Ported throttle body

[longbedder]

Has anyone here either purchased a ported throttle body or done the work themselves for a TBI setup?

I know it's fairly common for the MPFI performance crowd - I was just wondering if the gains they typically see translate to the TBI domain. Specifically, is the throttle response noticeably improved? I'm not that interested in WOT horsepower gains.

 

[bigblock72]

I have a 52 mm t-body that I bought off of sleeze-bay on my Blazer (s.b. 400) and it made a world of difference over the stock 350 t-body it had before. On a stock motor it doesn't make much difference even at WOT.

 

[Thunder]

I have a 46mm bored TB (590cfm) on my 350. It took a little tuning with the fuel pressure to find the sweet spot where it ran best. I also have injector spacer, TB spacer,a velocity stack, headers 3" FM exhaust. Once I got it running right I got better overall performance. Most of the gains were on the mid to top end. Pretty similar performance to stock at lower RPMs. Throttle response is better.
I would not recommend a bored TB on a totally stock engine. You at least need headers, exhaust, plus some bolt on TB mods.
If you install a larger TB you really need an adjustable fuel pressure regulator.

 

[longbedder]

I realize the TBI heads/cam have lackluster flow. I wouldn't expect to get past those issues with a different TB.

I'm not necessarily referring to an overbore TB, but rather a ported one (there is a difference). This basically involves cleaning up the casting and modifying the geometry slightly for more laminar flow at part throttle (but leaving the bore alone where contacted by the butterfly). The type of mod I'm talking about shouldn't affect top end much at all, but the guys that have done it on MPFI report a much "crisper" throttle response at low/mid RPM (all else being equal). I'm just wondering if that translates well to TBI. Seems like the injector pod being stuck in there may negate any efforts to clean things up?

 

[Thunder]

If better throttle response is all you are after then simply install a TB spacer.
Also getting rid of the stock air cleaner spacer can and replacing it with a power charger will help a lot too.
Go here:www.cfm-tech.com
The injector spacer, TB power plate, and Power Charger are all very good inexpensive mods that will give you a very noticible gain in over all performance. Espically if you have a good exhaust. Might even get a little better gas milage. It worked for me.
FYI Heres a little info on working over the stock TBhttp://www.thirdgen.org/ultimatetbi2

 

[longbedder]

Well, I'll admit this is mostly just hypothetical rambling on my part - I don't currently own a naturally aspirated TBI (I've got a supercharger sitting where the TB spacer you speak of would have to go ).

I had been banging around on CFM's site and came across their ported TB units. That's when this question initially popped into my head.

 

[Col_Sanders]

Well, I'll admit this is mostly just hypothetical rambling on my part - I don't currently own a naturally aspirated TBI (I've got a supercharger sitting where the TB spacer you speak of would have to go ).

I had been banging around on CFM's site and came across their ported TB units. That's when this question initially popped into my head.

So how do you like the supercharger? Its nowhere near the top of my to do list, but bolting one up to my 383 could be fun.