hi all

would like to know if I change the size of the throttle body does it make much difference to the power output

I have a 2.8 efi motor in my 240z

the size of the throttle body internal butterfly size is 50 mm

also has flat top pistons and a p90 head

after market ems stinger computer

it puts out 90kws at the rear wheels on the dyno

I was thinking of putting a 60-65mm from a vl commodore

or if somebody has a better changeover throttle body

could you please advise

thank you

rob

I have seen the XF throttle body used on Z's a few times, tried and proven.

Wedgey,

I used to think that it would be a waste of time to spent the money for a larger TB.

but After doing it..I'm a believer!!

I used a 60mm from a 240sx... bought it for $25 from a yard. Changed the linkage, and WHAM!! LOVED IT!!

MSA claims a 1/2 sec. off your Qtr... and a gain in high end horses, and now I believe it. Throttle response is unbeleivable, and accelleration is improved as well. On a motor like your, that has some light mods, it would be a great and cheap way to add a few hp, and improve your general performance.

240sx is a 180sx here don't know if it's possible to get those here easily, I think the XF throttle body is your best bet.

240sx and 180sx have different engines. If you want the same engine as a 240sx in australia, you'd be chasing a 2.4L pintara (KA24E) or a 90s bluebird (KA24DE).

Putting on a larger throttle body would only develop MORE power if your current t/body is proving a restriction. I suggest you perform a little bit of testing. So I suggest that you go back to the dyno and have them put their vacuum/pressure sensor onto your intake. (You can tap into the fuel pressure regulator hose with a tee). Run it from 1500rpm to whatever your maximum rpm is. WATCH the guage and see if it start to show vacuum at higher RPM. The other way is to get a vacuum gauge and go for a fang up the road. (The bigger gauge the better - more senstive) Have a friend watch the guage, or (as I do with AFR's), use my mobile's vid recorder. Have them watch the guage and call out, 2000, 3000,4000 etc. You'll have video AND audio to watch later. If the tb's too small, vacuum will INCREASE the more you rev it. But be warned, a non liquid damped guage will vibrate rapidly and be hard to read.

Anything more that about 1-1.5" vacuum and your tb's or intake plenum is too small. Plenum volume has an effect on relative airflow through the throttle. Bigger plenums act like a buffer zone reducing pulsations(in conjunction with a BIG cam), which can increase effective t/b flow.

Remember also that a larger t/b makes your car feel faster due to the fact that at say 50% open you may be getting 75% of the smaller t/b's airflow. I use a Ford 65mm on my L28 turbo. This runs a fabricated manifold though and makes a minimum of 550hp@motor (465rwhp/347rwkw).

The stock TB is probably not a contributing limitation to your present power output. Having said that, going a bit bigger should not do any harm, providing the ECU can handle it. Have heard that some SR20's have ~65mm TB's.