The Joshua Tree

Say you had a UK 2.5 Sti engine that had fairly recently been fully forged, and you were planning on buying the car but the conrods were only rated to around 500bhp, and you planned to go higher than that, but everything else was perfect on the engine. What would be the cost to pull the engine to change the conrods, also would it need to be re-honed for a conrod change, is their anything else that you may need to factor in when changing the conrods ?

Danjo

It would be a case of swapping out the rods and you can refresh the mains and big ends while you are there and check the crank over etc. Honing not required if you are sticking with the existing pistons. I assume they are 2618’s? 4032’s will be getting to their limit at over 500bhp.

As a side note, the EJ25 is really getting towards its limit as you start to get the thick end of 500bhp. The liners are thin (even more so when you start to move material away from them with honing or boring) and can crack, even with a close deck conversion or pinning. Some can take the power, others don’t. I know of one car built by a very reputable builder that split a liner at 630bhp within 2k miles recently. It’s a bit of a lottery. A 2.35 would be a better route to go ideally. But the cost of that is fairly substantial in comparison.

The Joshua Tree

The engine is closed decked and has the 14mm head stud conversion done but i appreciate everything you say above, especially about the liners. Yeh the pistons are 2618 forged pistons, i'll be looking in the area of 550 - 600bhp with similar torque, it will probably run around 2.0 - 2.2 bar i would think with the turbo i had planned for it. I know where their is a 2.35 that's already been built to a high standard with no expense spared but like you say they are not cheap and he wants a lot for it.

stockcar

Personally I would not run a std 2.5 block near 600 with std liners as they are a lottery...........we have successfully run them over 600 but isn't something that is remotely guaranteed

at that level we would advise fitting HD uprated liners and can even offer a 2.35 conversion on your 2.5 blocks if needs be

the EJ22T block whilst very strong does have its own issues simply due to age / rarity / cost and IMO is no longer the "go to" block.......

Vxr2010

i saw a cs400 with a cracked liner , it was only running standard power , the cs400 blocks are modified by cosworth and it still failed , depending on tuners depends on what people say as to how much bhp they can handle , i’ve heard 350 bhp to 400 bhp is a good range , i personally am happy with my 330 to 340 in my small fleet of Fsti 😁👍 , if i really wanted to go that high power wise then i would sell the 2.5 that’s in it now , and pay for a stroked 2 litre engine so at least it’s the best it can be for the power you want , as any other way is waiting for it to fail sooner rather than later and then the engine will probably be scrap any way , and running a 2.5 is half a job to get the power rather than do it the proper way 👍

stockcar

the Cosworth blocks were not CDB converted to my knowledge?? they added uprated components but this is of little help when using the std casting

hedgecutter

iTrader: (5)

What you need is an IAG billet block!

stockcar

not seen one running much if any more than our HD Ductile Iron linered / CDB blocks.........

and certainly less costly

Vxr2010

the cs400 was being rebuilt by Len at subaru4u , i know the block is different to standard blocks , i don’t know how it is different , i just remember him trying to sort a car400 block plus prices for it as it sounds like it was more expensive 👍

Danjo

I’ve seen a failed CS400 at Slowboy, looked like standard EJ25 case halves to me, certainly wasn’t a cdb. I couldn’t see anything that looked modified over a standard block.

lockheed

iTrader: (1)

Out interest what size can you make these?

stockcar

we can technically have custom liners made in any size but obviously total one-off's are more expensive............

we commonly use 97.5mm (2.2) or 99.5mm (2.5) sets

Vxr2010

it’s concerning hearing of 2 cs400 failures , for me it’s sort of saying is it really worth going 400 bhp plus , it’s the risk of failure and cost , it’s clearly an expensive route to go and to do it property , the 2 litres are less prone to failures , do many stroke the 2 litres i assume it would be a pretty tough engine producing a lot of power , it’s a real shame subaru did not stick to the 2 litre spec when building the 2.5 , i have three sti 2.5 engines running and a spare forged one in the garage as a back up 👍😁

stockcar

because of the architecture of the 2.5 IMO above 400 then you need a CDB conversion.......having said that it depends why they actually failed

a heavily pushed std block 2.5 is more likely to split a liner but both the 2.5's and later 2.0 cars suffer from the piston ring failures

The Joshua Tree

I've not driven or been in a stock Sti 2.5 hatchback, the only 2 ive drove are one i test drove in Birmingham that was around 435bhp with good torque and the one i currently own which was 436bhp when i bought it with around 380lb per foot of torque, the car wasn't mapped very well, after a remap with Bob Rawle the car is currently running 476bhp with 515lb per foot of torque.

To your point above, after being in 2 that are 400bhp+ i couldn't own one of these with less than 400bhp, it would feel too slow and nowhere near as much fun, as an example if i came out of my current car now and went into a fairly standard Sti it would probably feel like the car was hardly moving and it wouldn't make me smile like one that has had a good increase in power and torque.

Vxr2010

😂😂 mine are daily drives so not practicable for me , horses for courses , not saying it would not be fun with an extra few bhp , it’s an expensive road as i found out with my monaro , 12 k £ later , the tuning option was done by the previous owner so it added another 100 bhp to a na engine but cost 4k , so running about 440 bhp and same foot pound , the owner before must have had a death wish as he did not do the brakes , AP 6 pot now fitted , so instead of praying for it to stop it now stops 😂👍 as i found out mod one bit on a car and other bits need doing ie brakes etc