New E55 Ordered, Questions
04-29-2005, 11:35 AM
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2014 GL 350 on order
New E55 Ordered, Questions
MBWorld: been luking here for a while. Have a C6 Vet now and was on the list for the new C6Z06, but have always wanted an E55 since I had my 2001 BMW M5. Well finally sold the C6 amd my Pewter E55 is awaiting shipment from Germany soon. Some newbie questions:
1. why does a S/C motor have more torque than corresponding HP figures like a normally aspirated motor? Is MB lowballing the hp numbers?
2. How many 2005 E55's are there for sale in the U.S.?
3. I would like to mod mine with an entry level kit, like pulley change, ECU remap, etc. What does everyone think is the most "bang for the buck"?
4. Is there an AMG owners club in southern Michigan around Ann Arbor/ Western Detroit?
Thanks for reading this wordy post!
1. why does a S/C motor have more torque than corresponding HP figures like a normally aspirated motor? Is MB lowballing the hp numbers?
2. How many 2005 E55's are there for sale in the U.S.?
3. I would like to mod mine with an entry level kit, like pulley change, ECU remap, etc. What does everyone think is the most "bang for the buck"?
4. Is there an AMG owners club in southern Michigan around Ann Arbor/ Western Detroit?
Thanks for reading this wordy post!
04-29-2005, 03:00 PM
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Originally Posted by JokerzWld
1. why does a S/C motor have more torque than corresponding HP figures like a normally aspirated motor? Is MB lowballing the hp numbers?
For example, a 1990 Corvette with a 5.7 L V8 made 245 HP and 330 lb-ft with no blower. The peak power was achieved at around 4000 rpm. The motor. with its small valves and ports couldn't flow much air above that point, and it ran out of breath by 5000 rpm.
The DOHC ZR-1 Corvette from the same year made 375 HP and 370 ft lbs of torque, from the same 5.7 liters, but the power peak was at about 5400 rpm. The same motor, when modified with ported heads/intake, etc can make 500 HP at 7000 rpm, but torque will be in the 400-420 lb-ft range. It's the 7000 rpm peak (well above 5252 rpm) that inflates the HP number.
HP= Torque x rpm/5252....basically, HP = torque over time. So a higher revving peaky motor makes more torque at higher revs, ie high horsepower, but low end torque is lacking.
Supercharged motors (at least the positive displacement ones like in the AMG cars, Jaguars, Fords, Pontiacs, etc) have high volumetric efficiency at low RPM, hence the low end torque, and lower power peak. Aftermarket centrifugal superchargers do not follow this rule, because they don't have the copious boost at 2000 rpm that the AMG's lysholm blower does.
Hope that helps a bit....
Last edited by DoctorV8; 04-29-2005 at 03:03 PM.
04-29-2005, 06:33 PM
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'06 E55, '05 SLK55, a few others
Also, yes, the motors are underrated. An E55 supposedly has 469 HP, but the RWHP numbers are 400-425. This would easily put the crank HP in the 500+ range with the drivetrain in the E and any reasonable figure for losses.
04-29-2005, 09:42 PM
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Originally Posted by DoctorV8
The torque being higher than the HP reading is not unique to just supercharged motors, but rather, any motor that makes its peak HP at below 5252 rpm.
For example, a 1990 Corvette with a 5.7 L V8 made 245 HP and 330 lb-ft with no blower. The peak power was achieved at around 4000 rpm. The motor. with its small valves and ports couldn't flow much air above that point, and it ran out of breath by 5000 rpm.
docV8: very informative, thank you!
The DOHC ZR-1 Corvette from the same year made 375 HP and 370 ft lbs of torque, from the same 5.7 liters, but the power peak was at about 5400 rpm. The same motor, when modified with ported heads/intake, etc can make 500 HP at 7000 rpm, but torque will be in the 400-420 lb-ft range. It's the 7000 rpm peak (well above 5252 rpm) that inflates the HP number.
HP= Torque x rpm/5252....basically, HP = torque over time. So a higher revving peaky motor makes more torque at higher revs, ie high horsepower, but low end torque is lacking.
Supercharged motors (at least the positive displacement ones like in the AMG cars, Jaguars, Fords, Pontiacs, etc) have high volumetric efficiency at low RPM, hence the low end torque, and lower power peak. Aftermarket centrifugal superchargers do not follow this rule, because they don't have the copious boost at 2000 rpm that the AMG's lysholm blower does.
Hope that helps a bit....
For example, a 1990 Corvette with a 5.7 L V8 made 245 HP and 330 lb-ft with no blower. The peak power was achieved at around 4000 rpm. The motor. with its small valves and ports couldn't flow much air above that point, and it ran out of breath by 5000 rpm.
docV8: very informative, thank you!
The DOHC ZR-1 Corvette from the same year made 375 HP and 370 ft lbs of torque, from the same 5.7 liters, but the power peak was at about 5400 rpm. The same motor, when modified with ported heads/intake, etc can make 500 HP at 7000 rpm, but torque will be in the 400-420 lb-ft range. It's the 7000 rpm peak (well above 5252 rpm) that inflates the HP number.
HP= Torque x rpm/5252....basically, HP = torque over time. So a higher revving peaky motor makes more torque at higher revs, ie high horsepower, but low end torque is lacking.
Supercharged motors (at least the positive displacement ones like in the AMG cars, Jaguars, Fords, Pontiacs, etc) have high volumetric efficiency at low RPM, hence the low end torque, and lower power peak. Aftermarket centrifugal superchargers do not follow this rule, because they don't have the copious boost at 2000 rpm that the AMG's lysholm blower does.
Hope that helps a bit....
