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FAQ - CHI Cylinder Head Innovations

FAQ

Why are some of the heads called 3V?

The heads were given the name 3V as the original designs had the air flow of a 4V with the port size of the 2V, so 3V seemed appropriate.

Today there are 3V heads that way outflow 4V’s and the term 3V is given to all CHI Ford heads with raised inlet ports.

Do they need a special intake manifold?

Yes, the 3V heads need a matching 3V intake manifold. If you want to keep the manifold you have now, we do make 2V and 4V heads with ports in the original Ford location.

 

How do I choose the best Ford head for me?

There are a lot to choose from that’s true. To make the best choice you need to know roughly how much power you want to make and what camshaft you plan to use. Before the final decision is made, we will also need to work out what combustion chamber size is needed.

We have a couple of selection guides available, but if you’re not sure. Give us a call.

Ford Cleveland cylinder head range.

3V185 Heads:

185cc (as cast) intake runners. Ideal for Boss 302 or standard stroke 351 Cleveland engines up to 580HP.

Requires matching CHI manifold available in single plane only. Use with 2V or 4V headers

Available bare or assembled with 60cc or 67cc fully machined combustion chambers.

2V190 heads:

190cc (as cast) intake runners. Standard replacement for Cleveland iron 2V heads, suitable for a wide range of

applications up to 520HP.

Use with standard or aftermarket 2V manifold. Use with 2V or 4V headers

Available bare or assembled with 60cc or 67cc fully machined combustion chambers.

3V208 heads:

2.3” min CSA 208cc (as cast) intake runners. Most popular and versatile 3V head. Can be used on 351ci to 427ci engines up to 640HP

Requires matching CHI manifold available in duel plane or single plane. Use with 2V or 4V headers.

Available bare or assembled with 60cc or 67cc fully machined combustion chambers.

3V220 heads:

2.54” min CSA 220cc (CNC ported) intake runners. Raised (CNC ported) exhaust.

Small valve, small throat.  Designed for 5.0litre or bigger circuit race applications where a broad power range is required.

Requires matching CHI single plane intake manifold. Requires custom headers

Available bare or assembled with 60cc or 67cc fully machined combustion chambers.

3V225 heads:

2.4” min CSA 225cc (as cast) intake runners. Best suited to 393 or bigger engines up to 740HP

Requires matching CHI manifold available in duel plane or single plane. Use with 2V or 4V headers

Available bare or assembled with 60cc or 67cc fully machined combustion chambers.

4V228 heads:

228cc (as cast) intake runners.  Replacement head for factory 4V.

Use with standard or aftermarket 4V intake manifolds. Use with 2V or 4V headers.

Available bare or assembled with 60cc or 67cc fully machined combustion chambers.

Also available with 4V shape 75cc chambers to clear domed pistons.

4V240 heads:

240cc (CNC ported) intake runners. Replacement head for Factory 4V.

For those who want to keep their 4V manifold and have a CNC ported head.

Use with standard or aftermarket 4V intake manifolds. Use with 2V or 4V headers.

Available bare or assembled with 60cc or 67cc fully machined combustion chambers.

Also available with factory 4V shape 75cc chambers to clear domed pistons.

3V242 heads:

2.65” min CSA 242cc  (CNC ported) intake runners. Raised (CNC ported) exhaust.

Best choice for 700HP to 800HP applications.

Requires matching CHI single plane intake manifold.

Requires custom fabricated headers.

Available bare or assembled with 45cc or 60cc fully machined chambers (60cc reduces flow slightly)

3VKaase heads:

2.85” min CSA 258cc (CNC ported) intake runners. Raised (CNC ported) exhaust.

For applications above 800HP.

Requires matching CHI single plane intake manifold.

Requires custom fabricated headers.

Available bare or assembled with 45cc fully machined combustion chambers.

3VProSeries heads:

3.08” min CSA 268cc (CNC ported) intake runners. Raised (CNC ported) exhaust.

Intake ports raised .500” above the already high port Kaase heads.

Ford applications up to 1000HP.

Requires matching CHI intake manifold

Requires custom fabricated headers.

Available bare or assembled with 45cc fully machined combustion chambers.

 

Cylinder head selection chart. A graph that shows the power range of each different CHI series of Ford heads.

selection chart jpg

What head studs/bolts do I need?

Only the “raised exhaust” model Ford heads need special studs as the bolt boss is taller on the exhaust side ARP154-CHI3V is the part number.

All the other CHI heads will accept standard bolt or stud kits.

*note* If you are using original head bolts you will need to fit hardened washers under the bolt head.

What headers can be used?

The CHI “uni” exhaust port, standard on 185, 208 and 225 3V heads and 190 2V and 228 4V, will accept either 2V or 4V off the shelf headers. 1.3/4” will support up to approximately 650hp and 1.7/8” about 750hp.

High Port exhaust heads have HP in the part number and require custom made headers, in some cases 4V off the shelf headers can be modified to fit.

exh port comparison resized

What combustion chamber options are there?

The 185, 208 and 225 heads come in either 60cc or 67cc and have CHI’s unique chamber shape. They can be specially ordered with any chamber size between 55cc and 72cc maintaining the same basic shape.

We also offer a special 75cc chamber with the factory 4V shape to clear domed pistons.

Standard chamber size for Kaase and Pro Series heads is 45cc but they can be ordered with 60cc or 67cc CHI chambers or our special 72cc Turbo chamber.

What chamber shape works best?

Chamber shape is a critical part of any cylinder head and a lot of continuous effort goes into developing CHI’s shapes resulting in better flame propagation, cleaner burn and more power. As a result CHI heads tend to handle more static compression than most others and tend to work best with less total ignition timing.

Rough rule of thumb: the smaller the better. To achieve some chamber sizes offered we bring the valve seats down closer to the piston, this improves the flow greatly by un-shrouding the valve at lower lift figures and is worth the extra effort required to get piston to valve clearance. Eg: Valve drop on 45cc = 0”. Valve drop on 67cc = 0.150”.

What spark plugs do I need?

We suggest NGKBCP6ES as a starting point.

What roller rockers suit the Ford heads?

For solid roller race cams we suggest T&D #7205 or Jesel shaft type rockers.

For street solid roller cams or hydraulic applications, stud mount rockers are usually fine.

We us Comp Cams pro magnum or Yella Terra.

What roller rockers suit the Chev heads?

The CHI Chevy heads have a 60/40 valve spacing and so need offset shaft mounted rockers.

Yella Terra Platinum, T&D or Jesel.

What valves do you use?

CHI valves are made by Race Engine Valve company (REV)

What springs do the assembled heads have?

C1 Street assy: hyd flat tpt 120lbs / 300lbs @.600″  330lbs/in –  0.570”
C2 Street assy: hyd roller, solid flat 130lbs / 328lbs @ .600″  330lbs/in –  0.570”
C3 Street assy: hyd roller, solid flat 145lbs / 385lbs @.600″  400lbs/in –  0.650”
C4 Comp assy: street solid roller 170lbs / 434lbs @.600″  440lbs/in –  0.670”
C5 Comp assy: race solid roller 250lbs / 646lbs @.600′  644lbs/in –  0.800”
     
 At C.H.I. we only use quality components for our assembled cylinder head options.We use R.E.V. valves made specifically for us, Isky or P.A.C. springs, machined collets and chromoly or titanium retainers sourced locally in Australia or from US suppliers.Above are our standard assembly options and parts are kept in stock but we can customize and source components to suit your specific application.
 Spring part numbers and type:
C1 = Isky 805-DO single with damper                  C4 = Isky 9005 duel with damper
C2 = Isky 6105 duel with damper                         C5 = Pac 1225 duel with damper
C3 = Isky 8005A duel with damper

 

CHI Facilities

Here at CHI we carry out all R&D In-house with our DTS Engine Dynamometer Cell, which we have independently audited for room quality and repeatability, Superflow SF-600 flow bench with Flowcom software. And our own in house 5-axis machining for unparalleled quality control. On top of this we also have Faro 7-axis CMM, inhouse CAD modelling,  FEA (finite element analysis) and CFD (Compuational Fluid Dynamics) capabilities all to ensure our products remain at the cutting edge of technology and quality.

5 Times Engine Masters Champions

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