Lysholm vs. Roots: Is it worth it? - Honda Prelude Forum

ZDVS1 · 01-20-2003, 10:18 AM

Since Whipple doesn't post actual performance curves on their site, I contacted them and requested the information. Here's what I got. Had to scan them since it came snail mail.

Mods, sorry if they are too big, don't know how to resize them.

Enjoy every one. So do you think it's worth the trouble to make this work?

Scott

Artifex · 01-20-2003, 05:33 PM

Scott, I can't see those charts. They are just too small.

If you can give me a web link to a larger version, I can interpret them.

Have you read Supercharged! yet? The information there should help you interpret these charts.

ZDVS1 · 01-20-2003, 10:29 PM

Album #4290796747

This link should take you to the original album on imagestation. From there, you can access the full sized images. If it still doesn't work, PM me your e-mail addy and I'll send the original files.

I do own the book, however I haven't had the chance to read it yet. I have about $170 worth of books, all that were on the list from before. Including both Corky's books. I'm trying to start with engines-introduction, then move into that one. Time to read is just so hard to find.

-Scott

schwett · 01-21-2003, 01:00 PM

comparing those charts to the ones eaton supplies on the M62, i don't see how the lysholm blower is any more efficient.

given that it would have to turn at 10,500RPM for our motor, it shows a temperature differential of 104 degrees farenheit and a power requirement of 23.5hp at 5.8psi.

eaton claims the M62 uses 20hp and has a temperature differential of 100 degrees fahrenheit at 5psi. the eaton graphs are very small, but the differences are too small to really care about. i am bit confused by this, since the lysholm design is supposed to be significantly more efficient.

ZDVS1 · 01-21-2003, 01:23 PM

I may be confused by the punctuation of the charts. I don't see any charts at approx 5psi. I thought they were at 1.4bar, 1.6bar, 1.8bar, and 2.0bar. 2bar being about 29psi. Something a roots blower will probably never see. I am also curious as to the 40psi claim on Whipple's site. I don't see this chart anywhere.

The power numbers may be deceiving as well as the charts are in Kilowatts. 1Kw = 1.34Hp.

I'm also curious why you say it would have to turn at 10.5kRpm. The blower's max is at 13k. Though I'm planning to use a variable system(more on that in another thread), keeping in mind deminishing returns with discharge temp, shouldn't I be able to run the blower to max speed?

Please help me decipher these charts. I'm obviously missing something.

Artifex · 01-21-2003, 01:28 PM

Quote:

Originally posted by ZDVS1
Please help me decipher these charts. I'm obviously missing something.

I will. I am at work right now and very busy, but I will post something later tonight.

schwett · 01-21-2003, 02:18 PM

yes, i converted from Kw to HP, and also from Celsius to Fahrenheit.

The displacement of the blower is 1.6L, so it takes 1.375 revolutions to fill a 2.2L engine at 100% VE. The fuel cut on the H22 is 7600 RPM. 7600 * 1.375 = 10450RPM.

As far as the pressure goes... 1 bar is atmospheric pressure, so when we talk about "7psi" we are really talking about 1 bar + 7 psi, or Â± 1.5 bar. I could be mistaken, but I would be REALLY surprised if they were giving performance figures for 20.5 -> 29.5 psi. 6 through 15psi makes a whole lot more sense.

Quote:

Originally posted by ZDVS1
I may be confused by the punctuation of the charts. I don't see any charts at approx 5psi. I thought they were at 1.4bar, 1.6bar, 1.8bar, and 2.0bar. 2bar being about 29psi. Something a roots blower will probably never see. I am also curious as to the 40psi claim on Whipple's site. I don't see this chart anywhere.

The power numbers may be deceiving as well as the charts are in Kilowatts. 1Kw = 1.34Hp.

I'm also curious why you say it would have to turn at 10.5kRpm. The blower's max is at 13k. Though I'm planning to use a variable system(more on that in another thread), keeping in mind deminishing returns with discharge temp, shouldn't I be able to run the blower to max speed?

Please help me decipher these charts. I'm obviously missing something.

ZDVS1 · 01-21-2003, 03:01 PM

OK, i'm starting to see where the numbers are coming from. The actual boost pressure is the difference between the suction pressure and the discharge pressure. So the final graph is actually 1bar, being 1.4psi.

As far as the blower speed, that number of 10.5 would just fill the motor. Wouldn't you need a higher speed to build positive pressure? Or is that the necessary speed to sustain the current pressure?

This also brings another thought to me. My variable blower speed system may be pointless as I only need to maintain the ratio between the engine and the blower. What would happen if I did use this variable system and drove the blower at 10.5k while the motor was at 2k? Would this generate unpractical pressures or what would be the consequence? Would this be a way to reach the 40psi claimed on Whipple's site?

Just as a side note, this variable speed system is possible since I plan to use hydrostatic drive components instead of the belt/jackshaft type assembly. I can theoretically drive the blower at any speed and reduce the drive ratio of the blower as the engine speed increases. Therefore being able to keep the blower at an optimal speed, or reducing the speed while not utilizing the system ie. highway driving. It will be as simple as a electronically controlled valve system. I'm guessing the final product with the bypass valve/speed control will loosely mirror the functionality of the BOV/Wastegate of a turbo system.

schwett · 01-21-2003, 06:50 PM

Quote:

Originally posted by ZDVS1
OK, i'm starting to see where the numbers are coming from. The actual boost pressure is the difference between the suction pressure and the discharge pressure. So the final graph is actually 1bar, being 1.4psi.

correct, just as they recorded the actual outlet temperature, and made note of the inlet temperature. the delta is the difference between the two. eaton did it the other way around, graphing the delta in the temperature and pressure.

Quote:

Originally posted by ZDVS1
[b]As far as the blower speed, that number of 10.5 would just fill the motor. Wouldn't you need a higher speed to build positive pressure? Or is that the necessary speed to sustain the current pressure?
[b]

no, what the chart is saying is that the blower is pumping 1.6L of air at 1.4 bar. if you had a 1.6L motor you theoretically would spin them at the same speed. AFAIK the real value of those charts is in determining blower efficiency. that blower will be significantly less efficient on a LARGER motor because it will have to spin faster. i have no idea how they are getting a 2bar chart and a 1bar chart with the same internal pressure ratio and very little change in the parasitic losses.

Artifex · 01-21-2003, 09:18 PM

Quote:

Originally posted by schwett

no, what the chart is saying is that the blower is pumping 1.6L of air at 1.4 bar. if you had a 1.6L motor you theoretically would spin them at the same speed. AFAIK the real value of those charts is in determining blower efficiency. that blower will be significantly less efficient on a LARGER motor because it will have to spin faster. i have no idea how they are getting a 2bar chart and a 1bar chart with the same internal pressure ratio and very little change in the parasitic losses.

Maybe you are being misled by the wording on the chart. At the top of the chart, it does say "built in press. ratio 1.35". What that means is that the screw type actually has an internal compression ratio, as opposed to the Roots (which has none). Centrifugal compressors have one too, but smaller than a screw. The meshing of the rotors will actually compress the air a little, which in the case of the 1600a is a 1:1.35 ratio. This remains true at all speeds and inlet/outlet pressure ratios.

Frankly, I find these graphs surprising. It is very clear that these SRM units are not at all efficient. Scott, in your specific case, we wanted a target Page Ranking of 2.1. The closest chart would be to use the 2 bar chart. Looking at that chart, the adiabatic efficiency never goes above 65%. For a Lysholm compressor, that sucks.

Volumetric efficiency is not as important, although the SRM does have a small advantage over the Eatons in this case.

One big way to determine adiabatic efficiency is to look at the temperature delta, like Scwett was pointing out. If you do the conversions, the charts pretty much indicate flat out that the SRM is less efficient than the Eaton. That certainly doesn't make much sense to me. Part of the reason the Lysholm compressors are supposed to have an advantage is the internal compression ratio mentioned above. Apparently it's not helping.

One thing I will caution people about is to only compare blowers of similar displacement, at similar speeds, at similar pressure ratios. You may notice by looking at the charts that there can be a wide variation in temperature, efficiency, and drive power across these parameters. The only thing that is comparable to the 1600a is the Eaton M90, which is a 1.5L unit. Make sure you look at the M90 charts when comparing blowers.

If these charts are for real, I am now thinking that you might as well go with a Magnuson supercharger. Magnuson eked out a few more percentage points efficiency compared to a 3rd gen Eaton, so that may be the best option. Neither company graphs their adiabatic efficiency, but you could probably reverse-engineer it from the delta temperature.

I am still very surprised to see such crappy numbers out of the SRM compressors. They seem very inconsistent with their well known attributes. Scott, I hope your hydrostatic drive idea is working out, because the Lysholm idea sure isn't going anywhere.

ZDVS1 · 01-22-2003, 08:18 AM

Well shiot..... what a dissapointment. I was kinda curious about the high temps on the Whipple charts, I was hoping it was just me misunderstanding them. Oh well, on to another idea... hehe, glad all this information is being uncovered now, before I spend any money. I hate wasted expendatures.

I'm starting to wonder if my original idea of getting a used JRSC kit and retrofitting a M90 to it would be more cost effective. Have the jackshaft plate modified for cam gear adjustments, possibly an IC/custom intake manifold setup of some type and just leave it. The dimensions of the MP90 aren't that far off, it should fit in the engine bay, and most of the work is done already. I could put the money into an Endyn modification and run the boost up on that. One question on this approach: With the larger blower, is my assumption correct that it would move enough volume at lower blower speeds to maintain boost similar to the M62 and have less parasitic drag and lower temps?

EDIT: Better yet, similar blower speed/drag and temp with higher pressures??

thanks for all the help everyone

Artifex · 01-26-2003, 08:18 PM

I think I need to contribute one more thing to this thread.

There is a thread over on H-T regarding blower pre-cooling that I thought was interesting. Just on a whim, I decided to take another look at the charts on both the Eaton and the SRM compressors, because I was sure that I had missed something.

It appears as if I did miss something. There are a couple of things that screwed up my comparison. With my handy Corky Bell book and Windows calculator, I figured out the problem with the last comparison:[list=1][*]The Eaton lists temperature as a delta, while the SRM uses absolute exit temp.[*]The Eaton only shows data up to 10 psi. The SRM has data for much higher pressure levels.[/list=1]
It seems I failed to take my own advice regarding similar blower specs, pressure, and temperature. Revisiting this comparison, we can standardize this comparison by looking at specs for 10 psi, 90 deg F day. At 10 psi, Page Ranking=1.68, and a perfectly efficient compressor heats the air by 86 deg F (@ 90 F ambient). The following figures show exit charge temp and adiabatic efficiency:

The Eaton M90 is :
4k RPM - 162 F - 53% eff
6k RPM - 155 F - 55.5% eff
8k RPM - 160 F - 53.75% eff
10k RPM - 170 F - 50.5% eff

The Whipple stats for 10 psi I will average between Page Ranking 1.6 and PR 1.8.
The SRM (Whipple) 1.6L is :
4k RPM - 157 F - 61% eff
6k RPM - 159 F - 62% eff
8k RPM - 160 F - 60% eff
10k RPM - 166 F - 59% eff

As you can see from the data, the Whipple is a little more efficient. However, it is also plain to see that you are only buying yourself less than 10 degrees F difference. In my mind, cost is more important than such a small temperature delta.

Scott, in your particular case, the Whipple actually may be significantly better, because Eaton shows no indication of being able to support >1 Bar with any kind of efficiency. With a Page Ranking of 2.1, the SRM is probably worth it.

ZDVS1 · 01-27-2003, 05:49 PM

I wonder if Endyn, with all their Roots experience, could improve on these temps....

I'm also curious what ambient temp Whipple used for it's tests. And since they chart an absolute temp, not a change, what, if any difference there is with variances in ambient temps.

Artifex, you once commented about Lysholm blowers being able to support 2+ Bar pressure levels, I've searched high and low for some kind of confirmation on this and haven't found it. After looking at these charts, do you still think that's a posability with these blowers?

EDIT: Nevermind, 20C => 68F, answered my own question....