shardul

iTrader: (1)

Exotic_metal55 was kind enough to grind the stock 9mm shaft in my 74mm TB to 5mm.
Here are the calculation courtesy of Exotic_metal55

74 mm = 2.9314 dia. = 6.749 sq. in. 9 mm (.3543 dia) shaft x 2.931" long = 1.0385 sq. in. 5mm (.1969 dia) x 2.931 = .577 So 6.749 - the difference in a 9 mm and 5 mm shaft is .4615 sq. in. Equivalent flow area = 6.2875 sq. in = 2.8294 dia. = 71.866 mm.
78 mm = 3.0709 dia = 7.4065 sq. in. - 9 mm (.3543 dia) x 78 mm (3.0709) long = 1.088 sq. in. = 6.3185 sq. in. = 72.044 mm equivalent.
Math can't lie.

Considering this is a relatively cheap/free mod, the benefits were incredible.
Right of the bat the throttle is much more responsive in terms of power the car feels a lot stronger at WOT. In a few weeks i will dyno the car and let you all know the outcome. My butt dyno definitely tells me i have gain a few hp (for free).
Once again thank you Exotic_metal55. It is because of member like him the automotive enthusiast community / forums are an interesting place.

sneakyneon

Thats so cool! I'm totaly love finding diy mods that work! Supercharged cars are very picky when it comes to inlet restriction. Time to apply this to my 82mm TB

shardul

iTrader: (1)

it will definitely help

Forrest Gump 9

Any pics of how this was done?

NEMES1S

how come there is no throttle anything on the v12's? I have to assume there is some room for improvement

Exotic-metal55

I used die grinder with metal grinding bit and then some 3/4" round sanding bit`s to finish off. Also used a mic to take 5mm off.. Not much room to work inside the 74mm throat. The 80mm and 82mm are a lot easier.. Once you grinde the shaft down, be sure and use lock-tight on the tb blade set screws..

As you can see from the math, the potential flow area can equal an 80mm TB for pennies on the dollar.. Even with area being near equal, it is still possible for the 74mm to still out flow an 80mm but only a true flow test will verify this..
When I get my SL65, after a tune, I will make sure I find a way to adapt an 82mm TB to it Oh yeah and the blade will be ground down on it too..

TopGun32

need pics badly!

Houston boys are getting down with the latest DIY tuning..


Wonder if this can be a side business for somebody... hint!

NEMES1S

looking forward to it.

shardul

iTrader: (1)

similar to this one

By shardul at 2009-12-03

lowprofile

Math can't lie.....lol, good one!

NEMES1S

how hard is it to take apart the throttle body? I have a friend looking at getting some parts designed and fabbed up and could make some form of diy kit that would flow better

shardul

iTrader: (1)

well to do this mod, the TB did not have to be dismantled, only the butterfly plate had to be removed.

Exotic-metal55

Only some of the 03 TB`s could be taken apart and all the rest are epoxied together.. Trying to port the ID of these fly by wire TB`s is very tricky and fail rate high.. Idle issues are a big problem with the ID port.. Stick to the shaft reduction and you will get easy safe flow gains..

The TB shaft blocks close to 20% of the flow, so that is all that is ground and polished.. It is the easisest way to get the flow of the 80mm or more.. Nothing comes apart, just need a good air grinder, burring bit and 3/4 dia. sand wheel bit.

Sunir

Exotic Metal kind Sir...you are a true enthusiast and out of box thinker...any way this can be done on an 82mm TB kit...if so could you do it is shipped to you?

Exotic-metal55

It can be done on on all our TB`s. All the TB`s on my car get this mod done automatic. It is more old school than out of the box thinking..

blackbenzz

I'd be interested to see quantifiable results. Sounds like a good idea and cheap too. 82mm TB plus grinded shaft = even more air flow theoretically

Sunir

bro we may have to figure out how to do this...maybe talk to your guys that did the adapter plate/inlet job on the TB kits...I'd like to get a precision job done, do it once and do it right,,,that way when it's in you can forget about it!

AWOL

any dyno updates yet? on a scale of 1-10, how easy is this? true gains or only the imagination.

thanks

Kevinw23michele

Very interested in this, especially since Im looking at spending over $2k for an 82mm throttle body, and if this is pretty close, I would love to know if there is anyone in my area that would do this type of mod.

320 dreamer

if your talking about enlarging the body of the t/b maxbore does this. they can bore the 74 body to 77 mm and install a new butterfly and gasket match for 125$ shipped. if your talking about grinding the butterfly to a knife edge many on the srt-6 forum do this to the leading edge to improve airflow.

remember grinding the shaft down may weaken the mounting points. allowing it to crack and break. dont go to far!!

shardul

iTrader: (1)

After doing this mod and switching to a 180mm for a 175 I put the car on the dyno I gained 18rwhp and 38 rwtq. The tq gains were in the 3000 rpm range

Kevinw23michele

Any idea of what adding an 82mm TB yields power wise?

shardul

iTrader: (1)

To unleash the true potential of the 82mm you would need long tube headers

Kevinw23michele

I currently have kleemann long tube headers. Just trying to decide if it's worth spending a couple grand on a true 82mm or not.

shardul

iTrader: (1)

go for the 82mm then