[firechicken]

Originally Posted by Tom Vaught

Chicken, chill out a bit. It is Christmas.

My point was not related to Blower speed.

Nor was mine


People think that if you spin one blower higher than another blower you will make more power.

I don't and never suggested that

The F1-R can be spun to 70,000+ rpm and will still make less HP vs the F-2. [That was my point.]

I agree but is besides the point

It has to do with MASS FLOW. If you talk in MASS FLOW (lbs/min) you can get away from the boost pressure deal, the efficiency deal (which by the way is way over-rated) and a whole bunch of other stuff.

The original question was "boost is boost right?" and using 12 psi as an example.
The O.P. seems to be under the impression that more CFM = more power which is not the case and in turn relates to compressor efficiency. That is the point.

The Eaton TVS deal is one example:

"“This marks the debut of Eaton’s TVS supercharger into the world of competitive drag racing,” said Darryl Niven, general manger – Eaton’s Supercharger Division. “The success of the TVS at the drag strip further validates that the power behind our supercharger can not only improve a race car’s performance, but any vehicle application.”

The Eaton TVS supercharger is an all-new Roots-type positive displacement supercharger that features twin four-lobe rotors that are twisted 160-degrees. The intermeshing, high-speed rotor design pumps air directly into the engines intake system that, when mixed with fuel, creates more power. By comparison, the original Eaton supercharger design features three lobes twisted 60 degrees. The fourth lobe and added twist, when combined with redesigned air inlet and outlet ports, creates a smooth, highly efficient flow of air into the engine and improves noise and vibration characteristics. "

Seems to me that the new lobe design is more efficient at compressing air therefore heating the air less and making more power.

We actually ran a lot of dyno testing on the TVS units and did not see the same efficiencies (using a Research level Dyno vs a basic dyno).

Which one had higher efficiency?

You seem to be on the Bandwagon for the "Efficiency" deal.

It's a good "bandwagon" to be on. Much better than the "bigger is better" bandwagon

I have been there and would say that reported efficiencies on maps and real world efficiencies may differ by a substantial amount.

Not disputed

Don't get too hung up on the "Efficiency" deal Chicken. That is from a Boost Engineer.

OK


Tom Vaught

Merry Xmas

[Tom Vaught]

Quote: "The O.P. seems to be under the impression that more CFM = more power which is not the case and in turn relates to compressor efficiency. That is the point."

So here is MY POINT

Chicken, here is a histogram of Compressor Efficiency over the last 50+ years.

http://www.dresser-rand.com/insight/..._8fig3_pop.htm

Over 50+ years the efficiency of the Centrifugal Compressor grew by at most 13%.

Here is a link to a chart from Vortech for their Centrifugal Superchargers:

http://www.vortechsuperchargers.com/scspecsheet.php

The Smallest Unit, (the V-5 G-Trim) can move 750 cfm at 73% efficiency and deliver 550 HP at a maximum boost level of 15 psi.

The largest Unit, (the V-4 Z Trim) can move 2000 cfm at 77% efficiency (A 4% IMPROVEMENT IN COMPRESSOR EFFICIENCY) and deliver 1450 HP at a maximum boost level of 32 psi. A 900 HP difference.

The Highest Efficiency Unit, (the V-4 X Trim) can move 1700 cfm at 79% efficiency (A 5% IMPROVEMENT IN COMPRESSOR EFFICIENCY) and deliver 1300 HP at a maximum boost level of 29 psi. A 750 hp difference. You think that 5% Efficiency Improvement got you 750 HP. I don’t think so, personally.

So Chicken, where do you think that power improvement in the engine will come from, 550 hp to 1450 hp? The 4% improvement in Compressor Efficiency or the fact that the higher horsepower unit can move 2.66 times the CFM of air through the compressor?

There is only 6,000 rpm difference between the V-5 G trim and the V-4 X Trim. You think 6000 additional compressor rpm gives you 900 more horsepower?

Think about it.

Tom Vaught

[firechicken]

My point is if you run two compressors on the same engine at the same boost pressure, CFM is the same and the one with the highest efficiency is going to make the most power regardless of the max potential of the two compressors.

The point you make is irrelevant to the question at hand.

[Tom Vaught]

Originally Posted by firechicken

My point is if you run two compressors on the same engine at the same boost pressure, CFM is the same and the one with the highest efficiency is going to make the most power regardless of the max potential of the two compressors.

The point you make is irrelevant to the question at hand.

So is yours.

You can't get two superchargers or Turbochargers (of exactly the same type and size) to make exactly the same cfm at exactly the same boost pressure on the same engine at the same rpm. . There will always be production tolerances differences in the units. The two units will never match the test unit that generated the map that "reported the efficiency numbers"because a test stand is different from a engine in a vehicle compartment, and the list goes on. So how are you going to PROVE that one unit is more efficient than the other unit, Chicken?

Give me a real world example of how you would PROVE your theory.

That is the deal You have theory and I have reality.

Tom Vaught

[Tom Vaught]

Some people know what the term "Pi" (3.14159****) is. Other people have used "Pi" to make math calculations.

To date, some people have calculated Pi out to 1.24 trillion places. Yep, I agree that my number 3.14159 is not exactly accurate. The engineering people say PI should be 3.14 (plus 1.24 trillion places or numbers). Does anyone really care Chicken?

You can RACE Turbo or Belt driven Compressor "Efficiencies" all day long for as long as you care. The reality is a Z-Trim Vortech (with more cfm capability) will make more horsepower power vs a V5-G trim unit.

Yep, your THEORY is TRUE. The reality is Does Anyone Really Care on this board?

Tom Vaught

[firechicken]

Originally Posted by Tom Vaught

So is yours.

You can't get two superchargers or Turbochargers (of exactly the same type and size) to make exactly the same cfm at exactly the same boost pressure on the same engine at the same rpm. . There will always be production tolerances differences in the units. The two units will never match the test unit that generated the map that "reported the efficiency numbers"because a test stand is different from a engine in a vehicle compartment, and the list goes on. So how are you going to PROVE that one unit is more efficient than the other unit, Chicken?

Give me a real world example of how you would PROVE your theory.

That is the deal You have theory and I have reality.

Tom Vaught

The reality is that you have just proven it for me.
Because two compressors can't make the same lb/min(not CFM) at the same engine rpm at the same boost pressure means that one of them has a higher thermal efficiency and thus more power regardless of "reported efficiency numbers".
Simple isn't it?

[Tom Vaught]

Originally Posted by firechicken

The reality is that you have just proven it for me.
Because two compressors can't make the same lb/min(not CFM) at the same engine rpm at the same boost pressure means that one of them has a higher thermal efficiency and thus more power regardless of "reported efficiency numbers".
Simple isn't it?

And what would say that .5% difference in efficiency really buy you going down the track Chicken?

Merry Christmas.

Tom Vaught

[firechicken]

Not much, but when you're talking about the difference between an F-1R and an F-2(which are the compressors in question), it's plenty.

[62fatcat]

Tom,
could density be calculated with the same boost and different intake temps with the same engine combo an different blowers, and different blower speeds?
from what i get, is if you have 2 different blowers on the same combo at the same boost level, the cooler(denser charge) is more efficent, there for making more power.
it would be interesting what the temp differnces were on Brians combo's.

the boost is boost thread was started to help george out, as i have heard this from him and others to many times.

[bad69bird]

Originally Posted by 62fatcat

Tom,
it would be interesting what the temp differnces were on Brians combo's.

I agree. I would like to put the Aux box/RPM converter on this winter, but I doubt I will have the funds.

[BruceWilkie]

IMO you likely need to have a big difference in efficiency. Averaging 65% thru your rpm range is certainly going to be better than running at 50 %. In the end though if your supercharger can meet the mass flo required for the desired hp at 50% vs 65% efficiency either will make the same hp. The only honest catch here is detonation control if both are using the same fuel. Pressure and temperature could be very different at same mass flo due to efficiency. At some point that could be an issue.

[Tom Vaught]

Thank You Bruce, well said and in much fewer words to make my point.

Procharger has lower "efficiency numbers" at many rpm points vs the Vortech units BUT because the Procharger units used by racers are typically LARGER than the average Vortech units used: (Example YSI Vortech 1200 HP vs F-2 Procharger 1600 HP) the Procharger makes more power.

The F-2 will obviously make more HP but at a lower efficiency. Chicken is hung up on the efficiency deal. That is very important IF you were comparing units of the same mass flow. Procharger says "screw that" we will just make a bigger unit, and they did.

If the Procharger unit takes the racer down the track faster than the smaller Vortech unit then the racers are happy.

"Mike" Brian's buddy was actually faster with his Vortech YSi supercharger in his BB Chebby Nova than Brian in his Firebird with the F-2 for a long time. It is the whole combination, not just one "efficiency" parameter that makes you fast.

JMO

Tom Vaught

ps George does PRETTY WELL with his combination.

[BruceWilkie]

When you look at a compressor map you can see a few things. For example if you plot for boost at various rpm levels the line rises and curves right. If you want peak boost and hp at peak rpm you chose the compressor that maps most efficiently thru that curve. This is referred to as free floating in the turbo world. Its seldom done that way these days.

Instead we use a wastegate or blow off to limit max pressure and we setup to bring max pressure in much sooner. The plot on the compressor map starts out the same but when you hit your predetermined max the line on the map goes wide right. To get the most out of this compressor requirement you spread across the map.Instead of trying to stay center and max efficiency it can instead run from the surge line(less efficiency) across center island(max efficiency) then further to the right, to once again return into less efficient areas of the "map".

THESE two examples are where compressor efficiency can be looked at and kept in consideration.

MORE important to determine, is this. CAN the compressor I'm looking at deliver the mass-flow I need to acheive my HP target?

Next question becomes how wide does your powerband need to be? That is going to be a very application specific requirement. So , you have to determine what the lbs/min airflow(mass-flow) requirements are to meet your goals across that band.

Now you need to consider compressor rpm as well. The compressor that meets your needs at a lower compressor rpm is likely a better choice than a compressor slightly more efficient, but higher compressor rpm is required. Spool up on a turbo and drive ratio on a belt drive (its effect on hp bandwidth) are important considerations.

It indeed takes large percentages of efficiency to really make a difference in the overall picture. A pair of t88's might look like a better map due to efficiency than a pair of 62-1's doesnt mean the t88's would be a wise choice for their application.

So as you can see 12 lbs boost on the same engine can be different hp peak AND average power. Yes compressor efficiency and boost psi plays a role. But in the big picture its all about mass-flow thru the engine. Most mass-flow across the intended powerband wins.

Boost is Boost, but as a measurement of itself, it's only applicable to itself. There are many other considerations.

[firechicken]

Originally Posted by BruceWilkie

IMO you likely need to have a big difference in efficiency. Averaging 65% thru your rpm range is certainly going to be better than running at 50 %. In the end though if your supercharger can meet the mass flo required for the desired hp at 50% vs 65% efficiency either will make the same hp. The only honest catch here is detonation control if both are using the same fuel. Pressure and temperature could be very different at same mass flo due to efficiency. At some point that could be an issue.

So if I understand this statement correctly, pressure(psi) and temperature would have to be greater for the supercharger at 50% efficiency than the one with 65% to make the same power. Correct?
If this is indeed true, then the compressor with higher efficiency could be run at lower boost pressure to make the same power as the unit with only 50% eff.

I think this is in agreement with my previous statements. If not, I retract all my posts and apologize for my ignorance.

I realize that there are many other factors involved but I believe it can still be said that boost is NOT boost and compressor efficiency is a major factor in determining a supercharged engines performance.

[Torment]

A less efficient compressor will impart greater heat and thus greater boost in the same engine at the same mass flow of a more efficient compressor.

An 8-71 20%OD will produce about the same cfm as a 14-71 with zero OD. If the fuel is sufficient both should make similar hp, however the intake charge will be much 'friendlier' with the 14.

I'd take a 60deg helix standard outlet 14-71 blower over a high helix pie shape retro 8-71 any day of the week - even though it's less efficient.

[Tom Vaught]

Originally Posted by Torment

I'd take a 60deg helix standard outlet 14-71 blower over a high helix pie shape retro 8-71 any day of the week - even though it's less efficient.

Amen, Brother! (:>) You have to look at the whole picture vs "race Efficiency numbers"

Tom Vaught

[firechicken]

Originally Posted by Torment

A less efficient compressor will impart greater heat and thus greater boost in the same engine at the same mass flow of a more efficient compressor.

Exactly

An 8-71 20%OD will produce about the same cfm as a 14-71 with zero OD. If the fuel is sufficient both should make similar hp, however the intake charge will be much 'friendlier' with the 14.

Exactly, but the 6-71 will be at higher boost pressure.

I'd take a 60deg helix standard outlet 14-71 blower over a high helix pie shape retro 8-71 any day of the week - even though it's less efficient.

In this scenario, the 8-71 is driven harder and in turn runs at a lower efficiency than the 14-71 at the same mass flow even though the high helix has a higher peak efficiency.

[Tom Vaught]

Originally Posted by firechicken

In this scenario, the 8-71 is driven harder and in turn runs at a lower efficiency than the 14-71 at the same mass flow even though the high helix has a higher peak efficiency.

I thought I said exactly the same thing as related to the F1-R vs the F-2.

Maybe you did not catch that deal Chicken.

All I care about is the mass flow vs the power the engine makes with that mass flow.
Bragging about a higher peak efficiency, again, means little to me vs going fast.

Tom Vaught

[bad69bird]

You guys can debate over that root style chit all you want...my street car is sooooooo efficient that it sucked up a couple of those helix 8-71 blowers at Norwalk to get a spot in the Q-16!

All I know is my basic centrifugal supercharger kicks a$$!

Anyway... J/K guys!

[Torment]

BadBird - maybe my budget will let me come back to Norwalk to play next year Maybe I could give you a run. I can't run my mouth though cuz money is tight...