Boring or Stroking?

**PaulZX** · Saturday 14th March 2009, 05:48

Is reboring or stroking a T5 engine an option worth considering?

If so, how big can you go?

Just wondering coz a friend of mine is getting his mini rebored, and the actual rebore aint all that expesive... it got me finkin...

opinions welcomed... has anyone else done it?

**Alan M** · Saturday 14th March 2009, 08:54

Stroking will take a lot more detailed work from an engine designer. Norris Motorsport offers the service IIRC and they build some very powerful cars. There are various sizes of slightly oversized pistons available from Volvo for the T5 ening depending on what size piston you have in the car already. You can tell what items you have from the stamps on the block IIRC or from Rufe.

**p fandango** · Saturday 14th March 2009, 09:17

Originally Posted by TheFlyingFridgeMover

Is reboring or stroking a T5 engine an option worth considering?

If so, how big can you go?

Just wondering coz a friend of mine is getting his mini rebored, and the actual rebore aint all that expesive... it got me finkin...

opinions welcomed... has anyone else done it?

Originally Posted by Volvo Press release

With a displacement of 2,319cc, the four-valve per cylinder engine is derived from the
2.5-litre normally aspirated unit found in the 850 GLT.
This reduction in capacity has been achieved by reducing the bore to 81 mm (the same
as that in the 2-litre unit) with the stroke remaining unchanged at 90 mm. The
compression ration is set at 8.5:1.
This reduction in capacity enables a larger space between the cylinders and so increased
heat transfer - essential to achieve the higher cooling volume that is required in a
turbocharged engine.

they way its worded makes it sound like Volvo tried the 2.5 for the T-5 engine but had problems which is why they changed it to the 2.3

i'll tell you a few little secrets next time we meet up

**timbo_1975** · Saturday 14th March 2009, 12:07

I would agree, at the time of incarnation, the design had not allowed for an open deck for good cooling, and neither was it possible for general use due to the abilities of casting such a thing at the time.

In order to get a shorter block to fit the Focus platform, and the know-how was cheap enough for mainstream production, so Ford re-engineered the 5 cylinder block to the open deck arrangement on the current T-5 engines, now the technology exists to do it. But they do depend on LOW boost pressure otherwise the liners move and ping goes the HG.

That is why they expanded on the capacity to generate the torque and power, and then only lightly turbo it.

I see that Ford has cunningly added a brace-plate to the top of the block in the forthcoming Focus RS to restrain the liners, and a 3 layer copper-composite headgasket to keep it sealed, and only 1.2bar peak boost pressure with a VGT turbo, so they must still have had issues of keeping the thing together at supposedly 300bhp.

Tim.

**doug kyle** · Saturday 14th March 2009, 15:27

Would it not be just as easy to fit a later style 2.4 300bhp R engine,
then tune that up???

Pass i'm just thinking out loud.

I used to run a wee honda crx 1.6vtec race/ track car that was bored / stroked to 2056.
The bhp went from 141 to 256.
So know all about changing pistons, conrods, cams, injectors, throttle bodies,
skimming the head, valves, valve springs, valve clearance, bla, bla ,bla.
There was a lot of time & money went into this.
I mean don't get my wrong it was a quick car,
stripped out to 760kg's with a full tank of fuel & driver.
13.3@107mph 1/4 mile fwd n/a is good going by anyone's standards.

But at the end of the day it all comes down to how much money you are wanting / willing to put into the car & how quick do you really want the car to go????

**timbo_1975** · Saturday 14th March 2009, 20:03

[QUOTE=doug kyle;218101]Would it not be just as easy to fit a later style 2.4 300bhp R engine, then tune that up???

Won't fit within the chassis legs - too wide.

And 300bhp was the height of optimism!

**PaulZX** · Saturday 14th March 2009, 21:00

Originally Posted by doug kyle

But at the end of the day it all comes down to how much money you are wanting / willing to put into the car & how quick do you really want the car to go????

As fast as lightning, and a tenner.... do they still sell those red go-faster stripes? Sounds like I'll have more luck down that route lol....

**RT MECHANICS** · Sunday 15th March 2009, 09:14

Originally Posted by TheFlyingFridgeMover

Is reboring or stroking a T5 engine an option worth considering?
If so, how big can you go?
Just wondering coz a friend of mine is getting his mini rebored, and the actual rebore aint all that expesive... it got me finkin...
opinions welcomed... has anyone else done it?

An interesting subject but there are a few problems if you go past a genuine 350 hp in the 2.5 block you WILL have a cracked liner problem,we have seen a V70R with liners cracked ourselves,but as you can see some have problems with more than one liner

Or if you go past a genuine 400-500 hp in a 2.3 block you will have the same problem as i and others before me some maybe sooner than this power level if you run the volvo manifold

the answer is to re liner the block properly to gain back the strength but there is several other things to do to help the situation

Russ

**RT MECHANICS** · Sunday 15th March 2009, 09:17

[quote=timbo_1975;218141]

Originally Posted by doug kyle

Would it not be just as easy to fit a later style 2.4 300bhp R engine, then tune that up???

Won't fit within the chassis legs - too wide.

And 300bhp was the height of optimism!

It will fit fine its been done many times before

Whether thats the route to take is quite a different matter.......

Russ

**Alan M** · Sunday 15th March 2009, 12:06

The volvo blocks with a little fettling will fit the 850 bay with no problem. I will be fitting a B5244T in my car wich is from an S60 T5.

**RT MECHANICS** · Sunday 15th March 2009, 20:16

Originally Posted by Alan M

The volvo blocks with a little fettling will fit the 850 bay with no problem. I will be fitting a B5244T in my car wich is from an S60 T5.

Hi Alan

What do you have planned for your car ?

Russ

**woz** · Sunday 15th March 2009, 21:41

Originally Posted by RT MECHANICS

......the answer is to re liner the block properly to gain back the strength but there is several other things to do to help the situation

Russ

Russ - ever thought about writing a book???

We would prob. all buy a copy of there was one.
;>)

Woz

**Saaamon** · Sunday 15th March 2009, 23:12

Russ, will there be problems in the future with the focus engine when people try and push beyond 350BHP, or do they have a different liner in them?

In technical terms, what is it that cracks liners?

**RT MECHANICS** · Monday 16th March 2009, 06:19

Originally Posted by woz

Russ - ever thought about writing a book???

We would prob. all buy a copy of there was one.
;>)

Woz

there are many other 'experts' around who can 'talk' about these things so leave it to them....

Russ

**RT MECHANICS** · Monday 16th March 2009, 06:30

Originally Posted by Saaamon

Russ, will there be problems in the future with the focus engine when people try and push beyond 350BHP, or do they have a different liner in them?

In technical terms, what is it that cracks liners?

Hi Saaamon

I am sure there will be problems most of the focus st tuners have soon

realised the problem with the 2.5 block i am sure ford have done nothing to better the problem it will be the after market tuners who will take the engine further remember the liner/engine design is only for 300 hp not 600

The problem's are the design of the block ,the liner thickness and the exhaust manifold design.....like all the big horsepower swedish cars they all run tubular manifolds....

Russ

**gazjacko** · Monday 16th March 2009, 07:39

It would seem that in the tuning world, the manufacturers pay the price of listening to the 'bean counters'!
If you look at some of the legendary engines for tuning many of them can cope on 'stock' internals. The best example is probably the Skyline block where it would appear you can double the output before you even consider taking the head off.

**Tim Williams** · Monday 16th March 2009, 08:48

A Volvo manifold can safely support over 500BHP on a Daily Driver that is also used on track

.

As can be seen in the 2.5 liners more than one cylinder split, indicating a poor design (its consistent). On the 2.3 liner only one has split in the picture so that cylinder must of had a problem, maybe more than just the excessive scuffing on the liner that can be caused by running incorrect piston to bore clearance, This will cause a higher than normal temperature. Excessive heat in just that one cylinder is a common contributory cause of the number 3 liner to split. If every thing was equal then all or non of the liners would split.

**Alan M** · Monday 16th March 2009, 10:17

Liners are available for the ST 2.5 engine and have been for a while.

**Engineer** · Monday 16th March 2009, 19:18

IMHO if an open deck liner goes oval on the non thrust sides due to excessive heat then it will crack, when this will happen depends on the liner material and its heat fatigue values. Period.
If it does happen the piston may well scuff the thrust side as well

**RT MECHANICS** · Wednesday 18th March 2009, 06:33

Originally Posted by Tim Williams

A Volvo manifold can safely support over 500BHP on a Daily Driver that is also used on track

.

As can be seen in the 2.5 liners more than one cylinder split, indicating a poor design (its consistent). On the 2.3 liner only one has split in the picture so that cylinder must of had a problem, maybe more than just the excessive scuffing on the liner that can be caused by running incorrect piston to bore clearance, This will cause a higher than normal temperature. Excessive heat in just that one cylinder is a common contributory cause of the number 3 liner to split. If every thing was equal then all or non of the liners would split.

Can we see some details on this car ? What spec is the turbo and manifold of this daily driver ?

The liner that split did it just before the others did given a bit more time at high rpm/boost.....

Russ