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Pittdawg
Dodge Dakota
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3/09/2003
19:52:12
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 Subject: 4.7, 70mm tb, and low end
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Those of you with the 70mm tb, how did it affect the low end, Fastman says anything over a true 68mm hurts low end, what do ya'll think?
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TheSync
Dodge Dakota
JOIN HERE
3/09/2003
20:02:49
| RE: 4.7, 70mm tb, and low end
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Doesn't the 4.7 liter come with a stock 68mm throttle body?
And if it does come with a 68mm, is it worth it to upgrade it to a 70mm?
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Pittdawg
Dodge Dakota
JOIN HERE
3/09/2003
23:21:48
| RE: 4.7, 70mm tb, and low end
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Sync...2001+ have a 68mm with a 3mm restriction, rendering it a "true" 65mm. Once again, those of u w/ a 70mm, what do ya think?
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Demon Dakota
DakotaEnthusiast
3/09/2003
23:54:52
| RE: 4.7, 70mm tb, and low end
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The 2001+ come with a 68mm TB, but it has the torque hump that ramps it down to an actual inner diameter of 65mm. The FASTMAN 68-70mm TB's would be a very good improvement over the stock setup, with the milder modded engines using the 68mm TB, and more heavily modded engines (or future heavy modded engines like mine) can use 69-72mm...and yes, he'll go as big as 72mm if you want him to (has to be a 2001+ core, though). The 2000 4.7L TB is 65mm necked down to like 62-63mm actual inner diameter.
K&N Drop in AF (CAI during summer months)
True Dual exhaust and removed third cat
HO Cams & HO Intake
FASTMAN 70mm TB
Autolite 3923 Plugs
TPS @ .76 VDC
IAT Adjuster Mod
14.52@94.2 MPH at Silver Dollar Raceway
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DKZ 4seven
Dakota Enthusiast
3/10/2003
01:03:03
| RE: 4.7, 70mm tb, and low end
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Message:
Pittdawg...what are your upcoming mods for your 4.7? Cams, intake, etc.? I guess it might be safe to ask the balance between intake and exhaust C.F.M's. How does it work again, high velocity & low pressure = torque, visa~versa equals more H.P. @ higher speeds (e.g. midrange)?
If a 70mm TB does drop the low end a little due to a slower speed of air (less dense a charge of fuel/air) into the intake manifold at no or slow speeds, then maybe the gains in the midrange might be greater than the lower end loss overall. A bigger TB can handle a greater air volume (and lower pressure) that the engine uses at higher speeds.
If you look at some of the guys who are running H.O. Cams on their 4.7 (e.g. DemonDakota or Canucker) If I recall their previous posts correctly, I don't think that they experienced any loss of of low-end power (or maybe not much worth mentioning at all).
I hope that I'm partly right on this, at least.
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DKZ 4seven
Dakota Enthusiast
3/10/2003
01:08:20
| RE: 4.7, 70mm tb, and low end
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Whoops?! Sorry Demon, I was a little late on that one...
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Demon Dakota
DakotaEnthusiast
3/10/2003
10:24:03
| RE: 4.7, 70mm tb, and low end
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Message:
It's all good man :) My TQ has gone up (although only slightly with the HO Intake mod) with everything I've added so far. The HO Cams and the exhaust showed me the biggest gains overall (at peak RPM). Low RPM loss isn't really something I care about (hell, my dynos start at 2000 RPM, and it's plenty there). I can break loose more easily now then when stock, so those who say you lose low end TQ with these mods hasn't done them.
K&N Drop in AF (CAI during summer months)
True Dual exhaust and removed third cat
HO Cams & HO Intake
FASTMAN 70mm TB
Autolite 3923 Plugs
TPS @ .76 VDC
IAT Adjuster Mod
14.52@94.2 MPH at Silver Dollar Raceway
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Texas Todd
Dodge Dakota
JOIN HERE
3/10/2003
10:36:21
|  RE: 4.7, 70mm tb, and low end
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Message:
I think it's accepted that installing HO cams, INCREASES low end torque! MIne sure did! I thought everyone says you get alot more low end form the cams. Then, with dyno graph to back it, that the HO intake, doesn't really hurt the low end gains, and it pulls well about another 1000 rpms!
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Texas Todd
Dodge Dakota
JOIN HERE
3/10/2003
11:03:55
| RE: 4.7, 70mm tb, and low end
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And BTW, I ran accross a post about dyno runs, that show a 72mmTB, on a stock 4.7, adding 15peak HP! I don't have time now to find the link, seemed legit though.
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Demon Dakota
DakotaEnthusiast
3/10/2003
12:52:22
| RE: 4.7, 70mm tb, and low end
IP: Logged
Message:
Dang Todd, that guy with the 72 has to have more mods than me to get 15 HP from 2mm of TB size increase. That would be killer though!
K&N Drop in AF (CAI during summer months)
True Dual exhaust and removed third cat
HO Cams & HO Intake
FASTMAN 70mm TB
Autolite 3923 Plugs
TPS @ .76 VDC
IAT Adjuster Mod
14.52@94.2 MPH at Silver Dollar Raceway
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