Hi guys, I have a Holley Stealth Ram on a 327. This car will run mid 13s. Would a larger than stock throttle body make the car faster? Or is the stock MAF a larger bottleneck than the stock TB?

 

A bigger throttle body wont add horsepower unless your current ne restricts the airflow. I have a 250 with a stealth ram with a holley twin 58mm TB.

 

I know the science of CFMs suggests that the stock TB flows PLENTY for a mild motor, but you have to wonder why the 5.0 guys consider a 60 or 70mm "Cobra" TB to be a key ingredient in a bolt-on low 13/12 second Foxbody. Surely they don't just hate their manifold vacuum that badly.

 

The only thing you will see by bolting on a larger throttle body, IF you don't need it yet, is that it will be harder to modulate the power off-idle. As you tip into the throttle the car will lurch forward. For example the GM vortec 4.3/305/350 TBI has restricter riveted to it when used on the 4.3 and 305 to keep the truck from doing that. It basically blocks the front side of the throttle body opening at low throttle angles giving a better transition. Alot of people will take it off or get a 350 throttle body because they like the abrupt tip-in. The problem is more pronounced when you are trying to drive delicately such as on ice or a rain slick street. I have a hard time getting my 454 TBI on my built 305 to keep from blowing the tires away as I try to ease my boat out of the lake. It just wants to spin on the slick ramp.

 

a stock twin 48 mill tb flows something like 780 cfm. if you go to holley's web-site, they have a formula of engine size, max rpm, etc that will tell you how much cfm you need. - If you wouldn't need a bigger carb, you don't need a bigger tb. - as for the mudstain guys, they have a MONO blade 70 & 80 mm. we have TWIN 48 mm... where's the difference here?