Hey y'all, found this surfing the internet.

In all the "how to get more HP out of my 4.9" i always see exhaust and stuff , but never a throttle body spacer....

here ya go-
http://www.jcwhitney.com/webapp/wcs/...&storeId=10101

 

please pass go and skip this mod, as its a waste of $$.

 

I see alot of adds for throttle body spacers in magazines. If they're a waste of money, what are they supposed to get people to think they do?

 

It's an absolute waste on any multiport fuelinjected vehicle.

They even make them for diesels now.

100% unadulterated Snake Oil.

 

The intake system of any vehichle is a tuned instrument. The length, diameter and overall volume of the runners (individual tubes to each cylinder) are carefully matched with the plenum (common) volume, to create a specific power and torque curve.

Adding a spacer (throttle body or carb) increases the plenum volume and moves the tuning of the plenum higher in the rpm range. You might be thinking this is a good mod if you want to spin your engine faster, but no, even then, it is not a good idea, because the retuned plenum volume works against the runners.

On a fuel injected vehicle, the only way you'll see an increase in power would be a possible 5 or less horse gain on the top end, but this comes with a corresponding loss on the low end, so the net effect over the course of an acceleration run would be zero.

I know you're asking about EFI, but I see so many people putting spacers on carbed vehicles that it's even more important to say that the detriments to using a spacer with a carb are far more serious than EFI. With a carb, as plenum volume increases, the "signal" to the carb decreases, which means that a loss of low end driveability in direct proportion to the amount of plenum volume increase can be observed.

Carb spacers are only useful on racing engines, and even then it is hit-or-miss. Read any catalog of a reputable fuel system company (Barry Grant, for example) and it will say that the only way to determine if a spacer is appropriate is to make back-to-back runs (dragstrip or dyno) with and without. It is a murky science at best.

 

I have to agree about spacers. I have a 96 and spent $90 on a TBS and the only thing it did was turn the check engine light on. I got the best seat of your pants power from a Flowmaster American thunder system plus 2 MPG's.

 

Anyone ever seen a larger tb for this? That might be interesting.

 

supposidly u can mount a 302, 351 or 460 TB up with some port matching on the intake inlet. also u have to remove the water passages. but that isnt the restriction. keep ur 300 TB and concentrate on the head, specifically the valve bowls if u want better flow...