SSCJAY

Just removed high spec 2.5 today, the block has ACL's, modified crank, carillo's, Wiseco's. Big port JDM Heads.

Car is running rotated GT30, and estimated 500 bhp, Max Boost was set to 1.9 Bar, On a run in 5th gear boost peaked at 1.93 bar, then it went bang.

This engine has only done 1500 miles Max, is it normal for the liners to go so soon at that boost level?

Obviously don't want to de-tune, so any advise welcome on the next step.

Neil XR

iTrader: (1)

looks like a casting flaw to me

i would get another block just incase the other the side fails as well

Neil

unfeasablylargegonads

iTrader: (3)

looks like its failed at the same point I have seen all other pictures of 2.5 split liners fail at on here and 22b.

over 450/450 seems to be pushing your luck on a 2.5 according to a lot of the tuners.

have a read of this:
22B Bulletin Board: EJ257 build... Put off slightly by head gasket failure issue.

911

As above; quite a discussion on this subject on 22B, but not getting very far.
Was the short engine a UK or USA build/supply?

Begining to think the cost of a 2.35 on a CDB is the better option...

alanbell

iTrader: (6)

YES >> Thats what Im doing From a 2.5 To 2.35

Lateral Performance

iTrader: (20)

It isn't uncommon once you start going above 500bhp, and they nearly always crack where the block is relieved for the bolts.

I would also be very concerned about running a Walbro at that level of boost/power. We have problems with them running lean, even on the MD321T !

Mark.

SSCJAY

The Block was USA supplied, it is not from my car, so spec is not whats in view my scoob.

My car is running fine, thanks to the Jolly Green Monster yesterday!!

After reading the long winded post on 22b, have there been many people spliting the Linered blocks ? or just problems with the liners dropping.

911

Or both?

The way the block is machined locally is inviting failure (at these high levels), and the CDB does not have this issue.
Alan: we are going in the right direction.

Quite a foggy subject '500 x 500'!

p1prodrive

iTrader: (3)

2.3 cdb is without doubt the best way to go, take a look here as i have started mine

P1 Web Owners Club :: Warning, may contain nuts!

Jolly Green Monster

iTrader: (4)

1.9bar!!!... and it lasted 1500miles.. how many miles of that were run in??? too much boost imho..

Simon

SSCJAY

Hi Simon,

We are not sure exactly how many running in miles as the car had an MXL dash put in during the running in period, the running in was done by a very reputable tuner so have no doubt it was done correctly.

Jolly Green Monster

iTrader: (4)

what I meant was how many of that 1500miles were not at 1.9bar..

Area 52 Autosport

It's up to you which way you go from here, there is absolutely no reason why 2.5's can't run big HP and even bigger Torque, we turn them out all the time and haven't yet seen a single dropped or cracked liner in all the time we've been doing them, (over 5 years).

With likely HP/Torque you're expecting, we'd use our own custom liners in the block and we even do block linering for a few other "known name" scooby tuners.

It's also not really the boost level which has caused it, it's the cylinder pressures and other factors which are likely to affect in cylinder temperatures and pressures.

Area 52 Autosport

Depends which ship you're on there I guess, the view is crystal clear over here.

scooby-matt

iTrader: (3)

this is a common problem when people start mod a engine above 400bhp regardless of 2.0 - 2.5 litre. All subaru engines are an open block engine. if any 1 wants to mod a subaru above 400bhp and want a reliable engine go for a closed block.

Jolly Green Monster

iTrader: (4)

disagree.. the 2litre open deck block is not an issue in the same way the 2.5 is

Area 52 Autosport

Just so that if there are any new guys in here (and some of the longer standing members) who may actually believe that a statement as declaritive as that can only be summmed up by saying that statement is not true.

That kind of statement is the root cause of a majority of the "fables" commonly projected by the masses. (Sorry Matt, that's not meant to be a dig).

There are ways of approaching certain engineering "issues", and to say everything needs to be CDB for it to work is simply not true.

SSCJAY

As above the 2 litres are not a problem as the bores are smaller you don't have a big chunk out of the cylinder wall missing where the block halves bolt together!!

scooby-matt

iTrader: (3)

ok then, if your saying its ok too run 500bhp in an open block 2.5 sti, why then has the liner cracked??? looking at the fiqures it was boosting at 1.93 bar, i think that the engine has got too hot and the liner has explanded and at the point where it has cracked there is no support around the liner.

answer me this then scooby mania... why do the top tuning companies use atleast a semi close desk or even better a closed deck?..... beacause of the problem


matt

SSCJAY

If you look at the picture you will see it is a semi closed deck block, we knew this was close to the limit of the block case, and went on several independant advise that it should be 'ok', but really didn't expect it to last a matter of a few hundred miles on full boost, everything was being monitered via the MXL dash, and car was only pushed when all temps were 'normal'.

What we were all saying above is the liners in a 2.0L are stronger than the 2.5L, for the reasons I have previously stated.

robertgraham

iTrader: (2)

Join the "Cracked liner club", altough mine just had hairline cracks, not quite as spectacular at this!

Lateral Performance

iTrader: (20)

The main reason the 2.0lt steel liners don't crack, is because they are about twice as thick, and have double the support, of the 2.5lt's.


Mark.

SSCJAY

This is what the engine builder had to say about it:

"We have seen some instances where the liners have developed small cracks. Generally, these have all been extremely high power applications (700 to 800bhp measured at crank) and the customers were knowingly approaching or exceeding the limitations of the block. The liners of the 2.5L engines are considerably thinner and also have less surrounding material to support the liner when compared to 2.0L engines. Therefore when there are extremes of pressure and/or temperature variations the liner is literally torn apart by the distortion and expansion that occurs. For more extreme applications where the 2.5L block is being used we recommend sleeving the block. I don’t think anything can be done with the block you have since the supporting material behind the sleeve has cracked completely. With regards to the failure you have experienced….I have to say that the block may have had a flaw in the casting and/or the engine suffered detonation on that cylinder causing the pressure to build up so high that it literally blew the cylinder apart at its weakest point. Under normal circumstances the block would not have suffered this type of failure at the boost pressure and power level you are running. But your description of the event leads me to think that detonation occurred (the fact that it was a 5th gear run at full load and failure occurred at or near peak torque… this is exactly where an engine would be most prone to detonation)."

Area 52 Autosport

That's easy, as a "top tuning company" and the longest established experts in this field, the answer is we judge each engine build closely around as a minimum, what the customer wants, or may expect the engine to be achieving.

We've achieved MUCH higher figures than being discussed here, without breaking anything so we know its possible.

Area 52 Autosport

Mark has a (relatively small) part of the jigsaw here.
The 2.0L liners/parent block assemblies do have thicker liners Etc.
That's not the problem though. The problem is the cylinder pressures involved (Torque) on 2.5L over 2.0L regardless of total power output on 2.0L.

The kind of problem portrayed in this thread is predominantly (in our experience) avoidable!
Supported by more years experience in this field than any competitor and an unbroken (so far) "no failed engines" record.

terryb

Sorry to dispel a myth here, but my 2 litre open deck block copes quite well with up to 504bhp and 486lbft on race fuel running over 2 bar boost

Must have done 5k miles since the build and gets very well used eh Simon

Jolly Green Monster

iTrader: (4)

Very well used!!! lol

You had your name changed by Depol(sp?) yet Terry-Mor-Boost-Buckelup

still laugh at those three runs..

Something like
Me to Terry: which of those runs Terry felt quicker..
Terry: all three felt good and no different..
Me: First and last were at 1.8bar and middle one at 2bar and that's without me tweaking the fuelling and timing at 1.8bar as it is running safe timing for 2bar... so 1.8bar it is...
Terry: no 2bar 2bar 2bar..

lol

Simon

terryb

LOL Simon

So what will I be like next time with a 2.33CDB???

2.5 bar

Jolly Green Monster

iTrader: (4)

doesn't your boost gauge max out at 2bar???

just stick with 2bar but bigger turbo(s)

Lateral Performance

iTrader: (20)

Mike,

Can you just clarify at what power/torque you advise fitting your liners, on a 2.5lt ?

You appear to be recommending them for circa 500bhp, & above, or have I misunderstood, what you've said ?


Mark.