Do I need a bigger TB?
Do I need a bigger TB? i have a 383 with all forged internals, 1 7/8 lt, ported heads, carrying around 11 to 1......my question is should i spend the money and buy a bigger tb or is it just a waste of money. it seems to run pretty rich also
Wow man with a motor like that I'm surprised you didn't have one already. Yes it will help out some. Nothing crazy but it should help at least a little. You can find good used ones for cheap here on this site. Oh and if the intake is not ported for a bigger TB yet then it needs to be bored. You can do it with the intake and everythin in the car you just need to seal off the intake so no metal shavings get inside. That's how many people do it.
Yea you would definetly benefit from a 58MM unit. If the intake is not already ported internally I would send it to Lloyd Elliott and for $200 he opens up the runners, the TB holes to accomodate the larger TB, and takes some stuff out behind the TB openings. Combined you would definetly get a nice gain with your 383.
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Yes, but the gains are minuscule. I had a post where I accurately measured KPA loss and I determined that my current 58mm TB had almost 2KPA less loss at higher RPM than the 52mm TB. Tiny gain but it all adds up.
I agree, but he is going from a stock 48mm unit on a 383. The gains will be a bit better than compared to your situation. A 52 is plenty for most stock displacement setups imo...
-Dustin-
I used my Datamaster to log the KPA loss under various RPM's and load conditions. I clearly had less vaccum with the 58mm compared to the 52mm.
I also tested with and without elbows and CAI. I also tested my K&N CAI against my old AS&M. It was a good read with some very interesting info.
Last edited by wrd1972; Aug 25, 2009 at 06:02 PM.
From everything I've read a 52mm TB is good to handle up to 475 fhwp. That being said if your car makes 406 rwhp then you're probably in that area at the flywheel so a 52 would be fine. Plus that way you don't have to open the manifold at all since the stock bores are already 52mm.
well i supose i should throw in that is also setup to handle a 150 shot also wouldnt i want that extra flow with the 58 for my n.o.s. ive been away from cars for a few years know so ive been tryin to do as much research as possible so i dont look like a noob but if what u are sayin is true then 52 would work with me not adding the shot but with the shot then i need more?????????????