How much torque and horsepower could a spacer between the tbi and intake give a 350?
Not near as much as the advertisements would lead you to believe. On an otherwise stock engine it might bump the numbers by 2 or 3, maybe, on a good day.
You're so welcome.
When I was in a pre-employment program, in our performance unit one of my classmates did the research on Tower TBI spacers. Dyno'd his pretty much bone stock 350 chev half ton truck before and after and said the spacer gave him about 10 extra hp. This is his word, and in his report and our professor accepted it, who was IMHO quite experienced and smart on the subject. At sea level it would've been a bit higher of course. Why so low VW?
A few reasons. Yes there are spacers available that are of extremely high
quality that when installed on an engine and powertrain management system
that have been optimized for their use can get you that type of power. All
of this costs a substantial amount of money ($100-$150 spacer, dyno time,
However, normally they only improve power in a very narrow bit of the powerband, so while the peak number is impressive, the overall power gain isn't. Also most people don't step up to the good parts or do any type of optimization, they just bolt them on and go. Top that off with the fact that most of them are being put on a tired old engine, the gains get less and less.
So, there is no doubt in my mind that your classmate saw an additional 10 hp on the dyno. But most people aren't driving dyno's, they're driving an old worn out Chevy pick-up where 2-3 hp is a more realistic number.