Mustang and Ford Performance Forums banner
1 - 5 of 5 Posts

·
Registered
Joined
·
492 Posts
Discussion Starter · #1 ·
After reading a few replies in other threads about how a larger throttle body on a N/A vehicle can cost performance, I decided to throw my factory in and give it a whirl. Upon startup I immediately noticed that the engine came down from the rpms alot quicker than with the 75mm. Took it for a drive. Shifting into 2nd and third gears with traction control off, it felt like the traction control was kicking in. A complete bog down until it got some momentum. I dont know if this may be because the chip is tuned for the larger throttle body or not. Put the 75mm back on and it was kicking like always. Any inputs out there?
 

·
Registered
Joined
·
13 Posts
Good Question... I have the stock MAF but the first gen of TB's were 70mm which is what I have.. I think the stock one was 65mm.. I noticed the idle was higher when I first put it on, and it acted wierd when you used the AC.. That is one of the problems that was fixed by Randy's tuning..... The car runs 10x's better with the AC on.
I understand the concept of a performance loss by too large of a TB because the velocity of the air is reduced, not sure how that translates in real life though.
 

·
Registered
Joined
·
374 Posts
The thing with a larger throttle body that is very noticeable immediately is part-throttle response is usually increased. It has to do with the larger throttle plate, so at the same opening as a smaller throttle body, its allowing more air to enter the engine. It can easily be misinterpreted as "more power". Going from part-throttle to WOT with a larger TB results in a greater pressure drop immediately and velocity suffers. This is why you might see a minor HP loss on the dyno with a larger TB.

Obviously if the engine needs the TB, the WOT transition won't cause a dramatic pressure drop and the engine will respond crisply.

Tony
 

·
Registered
Joined
·
810 Posts
Hey did you check the TPS voltage when you swapped throttle bodies?
I always set mine to 0.996 volts for best performance.
Recheck that if you haven't thought of it.

Could be the tune with the chip also I guess....:confused:

You can always leave the larger throttle body on there!

:D

Cheers,
Ryan
 

·
Registered
Joined
·
492 Posts
Discussion Starter · #5 ·
Hmm, I never thought of that. Long story short, I put a new TPS on with the new TB, and left the original attached to the factory TB. Seems like something I should call the shop working on my car about. Have them check the TPS and make sure it's set right.
 
1 - 5 of 5 Posts
Top