52mm Throttlebodies -$199.99

This mod increases the airflow of your TPI/LT1 throttlebody. If you have more than 275hp, a 52mm throttlebody will give you a noticeable improvement. We saw a 20 hp increase on our TPI IROC-Z (headers/catback/ported tpi intake) with the addition of the 52mm TB. If your exhaust is already free flowing, you should see at least a 10 hp increase.

If your F-body or Corvette already has over 400 horsepower, you should consider the Accel 58mm throttlebody.
 

• Anodizeded MBA SPD throttlebody cover plate (red/blue/black/silver)
• Flows 790 CFM compared to the factory 48mm at 625 CFM
• Throttle bores opened to 52mm
• Larger butterflies are elliptical and matched to 52mm bore.
• You keep your IAC stepper motor, so your idle remains the same as you left it

Removal/Installation Instructions:

• Unlug TPS (on side) and IAC (bottom)
• Remove Coolant lines - now is a good time to do the free Coolant Bypass mod
• Remove throttlebody from intake - four 10mm  bolts
• Remove top cover (says Tuned Port Induction or blank) - 6 torx screws
• Remove bottom cover (this housing holds the IAC motor and has the coolant inlet)
• Throuroughly clean the TB with carburator cleaner and rinse with water
• Repeat till clean (note: $10 cleaning fee if it hasn't been cleaned)
• Put TB in a ziplock bag
• Package it securely in a box and mail to SPD
• Receive a box from SPD a week later
• Reverse to install (sorry - a little humor that you'll understand if you've ever read a Haynes manual)

We do have throttlebody cores for TPI and LT1 motors if you can't bear to be without your car for a week. The core charge is $125 which will be refunded in the form of a check when we receive your clean core. If any of the screws have snapped off, there is a charge to remove them.

Custom SPD throttlebody plates made by MBA are available in anodized red, blue, black, and silver.  Different standard MBA plates are available for $40 (outline engraved) and $50 (fill engraved) with your SPD 52mm throttlebody. Contact SPD for more details.

     Since many people have asked what the differences are between the four different throttlebodies, I should explain it. The differences are the TPS sensor style for the TPI and LT1 throttlebodies and then the way the cables mount..
     The early style TPI has a post for all three cables (throttle, cruise, TV kickdown). The cable has a fitting which slides over the post. The later TPI did away with the throttle cable post and uses a button in a groove. This is similar to the way your bicycle brake cables mount to the levers. The elliptical groove supposedly gives better throttle response, but I haven't found anyone yet who can tell the difference.

   The early and late LT1 share similar situations. The 93 automatic LT1 tb has a groove for the throttle cable, and then 2 arms for the cruise and TV cables. The 93 manual and all 94+ LT1 styles only have one arm, since the transmission is now electrically controlled, and doesn't have the TV cable.
     If you have a different year than the throttlebody you are purchasing, just convert to that year's throttle cable for the TPI, or for the LT1, just get a manual transmission so you don't need that kickdown cable...

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