When porting the TPI plenum, is there any reason not to siamese the throttle body openings together? If I went ahead and made one large oval opening like a monoblade TB requires would it hurt performance any with a stock or 52mm TB?

 

I dont think so, but i just didnt fock with it and just smoothed out the opening and matched it with the gasket. a Monoblade would be cool, but would be over kill unless you have a 400hp mill. Just open up the openings... dont play around with the center... just my .02

 

I bought a plenum from "Mike89GTA", IIRC, and he had done what you did...said he didn't have any issues with it...he upgraded to a SuperRam..reason he had it for sale.

 

i dont see why u can not do it but i dont think u will gain alot by it unless u have a mono tb to go with it because the opening will be blocked by the center of the twin tb.

 

It just seems like it would make it easier to get to the inner portions of the plenum for smoothing of casting flash, etc.
Plus add a few cc's of plenum volume maybe?

 

I think you time would be better spent on other things. I just ported mine and didn't see a need for it.

Conrad

 

just some info;
the larger aftermarket twin 56mm-58mm throttle bores flow more air than any 4 cylinders can draw during the same time period, theres absolutely no reason to port the twin 56mm-58mm or larger throttle bores into a large oval unless your supercharging or turbocharging the engine and even then twin 56mm-58mm throttle bores are able to supply the engines needs, those twin throttle bores flow over 900cfm-1000cfm, far more than any small block chevy can use. thats 8.24 sq inches of throttle bore, nascar restrictor plates have less than 4 sq inches of flow area yet those engines make well over 650hp
the stock twin 48mm throttle bores do pose a restriction but unless your trying to make over 400hp even those throttle bore sizes are not a big restriction on hp as they flow in the 650cfm range

 

thats some good info to know , thanx for sharing

 

I'm not talking about porting the throttle body. I mean the plenum in the area behind the TB. I know I'll never have need for anything more than a 52mm and probably not more than my stock 48mm one.