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Discussion Starter · #1 ·
Just checking in to see if the internals of the SRT-8 motor is actually forged or not? I would assume that the crank is forged, but not too sure about the connecting rods and the pistons. Does any one here have any idea?

Would be nice to put a little 100-150 shot of nitrous and scare that E55 MB out there!! :)
 

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D_Nyholm said:
Just checking in to see if the internals of the SRT-8 motor is actually forged or not? I would assume that the crank is forged, but not too sure about the connecting rods and the pistons. Does any one here have any idea?

Would be nice to put a little 100-150 shot of nitrous and scare that E55 MB out there!! :)

Quite the engine!!! Here's some specs: (taken from this link:

http://www.allpar.com/cars/lx/srt8-chrysler.html

The new 6.1 liter Hemi engine

The 425 horsepower, normally aspirated (no supercharger) 6.1-liter Hemi matches the gross horsepower rating of the 426 Hemi engine exactly, albeit with lower torque (420 versus 490 lb-ft). It seems to beat the Elephant Engine's net horsepower, which has various sources have pegged at between 330 and (again) 425. In short, the 6.1 Hemi is the closest any V8 has come to the most successful stock racing V8 to come out of Detroit - and it gets better gas (and oil) mileage.

The SRT group uses traditional HEMI engine cues such as an orange-painted cylinder block and black valve covers. Greater power was achieved by boring the cylinders (increasing their diameter) by 3.5 mm each; they also increased the compression ratio from 9.6:1 to 10.3:1, and made other changes as detailed below.

Engine breathing was increased with new high-flow cylinder heads, a specially designed intake manifold, and exhaust “headers” with individual tubes encased in a stainless steel shell, all unique to the 6.1-liter Hemi. Larger diameter valves and reshaped cylinder ports in the heads maximize air flow. The intake manifold was designed with larger diameter runners for higher-speed tuning. Exhaust is routed through a larger-diameter (2.75-inch vs. 2.5-inch) exhaust system with 3.5-inch chrome tips.

Performance-oriented camshaft profiles were developed to balance total vehicle requirements, allowing more air in and out of cylinders. This increases performance and allows a higher top engine speed, 6,200 revolutions per minute (rpm) rather than the stock Hemi's 5,400 rpm. Intake and exhaust valve stems are hollow, and the exhaust valve stems are filled with sodium to help dissipate heat more efficiently.

The 6.1-liter Hemi V8 engine is further strengthened with redesigned components, including a reinforced engine block with increased coolant flow, forged steel crankshaft, high-strength powdered-metal connecting rods, floating-pin pistons (cooled by oil squirters), and an oil pan modified for reduced oil foaming.

More information on the SRT 6.1 Hemi is on our standard Hemi page.

Power is channeled through an A580 five-speed automatic transmission with specially calibrated driver-selectable range control. A heavy-duty four-flange prop shaft sends the torque from the transmission to an upgraded differential and axles.

Chrysler 300C SRT-8 cars ride and handling

Chassis setup for the Chrysler 300C SRT-8 is aimed at all-around performance with a number of enhancements, including tuned dampers, specially tailored spring rates and suspension bushings and larger-diameter anti-sway bars. New front and rear suspension knuckles contribute to a ride height lowered one-half inch from the Chrysler 300C. The Electronic Stability Program (ESP) has been specially tuned for the SRT-8’s performance handling characteristics.

The Chrysler 300C SRT-8 connects with the road via a new wheel and tire assembly consisting of 20-inch forged aluminum wheels shod with high-performance Goodyear F1 three-season tires (four-season tires are an available option) with asymmetrical tread. Tire dimensions are a beefy 245/45/20 in the front, and 255/45/20 in the rear.

Braking

The braking system was specially designed to slow and stop the car safely and predictably, while providing benchmark braking performance, setting a new standard for sedans in its class.

All four wheels feature stout performance calipers developed by Brembo and equipped with four pistons for even clamping performance. Up front, the Chrysler 300C SRT-8 has 360 x 32mm vented rotors, with 350 x 26mm vented rotors in the rear.
 

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Discussion Starter · #3 ·
SO, it has a forged crank, but what the heck is HIGH STRENGTH connecting rods??? Are they cast, forged, made with kiln dried clay?!?! Couldn't they be more specific like they were with everyhting else? :)

I am assuming the pistons are just regular moly or if we are lucky, forged.

Thanks for the post, got some of it answered!
 

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Amazing Hemi Engine internals -rods

Rods: The powder metallurgy process, first used for high-performance applications by Porsche, allows for a more precision part than regular forging. This has allowed the deletion of the commonly seen balance pad, which saves a bunch of weight right off the bat. Add to this a cap bolt instead of a through-bolt, plus some thoughtful design, and the result is a rod that is significantly stronger but marginally lighter

Recognize Chrysler's renaissance of engineering - feel the force
 

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The way you talk makes my right foot twitch.
 

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vengra said:
The way you talk makes my right foot twitch.
Is he giving your big toe a woody? :D
 

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Amazing Hemi Engine internals - pistons

Pistons: The Hemi's piston has more in common with a race engine than that of a street car.

The slipper-style piston allows the use of a shorter, stiffer and lighter pin. A thermal barrier/anti-micro weld coating that allows the top ring to be positioned much nearer the crown. A thin 1.5mm ring pack is used instead of the normal 5/64ths ring. A plasticated graphite coating is used on the skirt to allow closer fits without selective assembly.

Recognize Chrysler's rejuvenation of performance engineering - feel the force
 

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goddardzilla said:
Pistons: The Hemi's piston has more in common with a race engine than that of a street car. . .
Recognize Chrysler's rejuvenation of performance engineering - feel the force
Give them credit! Everything the SRT group have turned out has gained respect where it counts. The little SRT-4 is a gas to drive. Almost track ready.

And they actually build all this magnificant machinery and warranty it at silly cheap prices, compared to other high performance enthusiast machines.

Mopar lives!
 

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Amazing Hemi Engine internals - valves

Agreed Nothern Rider

The Hemi engineers made a tremendous number of on target decisions, concerning the performance/reliability aspects of the engine design.

For example the SRT8s sodium-filled exhaust valves, as NR probably knows - him having a rallying background, they are plucked directly from race engine tech.

Sodium filled valves have a pellet of sodium metal in a tubular void in the valve stem. Sodium is normally a very reactive metal, which literally burns in the presence of atmospheric oxygen. Encased in the valve stem away from the oxygen, the sodium can be used to much advantage: at engine cold temperatures the pellet is solid resting nearest the valve head. As the exhaust valves are heated the sodium melts at 98C (208F) and then the liquid metal transfers heat from the hotter valve head to the cooler valve stem by sloshing about in the tubular void. The actuation of the valve gear moving the valve causes the sloshing every time the valve opens and closes. The benefits are a cooler running valve- the valve head and exhaust seat in particular, and a more even valve stem temperature. Under the extra stress conditions of a high performance engine this equals Reliability and longer valve life


Nyholm - any more questions about the Hemi engines? :)

Vengra - right foot any twitchier now? - Should I stop - or do you need more? ;)
 

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goddardzilla, Thanks for that explanation on sodium filled valves. I have read about them for years and knew they were good, but never understood the chemistry and pysics behind the process. Thanks for the info!
 

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goddardzilla said:
Agreed Nothern Rider

The Hemi engineers made a tremendous number of on target decisions, concerning the performance/reliability aspects of the engine design.

For example the SRT8s sodium-filled exaust valves, as NR probably knows - him having a rallying background, they are plucked directly from race engine tech.

Sodium filled valves have a pellet of sodium metal in a tubular void in the valve stem. Sodium is normally a very reactive metal, which literally burns in the presence of atmospheric oxygen. Encased in the valve stem away from the oxygen, the sodium can be used to much advantage: at engine cold temperatures the pellet is solid resting nearest the valve head. As the exhaust valves are heated the sodium melts at 98C (208F) and then the liquid metal transfers heat from the hotter valve head to the cooler valve stem by sloshing about in the tubular void. The actuation of the valve gear moving the valve causes the sloshing every time the valve opens and closes. The benefits are a cooler running valve- the valve head and exhaust seat in particular, and a more even valve stem temperature. Under the extra stress conditions of a high performance engine this equals Reliability and longer valve life


Nyholm - any more questions about the Hemi engines? :)

Vengra - right foot any twitchier now? - Should I stop - or do you need more? ;)
Man, you are good. I had to switch to my left foot in the middle of that. Keep it coming, I can amaze my buddies with this stuff.
 

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Basically this means that the rotating assembly is great for a naturally aspirated car. If you slap a blower on one of theese you'll want to ditch the pwdered metal rods and go with forged rods and slugs. At least for anything more than 8 lbs of boost.

Hmmmm... I'm right around the corner from Kenne Bell.....
 

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Amazing Hemi Engine internals - valve train

The SRT8 Hemi valve train is safe to over 6200 rpm, data indicates that over 6700 rpm is OK.

The design has a hollow (lower weight) high-positioned camshaft with enlarged journals and lobes: thus the standard roller-type lifters are subjected to less side load, reducing wear and fiction losses.

The high cam design uses shorter, lighter pushrods than conventionally positioned OHV V8 cams, reducing reciprocating mass, and allowing lighter components, while still staying away from pushrod flex or collapse, thus allowing high RPM safely.

Another element to the efficacy of this hydraulic roller-liftered valvetrain is in the design of the valve springs and rockers. The valve spring is a multi-rate beehive type, tapering from base to top. A much better design than a standard non-beehive springs; it can be lighter for a given valve mass rpm ceiling, staying further from hydraulic lifter collapse, and the loss of valve lift that collapse causes.

The valves are operated through a computer-designed (finite element analysis) investment-cast steel rocker. This has produced an incredibly light part just about devoid of any superfluous material, and of much reduced inertial mass. This adds up to the ability to operate the valve train with reduced component load and wear, at higher RPM, still within an good envelope of safety compared to other conventional, and even aluminium-rockered, pushrod valve train designs.

Nyholm - Convinced now? :)

Vengra - buddies suitably amazed?- or do you need more? ;)
 

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goddardzilla said:
The SRT8 Hemi valve train is safe to over 6200 rpm, data indicates that over 6700 rpm is OK.

The design has a hollow (lower weight) high-positioned camshaft with enlarged journals and lobes: thus the standard roller-type lifters are subjected to less side load, reducing wear and fiction losses.

The high cam design uses shorter, lighter pushrods than conventionally positioned OHV V8 cams, reducing reciprocating mass, and allowing lighter components, while still staying away from pushrod flex or collapse, thus allowing high RPM safely.

Another element to the efficacy of this hydraulic roller-liftered valvetrain is in the design of the valve springs and rockers. The valve spring is a multi-rate beehive type, tapering from base to top. A much better design than a standard non-beehive springs; it can be lighter for a given valve mass rpm ceiling, staying further from hydraulic lifter collapse, and the loss of valve lift that collapse causes.

The valves are operated through a computer-designed (finite element analysis) investment-cast steel rocker. This has produced an incredibly light part just about devoid of any superfluous material, and of much reduced inertial mass. This adds up to the ability to operate the valve train with reduced component load and wear, at higher RPM, still within an good envelope of safety compared to other conventional, and even aluminium-rockered, pushrod valve train designs.

Nyholm - Convinced now? :)

Vengra - buddies suitably amazed?- or do you need more? ;)
Man, am I going to sound smart. Where do get this stuff? Or are you an engineer over at SRT?
 

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Vengra

I am just standing on the shoulders of other giants:

My DC engineer buddy, and such fine, and eloquent automotive writers as L.J.K. Setright, David Vizard, and many others

One of my favourite L.J.K. Setright quotes

"Speed is a matter of how you use your brain. Driving in the end is not about the skills, because dependence on skills is terribly immature. It's really about judgement and intelligence, and so long as your brain can go faster than your going at any time, you're all right and it isn't fast." (quoted when in his seventies)

When I bought my first 150hp Sportbike at the age of 55 -- 0-60 in 2.95 sec and 10.35 quarter mile -- I found it particularly pertinent.
 

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