Frankenmotor: 2.5<2.2 heads single port vs dual ports

[MilesFox]

I have an ej25d block. I have dual port heads from a 1st gen legacy, and a 1st gen intake to swap components to.

 

My current car 96 legacy brighton 2.2 single port heads.

 

I was going to use dual port heads on the ej25 block, but if there is an advantage to using single port heads, i can consider them,but at the expense of a functioning engine for parts.

 

I read that the single port head has bigger valves. Is there an advantage with single port heads in regards to valves or cam options vs dual ports?

[Gloyale]

Valves aren't any bigger in 96 single port heads.

 

Although I do think the cams in that year are roller follower, and make better low end torque than the 90-94 dual port heads.

 

The only down side to the singles in my mind is the lack of interchange of exhaust manifolds. 

[86BRATMAN]

Personally I'd swap the roller assemblies and cams to the dual port heads and get the best of both worlds.

[idosubaru]

seems the difference is so small i'd just run whichever is the best fit and convenience regarding your particular use of the parts available.

[MilesFox]

The only difference in availability to me is either using heads off the shelf (dual port) vs taking heads form a complete motor (single port)

 

Perhaps i'll consider swapping the roller assemblies to the dual port heads essentially making '1995' dual port heads of them.

 

Now, this sparks eanother question, so that i can still have a complete spare engine: Will the standard dual port rocker assemblies swap onto a single port head?

 

And another thing to consider, the car currently has a straight pipe all the way back, so if i want to keep that, i;ll have to stay with single port. But this will require my hybriding or swapping heads. Otherwise, i already have a complete dual exhaust system to swap over with factory cats.

 

I guess i could go either way if there is nothing to gain or lose other than the exhaust pipe itself. My car will have to be emissions legal as it still has yet to pass.

[Gloyale]

Swap the Cams to match with rocker assemblies.

 

All intechangable but you want to keep the cams with their matched rockers.

 

 

Single port heads I do think make better low end torque.  The single port equalizes the port length in the head.  This plus the 95+ equal length header pipe helps scavenging at low RPMs.  Loses some of the nice boxer rumble though.

[impoutback 97]

I think the dual port heads would have more air flow per cylinder, especially if you were to upgrade the head pipes to the head pipes ive seen that run an individual tube to each exhaust port, merging just before the first cat.

[MilesFox]

Yeah, i cpuld do that as well, least amount of work using shelf parts, without having to disassemble a good motor. I wouldhave to steal the header off the forester, though. I think i'll stick with the dual port for simplicity and labor as i had originally intended. I would probably need a 1997 and later single port head for any potential gains anyway. I'll just swap the cams and rollers from the single ports as long as the lifter style swap onto the single ports to keep a complete spare engine around.

[el_freddo]

I believe swapping to rollers makes it an interference engine.  Correct me if I'm wrong pls.

Cheers

Bennie

[johnceggleston]

i assume we a talking about a manual trans car with no EGR?

if so use what ever you want.

 

but if the car has EGR, i'd stick with the heads that came on the car.

 

and i thought the 96 ej22 had HLAs.

 

i also thought the pistons created interference in 97, not the valves.

[86BRATMAN]

It was the pistons that created the interference change.

[Ibreakstuff]

Formula I saved years ago, not sure if I helps you any:

 

Originally Posted by grafton 

simple version of franken motor combos:

engine block + heads=

"best"
p2 2.5 + p2 2.2: highest compression ratio (stock gasket) better manifold options, decient heads

good
p1 2.5 + p2 2.2 again good manifold options and decient heads
p2 2.5 + p1 2.2 dual ports (header options & possible better flow than single ports) 
p1 2.5 + p1 2.2 dual ports 

ok 
p2 2.5 + p1 2.2 single ports
p1 2.5 + p1 2.2 single ports

thats for running completely stock, aka slaping it together and going.

if you can port & polish, do cams, or a valve job you'll be much better off

[86BRATMAN]

The thing is, p2 ej222 heads and p2 ej251 heads have the same combustion chamber volume, so you really aren't making a frankenmotor with them.

[Ibreakstuff]

The thing is, p2 ej222 heads and p2 ej251 heads have the same combustion chamber volume, so you really aren't making a frankenmotor with them.

 

Source? Everything I have read or researched begs to differ. Unless not all p2 ej22 heads are created equal.

 

 

"The phase 2 2.2 heads do have the same combustion shape as the phase 2 2.5 heads from 99 to 05. However, the combustion chamber volume for the phase 2 2.2 heads is 41 cc's where as the chamber volume for the phase 2 2.5 heads I believe is 51 cc's."

[monstaru]

ok, All of this speculation banter needs to be addressed.

 

https://www.google.com/#q=twe+compression+calculator

 

Top link will get you to the awesome that is awesomer.

cheers

 

 

 

[86BRATMAN]

Side by side comparison is my source.

 

That and simple math that this ej222 piston

 

Which has a 10cc dish at -.4mm piston to deck height, with a. 8mm gasket and a 41cc combustion chamber would have over 12:1 compression.

 

I don't have any pictures, but I bought a 99 L wagon a few years back that had bent valves because the timing belt went. Used ej251 heads on it and compared the two while it was apart.

 

Btw Brian, the twe compression calculator has absolutely no information on the ej222 or the ej22e for that matter.

[Ibreakstuff]

12:1, yep. Hence the whole idea of a high compression frankenstein, I stand by the numbers I quoted. The heads have the same shape, but different volume. I'll go pull some PaP heads and CC them, if you really want.. But there is plenty of info out there if you search nasioc.

 

Good read:

http://forums.nasioc.com/forums/showthread.php?t=631527

 

 

Side by side comparison is my source.

That and simple math that this ej222 piston Which has a 10cc dish at -.4mm piston to deck height, with a. 8mm gasket and a 41cc combustion chamber would have over 12:1 compression.

I don't have any pictures, but I bought a 99 L wagon a few years back that had bent valves because the timing belt went. Used ej251 heads on it and compared the two while it was apart.

Btw Brian, the twe compression calculator has absolutely no information on the ej222 or the ej22e for that matter.

 

[86BRATMAN]

I've read it all, and the pistons I showed are ej222, it doesn't have 12:1 if you could read you'd understand what I was saying. There is no way possible with a 10cc dish piston, and a .8mm head gasket and a 41cc chamber that you can get the 10:1 compression ratio they came with stock. It is physically impossible.