The new 2.5 Liter Ecotec -- Formula 1 Piston Speeds

[dwightlooi]

Interesting Fact:

With a 101 mm Stroke and a 7000 rpm rev limit, the new 2.5 liter Ecotec will have a maximum Piston Speed of 4639 ft/min. That is a little lower than the original (2.0 liter; pre-2004) Honda S2000, but right about where a 2009 Formula 1 race car (4689 ft/min) is at and higher than a Ferrari F360 Modena (4406 ft/min).

Piston Speeds

• Honda S2000 (pre-2004) -- 84mm Stroke x 9000 rpm = 4965 ft/min
  
• 2009 Formula 1 engine -- 39.7mm Stroke x 18000 rpm = 4689 ft/min
  
• Ecotec 2.5 DI-VVT -- 101mm Stroke x 7000 rpm = 4639 ft/min
  
• Ferrari F360 Modena -- 79mm Stroke x 8500 rpm = 4406 ft/min
  

Edited April 23, 2011 by dwightlooi

[G. David Felt]

Question, We care about the piston speed why???? As long as I have the Torque and HP that I need to move my auto quickly and I am the one paying the gas bill, why is the piston speed important to me or anyone else?

[loki]

dfelt...it's a testament to racing tech making it to consumer products.... material strengths. while being fairly cheap.

[dwightlooi]

Question, We care about the piston speed why???? As long as I have the Torque and HP that I need to move my auto quickly and I am the one paying the gas bill, why is the piston speed important to me or anyone else?

Because traditionally piston speed is the biggest limiting factor on permissible engine revs and the associated durability of the engine. Contrary to what many people think, revs don't kill engines piston speed do. You see... you can turn the rotating assemblies like the camshafts and the crank at few tens of thousands of rpms without much problems -- jet engines routinely do. The stuff going up an down are a different matter. Valves are one problem area, but the biggest is the piston slugs going up and down. This is where all that power and torque is being generated and where the biggest mechanical stresses are. These stresses are generally a function of the square of piston speed -- kinetic energy = 0.5 x mass x velocity^2 and that has to be decelerated and accelerated twice in opposite directions per revolution per piston.

So... very high piston speeds means either one of two things... GM has made serious strides in the stoutness and lubrication of its engines, or the engines are not going to last! I hope its the former.

Edited April 23, 2011 by dwightlooi

[Drew Dowdell]

What are the existing 2.4 Ecotech and 2.0 LNF piston speeds for comparison?

[mike12820]

Not sure where this data is supposed to be impressive really... My 496 BBC is a mild build and runs over 4800 ft/min, I would never claim I run a race engine. This is not max piston speed either but max average piston speed right? Max speed of my example peaks well over 10K ft/min. More impressive as GXP noted is the ability to handle the accel/decel loads on the pistons of high revving engines experience. Good crank and pistons help here but quality well engineered fasteners are the unsung hero.

Edited September 19, 2011 by mike12820

[Robert Hall]

piston speed? Never heard of that measurement...how does it correlate to max RPM?

[dwightlooi]

piston speed? Never heard of that measurement...how does it correlate to max RPM?

Piston speed = stroke (in feet) x rpm x 2

Basically, if an engine makes 7000 revolutions per minute, each piston is covering a traversed distance of 2 x 7000 the length of its stroke a minute. The common expression of piston speed is either in meters/sec or feet/min.

Piston speed is important because it is one of the leading indicators of stress at the wrist pins and journal bearings within an engine. The stress loads are generally a function of the square of piston speed. Hence, when the maximum rpms are raised from 6000 to 8000 rpm, this 33% increase raised stress loads by about 78%. This is why rpms is potentially much more harmful to engine integrity and durability than high torque loads from turbo or supercharging -- because stresses increase linearly with torque loads, but exponentially with rpm increases.

Before you get scared stiff however, know that an Ecotec engine only spends a tiny fraction of this duty cycle at or near its 7000 rpm red line or its 4639ft/min max piston speed, whereas a Formula 1 car spends the majority of its life there. If you run that ecotec at 6500~7000 rpm continuously under load for 3~4 hours straight and do that every day, you'll probably grenade it. But you won't.

Edited September 20, 2011 by dwightlooi

[Drew Dowdell]

Didn't the old Quad-4 get run at those speeds AND raced?

[loki]

new info?

GM focused on increasing efficiency of the new engine by reducing engine friction and designing a new combustion system with a higher compression ratio. Friction was reduced by an average of 16 percent across the operating range through the use of a variable-displacement oil pump and an actively controlled thermostat. The redesigned combustion chamber combined with higher-flowing intake and exhaust ports reduce engine knock while increasing efficiency, as well as power and torque.

Read more: http://wot.motortrend.com/chevrolet-dishes-more-details-on-2-5-liter-ecotec-for-2013-malibu-118679.html#ixzz1YTOZ6zzV

active thermostats? interesting.

more indepth "advancements"

http://ev-olution.org/?p=27433

Edited September 20, 2011 by loki

[dwightlooi]

Didn't the old Quad-4 get run at those speeds AND raced?

Not quite. The Quad 4 had a 94 mm stroke compared to the 2.5's 101mm. It also runs at a lower redline -- 6800 rpm for the unbalanced engines and 6500 rpm for those with balance shafts. Hence the Quad 4 runs with a maximum piston speed 86~90% that of the new 2.5.