Question about TB

[brokenujoint]

im building a 4.6 stroker bored out 0.020 over with a banks header and the head is port and polished with 24 lb injectors. Porting head for 120dls. i recently did a 99+ intake manifold upgrade with a dodge dakota 68mm tb. my question is, do you guys think that 68mm is going to big? most of you guys are going to 62mm.

[Muad'Dib]

I would think the big downside to that would be breaking your neck everytime you barely press the skinny pedal! LOL

[AGRESIVE]

I did the same swap, but I used a Fastman ported Dodge 68.5mm TB. I did this for two reasons; the swap is just cool and if you want the most out of your "air pump" you need to get as much air in and out as possible. Keep in mind what the Dodge engineers did for the 4.7L V8...

http://www.thefastman.com/Throttlebodies47.asp

History:
Dodge introduced the 4.7 engine and started with a 65mm Throttle Body. In 2001 Dodge enlarged the Throttle Body to 68mm and is the size still used today.
IMPORTANT!
Both the 65mm and 68mm TB's are really 3mm smaller than advertised because of the restriction above the throttle blades.
The Fastman 4.7 TB's remove this restriction and are a True 68.50mm bore all the way through.
Recommended sizes:
Working with the 4.7 motor has shown 68mm to be the optimal size for street performance use. This is the size I recommend. I can machine both the Dodge 4.7 99-2000 65mm and 2001-present 68mm TB's to a True 68.50mm bore.

[lafrad]

is the IAC with this motor plug and play with the Jeep TB?

[brokenujoint]

yes.

[AGRESIVE]

is the IAC with this motor plug and play with the Jeep TB?

Only up to 2002. After that it's entirely different IAC and not compatible at all.

[brokenujoint]

thats ok, i have a 97

[Cheromaniac]

I would think the big downside to that would be breaking your neck everytime you barely press the skinny pedal! LOL

The throttle response on my Jeep is neck-snapping enough with the modified Mustang 65mm TB so I can imagine with a 68mm TB, it would be doing rodeo when feathering the throttle.

[omegatron]

How did you mount the TB? Been searching the google machine for this upgrade and found another guy who ghetto fabbed his own tb spacer/adapter using a 8''x8''x1/2'' thick piece of aluminum.

Essentially he cut the 68mm hole, templated the '99 intake manifold, counter sunk the bolts, then used the tb for a template on the spacer etc...

Do you like the results of this mod? Thanks for the info/idea.

[commandtoad]

don't mean for this to sound like a contest, but i modified a 70mm ford TB off a 5.4 triton, more as an experiment than anything. it's on a 99 intake, heavy porting, custom cam, roller rockers, deck block, 24 inj and banks headers bla bla bla. it's in a trail XJ. it's a little touchy, i've gotten used to it but the power after 3k rpm is stupid.

[amcinstaller]

is there much gain past 62mm anyway? i mean besides throttle response.

[commandtoad]

good question. i should throw the stock one on there just to see.

[Muad'Dib]

is there much gain past 62mm anyway? i mean besides throttle response.

Probably not .. plus you will lose more vacuum.

[amcinstaller]

i was wondering that because im building a racing stroker for my spirit. not a 10 second monster like turbo tom, but if i can get 300 hp ill be happy. just like a throttle body spacer, id like to know what makes a difference and what doesnt

[omegatron]

It seems like a few companies support the idea of a 68mm tb for jeep and especially the stroker...painless and f&b. Here is a web page of an install (i'm sure you guys have read this as we all are slight google freaks).

http://www.off-roadweb.com/tech/0907or_ ... index.html

what would be the issues with loss of vacuum and is this further complicated by running a more aggressive cam with longer valve overlap?

if one has an adjustable map sensor is it easy to correct the effects?

and braking...if you do hydro boost upgrade or a double vac booster (using the '95 yj brake booster for earlier vehicles) are you able to get buy with lower vacuum?