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03:14:39 - 12/29/2024
Dakota Performance
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fot80
Dodge Dakota
12/03/2001
18:07:15
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 Subject: low end torque
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Message:
Hi, excuse me for my stupidity and ignorance, but I was confused about all the performance mods that take away low end torque like an exhaust that is too free flowing. Why does this happen and what can I do about stopping it? I have drop in kn filter, jba headers, and a 50 series single in/dual out flowmater muffler on my 4.7 4x4, but I can't feel any low end torque loss, probably because I still have 3 catalytic converters (2 of which are pre-cats that I want to remove). I'm also planning on possibly getting a 70mm tb from speedtweaks and the kenne bell supercharger. I heard the Kenne bell sc gives great low end power which the 4.7 kind of lacks. Does anyone know at what rpm the kenne bell system starts to give boost? Also, does anyone know any good tricks to give more low end torque to the 4.7? Sorry about being so long winded
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CW
GenIII
 
12/03/2001
19:54:29
|  RE: low end torque
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Message:
I think it has full boost at 2000rpm due to its design (being a screw type supercharger and not centrifugal type). The only down side is that they lack the upper RPM boost that a centrifugal has. They are very good in the heavy trucks but one like mine I think I will wait and see what speed tweaks comes up with in a turbo.
Try porting or replacing the TB with a perf unit it will give you a little more low end. I really didn't notice any loss in my truck with its mods so far.
2001 4.7 5sp 3.92 LSD sport plus
Ported throttle body, IAT adjuster, flowmaster cat back, adjusted TPS from .51v to .76v
Working on custom 4" cold air intake
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Bruce P.
Dodge Dakota
12/03/2001
22:21:56
| RE: low end torque
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Message:
(fot80)
A lot of mods just "move the power around" on the RPM curve. Since the Physics behind it are
( POWER = Torque X RPM )... You can see that a given amount of torque means MUCH MORE POWER at a higher RPM. Thus... moving the torque up into the higher RPMs produces more overall power.
Many highly tuned engines have very poor idle quality because they barely make enough power at idle to keep themselves going. Thus... the idle speed in increased to compensate.
The best way to keep low-RPM torque on the 4.7L V8 hemi is to NOT remove the intake plenum and DO NOT go over 2.5 inch exhaust.
BOTTOM LINE: Naturally asperated engines have trade-offs when it comes to producing power. Very often low-RPM torque is traded for high-RPM power.
SUGGESTION;
Go to the library and read some books on the basic physics of IC engines BEFORE you start to bolt stuff on to your engine blindly. Your self-proclaimed "stupidity and ignorance" will turn into knowledge and understanding.
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markd
Dodge Dakota
12/04/2001
12:29:41
| RE: low end torque
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Message:
I had power pulleys installed on mine to help low-end torque,works graet
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GlenC
GenIII
12/05/2001
13:38:16
| RE: low end torque
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Message:
I got the KB on my 4.7, and the ability to have full boost at 2000 rpm is nice, but now that i've been reading about turbos and the Paxton, it makes me wonder if i made the right choice. But then again, i am a 4x4 with a 3" suspension lift in planning, so i think having the power earlier is better for me. My only thing is, i have an auto, and with the KB Optimizer pushin my system, it likes to kick down a gear or 2 ASAP, that pushes me up to the higher RPM range where the Paxton or a turbo would be better. Right? Bah, i dont know, i'll i know is, as soon as i can get my hands on a 5.7, this little thing is commin out. :)
GlenC
'01, CC, SLT, 4.7, Auto, 3.55 LS
Gibson single catback.
Robert Shaw 180 T-Stat. Autolite 3923s
JBA Headers.
Kenne Bell supercharged.
Roadmaster active suspension.
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