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Discussion Starter #1 (Edited)
Porting the 3.5L V6 Throttle Body

I started this project last week and got quite a bit of questions and lots of inquiring minds so here is my best shot at explaining the porting of the V6 throttle body.

The Intake Diameter at the entrance of the Upper Intake Plenum is exactly 72mm. For the sake of this write up and assuming that the results are favorable to the theories presented the porting of the throttle body will be done in such a manner as to create a funnel or venturi effect into the manifold. I'm sure by now you are all aware of the physics behind this, after all the AirHammer is designed around these ideas as well as all other well-performing intakes.

Stock Throttle Body (Info):

* Cast Aluminum
* 70mm at the barrel entrance
* 68mm at its smallest point at the perimeter of the blade
* Exit diameter of 68mm tapered to 72mm

The Ported Throttle Body (the end result):

* 74mm at the barrel entrance
* Tapered to 72mm, smoothed into perimeter of blade
Note: Diameter of TB at blade area will NOT be altered (see further instruction)
* Smooth tapering of the ridge on exit of throttle body
* Sand / Polish (optional)

Tools Needed:

* Pneumatic or Electric die grinder
* Carbide Cutting Bits (cylinder with round tip works best)
* Flap wheels or Sanding cones (80 grit, 120 grit)
* Caliper (for measuring diameters to check for accuracy and consistency)
* 500 grit, 1200 grit, polish compound, 2" cotton rag buffing wheel (for polishing....optional)



Stock Throttle Body (Unported):



Porting, In Process - Carbide Bit, Rough Surface


Taper Back of throttle body, smooth ledge, do not remove to much near blade:





Sanding, Flapwheels or Cones (80 grit, 120 grit)
** Smooth the ledge into the blade area but do not go to deep, remove as little material as possible near the blade.



Check for accuracy last time before polishing:


POLISHING
* Sand with 500 grit until all major visible scratches are gone
* Sand again with 1200 grit until your fingers are numb
* Cover areas in polishing compound
* Use cotton rag buffing wheel on a drill or die grinder to polish to mirror finish

End Result:
 

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not bad.

you basically made the "funnel" more agressive, since there wasnt a change of plate (butterfly that allows the air flow)

only question i would have is did that alter the flow in a positive or negative way....

too agressive and it may make it harder for air to be "sucked" in.... if it takes more effect to suck it in, you've basically DE-Tuned the stock design which loses velocity and can impact low end in a negative way.


something like that, i would definately flow test FIRST to see if it made it harder or easier for air to achieve the "venturi effect" ;)


in real world relating, 5 lanes of traffic converging into 3 would be stock.... the left and right lanes merge towards the center.


now think of 7 lanes of traffic merging into 3.... there would be far more congestion. as the outer lanes now have to merge two lanes over VS just one lane of merge. more congestion means to merge to where it needs to be, it takes more work. making an engine more efficient basically means the engine does LESS work, and produces more power.


remember, if the butterfly is the same size, the three lanes of traffic and the size of the butterfly is still the common flow denominator.


when a company ports a throttle body, they port the center and add a larger butterfly plate.... this would be like making 3 lanes of traffic into 4 lanes of traffic.
 

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not bad.

you basically made the "funnel" more agressive, since there wasnt a change of plate (butterfly that allows the air flow)

only question i would have is did that alter the flow in a positive or negative way....

too agressive and it may make it harder for air to be "sucked" in.... if it takes more effect to suck it in, you've basically DE-Tuned the stock design which loses velocity and can impact low end in a negative way.


something like that, i would definately flow test FIRST to see if it made it harder or easier for air to achieve the "venturi effect" ;)


in real world relating, 5 lanes of traffic converging into 3 would be stock.... the left and right lanes merge towards the center.


now think of 7 lanes of traffic merging into 3.... there would be far more congestion. as the outer lanes now have to merge two lanes over VS just one lane of merge. more congestion means to merge to where it needs to be, it takes more work. making an engine more efficient basically means the engine does LESS work, and produces more power.


remember, if the butterfly is the same size, the three lanes of traffic and the size of the butterfly is still the common flow denominator.


when a company ports a throttle body, they port the center and add a larger butterfly plate.... this would be like making 3 lanes of traffic into 4 lanes of traffic.
I was thinking this while reading it. Does doing this really have an advantage since the butterfly area is still the stock size. Seems like it wouldn't do a bit of difference, especially for the effort put into it. But I hve been proven wrong a couple of times before.
 

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Discussion Starter #4 (Edited)
when a company ports a throttle body, they port the center and add a larger butterfly plate.... this would be like making 3 lanes of traffic into 4 lanes of traffic.
I understand all your points. This has been an on-going project for about a week and a half as I have recently found myself unemployed and fiddling with my car ;). I started only removing a little (roughly 2mm) making the inside diameter at the entrance to be 72mm...literally the size of the opening in the intake manifold. I drove with it like that and did some datalogging and sent it off to my tuner. I took some measurements and decided 74mm was the way to go so here we are.

In regards to companies porting throttle bodies....not entirely true. BilletTech and the few other companies offering ported HEMI (80mm) throttle bodies are doing exactly what I did here and not boring the entire length and replacing the blade. I dont follow all of the HEMI stuff but according to most of what I have read and seen the only production units available with a truly larger diameter AND blade is the 90mm Arrington and the 90mm CNC Late Model Speed units.

For lack of resources I will not be going anywhere near a flow bench unless someone volunteers ;). However, when I do the dyno testing for the ported lower manifold I am selling on LXforums I will also be doing dyno tests with this throttle body. The test car will have the Inertia Camshafts, custom tune, K&N CAI, catback, ported/polished lower manifold (test config 1) and then with the ported/polished throttle body (test config 2).

I can tell you there has not been any power lost thats for sure. Throttle response and power at freeway speeds is noticeably better and the 1st-2nd gear shift happens a bit later. Revs a tad harder and wants to go higher then it did before hopefully wont have an issue with limp mode.

As far as effort, worth every second... start to finish it would take me about 2hrs to complete the work on one of these. And even if it doesnt do any good why the hell not... thats like all the HEMI guys thinking oh well wtf our motors put out enough horsepower lets just leave them alone, I'm sure Chrysler did everything right lets just not mess with it we might make it worse. Its time someone grows a pair in the V6 market and starts playing with their cars. Stu got the ball rolling with the camshafts...just trying to continue a good thing.
 

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Great Write up !
 

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I understand all your points. This has been an on-going project for about a week and a half as I have recently found myself unemployed and fiddling with my car ;). I started only removing a little (roughly 2mm) making the inside diameter at the entrance to be 72mm...literally the size of the opening in the intake manifold. I drove with it like that and did some datalogging and sent it off to my tuner. I took some measurements and decided 74mm was the way to go so here we are.



roughly thats called port matching/gasket matching. nothing wrong with fiddling, but i've been there before as well. it still remains that the butterfly will only let through the SAME amount of air....

and like stated with using the analogy of traffic....you made the more area for lanes of merging....without actually making the 3 lanes in the middle larger. more congestion. not saying dont experiment, but before you do something, think about the basic logic in it.... some things will hamper performance and some things will help. thats just the way it goes in tuning.:clap: dont take my post as saying "its not gonna work"..... cause it may or may not. simple as that. all i am saying is not to go TOO agressive. thats all.




In regards to companies porting throttle bodies....not entirely true. BilletTech and the few other companies offering ported HEMI (80mm) throttle bodies are doing exactly what I did here and not boring the entire length and replacing the blade. I dont follow all of the HEMI stuff but according to most of what I have read and seen the only production units available with a truly larger diameter AND blade is the 90mm Arrington and the 90mm CNC Late Model Speed units.

Hemi stuff isnt relevant to ours completely, MAINLY because they dont have a manifold tuning valve nor a short runner valve in their intake manifold. basically those valves ALREADY control more airflow and manipulation of the velocity than the TB will.... which means 1 of 2 things.

-gains to the TB may increase, but also have a chance of decrease
-you may actually hamper in the upper rpm if the TB is congested (if the angle is too agressive) once that SHORT RUNNER VALVE opens in the upper RPM.

only a few i've seen proof of working, has been the 90 gimmick, and thats simply because i've visited HHP. and places like "MOES PERFORMANCE" are actually porting TB's as well. if people are copying this... theres no reason it would not be beneficial.



For lack of resources I will not be going anywhere near a flow bench unless someone volunteers ;). However, when I do the dyno testing for the ported lower manifold I am selling on LXforums I will also be doing dyno tests with this throttle body. The test car will have the Inertia Camshafts, custom tune, K&N CAI, catback, ported/polished lower manifold (test config 1) and then with the ported/polished throttle body (test config 2).

should be interesting. most will be awaiting your results for sure. porting and polishing isnt all that tedious to do. Standard abrasives offered the kit i used for heads and TB's before.


I can tell you there has not been any power lost thats for sure. Throttle response and power at freeway speeds is noticeably better and the 1st-2nd gear shift happens a bit later. Revs a tad harder and wants to go higher then it did before hopefully wont have an issue with limp mode.

is this with all the mods you listed above or still stock????? its hard to go off of the "butt dyno" for a mod that will only produce maybe 5 whp at best. the Hemis which are v8's are only getting 5 whp going up to as far as 85mm openings.... our engines are far less power to begin with, so starting with 210-220 whp, the gain from a TB will be like half that.

it would be hard for even the hardest trained "boho" (butt, booty, badonk) to register MAYBE???? 2.5-3 whp gains ;) we gotta be realistic about feeling gains from such a small mod.


As far as effort, worth every second... start to finish it would take me about 2hrs to complete the work on one of these. And even if it doesnt do any good why the hell not... thats like all the HEMI guys thinking oh well wtf our motors put out enough horsepower lets just leave them alone, I'm sure Chrysler did everything right lets just not mess with it we might make it worse. Its time someone grows a pair in the V6 market and starts playing with their cars. Stu got the ball rolling with the camshafts...just trying to continue a good thing.
hey if it floats your boat, go for it. i'm to the point where i try to only do stuff that makes a difference... if it doesnt, i dont waste my time with it. no one will ever see the inside of my TB....that i know of.... although polishing it may minutely help out with air flow, if it doesnt really do anything or make the car more efficient, i view it as time that could be spent elsewhere.

i agree, its not always about thinking "oh well i have enough hp" and all that gimmick.... but if you are gonna do something, at least have it make a difference and know it makes a difference. thats why when they add something it may only gain 5whp for TB, but they are also doing cams, long tube headers, or boost.... the majority of the 90mm tb's being sold are going to cars with MODERATE TO HEAVY N/A builds.... and they ARE replacing the plate from what i understand.

as for "people growing balls" remember theres also that saying about "brains over brawn".... just entails with knowing what to change, what things do, how they work...and not just on the high end engines, but on engines that have more systems than the high end engines. thats not a knock towards you or anyone.... but over the years (charity work aside) we all learn that doing something just to do it or because its there, isnt always as good as doing something cause it produces gains or because it works....i've seen people "chimney sweep" exhaust systems on cars that were not even kicking out 140whp.......claiming the carbon buildup robs them of power. for someone putting down 132.6whp... how much is really being robbed?? but they felt that worked for them.... god bless em! :D

a stock internal engine will STILL only takes in SO much air.... a larger TB on stock internals should only to move the powerband to a higher RPM....when you do this 99% of the time...you lose elsewhere.(mid? lower?) always remember "give and take". its like boosting an engine.... faster car, shorter engine life.... "give and take"... with the extra mods this may be more beneficial. question is....to what degree??? even the mild 426 strokers were having problems using the larger 90mm TB and had to revert back to the stock one... they lost power. if the engine doesnt require extra air then a larger TB doesnt benefit. that the bare bones really.....more space in the TB opening only serves to slow velocity a bit. my thoughts and views are that we'll have to worry about the intake manifold being less intricate before TB's come into play. mainly due to the tuning valve and the short runner. if the velocity DECREASES via the TB.... the manifold tuning valve will work to make the velocity raise again.


like said though....test away!:beerchug: i applaud you for doing so. anyone who has been into cars has done it or will do it. i found myself taking apart engines in my living room, among boring TB and making plates for em. just remember the Venturi effect is like and hour glass. some ported TB's still have a lip right by the TB plate.


when its done, there should be no lips



when it comes to airflow i'm just a bit more critical with questions mainly because theres a reason for all the air flow programmers and engineering that goes into intakes, heads, etc... its not just removing some material and hoping for the best. at least this day in age... even back then it and even now its still considered an art form with hot rodding. the biggest thing one learns when it comes to intake and exhaust....doesnt matter if its the heads, the headers, the intake..etc... "bigger is not always better"

g'luck with it.:bigthumb:;)
 

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Discussion Starter #7 (Edited)
As far as current mods here is what I'm running:

AirHammer HO
Airflow mods (removed silencer, lower radiator baffle, upper radiator baffle, CF nozzle from grille into airfilter area)
Blastin Bobs 10db dual conversion w/dynomax muffler replacing stock suitcase
Inertia Motorsport Camshafts V1.1
Ported / Polished "Gasket Matched" Lower Manifold
Ported / Polished 74mm tapered Throttle Body
Custom Tuning by Mike Lafrad @ Inertia Motorsports (with all the above mods)

Also in addition as far as the background for the testing I have been pulling Fuse 11 after each time I have done any of this porting work. The car requires 200 miles to adapt itself again to its circumstances and new mods. The car progressively gets a more noticeable gain as it learns this mod, so the perceived throttle response is not a result of pulling fuse 11.

As far as the variable tuning valves that is definitely a very good point. Those little buggers are actually a saint for our engines. Ask Mike Lafrad or John at Modern Muscle, those are the only 2 tuners with experience custom tuning a V6 I believe. I've spoke to both of them about these tuning valves and depending when they open and close can greatly impact the power band. In turn, they can tune these based on airflow and things that affect runner length like the design of an intake system, etc. Mike is still working on the adjustments for the Throttle body so we shall see what happens. So far no ill effects, hp/tq gains are a crap shoot because yeah...gains will be small regardless but the throttle response is something thats very obvious.
 

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you have to also take into account that yes, it is still the same butterfly flap that allows the FINAL amount of air into the engine. However, air can be compressed. by having it ported you are giving a smoother compression for the air molecules than if they had to make the turn completely from open to the diameter of the chamber. By having the sloping effect, your essentially compressing the air (not a lot of force all at once, but its still making the air into a smaller area) It will still allow more air to travel into the engine. its essentially makes the transition better for the air.

Good work over all! wish i had the know how to do it myself.
:clap:
 

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Discussion Starter #9
The car is going on the dyno this morning at UMS tuning with a CNC ported 74mm throttle body cut by Billet Technology that will be offered for sale to the masses. Numbers will be posted soon.

The test car:

2005 Dodge Magnum SXT
Inertia V1.1 Camshafts w/lash caps
Ported/Polished Lower intake manifold
Airhammer HO Intake
Blastin' Bobs 10db duals with Dynomax muffler (replaced suitcase)
Custom tune by Mike Lafrad

Throttle bodies being tested....Stock vs. CNC ported 74mm throttle body from BilletTech
 

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So what happend? It was like reading this great book and someone tore out the last chapter.
 

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Reading the responses, I wonder if people understand the difference between porting a TB and having a larger TB?

A stock throttle body is a straight tube.

A larger unported throttle body is a larger straight tube.

A ported throttle body, even if it is the exact same diameter at the blade, will produce increased airflow due to the 'Venturi effect'. Google it. :D

Or, is that already a pretty well known thing?
 

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Discussion Starter #13
Reading the responses, I wonder if people understand the difference between porting a TB and having a larger TB?

A stock throttle body is a straight tube.

A larger unported throttle body is a larger straight tube.

A ported throttle body, even if it is the exact same diameter at the blade, will produce increased airflow due to the 'Venturi effect'. Google it. :D

Or, is that already a pretty well known thing?

I forgot I even posted this over here. I never updated it with how I port the production units but doesnt matter much I guess. I think most people understand the difference between a truly larger throttle body and a ported one. But if not here is a bit of theory based on my experience and testing (for ported TBs) ... Since you arent actually increasing the true size of the TB (restriction at the blade) the point of the porting is to make it behave as if the blade is open further then it actually is and sooner. This occurs because the size of the opening or gap between the blade and wall of the TB is bigger then stock. The closer the cut to the blade the better but there is a fine line between just right and too much.

I cant post photos of the units I sell since I'm not a vendor here but there's lots of them floating around on the web if you do a search.
 

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Edit: Scrapped all the crap about the venturi stuff. I thought I had a reasonable grip on it, but I apparently don't entirely understand it's complete application here.

rwalshphoto said:
The point of the porting is to make it behave as if the blade is open further then it actually is and sooner.
I drew a perdy piktur, hur hur:

 

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Thanks backwoods. Im taking my car to the track next friday. I wana see how it runs with what I have then. I think im going to try and port my tb after so I can get a base to compare.
 

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No problem!

I'm sorry I had to edit my posts for erroneous comments regarding the Venturi Effect.

(Edit: The TB responsiveness is assured, i.e. the diagram. The following is simply about said effect and it's place within this application. /end edit)

I had a conversation with a friend of mine who is majoring in physics, and we agreed to conclude that porting the TB does increase the maximum airflow, although neither of us were prepared to bust out the calculations that actually show it. lol


The idea is that if you have a 1" pipe, you have a specific amount of airflow. If you have a 2" pipe, you have greater airflow. Then you have a 2" pipe, with a 1" constriction in the center, which has an airflow somewhere in between the first two. What happens is that, although the smallest point in the pipe is still 1", you have more pressure pushing the air through that hole because you're starting with a 2" collector funneling twice as much pressure down the pipe, increasing air velocity.

The Venturi Effect in itself simply states that, within a system with a specific amount of fluid flowing through it, fluid moving through constrictions in that system has to move at a greater velocity (and thus decreases its pressure there).

The important thing to not get mixed up about the Venturi Effect is that just because you're looking at a system where there is greater velocity at the constriction (in this case the blade), it might appear that 'well, if there is greater air velocity at the blade, there is more airflow'- Which isn't true, per se. You're just looking at part of a system with a specific overall airflow. Just because it is moving faster at one point in that system doesn't mean your overall airflow is increasing.
 

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this is a nice idea. Id like to see the end dyno results.
 

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Discussion Starter #18
this is a nice idea. Id like to see the end dyno results.
There are dyno charts available if you look for them. I cant post them because I'm not a vendor here. The ones that are sold are done a bit different then what this thread shows and I havent updated it for competitive reasons but if you do some searching you'll find dyno results for a couple different companies dyno pulls.
 

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i think this post, pretty much sums up why enlarging the ends (for the venturi effect), and not the actual throttle body center opening where the buttery fly can be kinda misleading...

for anyone wanting to port a TB, might wanna check this statement out:

The thing that is most important when it comes to airflow, be it a TB, intake manifold, intake runner, exhaust runner, etc. is CSA or cross sectional area. The true measure of a TB size is the butterfly size, which happens to be exactly the CSA of the TB. It is misleading when a TB is ported in the transition areas only without an increase in CSA to call it a larger TB than another. The TB can and will be considered ported, but it will only take advantage of decreasing turbulence through the TB, thus reducing eddys that rob fluid flow at or near the boundry layer of air flow. This does not change the fact that you can only flow X amount of air through a particular orifice size.

What we are demonstrating plain and simple is the difference between a truly larger throttle body and a stock, ported TB. The "other" TB is done well for a ported TB, but the blade size is not increased and the area around the blade is untouched by the CNC. Ours will flow more air in every single case, that is a fact and is indesputable.

Are we comparing apples to oranges, no, we're comparing a throttle body to a throttle body regardless of how it was designed or manufactured. These aftermarket TBs are superior to a stock TB, ported or not.
http://www.lxforums.com/board/showpost.php?p=2264293&postcount=9


same as when one gets heads ported and polished....polish will smooth the airflow...the port is what allows more air.

the opening through which air will flow is only as small as the smallest section. at least thats how i learned it years ago. it should still be the same as its been done since cars have been produced :)

in conclusion...porting a TB isnt a bad thing. it can smooth out airflow, raising the velocity...which is great. but for more air flow, you kinda have to widen the door so more air can flow.
 

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The Moral to this thread is simply buy the Thottle body offered by Moder Muscle! It's been tested & developed by people who have been in business for years. Although I admire the diy spirit.
 
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