I have a 01 S'Crew 5.4L. I ahve installed a 75MM throttle body with a spacer, i havent felt anything wrong and the performance is good but i dyno'd at only185hp. I cant Figure out if it was the throttle body swap or the truck? any Ideas?

 

throttle body spacer will rob a couple ponies they are a waste of money..

 

How can they rob power. If they were to do anything they would not do anything at all. They organize the air in one flowing direction until it hits the cylinders?

 

I wanted to do the same, but was heavily advised not too. The spacer is said to be an expensive paper weight and the t-body may give an increase, but not much. You'll only benefit if your supercharged and making over 400 hp's. Spend elsewhere. Even a cold air intake seems to be minimal gains.

 

Throttle body spacers are trash. Just like he said, expensive paper weights. The bigger TB itself isn't going to do anything for an unmodified truck. Your engine can only inhale and exhale so much air. Unless you're blown or sucking on a bottle then the stock unit will hold its own. Hell, I have a blown 5.4 and I only ported my stock one.

 

The engine can't use any larger throttle body.
The older 5L Mass Air engines only use 55mm stock.
The only possible gain is at the top end rpm.
You don't run around in first or second wound out do you?

Larger passages slows the airflow speed. You get no gain in power as you just found out.