^This is how I interpreted it as well.
That being said, there was an “engineer” involved in this blower selection process along the way, which is unsettling seeing the blower they chose.
I got the impression he was saying he wasn’t going to get a baseline run ie: the 1/4 pre-PES for fear of breaking the existing clutch. It seems like he’s willing to put it to the test once his kit is installed. We’ll have to wait and see how this thing plays out…and if he continues his quest for transparency.
I love when people boast about being an engineer…and then miss simple things like the fact that the M90 means your $9,000 supercharger kit will only match cars with headers and catback + LW parts and tune. Certainly the bolt on car will spend a boatload ($6,000 or so) but ask yourself what you’d rather have…a stock S4 with a $9,000 supercharger kit that makes you about 80 hp and you still have restrictive stock exhaust manifolds/downpipes (aka a dream cylinder wall scoring setup with the cast B67 pistons) or would you rather have the full JHM bolt on suite, and $3,000 in your pocket to make similar power? The opening of the JHM team boost vs. team NA video answers it…when they rev the two cars. I absolutely love that clip.
The PES supercharger should of came with a lifetime supply of ice to throw on the manifold
this guy is interesting
curious post here. estimated 850cfm at 7k rpm…
[QUOTE=tmorgan4;9923056]Lots of people are quick to jump on the ‘PES sucks’ bandwagon that know nothing about superchargers but like to repeat what others have posted. I’ve never owned a PES product and didn’t want to voice a negative opinion about PES without some facts to back it up. So I came up with this…
I was hoping to do some quick, completely unbiased calculations. Lots of assumptions were made that could significantly skew the results but it gives you a pretty good idea of how poorly the M90 is matched to the 4.2L.
I could only find the 5th generation M90 compressor map so that’s what I used. I don’t have PES or stock crank damper diameters so trying to figure out actual flowrates for a given rpm weren’t possible. I played with boost numbers using the Borg Warner Matchbot tool to approximate required boost to match a HP curve produced by PES.
The results speak for themselves.
http://i247.photobucket.com/albums/gg121/tmorgan444/AudiS4_PesG4.jpg
[/quote]
is he randomly plotting RPMs??? If you know the pulley size, and engine speed, you know the supercharger RPM. Iif you know the supercharger RPM, and you know that the manufacturer is telling you beyond XX,XXX RPM you’re at 30-40% efficiency (aka useless) you know the CFM you’re moving.
If you know the CFM you’re moving, you know the power you can make.
There’s a reason Eaton doesn’t chart much beyond the map shown. The RPMs are unusable and the efficiency is for shit, so nobody would bother looking at it.
Where he has his fictitious 7000 RPM noted, the blower would be pushing 17000-18000 RPMs, 20-30% efficiency, and basically the car would be going in reverse.
Here’s what a smart guy had to say about this 5 years ago…
[quote=beemercer]the absolute max effluent flow rate of a 5th gen Eaton M90 3 lobe roots compressor at 12k RPM is 540 CFM. Therefore the M90 really can’t provide the extra flow needed to produce extra power, so it relies on the extra pressure of the intake charge to increase mass flow. The problem is, that at 5psi of boost there is only a roughly 33% increase in pressure. This increase to intake charge density can be easily negated by a decrease in the temperature differential caused by the compression (Intake temp/Exit temp is directly proportional to mass flow rate).
[/quote]
Here’s what Eaton said…
[quote=Eaton’s webpage]Eaton M90:
To flow 450 cfm, the M90 must run at 10,000 rpm.
This requires 20 HP and results in temperature rise of 100 degrees F
[/quote]
450 CFM = about 300 hp for the record. You can see that boost is already causing heat and problems at 450 CFM. This guy is saying 800+ CFM? That would be 533 hp or so in a perfect world…but in a perfect world the car wouldn’t be boosting the hell out of the air and heating it up to the point it becomes useless for making power. You’re effectively driving your car at 8000 feet on a hot summer night
another classic
It seems like he is trying to advertise his shop or place of work for free but mask it with semi related banter. He has an odd way of trying to obtain new customers in that thread.
yeah, exactly . Wants everyone to know he’s smarter than them…then posts in his signature that he has a GIAC tune and ‘full exhaust’. Anyone want to bet me that it’s a Milltek?
this guy is interesting
curious post here. estimated 850cfm at 7k rpm…
[QUOTE=tmorgan4;9923056]Lots of people are quick to jump on the ‘PES sucks’ bandwagon that know nothing about superchargers but like to repeat what others have posted. I’ve never owned a PES product and didn’t want to voice a negative opinion about PES without some facts to back it up. So I came up with this…
I was hoping to do some quick, completely unbiased calculations. Lots of assumptions were made that could significantly skew the results but it gives you a pretty good idea of how poorly the M90 is matched to the 4.2L.
I could only find the 5th generation M90 compressor map so that’s what I used. I don’t have PES or stock crank damper diameters so trying to figure out actual flowrates for a given rpm weren’t possible. I played with boost numbers using the Borg Warner Matchbot tool to approximate required boost to match a HP curve produced by PES.
The results speak for themselves.
http://i247.photobucket.com/albums/gg121/tmorgan444/AudiS4_PesG4.jpg
[/quote]
is he randomly plotting RPMs??? If you know the pulley size, and engine speed, you know the supercharger RPM. Iif you know the supercharger RPM, and you know that the manufacturer is telling you beyond XX,XXX RPM you’re at 30-40% efficiency (aka useless) you know the CFM you’re moving.
If you know the CFM you’re moving, you know the power you can make.
There’s a reason Eaton doesn’t chart much beyond the map shown. The RPMs are unusable and the efficiency is for shit, so nobody would bother looking at it.
Where he has his fictitious 7000 RPM noted, the blower would be pushing 17000-18000 RPMs, 20-30% efficiency, and basically the car would be going in reverse.
Here’s what a smart guy had to say about this 5 years ago…
[quote=beemercer]the absolute max effluent flow rate of a 5th gen Eaton M90 3 lobe roots compressor at 12k RPM is 540 CFM. Therefore the M90 really can’t provide the extra flow needed to produce extra power, so it relies on the extra pressure of the intake charge to increase mass flow. The problem is, that at 5psi of boost there is only a roughly 33% increase in pressure. This increase to intake charge density can be easily negated by a decrease in the temperature differential caused by the compression (Intake temp/Exit temp is directly proportional to mass flow rate).
[/quote]
Here’s what Eaton said…
[quote=Eaton’s webpage]Eaton M90:
To flow 450 cfm, the M90 must run at 10,000 rpm.
This requires 20 HP and results in temperature rise of 100 degrees F
[/quote]
450 CFM = about 300 hp for the record. You can see that boost is already causing heat and problems at 450 CFM. This guy is saying 800+ CFM? That would be 533 hp or so in a perfect world…but in a perfect world the car wouldn’t be boosting the hell out of the air and heating it up to the point it becomes useless for making power. You’re effectively driving your car at 8000 feet on a hot summer night
another classic
I’ve been meaning to ask and I think Jimmy gave me an answer (I might have glossed over it) but why on earth did they place a small IC above one of the hottest areas of the B6/7 S? I’m open to a day of schooling [:)]
It seems like he is trying to advertise his shop or place of work for free but mask it with semi related banter. He has an odd way of trying to obtain new customers in that thread.
yeah, exactly . Wants everyone to know he’s smarter than them…then posts in his signature that he has a GIAC tune and ‘full exhaust’. Anyone want to bet me that it’s a Milltek?
He works at a shop that sells Giac tunes so he probably got it for free. A while ago he posted in one of his many threads that the previous owner made the exhaust. It has 3" downpipes with a 2.5" catback. That guy is cheap as shit.
There are just so many reasons in this thread to never go read audizine.
I’ve been meaning to ask and I think Jimmy gave me an answer (I might have glossed over it) but why on earth did they place a small IC above one of the hottest areas of the B6/7 S? I’m open to a day of schooling [:)]
There’s a fine line between ignoring AZ and trying to smack down some of the misinformation that can happen over there.
Very true. Hats off to all you guys. When all the good contributors leave the nuts run wild. There’s definitely a need for real information over there. I suppose my outlook is more point the interested people here let the nuts stay there and talk to themselves.