98 2.5l ford ranger performance/fuel mileage rebuild


Mark_88

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I used to have my hat on backwards too...but since turning my life around...it's on forward again...

This was a good read document that needs to be stickied or, at least, take the good information out and paste it in with the 2.0/2.3/2.5 document at the top...but it has some good stuff and suggestions.
 


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jpark6491

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Nothing like a good forum discussion, I wonder how this turned out. :p
 

Fredness

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I'm building one now - nothing like fresh logs for the pyre...
2001 Ranger 2.5L, 5R55E, E85 ECM (RVB0), 8.8" TL, 4.30:1 in an '89 Mustang.
:D
 

Fredness

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Just to clean the air, the Late Dual Plug heads (1995-2001) flow 24.31% better, on average from .050" to .600" lift stock than the 1981-1995 "D-Port" heads, and 8% MORE than the almighty "Turbo D-Port" heads.

I am testing the 1992-1995 Ranger Roller Cam and the 1995-2001 Ranger Roller cams - they have the same exact published specs, but they just use different roller followers.
The roller followers are the same 1.65:1 ratio.

188* Int/Exh with .354" Lift Int/Exh
The previous version of Mustang cam (Slider) was:
187Int/190Exh with .393" lift Int/Exh

These will be placed on a test engine and compared with a degree wheel/dial indicator to verify.
 
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poondobber

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Just to clean the air, the Late Dual Plug heads (1995-2001) flow 24.31 better, on average from .050" to .600" lift stock than the 1981-1995 "D-Port" heads, and 8% MORE than the almighty "Turbo D-Port" heads.
So where is the biggest restriction on the air inlet side? The intake on the later engines seemed to be restrictive with small throttle bottles and really long runners. These were most likely to increase low end torque with improving fuel economy.

The Boport build on the old head included bigger valves, port and polish, and a bigger cam. I wonder how much the bigger valves actually contribute.
 

Fredness

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This really depends on the year and equipment.
The long, narrow individual runners move the TQ curve down the rev range - better bottom end.
The short fat runners on the early Pinto/Mustang variants were for HP.
But so far the heads are definitely the largest restriction/HP obstruction.

Conversations with Boport suggest the Late DP plugs ('95+) are better, but to get the larger valves it is easier (and arguably better) to have the guides modified to 11/32" and use the old style valves and older cast iron roller followers.

Trying to get 2 intakes and 2 exhausts flow tested locally, but machines are "down"... :unsure:
 
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poondobber

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Conversations with Boport suggest the Lat DP plugs are better, but to get the larger valves it is easier (and arguably better) to have the guides modified to 11/32" and use the old style valves and older cast iron roller followers.
Can the big valves be easily added to the late DP head or is it better to switch to the old single plug head? Boport used to have the DP head on their website but I believe they took it off. Is there any other shops that can do a big valve install? Boport seems rather expensive.
 

Fredness

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You can Install larger valves in any flavor of 2.3L/2.5L head.
They can back fit 11/32nds valves to the '95+ 2.3 or the '98-'01 heads in a larger size by reaming the valve guides and install commercially available valves, or get custom made ones in 7mm.

Bo-port has any of the versions available, tell them what version of the head you need in the comments block when ordering
[According to what we've discussed via email]
 
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