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Old 10-11-2013, 02:16 PM
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Throttle body, is bigger always better?

I have not been able to find anything on the forums regarding this. If there is a post please help by pointing me in the right direction since I'm a new, first time poster.

First and foremost is bigger always better when it comes to the throttle body? The stock TB is 74mm (in my WK2 2012 V6) which seems quite large. I did some math based off an equation found here. From that I get ~64mm as a good balanced TB for standard driving. In addition I see the "racing" TB's are typically ~15% larger than the typical OEM TB, 15% more of 64mm is ~74mm. Which means you're keeping your RPMs quite high to take advantage of this benefit, also seems like car manufactures are starting to do this to be able to post higher HP. HP sells cars, torque wins races.

More on why a ~64mm TB might be a good idea is because a higher velocity lower mass gives the engine more lower end torque whereas a larger TB gives lower velocity and higher mass gives the engine more high end HP. (this is based off of some info I've gathered and Bernoulli's principle.)

I am not sure about you, but in this engine the 290hp happens at 6350 RPM, the car redlines at 6400 RPM and will rarely if ever hit the 290hp. Understanding this is an SUV and I would like some more pep in the typical RPM range of 1500-4k RPM. I wouldn't mind if the max HP was 280 or even 275 at 6000 RPM and raise the torque during the typical RPM range.

So has anyone tried a reduced sized TB on the 3.6 V6 with the 5 speed AT to gain more torque?
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Old 10-11-2013, 07:48 PM
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Re: Throttle body, is bigger always better?

never heard of anyone going smaller. Give it a try
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Old 10-11-2013, 08:22 PM
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Re: Throttle body, is bigger always better?

Interesting reasoning.
If you want to be a guinea pig I would love to hear/read the results of your testing.
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Old 10-12-2013, 11:33 PM
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Re: Throttle body, is bigger always better?

I looked at the math, and it is sound. However, there are a ton of variables not addressed. Where and when do you want max power? Is this a wide bore/ short stroke engine? What about velocity?
There are a ton of variables that need to be addressed based on engine use. Low end grunt, top end power, mid range torque are all tunable equations given a powerplant use.
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Old 10-13-2013, 03:58 PM
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Re: Throttle body, is bigger always better?

I agree with your reasoning on more low end 'grunt' versus the high end HP.

The low end torque would do more for daily driving and towing than high RPM HP.
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Old 10-15-2013, 03:25 PM
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Re: Throttle body, is bigger always better?

Would adding a fastman throttle body to my 14 JGC V8 require any reprogramming of my ECU to account for the change?
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Old 10-15-2013, 03:57 PM
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Re: Throttle body, is bigger always better?

no.....
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Old 10-15-2013, 03:59 PM
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Thanks, so it will just automatically adjust as needed?

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Old 10-15-2013, 04:32 PM
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Re: Throttle body, is bigger always better?

Dan Arcand at thefastman.com has been doing the throttle-body thing on Mopars for a very long time. He knows of what he speaks. I recall that he came to at least one Durango Owners Club plant tour at Newark, and there was some consulting as well as install activity in the Holiday Inn parking lot

He does not recommend going too big.

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Old 10-28-2013, 12:33 PM
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Re: Throttle body, is bigger always better?

Quote:
Originally Posted by 760hacker View Post
Would adding a fastman throttle body to my 14 JGC V8 require any reprogramming of my ECU to account for the change?
The short answer is "no". The correct answere is "yes, if you want to take full advantage of it." Without a tune you'll have a noticeble loss of low end torque and pick up a little top-end hp. With a proper tune you can eliminate the lost torque and shift the hp gains further down into the power band.
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Old 10-28-2013, 02:17 PM
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Re: Throttle body, is bigger always better?

Quote:
Originally Posted by hairless_ape View Post
The short answer is "no". The correct answere is "yes, if you want to take full advantage of it." Without a tune you'll have a noticeble loss of low end torque and pick up a little top-end hp. With a proper tune you can eliminate the lost torque and shift the hp gains further down into the power band.
So now there are conflicting answers. I'm sure it also depends on other mods to vehicle. I have a Magnaflow Catback and a K&N CAI, adding the throttle body will be the last performance mod I do for the foreseeable future. I'm sure having the exhaust and CAI also change the results from the throttle body. I'd really like a little more low end throttle response so I guess I'll just see what happens once i install it and go from there.
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