Winston

So I'll be getting my header soon, and full exhaust soon after that.

I have a 3" CAI, and I just ordered a Saab MAF.

I also have a stock IM ready to be ported and polished.

That leaves me with the burning question of what to do about a BBTB.

I ordered a OEM TB that I was going to send to Dennis to be bored out. But that only increases the diameter by a few millimeters.

So I started looking around for a different option and found that some people have used Mustang TB's and even a guy that used a TB from a Land Rover.

I looked on ebay and found that both the mustang TB and Land Rover TB can be had for $35-$55.

I know I would have to modify these TB's for them to fit (mounting holes, pulleys, TPS), but it seems like it's very doable for me.


My question is, how big is to big for a TB on an N/A tib. Can you actually lose power from having an oversized TB?

Most people with N/A tibs have between a 53mm (stock) and 62mm TB. Don't quote me on that though tongue.gif

The mustang TB's are between 70mm and 75mm. The Land Rover TB is 76mm.

Is this to big?


I just searched for countless hours trying to figure out the power-loss issue. I couldn't find a definitive answer.

Please help me!

likeyoumeanit

I was also wondering this, I was just to lazy to search for it, apparently I would have been wasting my time though

REDZMAN

It's oft talked about, but rarely quantified.

I've had the following.

1. Stock.
2. Rside 59/61MM
3. System GTR 62MM
4. Tigerlilly 65MM

I've also got the supporting mods, and live at about 5500 feet in altitude. Car runs better than great.

Random and others rumored for a long time that 65MM's would be unusable on a N/A car, some said they would stall out, others said they would be very slow at the low end.

Not mine.

They also said the 1.8L ECU wouldn't work at all in our cars, and that a CEL with a exhaust was just a way of life.

Ericy321

With the options available you cant really go to big.

Winston

Thanks REDZMAN, it's good to know that 65mm isn't to big.

So to answer this question once and for all, I just ordered---

-> 1999-2001 Land Rover Discovery TB (76mm?) --- $35 shipped
-> ???? year Ford Crown Vic TB (65mm) --- $37 shipped

The OEM Tiburon TB I ordered should be here tomorrow.

When I get all the TB's I will post pics of side-by-side comparisons and such.

I hope some attractive women hack my e-mail, because then they'll be like "wow, he must have 3 cars" lmao.gif


Anyway, I figure if one of them works I'll save at least $100 smile.gif

Ericy321

Actually they should all work. The Land Rover just needs the holes widened a bit really. Even uses the same TPS.

StrikeEagle

Nothing is too big. Just realize though, that the bigger it is, the less throttle response you have.

i8acobra

NA, 62mm is plenty big. That's what I had and I was running just about every NA part you can run except high CR pistons (head was decked though). I'd run a 58mm for a bolt-on car minus cams, 62mm with cams. I'd leave the bigger stuff for FI cars.

Stocker

^ what they said. I was going to bore my spare TB and then I started to think about throttle response. Most of my car's time is spent at very low throttle openings (driver, not racer) and I don't have forced induction... I sold the TB.

JonGTR

Personally, I'd run something below 60mm for N/A. First, it's not worth the hassle or money which could go somewhere else. Second, you lose response. Going too big will cause the car to jerk more at low speeds or from a stop.

There are EVO's running stock 60mm TB's on big turbo setups and pushing 550whp. Sure, they might pick up an extra 20-30whp by going bigger, but is it worth the $300 for it and loss of low end throttle response? Nope.

I just swapped a 240sx 60mm TB onto my 300zx which came with a 54mm TB. Odd huh? I'm putting out a lot more power than stock and needed it, but I noticed the response difference and don't really care for it. It's a trade off. If it didn't cost me $10 for the TB, I never would have bothered.

Bigger is not always better. Spend your money wisely.