300C's high mileage-a surprise

[John F. Russo]

In a recent Car & Driver magazine issue, the Chrysler 300C was compared to the Crown VIctoria.

(The following is a nice table in the preview screen but it doesn't come out in the final version. The numbers go as such: liters, highway, city and torque For example, Kenny Brown (4.6 liters, 19[actual], ?, 377)

Engine (liter) EPA Mileage (mpg) Torque (ft-lbs)
highway city

300C 5.4 25 17 390
Crown Vic 4.6 25 17 about 270(don't remember)

(Kenny Brown MM 4.6 19(actual) ? 377)
(I added my car for comparison)

I wouldn't buy the 300C because of the looks and because I don't support USA's major competitors- Japan and Germany.

But how does Chrysler have such a large engine with high highway mpg as compared to the Crown Vic.

I know a SOHC always has more torque capability than a DOHC. But it has more than my supercharged car!

______________________________ _____________________
2003 Dark Blue Pearl 300B (Canadian) w/Light Flint (reversed
traction control, mini spare, trunked 6 disc CD changer,
clock-in-the-radio, heated front seats/mirrors, hood light)
-Born 12/10/02; converted new then used 2/28/03
-23,000 miles
-18.5 mpg at a steady speed of 80 mph, one tank of gas
-Stock transmission (upgraded with Performance Automatic
clutches and band after stock tranny failed in 8,800 miles)
-Wheel locks (Ford); godshead valve stem caps
-Badgeless front grille by “Zack”
-Zaino waxing; RainX
Kenny Brown: 6th “Signature Series” conversion (450 hp) Born
3/28/03 (first drove it)
-Vortech supercharger (3 to 7 psig boost)
-377 RWTQ
-4.10 gears
-Baer front brakes 14 in., two piston, slotted/drilled rotors
-MMX Driveshaft
-Precision, triple disc, P/N469018-3 Precision, triple disc, P/N469018-3
-Ford Racing Stud and Girdle
-Pirelli P-Zero Asimmetrico (front 255/45ZR18 99Y; rear
255/50ZR18 102Y)
-Dead pedal
-FordChip
-3/4 of a coil from each front stock spring removed to produce
the “same” effect as an Eibach spring
-Ground clearance: 5 in.
______________________________ ___________________________
1961 Ford Galaxie, 2 dr. Club Victoria, 390CID, 375hp, 4 barrel (gone)

[Constable]

It's their multi-displacement technology thingy. Under light throttle, only 4 cylinders are in use. Under hard throttle, all eight fire. This gives you great fuel economy AND tons of power when you want it.

[RF Overlord]

I wouldn't buy the 300C because of the looks and because I don't support USA's major competitors- Japan and Germany.

Agreed.


But how does Chrysler have such a larger engine with such high mpg as compared to the Crown Vic.

Especially considering that most of their trucks and SUVs get abysmal mileage...usually dead last in comparos...

[duhtroll]

Average reports fromthe Hemi boards say the mileage is MUCH less than advertised.

Sure you can get 28MPG in one - if you go 55 all the time. Once you add the power, the mileage takes a dirt nap.

-A

[BruteForce]

... the mileage takes a dirt nap

:lol: never heard that one before. :D

[Bluerauder]

It's their multi-displacement technology thingy. Under light throttle, only 4 cylinders are in use. Under hard throttle, all eight fire. This gives you great fuel economy AND tons of power when you want it.
Someone posted here recently that 300C owners weren't getting the advertized mileage and suspected that the multi-displacement wasn't working out as well Chrysler had hoped under actual driving conditions. Your mileage may vary. Batteries not included. Some assembly required. :up: :up:

[SergntMac]

Yawn...Another 300C sumptin...John, one thingy at a time, eh?

[Krytin]

[QUOTE=John F. Russo]
I know a SOHC always has more torque capability than a DOHC. But it has more than my supercharged car!

I'm not sure the # of cams are going to dictate torque as much as displacement, bore/stroke ratio, camshaft grind and tuning will. If the nessecary trade-offs are made (usually top end hp), more torque can be found at the low end.

[TripleTransAm]

I'm not sure the # of cams are going to dictate torque as much as displacement, bore/stroke ratio, camshaft grind and tuning will. If the nessecary trade-offs are made (usually top end hp), more torque can be found at the low end.


Don't forget intake port configuration. (not so sure about exhaust port, though, anyone know?)

Too big an intake port and although you are capable of flowing a lot of air, at low RPMs (and low throttles) the velocity takes a hit.... while you may be able to reduce the restriction of the air flowing towards the intake valve(s), you lose the 'ram' effect of having a less-wide column of air speeding towards the valve(s). Sort of like a crowded narrow hallway... the folks up front can get pushed by the folks behind them, especially if everyone's moving at a good clip... not so with a nice wide hallway. (air molecules don't get trampled, though, so that's where the analogy stops...)

From recollection of when my motor was apart, the DOHC 4.6's ports are big but I don't recall them being necessarily "huge". Combined with a low restriction (and short) intake path leading to it, I can see where the 4.6's low end might suffer a bit.

There are patch solutions to large intake ports and low end torque, it would seem. I've seen LS1 ports and for the size of V8 they are positively cavernous, especially considering they feed but one intake valve per port. I think the tuned intake runners make up for this in some way... they had done away with the long-tuned runners for the LT1 (as compared to the older Tuned Port Injection) and I was surprised to see it return.

Another solution (easier for multi-cammers) is to play with valve timing as RPM increases. Changing the points at which the valves open and close with respect to the piston position (and velocity) seems to have a big effect on the torque curve. Before choosing the Marauder, I investigated the Acura 3.2TL Type S's VTEC motor and was surprised at how broad the torque curve was, considering the high RPM capabilities.

[Krytin]

Yeah TTA, that too! The variable valve timing is a concept that would flatten out the torque curve nicely & allow the motors to make big HP and big torque.