on a boosted v8 what is the hp diff from our stock 48mm tb to whats say a 58mm tb??? and is the 300$$ price tag worth the extra hp??

 

It really depends on the rest of the system. First of all, since you are pushing the air into the engine it does not effect HP at a given boost level. However, if it is the restriction in the intake tract you will get a higher boost level inside your manifold by upgrading. If you are running a turbo this shouldn't effect you much, if you are running a supercharger then this would be a big deal for you.


Lets look at your cross sectional area for starters. (using pi*r^2 and neglecting pipe thickness)

2.5" intake pipe = 4.908ci cross section
3.0" intake pipe = 7.069ci cross section

48mm tb(2) = 3619 sqmm = 5.06 ci cross section
52mm tb(2) = 4247 sqmm = 6.58 ci cross section
58mm tb(2) = 5284 sqmm = 8.19 ci cross section


So if you are running a 2.5" intake pipe then the piping should be more of a restricion than the TB. If you are running 3" intake pipe then you should upgrade the TB. This is assuming that you have a smooth transition from the pipe to the TB as well. But if you are worried about spending $300 on a TB this may not be the right hobby for you.

 

cool info


still think 300 for a TB is way to much

 

Keep in mind you can pretty much choose your HP level with a blower via pulley swaps, so IMO not worth it. Only reason I have a BBK 58MM is to make the absolute most out of my little Powerdyne that can't be pullied up anymore. Once I switch to a Vortech (if I ever really do) my BBK will kind of be a moot point IMO. Some may prefer the larger TB for the increased throttle response though (throttle % for throttle % you'll flow a lot more air with the bigger TB)....just the opposite of the carberation world where bigger usually means less response.