Has anyone bored out the throttle body on the 3.5L? Just wondering what kind of gains could be made. I'm a toolmaker/machinist and could do it at work and could definately make a spacer. But I have no idea if it is worth it. Free mod but would there be any gains ?

 

I think in order to get gains, u must back it up with more mods....i'm not totally sure tho....i'm sure with basic bolt ons, you wouldn't see too much of a gain

maybe if your pushing higher rev limiter, afc tuning, intake manifold....then a bigger TB should benefit more

 

That would be almost equivalent to the TB restrictor mod for VQ30's. I felt the gain...

I swear - the whistling had to be whp!

 

I used to owned a 280Z 1978 inline 6 with headers and everything on that puppy. There was a company that actually made a BIG THROAT for it. The price was around $90, but the car was a different one after I added the BT... the change was amazing.

 

TB can add HP, but they can be tricky. To big can hurt, and to small can hurt. Most of the time you first want to figure out how much air your engine can bring in max at redline at 100% VE. Of course keep in mind 100% VE is impossible to have unless you are turbo/supercharged. Remember your engine is nothing more than a air pump with a big bang in it. It can only pull in and ex-spell X amount of air under certain conditions no matter how big you make the exhaust, or intake. This of course excludes forced induction.

The math is like this Air flow equals: Cid X RPM X 0.5 X VE/1728
213 X 7000 X .5 X 1.00/1728 = 431CFM This is the max amount of air the 3.5L will/can handle at 7000RPM NA. Keep in mind this is at 100% VE, meaning that this number is higher than what will be true world.
213 X 7000 X .5 X .85/1728 = 367CFM This is much more realistic. Even 85% VE is high, but it's a good number to use. Knowing all this you can now figure out what size TB you need. 431CFM being the max NA. I’d aim for something that flows around 450CFM. You really want to keep your velocity up it’s very important. The problem with to big a TB is you loss velocity, and you effect cylinder charging which effects your fuel/air mixing, which hurts power. You also have to keep in mind that the air path is not perfect, so you have to allow for that, which is why aim for something that flows a little more.

 

If you have taken a close look at the 2k2/2k3 TB, you will notice there is not alot of meat that could be removed to make a big bore TB. Plus with the TB being e'gas, it is nearly impossible to take apart, then get back together. If you'd like to see some pics of it, I will post a few below.

For more pics, see my CarDomain site :

http://www.cardomain.com/ride/301377/8

 

Man your showing your age.... I guess it's my turn. I had a 1976 280Z and did the same thing... did you install yours. Well I did and what a PIA it was to get those contact points lined up just right on the TB. It made a huge difference on mine as well. Those were the days....

 

You are incorrect.

The Z33 can achieve 105% VE on an N/A engine from the factory.........no boost.

 

Is the z33 the only car to produce 105% VE n/a?

if its the only one...then thats quite a feat if u ask me...able to flow air like a turbo/sc but without one!

 

350Z/G35. There may be more, but those are the ones that I know of.