4.7-Throttle Body Sizing
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Joined: Mar 2011
Posts: 13
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From: San Antonio, TX
4.7-Throttle Body Sizing
It's time for my next mod, and I was thinking about a throttle body.
I DO NOT want to spend over $200, so my options are limited.
Its either Fastman or HiPotek, unless I find a used F&B.
Anyways, I'm debating what size I should use!
Since this is my first thread and I dont have my mods listed, or even what I drive for that matter, here it is:
2002 QC Ram 4.7
HO Cams
JBA Shorties
High Flow Y-Pipe
Single 3" Exhaust, w/High Flow Cat and Muffler
2008 Intake Manifold
AIRAID Intake
SCT Tuned
And 4.56s as soon as I can afford it lol
With that said, I would also like to add that I am really after some low-end torque. When I swapped to the 08 intake I definitely lost power between 2000-3200 RPM, but I gained a ton from 3200-up. This combo really sucks for the street and I dread laying into the throttle from a stand still.
I know that I will not completely eliminate this dead spot, but I know that some of it should be solved by the use of a larger TB. I am vexed by claims from Fastman stating anything larger than 68.5mm will result in negligent gains and losses in bottom end, while AIRRAM claims 70mm is the SMALLEST he would go and recommends 72mm if you have SCT.
SOOO, I dont know what size to go with! I just want some torque lol!
Any advice/experience would be greatly appreciated!
Thanks,
Lucas
I DO NOT want to spend over $200, so my options are limited.
Its either Fastman or HiPotek, unless I find a used F&B.
Anyways, I'm debating what size I should use!
Since this is my first thread and I dont have my mods listed, or even what I drive for that matter, here it is:
2002 QC Ram 4.7
HO Cams
JBA Shorties
High Flow Y-Pipe
Single 3" Exhaust, w/High Flow Cat and Muffler
2008 Intake Manifold
AIRAID Intake
SCT Tuned
And 4.56s as soon as I can afford it lol
With that said, I would also like to add that I am really after some low-end torque. When I swapped to the 08 intake I definitely lost power between 2000-3200 RPM, but I gained a ton from 3200-up. This combo really sucks for the street and I dread laying into the throttle from a stand still.
I know that I will not completely eliminate this dead spot, but I know that some of it should be solved by the use of a larger TB. I am vexed by claims from Fastman stating anything larger than 68.5mm will result in negligent gains and losses in bottom end, while AIRRAM claims 70mm is the SMALLEST he would go and recommends 72mm if you have SCT.
SOOO, I dont know what size to go with! I just want some torque lol!
Any advice/experience would be greatly appreciated!
Thanks,
Lucas
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Joined: May 2008
Posts: 9,657
Likes: 24
From: Louisville, Ky
You will not gain any low end power from a larger TB. Any time you open up the intake and exhaust, the powerband goes up higher into the rpm range, much like it did with the 08 intake.
A larger TB give the placebo effect on throttle response because you are letting in more air due to a bigger butterfly. But under hard acceleration, you still have the same problem of more airflow and the powerband being raised.
The intake, cams, and exhaust have all improved airflow thus killed some lowend.
The gears are your best bet. it will keep the rpms up where they need to be.
You may see some improvement in throttle response with the larger TB, but I don't think you will gain much torque. If it were me, I would save the money and put it towards the gears.
If you do go ahead with the TB, then i would say 70mm would be more than enough. That's all I run on my built 5.0 in my Mustang and it flows more air than 4.7L.
A larger TB give the placebo effect on throttle response because you are letting in more air due to a bigger butterfly. But under hard acceleration, you still have the same problem of more airflow and the powerband being raised.
The intake, cams, and exhaust have all improved airflow thus killed some lowend.
The gears are your best bet. it will keep the rpms up where they need to be.
You may see some improvement in throttle response with the larger TB, but I don't think you will gain much torque. If it were me, I would save the money and put it towards the gears.
If you do go ahead with the TB, then i would say 70mm would be more than enough. That's all I run on my built 5.0 in my Mustang and it flows more air than 4.7L.