25+mpg 4.0l ohv build

[konrad911]

gaz my 2 cents - please do measure the volume of combustion chamber by yourself. I've seen that advertised pistons with certain CR had almost 1 point lower CR in reality.
I will measure mine for sure, but these are the other way round - late pistons and early heads on early block

 

[RonD]

1995-2000 heads had the same chamber size
1998-2000 heads had smaller exhaust ports to increase velocity of exhaust flow to warm up Cats faster, 1.7" down to 1.4" exhaust ports

1990-1994 had slightly larger chambers and the 1.7" exhaust ports

 

[gaz]

gaz my 2 cents - please do measure the volume of combustion chamber by yourself. I've seen that advertised pistons with certain CR had almost 1 point lower CR in reality.
I will measure mine for sure, but these are the other way round - late pistons and early heads on early block

@konrad911 ,
What I will do is measure the dish in the 94 pistons then subtract that from the equation since SOHC's are flat. In regards to the 98 combustion chambers, it is published as a 10cc/cylinder reduction (-60cc) and there was minimal bowl work performed. If I wanted to lean to the side of losses, instead of using -60cc, I could call it -54cc as a 10% loss from bowl work.

Either way, I will measure the dish in the 94 pistons, good idea

 

[gaz]

1995-2000 heads had the same chamber size
1998-2000 heads had smaller exhaust ports to increase velocity of exhaust flow to warm up Cats faster, 1.7" down to 1.4" exhaust ports

1990-1994 had slightly larger chambers and the 1.7" exhaust ports

@RonD ,
Yes, as mention on our tech pages 95-99 OHV combustion chambers are about 10% smaller.

I had the smaller 98 spec exhaust ports flow bench ported to the JBA 2.9l header tubing. Should be interesting as it is still smaller than the oversized stock Ford 4.0l exhaust manifold's inlet size.

 

[gaz]

Hello,
Phooooooooooph‼. Gaz blows the 5 year pile of dust off own...old 2018 thread

There have been a few changes to the list of components and a couple additions to the list. Additionally, the time line, that was back burner time and time again for the past 5 painful years has come to a head.

CURRENT COMPONENT LIST
• complete 1994 SFI-MAF-EDIS OHV 4.0l with harness/EEC
• Hypertech Performance CHiP
• MSD DiS-4
• Oregon Cam Grinders custom reground cam
• 1.55 rockers
• NOS lifters
• custom length push rods
• balanced 2.9l adjustable rockers
• free floating rocker arm spacers
• Endrigo flow benched port/polished 98+spec heads/intakes
• Endrigo performance valve job
• Endrigo bored stock T/B to 64mm
• Mahle 01 SOHC 4.0l flat top pistons
• light weight OHV 4.0l rods
• JBA 2.9l Headers
• Flowmaster 200 series cats
• tandem Borla ProXs mufflers
• true dual 2¼" exhaust
• Cloyes timing set
• Gates water pump
• Melling standard volume oil pump
• 2001 SOHC 4.0l upper/lower oil pan

Most notable change is that my machinist/engineer comrade finally convinced me that a full bottom end balance will have a minimum value in my daily driver (completely apologize to all on here who failed to convince me).

MY GOAL
"Purpose-built" OHV 4.0l (speculatively 237 HP/275 TQ @ the crank) in 1987 BroncoII chasis (3,200 lbs) achieving 34.6 mpg during dedicated highway driving (cross country drives) on a 4" suspension lift, 3.73 gearing and 32" to 33" tires using only premium fuel.

 

[alwaysFlOoReD]

Hello,
Phooooooooooph‼. Gaz blows the 5 year pile of dust off own...old 2018 thread

There have been a few changes to the list of components and a couple additions to the list. Additionally, the time line, that was back burner time and time again for the past 5 painful years has come to a head.

CURRENT COMPONENT LIST
• complete 1994 SFI-MAF-EDIS OHV 4.0l with harness/EEC
• Hypertech Performance CHiP
• Oregon Cam Grinders custom reground cam
• 1.55 rockers
• 98 spec heads/valves
• Endrigo flow benched port/polished heads/intakes
• Endrigo performance valve job
• Endrigo bored stock T/B
• 2001 SOHC Ford 4.0l flat top pistons
• JBA Headers for Ford 2.9l
• Borla true dual 2¼" exhaust
• Cloyes timing set
• Gates water pump
• Melling oil pump
• 2001 upper/lower oil pan

Most notable change is that my machinist/engineer comrade finally convinced me that a full bottom end balance will have a minimum value in my daily driver (completely apologize to all on here who failed to convince me).

MY GOAL
"Purpose-built" OHV 4.0l (237 HP/275 TQ) in 1987 BroncoII chasis (3,200 lbs) achieving 34.6 mpg during dedicated highway driving (cross country drives) on a 4" suspension lift, 3.73 gearing and 28.5" to 30" tires using only premium fuel.

Timeline? Another 5 years... /jk

 

[bobbywalter]

Hello,
Phooooooooooph‼. Gaz blows the 5 year pile of dust off own...old 2018 thread

There have been a few changes to the list of components and a couple additions to the list. Additionally, the time line, that was back burner time and time again for the past 5 painful years has come to a head.

CURRENT COMPONENT LIST
• complete 1994 SFI-MAF-EDIS OHV 4.0l with harness/EEC
• Hypertech Performance CHiP
• Oregon Cam Grinders custom reground cam
• 1.55 rockers
• 98 spec heads/valves
• Endrigo flow benched port/polished heads/intakes
• Endrigo performance valve job
• Endrigo bored stock T/B
• 2001 SOHC Ford 4.0l flat top pistons
• JBA Headers for Ford 2.9l
• Borla true dual 2¼" exhaust
• Cloyes timing set
• Gates water pump
• Melling oil pump
• 2001 upper/lower oil pan

Most notable change is that my machinist/engineer comrade finally convinced me that a full bottom end balance will have a minimum value in my daily driver (completely apologize to all on here who failed to convince me).

MY GOAL
"Purpose-built" OHV 4.0l (237 HP/275 TQ) in 1987 BroncoII chasis (3,200 lbs) achieving 34.6 mpg during dedicated highway driving (cross country drives) on a 4" suspension lift, 3.73 gearing and 28.5" to 30" tires using only premium fuel.

do you mean diesel fuel?

 

[RonD]

1987 BII with 4" lift that gets close 35MPG would be electric hybrid

 

[bobbywalter]

1987 BII with 4" lift that gets close 35MPG would be electric hybrid

or being towed by a dodge 3.0 diesel....

 

[RonD]

or being towed by a dodge 3.0 diesel....

Which was being towed by a Rivian

 

[gaz]

No denying the brick like shape of a Bronco II. I remain hopeful that the horse power to weight ratio difference and improved efficiency can muster my goal. My best lessons learned have been from failing, this could be a duesy.

After going over the numbers again with my machinist, he now recommends using a true dual 2¼" exhaust; this was confirmed by the technician from Borla.

 

[gaz]

SOME 4.0 TO BII DIFFERENCES
• BroncoII (BII) brake fittings do not fit 94 Explorer (Exp) brake master cylinder's (BMC), so unless BII fittings are changed, reuse the BII BMC.

• 94 Exp transmission coolant lines do not fit the BII radiator fittings, possibly even earlier Exp radiators.

• a complete 94 four door Exp fuel system can be installed in a BII, if you run it across the body vs in the frame rail with the Exp's fuel pump assembly unit, because of the fitting changes from BII to Exp. A better alternative is to lengthen the complete Exp fuel system about 12" (or as needed), then guide the fuel lines inside the frame rail, as they should be.