipboard applications. One of the more recent was the TF50A engine in the LCAC. Kind of a neat vehicle.

http://www.fas.org/man/dod-101/sys/ship/lcac.htm

Note those HP numbers

Hymee
Nice post. When are we going to be able to buy the "sCANalyse Live" system? and dare I ask... am I going to have to sell one of my kids to buy it? By the way... I'd consider letting you have one cheap, two cheaper, and if you're willing to take all three I might even be willing to pay. Note: They are at very productive ages 19, 20, 21.

For those growsing about the weather. I do live in sunny Az. As usual, it's been sunny and in the sixties for the last few weeks. Albeit, we've had a wet winter. I think something like 2-3 inches of rain in the last 3 months. We're still bailing

ep
I'll let you slide on the torque thing. Just didn't want anyone getting the wrong impression (wry smile).

By the way... just to have some fun. Back a couple weeks ago, there was an interesting discussion about the speed of sound. Some bad stuff was passed along during this discussion.

1. Speed of sound = SQRT( gamma * R * gc * Temp) where gamma is the ratio of specific heats Cp/Cv, R - the specific gas constant, gc - getting the correct units for us old hat fuddy duddies, and Temp is just that (Temp in absolute units) - in short hand this is Richards 49 *SQRT (T ).

However, assuming we are using an ideal gas (yes air qualifies) . Then P = rho * R * T.

In which case
2. Speed of sound = SQRT( gamma *P / rho ), Which shows that the speed of sound is also a function of the pressure and density of the fluid your working with. This of course is why when you breath Helium (not recommended for long term longevity) and talk, you end up with a squeeky voice. Helium is a small molecule (ie low density fluid) and the speed of sound changes accordingly... (the Micky Mouse Voice)

Sorry to be such a **** retentive bastard but I don't want anyone to fail thermo, heat transfer, or fluids because of our contributions. Snicker... Snicker

 

You've got me thinking about how this pertains to the Renesis or any other engine for that matter. In the Renesis, part of the S-DAIS intake sysem is the VDI system. This is a valve that opens at a higher rpm to retune the intake manifold to a higher point so that the powerband stays stronger for longer. It relies on the pressure wave of the intake port on one rotor closing and it's interaction back through the manifold to the other rotor where it's effect is seen as a positive pressure wave that helps ram more air into the port right before it closes. The longer the runners, the lower the benefit in rpm. This wave travels through the intake manifold at the speed of sound. The question as it pertains to your statement is will this effect be changed with the addition of forced induction? Might it be necessary to change this valves opening point to a different rpm because the effect is no longer where it would be on a naturally aspirated engine? Your statement confirms something I have always thought about but now I'd like to know if the intake tuning sees this change.

 

Resonant intake tuning is useful in a NA engine for the very reasons you stated (slight pressure increase at the intake port). However, it is usually not included in a blown engine -- the friction losses in the runners are more than the tuning gives, and even without them the gain would be miniscule compared to the mechanical boost that is being applied. So blower kits usually toss the tuned intake tubes out with the trash.

Note: I had a '59 Plymouth Sport Fury with a 383 cu in B block that had the long cross-ram manifolds on it for a while. No, that wasn't the way Chrysler Corp. made it!

 

Richard,

Great to see you’re still making these jewels. Seems like I had a fancy four-color brochure offering your Latham kits for Camaro/Corvette around mid-80s? Does that sound right? Or maybe it was a magazine article. Anyway, I remembered them from the sixties and was impressed at your efforts and by your product… figured I’d have one on something some day. Then I didn’t hear anything about Latham SCs… but always thought about them whenever I thought about forced induction.

I saw a rat rod a couple of years ago in traffic near Indianapolis Raceway Park… it had a flathead Ford engine with a Latham blower, so I tried to get turned around to chase him down and see if he knew anything about the current availability; got hung on stoplight and lost him… I was very disappointed.

Just for the heck of it I googled Latham yesterday, and read this thread straight through except for a couple hours of sleep. Impressed all over again. Good luck with this latest iteration.

 

Found another axial flow Latham picture on the internet.

 

I’m still confused about the axial flow compared to positive displacement sc. Hymee stated:

“Axial flow – linear. 2x rpm = 2xboost”
“Positive Displacement – constant. 2x rpm = same boost. ½ rpm = same boost”.

Then RG said;

“You've got the explanations for PD and axial confused with each other.”

Then Hymee corrected himself, but just reiterated what he stated earlier:

Centrifugal = "exponential" boost
Axial Flow = "linear" boost
Positive Displacement = "constant" boost


So, which is it?

Is the axial flow sc PSI a function of the rpm or is it constant regardless of rpm?

*ponder*

 

I think you're confused because Hymee went back and edited his post for correctness? It looked right by the first time I saw it too...

jds

 

I think I'm just confused :P.. That makes sense yes. Thanks.

 

Before Hymee corrected his post, it said that centrifugal was a linear and axial was an exponential. That's backwards. Now it reads correctly.

 

I noticed that some cars with SC installed from factory have the ability to disengage the SC when cruising. How hard would it be to implement something like that with a bolt on kit?

“The Eaton superchager in a Mercedes-Benz application showing the magnetic clutch used to disengage it for cruising efficiency.”

 

With the Eaton (or any other positive displacement SC) stopping the rotor means stopping air flow completely. Mercedes must, therfore, bypass the blower completely with the induction system when the clutch is disengaged. Virtually all the other Eaton installations simply recirculate SC outlet air back to the SC inlet when boost is not called for... in some of them this passage is built right into the blower itself. When recirculating, the blower uses virtually no power. Not sure why Mercedes added the complexity.

As for a clutch on the axial flow... I don't think it's pumping as hard at low RPMs as a roots is, so there would be far less benefit to disengaging it... and I'm not sure how well, if at all, air can flow through the axial flow if it's not spinning.

 

Speaking of recirculation, can you just oversize a non-PD supercharger so it has, say, 8psi at 3000(engine)RPM, and then variably bleed air (pressure) from its outlet back to its inlet (ECU controlled, of course) to keep the manifold pressure from going any higher as RPM goes higher? The same bleed circuit could be used to "unload" the power consumption during crusing, as the Eatons do.

Can this type of recirculation be used with an axial flow SC?

 

you could, but you'd still be stealing power from the crank to drive the blower thus creating a huge ineffeciency

 

I don't think so... Eaton claims 0.3 hp is used to turn their (~Roots) SC when it's recirculating... a screw type (Lysholm, Autorotor, Whipple), on the other hand has actual internal compression, so it would still be doing work. The axial, since it isn't doing internal compression, would not use much, if any, power.

 

Let's see if I can get all this answered. With the AFS if you remove the belt it will spin quite happily along as you drive. In fact it will take several seconds to stop after you shut it off. The axial DOES have internal compression. The thing is that when used as a draw through it uses almost no power when the throttle is not open. If the air is thin it doesn't compress anything so uses no power.

Recirculation is not all that good as you return heated air to the intake. Now I know someone is going to tell me that the air will expand in the intake and the heat will go away. Well this might sound good but you can't change conditions without paying for it, some energy is lost.

Why does Mercedes add complexity?? Because they are German. That's why they lost the war, they built everything so complex, heavy duty and rebuildable when it should have been built as a throw away.

 

The axial does have internal compression through each of its stages.

Internal compression makes for higher adiabatic efficiency. That is why a twin-screw is more efficient than a roots.

Cheers,
Hymee.

 

RG, That is a strange blower in your photo. The only units made that were not polished were test units. Also the pulley is not hard anodized. That look's like a mid '80's production unit. I remember one person requesting it not be polished but I can't remember who it was. There was another sold to the Canadian telephone company to pressurize wire ducts. That was to keep water intrusion out of some failing pipelines where they didn't want to dig them up.

But if my memory is correct they split it up into two compressors to use at two sites. I know that because they requested the extra parts at some later date.

It has the single right side inlet which is standard configuration. It uses the four brl carb nipple and not the Weber side draft. That's all I can tell from the photo.

 

BTW, The axial flow has seen favor from the FAA as a aero supercharger. They favor it over all others as it will spin freely if a belt is lost and if it were to seize, air will be restricted, but enough air will go through to allow cruising and landing power.