Bigger is not always better

Typical logic implies that larger throttles will flow better making more power at higher RPM’s, while smaller throttles will generally provide more low and mid-range torque.  Something that is overlooked is how far away the throttles are from the port.  If two sets of ITBs have identical runner volume and taper, a smaller throttle placed near the head will perform the same as larger throttle near the velocity stack.  Thus, throttle size can be misleading when quantifying ITBs as larger throttles tend to be placed much further away from the port. 

URGE Sonic ITBs throttles <3” from the head port vs 4-5+” with competitive ITBs options.  Not only does this mean we can run smaller throttles and have enough flow, but it also means better response as air has less volume to fill when the throttles open. 

Port Entry Optimization

An important consideration is runner port entry design.  The idea is to maximize airflow with the smallest runner port area possible, producing optimal air velocity and maximizing torque across the broadest RPM range.  Based upon runner test flow data, changing the port entry angle a few degrees noticeably improved flow several percent.  Since AT throttles are machined and not cast, we were able to make custom changes to optimize air flow. 

Custom Runner size

We tune the runner length and volume based upon motor capability.  F20C pull the least amount of air so we keep our runner diameter to 55mm which improves response and torque for the smaller motors.  On the F22C, we step up to 60mm diameter as they can make more power.  For stroker motors 2.4-2.5 L, we step up again to 65mm runner diameters to ingest more air and shape it properly as it enters the head. 

Additionally, we can tun the length of the runners if someone is looking for peak power outside of the normal 7500-8500 RPM window.  If space is available, we can lengthen the runners to tune for the 2nd harmonic improving power potential 5-10 hp. 

Shaftless Throttle

Another significant ITB opportunity is the shape of the throttle itself.  Even at wide-open throttle, the bulk of the throttle blade and shaft can reduce airflow by 5-10%.  AT Power is an innovative induction company that created a new throttle design that is “shaftless”.  Their throttles are a thin tapered blade that is CNC’d as a single piece with the rotating shaft.  With this innovative shape there is nothing needed to support the shaft inside the runner port.  AT Power’s testing proved their design reduces airflow by only 0.5% (vs 5-10% in traditional setups), providing flow rates of barrel throttles without the cost or high maintenance. 

We applied a custom port entry angle with AT Power runner design & 52mm shaft less throttles to come up with an optimal set of ITBs that maximizes air velocity.

ITB Flow testing data points

• Ported head flow compared to various ITBs attached to head  
• URGE 52mm flowed the same as the 60mm Kinslers that have much larger throttles 
• 50mm Jenvey flowed a little better than the AT Power 45mm 
• ITB Flow testing vs Velocity Head and Stock Manifold  

Below are a few ITB dyno test to find the optimal throttle size 

• 52mm URGE designs vs 60mm Kinslers, on built 2.3L motor, 12:1 CR, pump gas, custom cams and header 
• URGE 52mm makes 10-15 ft-lbs more torque and power gains from Improved Air Velocity due to smaller throttles & runner + shaftless throttle and great flow 

• 52mm URGE designs vs 45mm, on built 2.3L motor, 12:1 CR, pump gas, custom cams and header 
• 52mm able to match the 45mm ITB low end while providing more gains up top. 

Based upon our testing, the 52mm ITBs are the optimal size for the S2000.  The 52mm throttles have similar air velocity to smaller 45-48mm ITB’s, providing good low and midrange torque and similar air flow to larger 60mm throttles providing top end power.  With innovative R&D we feel we have made the optimal ITB’s for stock as well as fully built road race engines. 

• URGE 52mm ITBs on F22 stock bottom end vs tuned intake and exhaust 
• 10-15 ft lbs of midrange and 5-10 hp up 

• URGE 52mm ITBs on fully built 2.5L URGE Paragon motor, 12.5 CR w/ 3” Stroker Unicorn Header 
• >300 whp on a Mustang dyno or >380 at the crank 

• Flexible ITBs work great on stock bottom end and fully built motor, just need to adjust runner/trumpet diameter 

OEM fuel rail Integration

Although we have gone through many small iterations to continuously refine the Sonic ITBs, in late 2020 we decided it was time to make a major revision based upon customer feedback leading to the current V2 designation.  The original Sonic ITBs came with an CNC fuel rail that had AN6 fittings.  This required ordering additional parts and modification to the OEM fuel lines.  Additionally, the fuel rail required a fuel pressure regulator. 

By Integrating with the OEM fuel rail vs including a new one, installation with the OEM fuel system is plug and play.  This also reduced cost by not including a new fuel rail and fuel pressure regulator. 

 Another $300 to $500 cost savings can be realized as customers can reuse OEM fuel injectors with OEM bottom end.  The OEM injector can support the HP gains made with ITBs and typical bolt-ons.  If customers compliment Sonic ITBs with Velocity headwork, Jerk cams or Halo Stroker kit, larger injectors maybe needed to support the larger gains.  Customers with URGE designs Halo Storker kits or other aftermarket stroker kits will require larger injectors.