Aloha! I got a BBK 58mm throttle body from a friend for free. I had to change my thermostat this past weekend, and while I had the stock throttle body off, I decided it would be a good time to slap on the 58mm unit. Put everything back together, reset the computer, and I can feel a difference in the throttle response (little faster). After I did the swap I did a search on this website and read mixed ideas on this swap. Now my question is, what other things can I do myself with the TPI intake to let this new throttle body really breathe?

My setup is a Speed Density L98 with a Vortech S-Trim V1 supercharger. The TPI intake is completely stock. It looks like there are basically 3 more components to the TPI intake that I can modify, the Plennum, the Runners, and the Base. What parts can I port myself? Is it true the stock plennum TB ports are made for the stock 48mm unit? Can I port this out to flow with the 58mm unit? Just curious what mods I can do now to let the intake breathe a little more. Can I port the runners or the base?

Thanks!!

 

First you can port your plenum to flow more air. If you remove the tb you will see two little "walls" just behind the opening for the tb. For some reason these where part of the plenum's original cast, you can use a dremel to shave these down. Also around the openings for the runners on the plenum you can shave down the walls between each runner opening. Second, I think but I'm not 100% sure, if you gasket match the new 58mm tb opening to the plenum you should notice that the plenum opening is smaller than the tb, use a dremel to make the plenum tb holes bigger. You can also shave down the little lips just inside the runners. You can see where the runners were cast into the runner walls, and on the inside there is a little lip that can be shaved. Also you can siamese your base. Use a search to find out the procedure for that. I did all of this except the siamesed base and noticed much better throttle response, nothing earth shattering, but a difference is a difference. Hope this helps.

 

Put a stealthram behind it.

 

yes, the plenum opening for the T/B is ported for the 48mm, so you've definately got some work there. Speed 88 pretty much covered it all, as there isn't much really to do on the factory pieces that would give you much (apart from siamesing the base)

 

Thanks for the replies guys!! I will do what you guys said because I'm curious how much of a difference it'll make, but I have a feeling I will ultimately be doing what 12 Sec GTA recommended. I want to pull to 6500 rpm.

 

BTW, my 52mm Edlebrock T/B came with 48mm gaskets. So, double check your gaskets.