Subaru engines' weights
 

This isn't really to do with the FT-86/FR-S engine so I put it here.

The conversation:
I found this from an aircraft engine supplier:
http://www.prekas.nl/subaru.htm

I converted the numbers in bold to lbs. But I think this gives the idea that I really think they are different and not just a shared block with different bores and strokes. They're last generation engines, heck the 1.6L and 1.8L aren't even a part of the EJ series so maybe they're completely different. Needless to say the difference between the EJ22 and EJ25 is 33lbs. These numbers are unofficial and they're for complete engines w/o accessories like PS or AC too.

So it's your turn Old Greg.

First, I just want to point out that the "EJ33" is actually the EG33 and is a very overweight flat six, just in case anyone may wonder in the future.

I counter with this:
Attachment 1718
As found here:
http://locostusa.com/forums/viewtopic.php?f=4&t=4299

It's impossible to make direct comparisons though.

PS. That includes the flywheel and engine mounts, which I'm not sure would be used on an airplane.

I'd also like to know exactly which versions of the EJ22 and EJ25 he weighed, as there have been quite a few. Assuming the engines were in a similar state, I'd say most of the difference in weight is in the heads. The common EJ22E (90-97) was SOHC, and the EJ25D (96-99) was DOHC. I believe theses are most likely what he was using.

PS: The EA71 and EA81 are carbed pushrod motors from the early 80's

EDIT:
EJ22E Heads
http://www.rs25.com/forums/f7/t14983...ification.html
EJ25D Heads
http://www.rs25.com/forums/f177/t117...ng-covers.html

And since you snuck this in on me...:)

The EJ15/16/18 are just small bore and/or short stroke EJ motors, very little different from an EJ25. And the EL15 is heavily based on the EJ, heck it uses an EJ25 crankshaft. They're interchangeable.

The EJ is dead. The EL15 might stick around for another year or two until a small displacement FB comes along but it's fate is sealed, it's old tech.

On a side note, self-moderated forums are pretty damn cool. Good job guys :)

Old Greg, could you answer something for me? I've heard that the EJ series also varies as to whether it is a closed, semi-closed or open deck block.

What I've heard is the rather rare 1st Gen Turbo Legacy EJ22 is a closed deck, whereas the standard EJ22 is open, and that the EJ20(5?) WRX motor (North American) is open but that the EJ25(7?) STI motor is semi-closed.

Any truth to this?

And there was something about the FB having two cooling circuits, one for the head, and one for the block (I'll edit with a link when I find it). Do you know anything about this? Dry deck?

Just one correction. EJ15/16/18 vs EJ25 have a lot of difference in heads & comp ratio too. EJ15/16/18 are single port exhaust while EJ25 are dual port exhaust. Comp ratio for EJ15/16/18 9.5~9.7:1 are common, while EJ25 (NA) 10.0:1 is common. EJ15/16/18 are more close to older EJ20/22 series.

EL series are a lot close to EZ series. EL comes w AVCS

All of that is correct to the best of my knowledge.

I don't really consider the differences in head design to be "differences" in the context of the debate that Allch Chcar and I have been having. The EJ has had a wide variety of heads over the years, but the point that I was trying to get across to Allch Chcar is that EJ's use more or less the same block (I know there are differences) regardless of displacement.

Clearly I'm not as researched in the Subaru engine design over the years but I can see old gregs' point in them de-stroking a FB20 block to create a FB16. It is feasible because they've done that in the past after exhausting bore reduction.

Dimman I believe you posted this earlier but with a 72mm stroke FB20 block (bore 84mm) would result in a 1596.03cc FB engine. Coincidentally a 72mm stroke FB25 block (bore 94mm) results in a 1998.66cc FB engine.

I believe that was Old Greg as well, I expanded a bit on the AWESOME potential.

Sorry about that Old Greg :). It was my last post and I just went ahead and moved it over with the whole topic.

I'm familiar with the EL15 a little bit and I don't disagree but I think there is enough evidence that your suggestion that the FB engines would be the same block/heads with different bores and strokes and even the same weight is if anything premature.

And those engine weights you linked to are woefully inconsistent, they even mentioned that they needed a consistent system for comparison. The engine weights I gave included were older engines like the EA series but they were dry longblocks w/o PS or AC and naturally aspirated. Plus the engine you listed was a newer one and it could have had anything or nothing on the serpentine belt.

Even if the EJ25 from the '06 forester are similar to the engines I listed I'd bet the EJ20 were at least 30lbs lighter :bonk:.

I am arguing that they have enough of a difference in regard to the block and heads since there is significant weight differences. If the EA series were 1.6L-1.8L and they are almost 70lbs lighter than the EJ22 in older engines, why would the newer EL15 or the unknown FB16 be based on heavier engines like the EJ20 and FB20 respectively and weigh exactly the same?

If anything the weight difference between the EJ22 and EJ25 was enough to validate my point. And my point was that there were huge weight difference for engines that were similar (EJ22 and EJ25) therefore there is probably significant difference for the newer versions of the sub2L ones aswell. I admit I don't have weights for the EL15 for comparison but hopefully that gets my point across.

You are probably right about the differences or lack thereof in block and heads but I still kindly disagree that all EJs weigh the same :bonk:.

Remember too that the different strokes have different sized cranks and rods, which are steel unlike the aluminum blocks, so this could also be a contributing factor.

The consistency of their testing is irrelevant to this discussion as I only used the weight from one engine. Furthermore, I myself said that there can be no direct comparison.

The EA motors have nothing in common with the EJ motors aside from both being Subaru flat fours. In addition to having tiny OHV heads, they undoubtedly have a shorter deck height and a smaller bore pitch. They are not comparable.

It is illogical to argue that a small displacement FB will be lighter because the EJ22E had dinky little SOHC heads. You yourself say:
Such an engine would need all the breathing ability it could get. It would not have heads significantly different from an FB20/25. They would be large complicated DOHC heads, with variable vale timing and lift.

The EL is based on the EJ because it is, this is a known fact. Your hypothetical FB16 would be based on the FB20/25 because it's an FB16. If it were an XYZ16 then it could be anything you wanted it to be and I would gladly agree that such an engine could be 50 lb lighter.


The difference in weight comes almost entirely from the heads. See this discussion as evidence:
http://groups.yahoo.com/group/AirSoob/message/39751
In which the weight of an SOHC EJ22 longblock is given as 182lbs, and that of an SOHC EJ25 is given as 186lbs. Another poster claims to have weighed his DOHC EJ25 longblock at 202 lbs. Further a third party is claimed to have found the DOHC heads to weigh ~15.5 lbs more than the SOHC heads. According to these guys then, there is approximately a 4 lb difference between the EJ22 and EJ25 shortblocks.

As I've previously said, a turbo FB16 would use the same heads (or bigger,to be honest) as an FB20. There would be a negligible weight difference in the shortblock. Both would use plastic intake manifolds which hardly weigh anything, and both would use the same accessories. The weight difference would be negligible, and that's before you consider the weight of a turbocharger, intercooler and heavy duty exhaust manifolds.

No argument there, I just thought it was worthy of note, nothing else.


The EJs are both SOHC and I thought that was interesting enough how big of a weight differences they had. The fact that Subaru had separate engines for the smaller displacements that were much lighter than the bigger displacement EJ series was what I was pointing out though.

Even if you add 20lbs to it for heads and then add whatever the thicker sidewalls would add and reinforcing the block, an aluminum 1.6L shouldn't weigh 200lbs+. Remember also it's going to be specially built by Subaru/Cosworth for their reintroduction into rallying. I doubt they'll use a heavier engine and just debore/destroke it. Plus do you know what an EJ15/16 weighs?

Certainly, if you say so.