A 70MM is only needed if you have a power adder, if your N/A then you dont want any bigger then 65[/QUOTE]
I am not saying that you are wrong, and I know that most knowledgable people in this forum agree with the above statement, but can somebody explain this to me:
In the December 2002 issue of MMandFF they tested a throttle body that is a one size fits all from Ground Pounder Performance Products. It is 75 mm but you can insert sleeves to choose from 65, 70, or leave them out for 75mm. The test car is an 88 5.0 Saleen with TFS heads, Competition Cams roller cam and Valvetrain, a Holley SysteMax intake and fuel system, and 8 psi
vortech.
They tested it with and without the supercharger belt attached and here are the results...
Test 1: Non Supercharged oem 60mm TB-226.7hp@5500 rpm 235.8lbs-ft.@4250
Test 2: Non supercharged w/65mm insert and 75mm egr spacer -228.6hp@5500 rpm 241.3lbs.-ft.@4250
Test 3:Non Supercharged w/70mm insert and 75mm egr spacer-231.8hp@5500rpm 242.7ft.-lbs@4250 rpm
Test 4: Non supercharged W/out insert(75mm) and 75mm egr spacer-232hp@5500rpm 243lb.-ft@4250
I wont waste our time with supercharged results because thats not the issue here, but an interesting note is the supercharged set up went way down from the 65mm to the 70mm and 75 mm.
So maybe there is some other reason I dont know about other than increased hp and tq not to go with a bigger TB, and if there is I would like to know so I dont make the mistake of doing it. I am not trying to prove anybody wrong or piss anyone off, I am just baffled by these test results.
What does everyone think?