SideStep

Why does the Maggie's boost take a jump right 5200rpms???

andereck

So where was the test done?

Not photoshop I hope.

I am disputing the magnason's boost curve, and I'll happily eat crow if you'll share the test facility.

unit213

Very good illustration Tony.

Of course, everyone has differing opinions/views/results with centrifugals vs. positive displacement/roots blowers. That graph displays the typical
relationship between the two. This should prove useful to the folks who
aren't all that knowledgable regarding blower setups.

LSs1Power

iTrader: (5)

Looking at that graph again i just noticed that a stock LS1 will make more TQ and HP than that procharger setup you listed below 3K RPM which is just not possible. That is very low and i wouldn't base any purchase based on this dyno sheet.

andereck

and just cracking the throttle on the magnuson is worth 100lb/ft.

Nine Ball

iTrader: (38)

this is a low compression 5.3L truck engine with stock heads, not an LS1.
5.3L = rated at 285 hp stock
5.7L = rated at 345 hp stock

At lower rpm, you also have to consider the parasitic losses of turning a blower, and that a centrifugal blower isn't making full boost. It could very well be 'less' than an NA setup at lower rpm.

You guys are reading into the numbers too much, just consider these curves and the shapes of them as representative of the types of blowers. Sure, if we had a chart showing 15 psi boost and maybe 8K rpm, the centrifugal would shine. This is merely a comparison of two combos in a very well controlled environment, with hardly any variables changed.

andereck

I am not disputing the fact that a positive displacement blower is going to have a flat torque curve. The reason it has a flat torque curve is because its airflow is fixed. The torque doesn't come out of thin air (sorta a pun) . The roots also has a flat boost "curve". It doesn't dramatically ramp up through the powerband like a centrifugal. It will peak up at the end as VE% takes a downturn after the torque peak. This is due to breathing restriction of the engine combination.

The magnuson gets its own intercooled intake manifold that the procharger doesn't "benifit" from. Is this intake worth 100 lb/ft at the start of the dyno pull? Maybe? If it is then they have done a helluva job on the intake. Now for the sake of arguement give the procharger that intake with an adapter. What happens to your curve when the procharger gets another 80-90 lb/ft from the manifold? You can't say the magnuson is giving it 100 lb/ft at the start of the pull because its not registering the 4-5 psi you'd have to have to do that yet.

You're right, I am reading a lot into the numbers because that's what its here for. Otherwise there wouldn't be any numbers on the chart.

Its not apples to apples because of the necessary intake swap and the bogus boost curve.
Here is a test by Duttweiller on magnuson's site: http://www.magnusonproducts.com/images/dyno/dyno011.jpg

You'll notice that this is also about a 10 psi setup. From 3500 to 6500 the boost only varies 1 psi and tails up at the end due to breathing restriction. This is a far cry from what was posted you have to admit.

Parasitic loss is not an issue. The procharger is a centrifugal compressor and parasitic loss increases with the mass of the charge its compressing. It increases with airflow so at low rpm the loss is minimal. The magnuson on the other hand is a positive displacement blower and the compression is done in the intake manifold. Its parasitic loss is fairly high from the time the throttle is fully open and also increases with rpm.
This does not explain the low rpm power discrepancy, and it is a discprepancy.

I don't want to sound as if I'm complaining about a magnuson dyno test because the eatons have their place and are a solid unit. I also recommend a setup like that for someone who does a lot of towing. Which I often do. You may or may not know what I do for a living. If you do then don't think I don't have an open mind because of that. There are plenty of magnuson tests out there and nobody is disputing their solid torque production but I don't think procharger was given a fair shake and I don't agree with the results as posted.

gametech

iTrader: (1)

The boost curve shown for the magnuson looks entirely wrong.

94notopz

Is a nice comparison but, I think all the parameters were set in the Magna's favor. The D1 is probably oversized for that motor and boost. The D1 should be able to make 20psi boost on that engine yet they are only comparing what the D1 will do at half's its speed. Would be curious to see what a better sized P1 would do since it is more tailored to that amount of HP and boost. Still may be the same results though... who knows.
The "old school" non-intercooled roots were very ineffiecent but, the newer and intercooled roots are so much better.

PappyDan

iTrader: (4)

nine ball the graph you are showing is not right.
if you check out the post over on PT.net and look over to the right on boost pressure you will see that the magna is at about 5.5 psi at 2000 rpm.
the way you have it posted now shows the pressure lower then what it should be.

DeltaT

iTrader: (5)

Also hobbling the centrifugal with an advance curve for a Roots is bogus, since you'd be running pretty much normal advance for the first half to 2/3rds of the rpm band.

I'd call this "Marketing data", processed, tweaked and canned, instead of factual data.

If you took a motor optimized for the centrifugal and slapped a Roots on without changing anything (especially advance curve) it would probably break hard.

Jim

andereck

After looking at the posts on performancetrucks.net is see where the graph was created from two tests and nineball pasted them together for ease of comparison in that thread. Some information was reformatted and the scaling is off but I understand the motive.

While I'll disagree with some of the finer points I don't think it was intentionally done to mislead, though it will. Such is the nature of any information presented on the internet though.

Good times!

LS1 Cobra

A fairer comparison would be to give the two combinations to two different tuners. Set the rules for the tune i.e. Maximum RPM, Maximum Boost, Safe AFR ratios and no knock etc. Let them try for the best results out of their combination and then run them both up on the same dyno.

I'm currently building an Eaton M112 setup for the LS1 in my Cobra. Other guys in the club are running centrifugal blowers with good results but I just wanted something different. Both will make more power than you can realistically use in a light weight Cobra. It then comes down to what you want to see when you open the hood.



Cheers

2001WS6Vert

I think Nineball is just trying to enlighten some FI people about how the Maggy pulls down low (he's owned a couple Mag cars I think). I was in an 01 Z06 that BLWNTA installed a Magnacharger on and was quite impressed with the pull in the lower RPM range. For a street car it really is nice. For a truck I don't think I would consider anything but a Magnacharger or Kenne Bell due to the low RPM power gain. It's cool the way they wrench they tires loose right off idle. I don't think there is intention to mislead, it is just showing that if your desire is more power down low you should consider this type of blower because in that range it is superior.

obZidian

iTrader: (2)

exactly, its just a representation of HOW these blowers react when installed.

Now, the tune is key in both applications and both can be made to outshine the other within a certain boost range. The procharger graph is off, tune is FAT, its not given enough room to flow and make the power. The maggie is also a bit skewered and a misrepresentation of its typical boost charactertic.

HOwever, basically this just shows that the eaton will creat a swell of power from the line while the prochager waits a bit before surging up with power. Pick you poison, they both do a nice job within their respected ranges.

novi2000

iTrader: (2)

nice, but i have never seen a roots/eaton out perform a centri on the top end of the rpm band, normally the roots fall off at about 5700 and the tourqe is flat line and the centri just keeps climbing.

smokinHawk

iTrader: (48)

ya same question, which super charger was that tuned on, since each boost curve is different they would need different tunes to take advange of each.

LSs1Power

iTrader: (5)

Usually it doesnt... Most of the dyno's i have seen for similar setups shows that the Maggie TQ pulls ahead until 3000-3500 RPM and after that the D-1SC will pass and never look back. That D-1SC graph is misleading and one of the worst SC graphs i have even seen. Hell a powerdyne is not that bad lol. If you wanna see a true D-1SC graph with 7.5-8psi look at this graph... 258rwhp 186rwtq gain with a D-1SC 8psi and a cam with stock heads over stock and of course the full exhaust.

Gold Phoenix

iTrader: (1)

I agree with the timing issue. With a positive blower, you have to pull some timing from the lower RPMs to prevent knock since you have boost almost right off idle. If you use the same tuning on the D1SC, you loose alot of low end torque. Also, with the boost off idle, you are pushing more pressure again the blower which in turns require more power from the engine. The D1SC is less likely to require much power until it starts seeing boost. At the higher RPMs, the D1SC will have cooler airflow over the roots. The Roots setup uses a water-to-air intercooler versus the Air-to-Air of the Procharger. The water type has a better way of removing the heat from the compressed air. That is also assuming that ice water wasn't use. And once last comparison, the roots is a draw-thru induction with short intake runners where the Procharger is blow-thru with the stock long intake runners. If anything, the Procharger should show a fatter torque curve than show here since the long runner promote better low-end torque. So yes, these test are not equal.

Nine Ball

iTrader: (38)

Thats incorrect. The Magna on my C6 makes peak power at 7000 rpm, which also happens to be my rev-limiter. If I had the ***** to spin a stock bottom end to 7500 rpm, it might peak a tiny bit higher, but its still climbing, not falling off.



The main restriction on older Magnas was the 78mm t-body. With the 90mm t-body they pull pretty good at higher rpm.

Mine is making ~550 Dynojet rwhp at 5 psi max boost, stock LS2 with a 230/230 114 cam. Stock unported heads, with longtubes.