HYEPWR

7psi should "ideally" increase power by ~45%. So a 354hp engine should get to close to 515hp. 470 is pretty close to that. From what I remember from those that have it and attach boost gauges; they dont quite hit 7psi. There is some variance there---5.5 to 6.5 psi is what i recall. That 1 psi makes a difference. Plus, any boost above 5psi tends to become less efficient. All in all, getting 470hp when u are expecting 500hp is pretty close.

The Kleeman is a perfect example. In a same sized very similar engine--7psi is getting giving them 470hp.....but our AMG mills are getting 500hp with 12-13psi? doesnt quite add up.

blackbenzz

Bigger charger and higher compression engine = more power

ABALONE

Yes, but in this case Kleemann adds Eaton/Roots style type S/C on the N/A 10:5 compression M113 engine in E55/C55/CLK55. And it is in no way superior to the IHI thats in the W211 E55. The IHI is more like our Swedish Lysholm supercharger, in other words almost a "real" Twin-screw charger that is way more efficient then a Roots style like Eaton.

Slap a BIG Vortech charger on a E55 W210 N/A and then we can talk about bigger charger = more power on a high compression engine

So I think HYEPWR has a good point here regarding the psi in W211 E55.

splinter

+1

When another manufacturer supercharged an existing 6.2 liter engine, their results were significantly different. Say what you will about oft-maligned GM and their vehicles; its powertrain group engineers and produces decent machinery, IMHO.


Normally aspirated LS3:
10.7:1 compression ratio
436 horsepower at 5900 RPM
428 lb-ft torque at 4600 RPM
source

Supercharged LS9:
9.1:1 compression ratio/10.5 PSI boost
638 horsepower at 6500 RPM
605 lb-ft torque at 4000 RPM


Of course, there were myriad other detail changes between the two - like dry-sump lubrication - but the percentage and absolute differences in their respective output nonetheless supports your observation.

Snazzy ZR1 hardware -



Okay, no more thread jacking from me.

blackbenzz

The old Kleemann charger was not a Eaton/Roots but a 2.2L Autorotor compared to the 1.8L IHI on the E55. I'm pretty sure thats corect but not 100% sure. Are you telling me a 1.8L charger will flow more than a 2.2L?

HYEPWR

regardless of what the boost pressure is---its very obvious that the same mass of air is NOT getting into the combustion chamber. Its very simple math...u start with 285whp engine at sea level (14.7) and you give it 1 bar or DOUBLE the mass of air....you get double the power--570whp.

Ahmed....a drop in compression of 1.5 points is worth about -4% hp. So a Kleeman@6psi & 10.5:1 compression is equal to an E55 with 9:1 at 12-13 psi?? Every psi is worth 6.8% hp....yest the drop in compression only cost u 4%

blackbenzz

I never said the two made the same power. I disagree that every PSI of boost is worth 6.8% hp. Too many variables to make a blanket statement like that. Sc cars have parasitic loss, the more boost increases the less each PSI is worth due to heat and parasitic loss. The kleemann intercooler setup is much more efficient than the AMG one as well.

prodigymb

+1

+1

+1

ABALONE

Hey, We where talking about the new gen Kleemann, not the one you have in your car. I know the one you have is better then the IHI since it's Autorotor/Lysholm Supercharger, but not the new gen Eaton Roots, thats not a Twin-Screw.

And when Kleemann had the Autorotor/Lysholm in their N/A M113 kit, the power gain was WAY higher then today, but when you ask Kleemann it's no differens Believe me, I've actually been there in person and talked to them, and they still keep ignoring this like it's not a problem . Their speed world record car had 607 HP with a Autorotor/Lysholm.

The point is, that 0.5 bar in a 5,4L V8 should deliver 520+ HP without any further mods. And that doesn't the Eaton/Roots do.

HYEPWR

Not to belabour the point (lol...waaay too late for that)

....but; the 6.8% is from this simple fact. At sea level, normal atmospheric pressure is 14,7 psi---thats what goes in the engine. Combine that with the right proportion of gasoline and get X horsepower. Increasing atmospheric pressure by 1psi will introduce 1/14.7 more air. Which is 6.802% , which if burned at the same efficiancy, will result in 6.8% increase in power(ideally).

For sure, pressure ratio or Mass air would be more accurate. This is a rough calculation that is suseptable to many factors(many more than u even mentioned). that said, there are many online hp calculators one can use to make these approximations(ray hall turbochargers website for example). Ive found them to be quite accurate. Sure, there may be some off factor--but a factor of 2?? (taking 13psi to make 7psi hp).

HYEPWR

Just in case anyone was wondering---Im not an internet know-it-all. I just like figuring things out---especially mathamatical models.

Lets look at this problem from reverse....

In my pervious example--I said; assume the e55 engine makes 280whp NA. If we add 7psi(what I feel the combustion camber see's)...my calculator says it should result is ~420whp. Now lests add a pulley and tune. Pulleys up boost by 3 psi right?? Now plug in 10psi(7psi stock plus 3psi from the pulley) and my calculator puts the power at 475whp. Isnt this right around what pulley and tune cars put down??

So the question is;

"How can the calculation be accurate for a delta but off by a factor of 2 generally"

HYEPWR

Dont know if anyone cares, but I think I found my answer. I am posting it now for some closure to this subject.

I was look through some old posts, when I came across this old post by Marcus Frost about his Let Stage 1 results....

https://mbworld.org/forums/w211-amg/...l-writeup.html

What's interesting is the graph showing the BOOST CURVE..



As we can see: Although the stock E55 DOES INDEED reach close to 10 psi at MAX(stock)...the curve is NOT straight. At 6000rpm, where the car make peak power---the actual boost has fallen off to 8psi. A 5.4L engine with 9:1 comp running 8psi should make close to 440rwhp.....this is exactly where our E55's are at.

Similarly, when looking at the "PULLEY" Boost curve........the car PEAKS at nearly 13.5psi.....but....the boost at 6000rpm is only ~11psi.


Does anyone have any idea why boost curve looks that?? Shouldnt it be pretty much a straight line? I can understand falling off at higher rpm...but whats that double hump all about??

Ohbev

well im guessing the bypass is letting out to much boost at the start ?

HYEPWR

Finny has logged the opening of the bypass valve and reported that it pretty much stays closed under boost.

E55Pilot

The bypass valve will only open when the car is off boost under a vacuum. It is allowing the intake to bypass the supercharger when the supercharger is not engaged.

The reason you are seeing less boost on top is belt slippage. Of the top of my head and not doing the math I'm betting that even with the belt slipping the compressor is absorbing as much as 50CHP to run at 6000rpm.

The dip in the dyno chart may be ECU programming where the car is reducing the boost (probably by modulation of the throttle plate and pulling timing) in order to reduce BMEP (Brake Mean Effective Pressure) at what should be peak torque.

Does anyone know if Finny has some data logs? One quick look at a stock programming data dump will most questions

HYEPWR

If belt slip is truely the culprit.....those with the "BELT WRAP KIT" would see a 30-50whp gain the min they put it on.

As per the second part of what you said....it does make sense except that boost maxes at torque peak then falls off(according to data logs). its really weird.

E55Pilot

You can watch the boost fall off as the belt slips at high RPM's with a boost gauge.

Didn't AMG artificially plateau the torque from 2650-4500? that would explain the dip

aleksandar1099

On a side note.... What ever happened to the VRP belt wrap kit?

E55Pilot

I have one if you want to buy it

aleksandar1099

Is it worth it?