GM has yet to deliver a volume production high performance engine even close to the Lampredi SOHC or Twin Cam.
This GM 1.4 turbo Eco-Tech has a block that not impressive in any way. With a bore of 74mm and stroke of 81.3mm makes this a low rpm torque configuration. Adding to this problem it has short connecting rods of 130mm. 74mm bore is not ideal for burn as is the long stroke of 81.3mm. This makes a stroke to con rod ratio of 1.6, gonna rev like a tractor motor. Sort of ok for a low rpm turbo motor, but it will never be a performance aspirated motor like the SOHC Lampredi motor.
The Lampredi SOHC motor (1300cc to 1600cc versions) has a basic bore of 86.5mm which is near the idea diameter for burn. The 1300cc has a stroke of 55.5mm, and con rods are 120mm. This results in a stroke to con rod ratio of 2.16 !!!, only real race motors have this. It is why the stock 1300cc engine and be run to 8,000 RPM with cast iron con rods for a very long time and not explode. Much has to do with the lower stress due to the mechanical configuration. The 1500cc variant is not much lesser, bore of 86.5mm, stroke of 63.9mm, con rods of 128.5mm results in a stroke to con rod ratio of 2.01, still very high for a mass production engine. This is one of the reasons why the Lampredi SOHC motor is such a enduring rev for ever engine.
This coupled with the cam on buckets valve train makes the Lampredi motor special. It's limitations are displacement and combustion chamber shape and two valves per cylinder.
This Lampredi SOHC motor is absolutely capable endurance race motor as proven by the Lampredi SOHC LeMons race motor.
This same Lampredi SOHC motor that has gone two full LeMons races and more will go into the 74' at some point.
Oh, for fans of Hemi combustion chamber heads, these have inherent burn flame prorogation issues. Much to do with the distance from the centra spark plug to piston top distance. This is why twin spark plug hemi cylinder heads work better than the single spark plug versions. In the Lampredi twin cam, it has a two BIG valve pent roof combustion chamber, one of the many reasons why this designs has endured and worked in ways no hemi cylinder head can. The four valve pent roof combustion chamber cylinder head that has become SO common today is also found in the Rolls Royce Merlin aero engine.
Much of what is required to make a uber performance engine is very well known and understood today, marketing goals and demands and such are the driving factors as to what goes into mass production. CNC machine tool technology, materials technology and more is what allows previously well known performance engine inventions to put into mass production at very low per unit cost. The design process often happens by modeling on powerful computing with prototypes made by computer controlled manufacturing methods in short time reducing the development cycle. Modern race engines are a prime example of this to meet and game the rules of any race series.
As for GM motors.. they do not have a good record being endurance raced at LeMons. Sure, there have been teams that have put a new GM, LS series crate performance motor into their LeMons racer only to have that LS motor grenade. The Only GM motor that has any reasonable record of not exploding in LeMons endurance race duty has been the Buick 3.8L v6.
The Fiat 500 multi air is a technological marvel. Inventive idea from Professor Rinaldo Rinolfi (aka, known as the father of the common rail diesel), Multi Air (MA) demanded a series of technological innovations to work from the electronic valve train to the much involved engine management system. Time from concept to production took decades of technical work. Parts of this were licenses to BMW (vvt) to fund development of MA at a time when GM would not give MA development a penny. MA's goal was to increase fuel efficiency partly by reducing pumping losses and tighter per cycle burn via engine management. It was not intended to be a performance motor concept, but it is possible. While it is possible to graft the Fiat 500 MA power train into an exxe, it would demand integrating the entire power train system and more into the exxe. The results would be a less then ideal performance power train upgrade for the exxe.
Read this car news article from 2009-06-04. MultiAir, New Engine Technology by Fiat
www.auto123.com
IMO, there are FAR better power trains that can be installed into the X chassis once brand loyalty is discarded and the inherent goodness of a power train being the prime driving factor.
Bernice
LOTs more than simple displacement. There is significant stuff like
It might be interesting to see if the GM 1.4 turbo motor has any similarities to the 500 motor. Not sure if there is any crossover from the GM/Fiat association from the early 2000s.
Both have iron blocks, kind of an oddity when aluminum blocks are in favor.
The GM 1.4 has a normal twincam 4 valve layout. It has variable valve timing, and a simple (for these days) port injection system rather than direct injection. Most or all GM 1.4s are turbo.
There is a lot of aftermarket support.
Looks like it could be built in any form from a simple fixed cam, carbed, crank triggered NA configuration to a fully built turbo or supercharged race motor.
Does it fit? Don't know.
500madness.com
shopeurocompulsion.net
www.midwest-bayless.com
