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4v navi heads comparable to any 4.6 4v head?

n2ostang

Member
hi guys im fairly new to the modular world. I am wondering if the navi heads are the same as any other 4v heads?
 

ModFoxMustangs

Well-Known Member
Staff member
DOHC Engines
The Modular V-8's greatest asset has long been the deep-breathing four-valve head. The way this head works is simple. There are two intake valves and two exhaust valves in each chamber. Below 3,000 rpm, we're on the primary port in the intake manifold, with the secondary butterflies closed. When we mash the throttle and open the secondaries, we're on both intake valves, taking full advantage of airflow. This was a good idea in theory, but in actual use, it didn't work very well in the beginning. Low- to mid-range torque was poor with these engines in normal driving, despite a big burst of power at high rpm at wide-open throttle.

Beginning in 1999, Ford went with the Tumble Port head. As its name implies, the Tumble Port tumbles the air and fuel as it rolls into the chamber, keeping fuel droplets in suspension. Not much changed aside from the shape of the chamber, which improved low- to mid-range torque. The 5.4L DOHC got its own kind of Tumble Head at the same time for use in the Lincoln Navigator.

"In 1999, Ford improved the DOHC head, just like it did with the SOHC. This is the DOHC PI head, correctly known as the Tumble Port head."

Ford brought performance enthusiasts the FR500 four-valve head in 2002 from Ford Racing Performance Parts. Although mostly a racing cylinder head, it does have a purpose on the street--yielding as much as 7,000 rpm and a whopping 500 hp. Bolt these onto your DOHC and make as much as 50 more horsepower from the heads alone.

The FR500 head is similar to the '03 Cobra cylinder head, which was introduced with an Eaton supercharger. This head's intake ports flow 233 cfm at .500-inch valve lift. Exhaust ports yield 168 cfm. These factors make the '03-'04 Cobra head a popular head with performance buffs that love Mod motors. Mercury copped this head for the '03-'04 Marauder; ditto for Ford with the Mustang Mach 1 and Lincoln's Aviator.

Like the SOHC engine, the DOHC has twin camshafts with pressed-on lobes. The primary lobe profile is different than the secondary lobe profile. This means two different cam profiles for each engine: one for intake and one for exhaust. The aftermarket offers billet camshafts for the Ford DOHC.

So, which head is best for your 4.6L DOHC project? It can be safely said Ford has a healthy variety of factory DOHC castings that will work well for your four-valve project.

Read more: http://www.mustangandfords.com/tech...r_v8_engine_part_2/viewall.html#ixzz1i1WKws1Y
 

ModFoxMustangs

Well-Known Member
Staff member
4-valve
250px-96Mark8Eng.jpg

4.6 L 4-valve DOHC InTech V8 installed in a 1996 Lincoln Mark VIII
250px-2003_Ford_Mustang_Cobra_32v_Supercharged_engine.jpg

4.6 L 4-valve DOHC supercharged V8 installed in a 2003 Ford Mustang SVT Cobra


The 4-valve DOHC version of the Modular engine was introduced in the 1993 Lincoln Mark VIII as the 4.6 L Four-Cam V8. Lincoln marketed the engine under the name InTech after 1995.[5]
The 1993–1998 4-valve engines featured cylinder heads with two intake ports per cylinder (split-port) and variable runner length intake manifolds with either vacuum or electrically activated intake manifold runner controls (IMRC) depending on application. The engine was revised for 1999 with new cylinder heads featuring tumble-style intake ports (one intake port feeding two intake valves), new camshaft profiles, and fixed runner-length intake manifolds. These changes resulted in more power, torque and a broader power-band when compared to the earlier 4-valve engines.
All 4.6 L 4-valve engines featured aluminum engine blocks with 6-bolt main bearing caps, the only exception being the 2003–2004 SVT Cobra which had a 4-bolt main cast iron block. The 1999 and earlier engines featured an aluminum block cast in Italy by Fiat subsidiary Teksid S.p.A. Since 1996, all of the 4.6 L 4-valve engines manufactured for use in the SVT Cobra have been hand-built by SVTtechnicians at Ford's Romeo, Michigan plant.[6]
The 4-valve DOHC 4.6 L engine was on the Ward's 10 Best Engines list for 1996 and 1997.
Vehicles equipped with the 32-valve DOHC 4.6 L include the following:
 

ModFoxMustangs

Well-Known Member
Staff member
The 2002-2005 Explorer combined the aluminum block with 2V heads; this combination was also used briefly by the Expedition SUV.

2012 Ford Racing Performance Catalog
 
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