ls1_mast

i was wondering if anyone notice any difference in boost levels after installing the 82mm or bigger throttle body...
the stock i believe is 76mm but the SL55 2006 came with the 82mm if i am not mistaken.. this car produce more power...
so i guess the question should be when the stock throttle body size becomes restrictive ....

here is my experiment

i installed the 85mm throttle which came from the w221 S550 with an adapter a month ago to test it but i noticed no difference, then i replaced it with the stock again out of curiosity to see if there is any boost or ignition timing changes but i couldn't find any.... and to keep things in perspective, my car has the following mods:

-180mm crack pulley
- 83mm supercharger pulley
- k&n in box filters
- 630cc fuel injectors
- belt wrap kit ( custom made not VRP or any other brands)
- all catts delete
- methanol injection (15% methanol 85% water) ( not that is relevant to that discussion
- truck water tank
- eurocharged tune

one thing that could be the key here ( correct me if i am wrong) ,, when i installed the 86mm throttle, i did not NOT change nor port the supercharger snout to a bigger size..... so i am now wondering if the snout makes any difference...

there is another way to approach this which is by CFM numbers for each one and compare it to what CFM can be measured from 700hp engine .... as far as i know the stock throttle will pass something around 830CFM and the 82mm will allow around 950CFM , keeping in consideration the air filter restriction.... so how many CFM needed for a 700hp engine??!

according to this website ( https://calculator.academy/cfm-to-hp-calculator/) 700hp requires around 500CFM of air which waaay lower then the stock throttle limits...... any ideas ?

SICAMG

What good is it if you put a say 100mm throttle body on to a 74mm opening it will flow basically no more cfm. So that explains why you would see no difference.
I picked up "almost" 1 pound of boost going from the 74 to the 82 so yes it does flow more to the blower and makes more boost.
Gutting the intake,removed the bypass valve restriction area, gained me nothing so I am glad I did not buy a $800.00 VRP snout.

SICAMG

What is the 85mm throttle body part number ? The S550 are coming up 82mm.

ls1_mast

that is interesting, 1 pound of boost is not a little difference , in my case i didnt see any difference ... i guess i have to try experimenting with the it again...

the pat number is 273 141 03 25 , do you have any experience with this throttle ?

SICAMG

You already answered your own question. If you did not port the intake it will not flow more air so you will not see a difference.
That throttle body number,2731410325 is for a 82mm

ls1_mast

from the snout porting stand point i think you are correct that it will not flow more air ... however what i dont understand is if the 74 already flow 830CFM( which is more then required to produce a 700HP) then why installing a bigger one makes the engine produce more boost ?

and yes you are correct here too, that part number is 82mm i just measured it...

SICAMG

Simple. A supercharger trying to "draw" air through a hole is far more difficult than "blowing" air through a hole.Our blowers are very much "not" very good air pumps beyond stock and will generate a lot of heat as we all know.Putting a larger throttle body will allow the blower to have an easyer time of trying to get air in so bigger will always help for sure since it is trying to suck the air in and is not that good at doing so.
Another example....Fuel pumps. Fuel pumps are horrible at sucking fuel in and need a constant pressure or volume at the suction side. But they are fantastic at pushing high pressure and volume.