I know there are dozens of posts regarding the Ultimate TBI, the 454 TB swap and the Holley 670cfm setups. I've read most of them *lol*

My question is, at what point does it become worthwhile to modify your TB? I don't really want to dremel my stock unit unless I am going to get something out of it.

Can anyone shed some light on this?

 

The Ultimate TBI will work great for a stock engine, and a worth while free mod. A Holley or 454 TBI is only required after you've done some major engine work such as heads and cam. Most people will tell you that the stock TBI w/ the Ultimate mods done will hold you 'till about 250-270 hp

 

I am still running the stock TBI, with ultimate TBI mods and 350 injectors. I may consider upgrading the the 670 and a single plane manifold next summer. I don't think that modifying the TBI will be necessary untill you have done full exhaust and replaced the intake manifold. But it couldn't hurt.

 

I'm just leary about taking a dremel to my intake. I've seen people really mess them up that way. And the flowbench R&D we did on the 3.4 head design taught me that simply eliminating ridges and smoothing surfaces is not always the best way.

I think I will hold off for now, at least until I get to cam/manifold.

 

I don't completely agree with all the ultimate tbi mods... even if we were to get the lo3 to 100% volumetric efficiency, we would not see close to the stock 480 cfm flow that the tbi has available to it.

Headers, cam, intake, heads are the most limiting factors on the TBI lo3 setup. Headers will give a good boost per ease of installation. Cam will give the biggest boost by far provided its flow matched to intake and heads.

The rest will give mior boosts in addition to the first two mods.