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08:28:04 - 11/17/2024
Dakota Performance
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.alex.
Dodge Dakota
JOIN HERE
11/26/2002
16:01:58
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 Subject: Loss of low-end on 4.7??
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Message:
There has been all kinds of complaining rumors and general whining about loss of low-end torque after installing various parts. Thos parts include the 70 mm TB, the 72 mm TB, the HO intake manifold, the 3" cat-back exhaust, etc.....
Three things:
1. If you mean the torque range from 1000 rpm to 2000 rpm, then you have bought the wrong engine. You needed to have bought a 5.9 liter and stroked it out to a 408 motor and then added the KB Supercharger on top of that. That's the only way to make torque. Better yet, you need to go get a Cummins Diesel.
2. Things work together in systems on an internal combustion engine. You can't just bolt on one thing and have it be completely effective by itself. If you add a 3" cat-back exhaust, and nothing else, you will not see very impressive gains. If you add a 72 mm TB and nothing else, you will not see very impressive gains. You have to think in systems. And you have to be willing to install things in systems, as well. Groups of parts will get you effective power gains.
3. I have the following list of engine modifications:
* 72 mm F&B Throttlebody
* Leach PCM Flash
* 3" Exhaust from the factory y-pipe all the way back
* No Clutch Fan
* Volant Cool Air Tube & Filter
* 21# Ford Motorsport injectors
* HO Cams
* HO Intake Manifold
* For Dyno Runs & Drag Strip Only: Short Belt that misses the Power Steering Pump & Alternator, and Removed Air Filter
I have dyno'd my truck with both the 70 mm TB and the 72 mm TB. On each dyno run, the operator punched it at about 1800 rpm and from that point, it was making +/- 270 lb/ft of rear wheel torque all the way up to 2800 rpm. From 2800 rpm, the torque curve rose up to 304 lb/ft with the 70 mm TB and up to 308 lb/ft with the 72 mm TB. The torque peaked at 3750rpm with the 70 mm and it peaked at 3500 rpm with the 72 mm.
From that point forward, the engine is running too rich and the Leach Flash will have to be modified. I will be working that out before Christmas.
As far as losing low-end torque, I'm not sure what you mean. The motor is rated at somewhere close to 300 lb-ft of torque at the crank (not the rear wheels) from the factory. If you account for 15% loss from the 5-spd driveline, then this motor is making a dinner-table flat 315 lb-ft of torque from 1800-2500 all day long. It only climbs from there.
3b. Let me repeat: if you are worried about losing torque from 1000 rpm to 2000 rpm, then you bought the wrong motor. Please buy a diesel and get happy.
That is all.
alex
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Chipster
Dodge Dakota
JOIN HERE
11/26/2002
16:36:22
|  RE: Loss of low-end on 4.7??
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Message:
Hey Alex, Ive got almost the same setup as
you. It all works together. After I did the 3"
from the Y pipe back, my truck won't accelerate
as quick as it did before. My next step was the
Kenne Bell flash (I have a 2001 Auto, no
Leach available). That put everything together
and now my truck screams. I ran a 14.90 @
92mph, with a 2.24 60'.
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.alex.
Dodge Dakota
JOIN HERE
11/26/2002
16:42:46
| RE: Loss of low-end on 4.7??
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Message:
You're right in line......
I ran a 14.99 in full street trim. I am hitting 14.5's @ 92 mph with sticky tires and my 3.55 rear end (Club Cab). Once I get the air/fuel ratio tuned on the Leach flash (it's waaaay fat from 3500 rpm on up) I'll be looking for a few more tenths....
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Dr.Dakota
Dodge Dakota
JOIN HERE
11/27/2002
16:46:38
| RE: Loss of low-end on 4.7??
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Message:
I got the Mopar Ho cams and intake, 360 air intake, IAT adj, TPS @ 0.76VDC, indexed 3923's, 180 thermo, 3" exhaust w/ hi-flow muffler, all in a AWD/Automatic '01 4.7L CC, and when I added the HO cam and Intake (the last modification I did) my truck accelerates better. Both from a standing start, a rolling start or passing at highway speed. No noticeable loss of torque. In fact I would go as far as saying that:
Add cam, more hp and torque vs. stock.
Add intake, more hp and torque vs. stock
Add both, more torque and much more hp than stock.
Either way, more torque than stock...so why do people say I'm losing torque. Those are the same people that haven't even used the ho stuff yet.
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