Lets see who can figure out this idea for controlling boost pressure


Compressor speed (boost pressure) is ultimately controlled by controlling the hydraulic fluid flow through the motor.

Low compressor drag during off boost condition if TB is on the inlet side;
Despite the

 

Servo valve across the "drive" hydraulic pump head. I think Herion make some nice ones for cheap. Impeller RPM is now independent of engine RPM. You were probably looking for more detail than that?

-Doug

 

yep that the idea

compressor speed is independent over a specific threshold for the minimum input power/seed for the pump to run the appropriate flow to get the desired boost pressure after that threshold the pump would continue to push more flow and pressure since it is coupled to the engine crank so it become necessary to vent/bypass some of this flow to control the turbine speed.

if the hydro motor could be made small enough that the appropriate steep up in speed can be achieved(no gears) and be small enough it would be nice to do something like this for a true straight through compressor.

 

[QUOTE=MugenRioS2k,Nov 9 2006, 01:52 PM] Lets see who can figure out this idea for controlling boost pressure


Compressor speed (boost pressure) is ultimately controlled by controlling the hydraulic fluid flow through the motor.

Low compressor drag during off boost condition if TB is on the inlet side;
Despite the

 

Feb 2005 - "At the moment we are finalizing the Mazda RX 8 blower"

Must be the biggest overstatement of the past couple of years

Should have been certain before posting. It is because so many unknown variables come into play that one shouldn't bite off more than they can chew at that moment.

It seems he's gotten lots of people's hopes up to just have it deflated. But I'm sure many people are still anxiously awaiting this. For some weird reason I JUST read this thread yesterday. Don't know what rock I've been hiding under.... but wow I got really excited to see this. That is until I saw how slow things were progressing.

But still, I am very pleased to see something like this in the works (possibly) for the S. This is something I definitely would be interested in doing in the future *fingers crossed*

I wouldn't get my hopes too high though!

 

Boy I wish I could shut off the brain some times.


The hydro idea has apparently already been tried by Garret a couple of years back (hydro-charger). The abandoned the project but gave no reason either.

After looking around last night I was unable to find a hydro pump/or motor that would meet the necessary requirements to run any type of compressor wheel of turbine at the speeds and input power required to produce boost pressure while trying to keep the motors and pump in a design volume that is around the size of the AFSC.

Did find a pump that was capable of running 10K but the max output shaft power at the speed was in the range if 120 IN LBS (yep inch lbs) any thing over that and damage to the pump would occur.


Which would be very bad since that motor requires an input pressure of 4000psi on the input fluid.

4000psi

 

LOL, I have no control what-so-ever, and mine always shuts down at the worst possible time.

OK, I'll stop trying to learn more about hydrolic motors. I did find all the equations needed to calculate things like power, given pressure and flow rate, but never did get a good feel for the size and weight for a given power. Both the pressure and the temperature of the fluid are hazardous, but normally hydrolics are used in applications where weight doesn't matter, so I assume everything is built with a wide margin for error. Some of the hydrolic lines on the mining equipment the kaolin companies use look like they've been on the machines since they left the factory back in the 50's. Accidents due to hydrolic leaks are very rare.

Anyway, I guess that's all moot now.

[QUOTE=MugenRioS2k,Nov 10 2006, 09:56 AM]Chuck
Would love to do the Rotrex step-up + our idea === very stable and precise

 

boy if RP ever gets back on this thread he is going to have a lot to think about


using the Rotrex steep up would reduce some of the losses associated with standard gears. with a + of getting more lower turbine speed for better lower rpm boost response with out having to change the main belt pulley diameter so much.


Still think our idea is the simplest and most efficient way to control boost pressure.
Just the Rotrex may further reduce some of the losses in the system.

More power at the wheels at the same air/fuel flow rates due to a more efficient blower system(less parasitic drag ). The question that is hard to answer is; this increase in Wheel power we may get by adding in the Rotrex how much is it and is it worth the added complexity to the system9 taking apart a perfectly good RP design and adding in this thing + the cooing and pump system associated with the friction gears.)



By far the best way to get the boost profile we want is to add a couple of stages to the compressor and use our device.


To explain the sheer drive I would need to talk to you in person. I will be in Macon over the Turkey-day break we should get together one day.
Did you want any pictures of the car for the shop before I start making the body mods I have planed?

 

Yea, for sure I want some pictures of the car before you change it. Digital images are best, so if you can burn them to a CD or DVD and bring them when you come down to visit. We'll get together while you're in town and I'll buy you a Big Mac or something.

 

The Rotrex fluid is likely to be thixotropic, so shear strength reduces as RPM goes up. this may be all or part of the 8% slippage change they mention. This works to a small advantage though.
Using the specs for their C30 blower from Rotrex.com:
-120,000 max impeller RPM
-1:9.49 ratio (drive:driven)
-assume a 1:1.375 RPM increase from engine to the unit via the pullies/belt
-also assume a safety margin - max engine RPM of 10K won't overspin the blower
So,
engine RPM of 3,000, Rotrex output RPM = (3K X 1.375) X 9.49 = 39,146
engine RPM of 9,000, Rotrex output RPM = (9K X1.375) X 8.73 = 108,034
** Rotrex ratio effectively becomes 8.73 due to the 8% slippage
If there were no slippage the drive ratio would have to be fixed 8.73 in order to not overspin the impeller. At 3K engine RPM, though, this reduces the blower RPM to 36,011. So the slippage provides an impeller RPM increase at lower engine RPM, without exceeding the max allowable impeller RPM at high engine RPM.

Side note: one of the pages on the Rotrex site shows an electric-motor driven version for total RPM control.

-Doug