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Power Delivery Similar to Two Stroke?

2K views 15 replies 13 participants last post by  DRX350 
#1 ·
Am I the only one that feels like this truck is a dog off the bottom? If you floor it the truck will accelerate somewhat softly and then it hit's it's power band and takes off with a kick in the ass. Old school dirt bike riders will understand exactly what I'm talking about. Did Dodge just tune this thing for for top end so they could claim a nice HP #?
 
#2 ·
i understand why you say that.....
 
#3 · (Edited)
Brace yourself for the slew of "it's a truck not a race car blah blah blah" comments!

But yeah, I agree. I actually feel that is something that is kind of par for the course across the entire Hemi line. In fact, Truck Trend has a review of the 2014 Grand Cherokee SRT on their website right now and they say the same thing about the 6.4.

Folks with the 8 speed and/or 3.92 gears seem happy with their bottom end, but it still doesn't change the fact that it is just a peaky design.
 
#10 ·
I wonder if it's the torque management that Ram invokes to keep us from breaking our Rams our our selves? I can't say that I've ever noticed it though but then again I have yet to floor mine from a standing start. I have gotten on it when rolling and it jumps pretty quickly. I also have the 8-speed and 3.92 gears.
 
#11 ·
The hemi is a high performance engine which started out as a car engine, adapted for our trucks with perhaps different cam profiles/timing and electronics. The hemi's in Chrysler cars also have a little lag from a starting stop, so you have to adapt by learning that not punching it from a standing start is better (it actually works better if you only half punch it at the beginning, as there is a delay programmed in for wide open throttle start). In the old days, truck engines had torque at the lower end but not much top end. As well, throttle by wire and all the other electronics are controlled by what the engineers thought the best compromise for performance, plus the fuel economy they're all competing for. Not all parts of the rpm range power delivery will be the same nor is it linear in a high perf. engine.

IMHO, a truck wasn't designed to be a racer, so you drive it differently than a car. I do notice the bit of lag from a standing start, but better if you let the rev's build a bit before you punch it. Turbo's have much worse lag........... Anyway, I try to keep my foot out of it and drive nice. Gasoline is too expensive..............
 
#13 · (Edited)
The hemi is a high performance engine which started out as a car engine, adapted for our trucks with perhaps different cam profiles/timing and electronics.
If I recall correctly the 5.7L Hemi was only in Dodge trucks for its first two model years before it finally became available in cars.

My 2004 Durango had one and besides that the only other Hemi vehicles on the road were 2003/2004 Rams. This is, of course, not counting people driving around in older cars with Hemi engines since they don't have a lot to do with the modern version which is more of a marketing deal as opposed to a truly hemispherical chamber.

As it relates to the original topic, both my personal 2003 Durango and 2005 Charger Daytona (as well as my current Ram and every Charger pursuit package I've ever driven) were all peaky. While I would personally prefer more low end power in a truck I'm not necessarily saying this is a negative...it is just a characteristic of this engine family. Is it fast enough? Sure. Would the 8 speed help compared to my 5 speed (which Ram tries to claim is a 6) as well as 3.92 gears? Absolutely. But even with all of that the engine still has a large performance jump once the tach sweeps past the magic 3K mark.
 
#12 ·
I wish you guys who think your truck is a dog off the line could have driven my 09 Sierra!!

My 13 Ram with the hemi, 6sp and the 3.55 gear is "WAAAY" better than that Sierra could have ever been!!

It had the 5.3, 4spd and a 3.73 gear ratio and without a doubt, my 13 Ram would simply slaughter it from a start guaranteed.
 
#14 · (Edited)
My Ford 5.0 was like that but if you looked at the torque curve you'd know why. My new Ram has so much more torque down low it isn't funny. Yes I feel a strong surge in power as the revs climb but this isn't our fathers 2 valve pushrod engine from the 80's and early 90's that put out peak torque at 2,500 rpm and peak hp at 4,000. Peak torque is at 4,200 and hp at over 5,000. The 5.0 in the Ford puts out 315 lb/ft at 2,000 rpm and 330 lb/ft at 3,000. This is eyeballed from a torque curve published by Ford. The Hemi, at least the 2012 model, pumps out 350 pound feet at 2,000 rpm and 375 at 3,000. The torque peak occurs at higher revs than in the days gone by but across the rev band the new engines are stronger everywhere. They are just MUCH stronger at higher rpms. I am sure we all know that hp = (torque x rpm)/(5252) so more revs equal more power.

I don't think this truck is doggy off idle at all. It just really hauls booty at higher revs. I do have the 3.92 with the 6 speed which probably helps. All the new engines are like this so I am not worried about it. I'd rather have what we have now then the old engines the only felt strong off idle because the power fell away so quickly.

NC
 
#16 ·
A lot of this also has to do with the electric throttle body, it's designed to open in a smooth motion and from a dead stop, can make engines feel doggish or less than responsive, mid 2000s GMs have an issue, on my '06, I went to a bigger TB with a faster servo, BIG CHANGE!
 
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