Andy.F

Mark

The cossie engine isn't really race bred, more transit van bred !!It stole the block, bore, stroke, oil pump etc from mainstream design. Even the cranks and rods are not much different to look at from old Cortina parts !!! decent head, that's it !
Having adopted the same approach to tuning both engines, I have to say they both responded in a very similar way The only limitation I have come across is the inherent problems with designing a short exhaust manifold for the subaru. That aside, I can see no reason why the subaru shouldn't make exactly the same bhp as a cossie, perhaps more ? due to the better bore/stroke ratio And of course the short crank

[Edited by Andy.F - 12/7/2002 12:53:07 AM]

rex11

Just wondering if anyone has ever seen a stroker crank for the EJ25 engine?

Pavlo

A 2.2 stroker crank for the ej20 is 81mm stroke, 2mm longer than the standard EJ25 crank, giving 2.54L on 100mm bores.

You could also consider getting a phase 2 ej25 with 52mm big end jounrals and stroking it to take phase 1 rods, with 48mm jounrnals. This would allow you to go to a whopping 86mm or so with the stroke, but I can't say whether the rods would clear the block. And you would be pushing the limit of space available in the bores, it would require shorter skirt pistons, or the block to be machine and relinered to take slightly longer liners. You would also be pushing the limit on either the piston pin location or rod length.

But in theory you could end up with a 2.7l engine on a 100mm bore.

Is it worth it though? The EJ25 is stretched from an EJ20 as it is and isn't optimised at all, compromises have been made with the rod length, piston skirt length, oil rings running (just the lower one) past the gudgeon pin holes in the bores etc.

Get a 3.0 H6 engine!

Paul

rally colin

did you want a H6 engine?

Pavlo

Colin, your library of parts amazes me!

Is there anything you don't have?!

Paul

R19KET

Paul,

Where is this 2.2lt stroked 81mm crank coming from ?

Any crank, other than a 75mm, or 79mm, is going to be a "custom" crank, either offset ground, or custom made from billet.

I think stroking it to 86mm, would be a disaster waiting to happen.

Mark.

Pavlo

BPM stroker crank

siwrx

ahem

www.junauto.co.jp

got and english section look in the engines and they do a 2.2 and a 2.5 kit. My car came with a 2.2 though i want the 2.5 now

Pavlo

the question was stroking a 2.5 further

you can make your own 2.5, with subaru block and crank, with aftermarket rods and pistons

paul

siwrx

subaru crank is made of finest galaxy chocolate though, ud be best buyin a jun kit which comes with all the internals and not scraping your engine off the floor in a few weeks

P20SPD

iTrader: (1)

Paul,

Adam M

siwrx,

sorry, but subaru crank is one of the strongest standard cranks you will find on any car.

It is forged for a start, adn on top of that being a 4 cylinder boxer, has 5 main bearings for four cylinders! Plus it isnt much more than two cylinder bores long!


Most of the stroker kit cranks available, use the standard 2.5 crank. Failing that, they grind the journals down further and offset them to produce a longer stroke. Regardless they still use the standard crank.

Those that use a billet crank do so at massively extra cost.

How many snapped standard cranks have you heard of?

I have heard of only one, in a 450lbft engine. It was also a competition rally car, so was sujected to the shock of landing from jumps all the time.

I would like to know what question was being asked originally.

Youc an put in a longer stroke, as Paul says, probably up to 81mm. I would not want to do that personally as you lose the free revving nature of the engine and keep increasing the side load ont the pistons.

You do have to use reduced ig end diameters, as for the con rod to have any meat remaining in it, it will be hitting the block.

Andy.F

FIVE main bearings I wonder how many a Cosworth or Evo or even a standard 1.3 Lada have

Pavlo

very clever andy.

even so, standard crank has proven to be good for 500hp at the wheels on australian cars.

Paul

rally colin

Paul I do like to have a stock of engines!
Never know when you might need them!

Adam M

well each of the 5 main bearings is clamped bewteen two halves of the block, rather than just having a bearing cap placed over it.

The main advantage of the subaru crank is the fact that it still has 5 main bearings despite being very very short compared with your standard cosworth, evo and lada in line fours.

this reduced length menas it can handle greater torsional loads without snapping compared with the standard offerings from cosworth, mitsubishi and lada.

Pavlo

Steven,

Is there something I should know about? Have you purchased one of these 81mm stroker cranks???

I thought you weren't going internal?

Paul

R19KET

Paul,

I think you'll find companies such as BPM, offset grind the EJ25 crank to 82.5mm to give 2.216lt using a +.5mm overbore.

Using the same bore size, an 81mm crank will give 2.176lt.

I'm only aware of one 81mm crank in existance

Mark.

Pavlo

I thought I got the info off the BPM site, and remember thinking it must be a phase 2 crank ground down to 48mm journals. Having just read the scoobyshop ad, it does indeed show an 82.5mm crank.

Not that it's fancy technology or anything, standard practice, except usually done with different bearing shells.

I assume the reason 81mm stuck in my mind is having seen it elsewhere, as it means that you can use EJ20 rods and normal stroker pistons.

I wonder where I saw it now?

Paul

Adam M

perhaps you never actually "saw" it.

I think you are confused paul.

Perhaps you should take a lie down!

Pavlo

Perhaps you're right, I know I saw the BPM kit, making 2.2l just from additional stroke, and I also know of an 81mm crank being used elsewhere, and the 2 got merged into one.

Paul

Andy.F

Adam - Really ??? So the increased CSA of said cranks does not compensate then ? Can you enlighten me to the methodology used by yourself to ascertain the relative torsional strengths of the above crankshafts.

Pavlo

leave the handbags please!

I think it's a big enough achievement to fit all the journals on the crank in the first place! Something I am sure Andy can marvel at when he grenades his engine, which is surely long overdue by now!

Paul

Andy.F

Just get a bit pi55ed at some people making unqualified statements

Adam M

Andy,

why do I suspect you are taking the p1ss out of me?

do you really need an explanation as to why a shorter crank can withstand a greater tortional load than a longer one?


Have you never been forced to use a long screwdriver to tighten a screw because you cant manage it with a shorter one?

I thought you had enormous experience working on engines etc?

Andy.F

Adam

Not taking the ****, just being technically correct !

There is a LOT more to determining a crankshafts torsional strengh than just looking at its length. Cross sectional area, web design, material, grain structure, heat treatment and surface finish are but a few.

I don't believe you (or I )can look at a subaru crank alongside a cosworth crank and say which has the greatest chance of snapping.

Thats all.....

Adam M

Andy,

I agree with what you are saying, CSA is a valid concern.

How different are the CSAs? or are they similar?

I would be willing to bet that the most significant contributing factor to the ability of the crank to handle torque is its length.

The material is obviously important, but I would not be surprised if there was little if any difference in the mechanical properties of the materials of the cranks used across the marques.

Pavlo

Boys, stop it.

SThe ubaru crank is good, and that's all we need to know really.

Adam M

I didnt start anything, I just got started on.

There is no question that the subaru crank is fundamentally a great design.

Andy.F

Sorry, we just keep disagreeing Adam, the big end oiling design on the subaru crank lets it down IMHO