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454INT Tillotson HR Intake Manifold for Honda Clone Big Block Engines
454INT Tillotson HR Intake Manifold for Honda Clone Big Block Engines
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454INT Tillotson HR Intake Manifold for Honda Clone Big Block Engines

Part Number: 454INT
Online Price: $59.99
EC 454INT Billet Intake Manifold for Tillotson HR & XHR Carburetors – Fits GX390, Predator 420 & Wildcat 460
Availability: In Stock.

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Description

454INT Billet Intake Manifold Adapts Tillotson HR-Series Carburetors to Honda GX390 Big Block Engines


Adapts Tillotson HR-Series & EC XHR Carburetors to Honda GX390, Predator 420 & Wildcat 460 Engines


Unlock maximum airflow and throttle response in your big-block racing engine. The EC 454INT Billet Intake Manifold is engineered to perfectly adapt 1.355" 

Tillotson HR-Series diaphragm carburetors—including the championship-winning EC XHR Intimidator—to the Honda GX390, Predator 420, Wildcat 460, and other big-block clone platforms.


Built for open-class racing, this intake ensures the ideal vacuum signal, precise port alignment, and consistent fuel delivery needed for top-tier performance on the track or strip.


Why This Intake Manifold Outperforms Others

Unlike generic manifolds, the 454INT includes:


Pulse Fitting + Pulse-Through Porting

A precision-machined pulse fitting and an internal pulse hole aligned specifically for Tillotson HR-series carburetors ensure:

  • Strong, reliable diaphragm operation
  • Stable fuel delivery at high RPM
  • Compatibility with external vacuum pumps

Engineered for Big-Block Power

Designed around the airflow needs of 1.355” diaphragm carbs, this intake supports:

  • Big-valve cast heads
  • Fully ported racing heads
  • GX390/420/460 open-class builds
  • High-RPM throttle response without the tuning inconsistencies common with longer runners


Why Pair It With the EC XHR Intimidator Carburetor?

For maximum results, match this manifold with the XHR Intimidator—the most proven 1.355” carburetor in open OHV racing.

Compared to standard Tillotson HR carbs (designed for 2-stroke engines), the XHR-7 (methanol) and XHR-10 (gasoline) deliver:

  • Custom-built fuel circuits for OHV engines
  • Faster, cleaner throttle response
  • Superior mid-to-top-end power
  • More consistent tuning with fewer compromises

This combination offers an unmatched performance edge in karting, mini bike racing, and open modified OHV classes.


Precision CNC-Machined for Maximum Airflow

The 454INT is fully CNC-machined from high-strength billet aluminum to ensure:

  • Smooth, unrestricted laminar airflow
  • Zero turbulence at the head-manifold transition
  • Accurate fuel atomization
  • Strong, consistent intake pulses

This results in better throttle response, quicker acceleration, and improved fuel metering under load.


Intake Runner Length: Tuned for Real Racing

Diaphragm carbs require strong intake pulses—something many aftermarket intakes weaken.

The 454INT is engineered with the ideal runner length to maintain:

  • Crisp throttle response
  • Accurate diaphragm actuation
  • High-RPM stability
  • Broad, usable powerband

Longer intakes may tune for peak RPM, but also weaken the pulse signal—this manifold avoids that compromise.


What’s Included

  • EC 454INT Billet Intake Manifold
  • Pulse fitting (pre-machined for HR/XHR carbs)
  • Mounting hardware
  • Intake gaskets


Compatibility

Carburetors (1.355” Bore)

  • Tillotson HR-Series
  • EC XHR Intimidator Series

Engine Platforms

  • Honda GX390
  • Predator 420
  • Wildcat 460
  • Other Honda-based big-block clones

Best Use Cases

  • Open class OHV racing
  • Big-valve heads
  • High-flow ported cylinder heads
  • Performance karting & mini bike racing



FAQ

Q1: What carburetors fit the EC 454INT Billet Intake Manifold?

The 454INT is designed for 1.355” Tillotson HR-series diaphragm carburetors, including the EC XHR Intimidator series, which are optimized specifically for OHV racing engines.


Q2: Which engines does this intake manifold fit?

The intake fits Honda GX390, Predator 420, Wildcat 460, and most big-block Honda clone engines used in kart racing, mini bikes, and open-class OHV performance builds.


Q3: Why does the manifold include a pulse fitting?

Because HR-series and XHR carburetors rely on a diaphragm-style fuel pump, the intake includes a precision-machined pulse fitting and aligned internal pulse hole to ensure strong, reliable fuel pump operation—even at high RPM.


Q4: Does this intake improve performance over stock manifolds?

Yes. The 454INT is CNC-machined from billet aluminum and designed for smooth laminar airflow, better vacuum signal, and tighter port alignment. This results in faster throttle response, improved fuel atomization, and stronger top-end power.


Q5: Do I need to modify my cylinder head for this manifold to work?

No modifications are required, but the manifold performs best with big-valve cast heads or ported performance heads, especially in open-class engines.


Q6: Is this manifold suitable for both gasoline and methanol?

Yes. The intake is compatible with both fuel types when paired with the correct carburetor:

  • XHR-7 for methanol
  • XHR-10 for gasoline


Q7: Will a longer intake runner make more power?

Not with diaphragm carburetors. Longer runners weaken the vacuum pulse required for consistent fuel delivery. The 454INT’s runner length is engineered to maximize power without sacrificing pulse strength or throttle response.


Q8: Can I use this manifold in kart racing or mini bike racing?

Absolutely. It is specifically designed for open-class OHV racing, making it ideal for high-performance karting, drag mini bikes, endurance racing, and modified big-block builds.

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