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I was told that the 2.4 is way more stronger and can hold a lot more power/boost than a 2.5 even if both blocks are shimmed. But I looked at both of the blocks and they look the same internally. Can someone explain why the 2.4 is a lot better than the 2.5?
 
In this comparo, you have to be looking at the 2005+ R 2.5L and the 2005+ T5 2.4L engines. They are basically the same (same head, same intake, same turbo, same exhaust manifold) but the T5 2.4L has thicker cylinder walls that are less prone to cracking.
 
This blog talks about the R http://www.autozine.org/Archive/Volvo/old/S60.html

"Volvo's inline-5 engine has been around for more than 10 years. In the early T5 form, it displaces 2.3 litres and generates 250hp. However, S60R's powerplant is derived from the 2.4 low pressure turbo version. It has continuous variable valve timing in both intake and exhaust camshaft (T5 has none). Engine capacity has been increased to 2521cc. A stronger KKK turbo generates maximum pressure of 1 bar, feeding the engine through not only one but two intercoolers. Both con-rods and crankshaft are strengthened to cope with the increased torque, now 295 lbft across a wide band from 1950 to 5250rpm. At 5500rpm, this engine gives Volvo the first taste in the 300-horsepower horizon."
 
The 2.4 T5 (B5244T5) is definitely a stronger block than the 2.5 R engine (B5254T4). I haven't messed with either engine myself, but from my years of reading on forums and whatnot, I hear of WAY more block/cylinder wall failures in the 2.5s than the 2.4s. That 2mm bore difference does a lot more than you would think for strength.
 
For how much thicker it is it can't be SO much better than the 2.5 like some people have said is it?
It turns out that an 81mm bore is 30% stronger than an 83mm bore whiteblock.

The other difference is the 4t4 motor is running 1 bar of boost stock while the 4t5 motors only run 0.68 bar max. Me7 tends to run knock control somewhat haphazardly too, allowing excessive knock before pulling back timing and enriching to ride the target lambda 1. Thats a major contribution to why k24's end up cracking the exhaust housing as well.
 
Hi guys, I have an 06 S40 with a 2.5 engine, my piston rings were melted inside the cylinders, my question is, can I replace my 2.5 engine with a 2.4 and install the turbo on it? I've noticed they are both the "same" at first sight.
 
No, you would have to make a lot of changes to make this happen. I would recommend just finding a 2.5 T5 engine.
 
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