Throttle body

does the aftermarket spacer plate for the throttle body really make a difference on the 99 4.0 engines?

I don't know about a spacer plate but I put a 62mm TB compared to 58mm stock, its 62mm all the way through, and it made a noticeble difference.
http://www.thefastman.com/Throttlebodies40.asp

But I read some were on here that a spacer plate is good for 1-2hp.

The spacer does work, but it won't make a huge difference. I think Dino said its about a 5 lb-ft gain on the low end, and a 3 lb-ft gain at the torque peak, but only about 1 or 2 hp like raypla said.

A throttle body doesnt do much for horsepower and torque numbers.
All it really does is move the powerband. I personally would definitely rather bore out my throttle body.

j99xj said:

The spacer does work, but it won't make a huge difference. I think Dino said its about a 5 lb-ft gain on the low end, and a 3 lb-ft gain at the torque peak, but only about 1 or 2 hp like raypla said.

Click to expand...

Yup. That's exactly the sort of torque gain that I reported from my Poweraid TB spacer. Is it worth it? For a mere $50, definitely yes.
If you're going to install a 62mm bored TB (good idea), I suggest you also have the spacer bored to the same diameter. You'll lose the helix in the spacer bore but that does bugger all anyway so you won't miss it.

Not to high jack this thread because i do have a spacer and i like it and i can tell the difference. But the question for everyone else is - does your spacer make your air intake whistle? Sounds like a have a super charger under the hood?

I bought a red poweraid tb spacer for about 70 bucks 4 years ago and it whistled like crazy, and drove me insane, mainly because the highest pitch whistle occured right at my normal highway rpm. So I took it back.

Then about 2 years ago, I was on ebay and I found a 62mm tb spacer (smooth bore) under one of the those "buy it now" things for like 20 bucks. (I know, what a steal).

And NO whistle. I couldn't have been happier.

I think the whistle has to do with those fins cut into the poweraids, which most agree is worthless on a fuel injected engine.

Anyway I try not to buy performance products with flashy name brands and colorful boxes, because there is almost certainly a better product out there for far less money, if you have patience and can look around a little bit.