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2.5 head question/observation

27K views 62 replies 10 participants last post by  koke'sfocus 
#1 ·
So I picked up a 2.5 and 2.3 head for my next turbo build, so I have a 2.0, 2.3 and 2.5 head to mix and match parts.
The 2.5 head is VCT as I understand, but I wanted one in my hands to see what exactly is different. I was curious whether or not I could simply use the cams from a 2.0 or 2.3 in the 2.5 head. From what I can tell I see no reason why I cannot.
Can someone please see if I'm overlooking anything? I see the first 2.5 cam cap oil circulation pathway is different than the 2.0/2.3, so the 2.5 caps would have to be used.

Here are some photos of the 2.5 head with a 2.3 intake cam. I have not removed the exhaust cam.





 
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#2 ·
I am thinking the sam thing. That 2.5 head is sooo meaty. So open. I would love to use it with stock 2.3L cams ( or even upgrades)

My guess is it might be a valve travel issue?

I am game to put the 2.5head back on this motor i am building - but a 2.5L head with 2.3 block under it would be super super interesting.
 
#4 ·
I believe the valves/springs are identical for the 2.0, 2.3 and 2.5. I need to get a spring compressor so I can get those measurements. This 2.5 head needs rebuilt anyway as it's obviously been sitting a while.
My primary concern is getting oil properly to that first cam cap. I know there is an oil regulation valve that controls how much oil gets fed into that cam to control the VCT, but I don't know exactly how that system works yet.
My initial assumption is there is 100% oil pressure feeding that location at all times, but the valve limits the pressure 99% of the time to limit how much oil is in that VCT gear.
Therefore if the oil pressure valve is not present the cam should get 100% oil pressure as desired. I need to find that out.
 
#5 ·
Much larger height, but the same width. I'll write down measurements sometime.
The combustion chamber appears identical. The diameter is the same (~87.5mm).
 
#7 ·
I believe I have the 2.5 intake cam oil feed figured out (mostly).

The 2.5 head has an extra oil feed port that enters through the bottom and feeds that first intake cam area. There is an actuator/valve that controls the oil pressure from that additional feed port to the VCT.
My 2.0 block does not have that feed port, so as-is no oil would be going to that first intake cam cap.
That being said, the primary head feed line still exists in the 2.5 head, which runs directly under that first cam cap, it's simply not drilled through.

My plan at the moment is to
1) Drill a new oil feed down into the first intake cam area
2) Tap the existing 2.5 feed port and block it off to keep oil from draining to nowhere (against the head gasket and just sit there)

I'm in no particular hurry, this is just thoughts of the night and I'll likely come across other issues.

2.5 head with extra oil port (bottom left)


2.0/2.3 head (no port)


2.0 block (no port)


2.0/2.3 head (see tiny oil feed port in cam valleys)


2.5 head (no oil feed port in the cam valley - needs drilled)
There is a feed line that runs the length of the head to tap into.


2.5 cam with oil ports vs. 2.0/2.3 cam without


2.5 head


2.3 head
 
#8 ·
Measurements

2.5L
Intake port: 41.6mm x 50mm (H x W)
Exhaust port: 37mm
Combustion: 87.6mm x 15mm (depth rough estimate)

2.3L
Intake port: 37mm x 50mm (H x W)
Exhaust port: 37mm
Combustion: 87.4mm x 15mm (depth rough estimate)

Now, the kicker is that my 2.0 head measures exactly the same as the 2.3 head I just bought. Either 1) I was sold a 2.0 head, 2) They do measure the same on the outside edge of the ports and the difference is on the inside, or 3) The 2.3 head isn't actually bigger that the 2.0, which I doubt.

If someone has a spare 2.3 head and would measure the intake port height I'd appreciate it!
 
#10 ·
Exhaust ports are the same. I ordered a valve spring compressor but it's not here yet. I'll measure the valves when I get them out. Cross-referencing parts on RockAuto.com tells me they should be identical.
 
#11 ·
Hey gang - what i used to do valve spring removal / install was the socket method....super simple to take them out -= PITA to put them back

LINK: http://www.youtube.com/watch?v=aZTnODXfDvA

Also - i think we dont need to worry about that extra oil port that feeds the VCT in a 2.5L block/head

when i thnk about combustion pressure of the cylinder vs any type of oil pressure - if you have the proper torques, i think you are good to go.
 
#12 ·
Entertaining, but I don't think I'll be using that method. I'd also not show my rotted-out roof if I posted a video on youtube. [:D]
 
#14 ·
I completely stripped the 2.5 and my 2.0 head last night. I highly recommend the OTC 4572 Large Valve Spring Compressor, it made the valve removal a piece of cake, and the way it locks will make the assembly easy too.

The valves measure exactly the same for the 2.0 and the 2.5. (rounded to the nearest tenth)
Exhaust: 30mm x 104.7mm
Intake: 35mm x 103.4mm

There are two more differences I found between the heads: the head temperature sensor and the spark plugs. After much cross-referencing I believe the Mazdaspeed 3 plugs will work. One step colder than stock plugs for the MS3 are the Denso (5340) ITV22 Iridium, which are very well reviewed by the MS3 guys.

6M8G-12405-BB (2.5 Escape) vs Autolite 103 (from my 2.0)


Autolite 103 comes up short in the 2.5 head: (yes it's filthy. It's a salvage head and I haven't cleaned it up yet)


The 2.5 has a shorter temperature sensor. I'm honestly not sure why. The depth of the hole in the 2.5 is the same as the 2.0, and the 2.0 sensor fits fine in the 2.5 head.
 
#15 ·
My updated plan at the moment is:
1) Drill a new oil feed down into the first intake cam area
2) Tap the existing 2.5 feed port and block it off to keep oil from draining to nowhere (against the head gasket and just sit there)
3) Use Crower valve springs 68195-16
4) Use Crower steel retainers (instead of titanium) 87085S-16
5) Use stock 2.0/2.3 cams, valves and valve cover
6) Denso Iridium (5342) ITV27 plugs (3.5 steps colder than stock Mazdaspeed 3, which runs lower compression than this motor)

When I get all my pieces together I'll start a new turbo build thread with all details.
If you want photos of anything let me know now, before it all goes together.
 
#17 ·
I'll be putting the 2.5 head on a built 2.0 block. I got as far as I needed at the moment with measurements and analysis. I see nothing preventing me from moving forward, I just don't want to buy everything at one time when I have no particular deadline to meet. I'll finish up the short block in the next couple weeks and then come back to the 2.5 head. If I get ambitious I'll go ahead and order the valve springs and assemble the head sooner.

The end result should be something like this:
- 2.0 block
- supertech 10.4:1 pistons, forged H-beam rods, clevite H bearings, ARP main/head studs
- GT2871r turbo
- custom log manifold
- custom 3" exhaust
- 2.5 head with stock cams and crower springs/retainers
- 60lb injectors, stock fuel pump (going to try and stay within the limits of the stock fuel pump. It will give me something to do next year...)
- Cosworth flywheel, SPEC stage 4 clutch, Torsen LSD

I'll update this thread and likely start a new one as I move forward. I'm also doing home renovations and it's running season (5/10K's) so that takes up time also. [thumb]
 
#19 ·
Yes the bolt pattern is the same, and while the Cossie IM port/flange area is larger, I can't measure it while on my car. Chances are good the stock D-shaped gaskets will not fit and a custom gasket will have to be made.
I also confirmed the 2.0 injectors and fuel rail fit the 2.5 head. The injectors protrude just a bit further (maybe a couple mm) into the intake ports than the 2.0.
 
#22 ·
I'll be using 2.0 cams in the 2.5 head. (I still think I have two 2.0 heads on my bench, so I'm not sure I even have a 2.3 head. MainiaxMotorsports are you sure that was a 2.3? All measurements are the same as a 2.0)

Since the 2.5 combustion chamber is the same size as a 2.0 head, I see no reason why the compression ratio would be altered. As long as the cylinder bores are good I'll be using P4-DU875-N2 Supertech 10.4:1 pistons. I actually have two sets of these at the moment after being duped by another member into thinking I was buying 88mm Supertechs. That's another story.

The 2.0 block I'm using is from my original motor that blew a ring landing. Amazingly there is no apparent damage to the cylinder walls or valves. All the loose aluminum bits were in the oil pickup tube, and probably the oil filter.

As far as progress, I'm still gathering last-minute parts. I'm focusing on house remodeling at the moment and will come back to this soon.
 
#23 ·
MM go no smaller then the 2.3 cams , In my opinion I would do a set of stg 3 cams for what your doing

Your not going to get much from the 2.5 head doing small 2.0 or 2.3 cams , you need the extra flow to keep the velocity up or the larger head is worthless if you only going to flow the amount of a stock 2.3 cams capability

Just my opinion

Tom
 
#28 ·
Hey Bud - yeah - i am running the 2.5L bottom with a 2.3L head - 2.3Cams, oil pickup, etc.

Not dyno'd yet but with the Coswroth style IM - port polished head, and smoothed out TB i suspect she will do 180hp at the crank on race gas. Compression calculates at 11:1 or so - hence will only be running race gas to try to eliminate detonation.

Axles go back on this weekend - will post some road test / BUTT DYNO vids

sounds amazing to be honest

ps. NOT first start - ran it before i got the camera on

http://www.youtube.com/watch?v=vK3Wq7Y9Nuw
 
#34 ·
What is the size of the exhaust ur using? I really think u will do more than 180 to the crank I would say easy 180 to te wheels
 
#33 ·
I can't find specs online, so I'll need to get someone with a 2.3 head to measure their intake ports. I can't interpret the castings. I'm not sure what LO 05 means on the end of the head, even though that usually represents the displacement. If you can measure the other head you have when you get back to your garage I'd appreciate it. [thumb]
 
#31 ·
Thanx much.. Looking forward to hearing what the difference is.. Also, would you know if the Focus 2.3 head has the same specs as the 2006 and later Ford Ranger with the 2.3 Duratec.. I'm planning to use the same setup N/A in a RWD configuration and would prefer to use the Ranger top end as it would already be have the necessary plumbing and accessories.. I'll be changing the cams to either Crane or Crower stage 1 units along with the associated VS kit as the car will be running ITBs and an MSNS3 for management..
 
#40 ·
Sorry 2013 ended up being a house project year. I'm hoping to get to this in late spring, after I renovate the bathroom.
Since I started working from home I don't have much enthusiasm for modifying a car I never drive. I think I put maybe 100 miles on it in 3 months. [:0]
 
#41 ·
I know how it is putting stuff on the back burner. I jus got a 2.5 head. I thought I was getting the 2.3 but I got a different year so I'm gonna stick with it. So from what I've been reading to make it work on the 2.0 is doing the vct delete kit from massive. Plug the one oil port, drill a new port? Also, looking at the cams, I wonder if I could use the 2.5 cams? I have a 2010 and I noticed the cams have the same 5 prong setup as mine for the cam sensor. Also using the 2.0 valve cover because of the vct delete and the dipstick location on the 2.5 being on the valve cover. Hopefully I could use the cams, I'm gonna test it out when I finish building a spare block.

Sent from my Nexus 7 using Tapatalk
 
#48 ·
I know how it is putting stuff on the back burner. I jus got a 2.5 head. I thought I was getting the 2.3 but I got a different year so I'm gonna stick with it. So from what I've been reading to make it work on the 2.0 is doing the vct delete kit from massive. Plug the one oil port, drill a new port? Also, looking at the cams, I wonder if I could use the 2.5 cams? I have a 2010 and I noticed the cams have the same 5 prong setup as mine for the cam sensor. Also using the 2.0 valve cover because of the vct delete and the dipstick location on the 2.5 being on the valve cover. Hopefully I could use the cams, I'm gonna test it out when I finish building a spare block.

Sent from my Nexus 7 using FF Mobile
I'm not sure about using the 2.5 cams. Without going out to the garage and looking, I believe the cogs from my 2.0 cams wouldn't fit properly. The 2.5 head I bought didn't include the cogs, so I don't have those for a comparison.
The biggest issue/concern I had was the intake ports lining up since the 2.5 is so much larger. I have not been able to check to see if the Cossie-style manifold ports will line up. That is about where I left off.
 
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