Engine swap, 140bhp for a 170bhp - what's involved?

[tony209]

I have an 02 Torslander, 157,000 miles, it has a seized or broken compression ring so I am going to swap the engine for one from a lower mileage car. If I wanted to up the power by replacing the 140 bhp (B5244S2) for the 170 bhp engine, what would this involve - anyone done this before?

[Clan]

Originally Posted by tony209

I have an 02 Torslander, 157,000 miles, it has a seized or broken compression ring so I am going to swap the engine for one from a lower mileage car. If I wanted to up the power by replacing the 140 bhp (B5244S2) for the 170 bhp engine, what would this involve - anyone done this before?

The engines are mechanicaly identical , it is the ECU and it's software which are different . I believe there are companies which can alter the software to suit ..

[tony209]

Originally Posted by Clan

The engines are mechanicaly identical , it is the ECU and it's software which are different . I believe there are companies which can alter the software to suit ..

I did think it would be just down to the ECU but the engines have different codes B5244S and B5244S2. I wa wondering if there were other differences - injectors or maybe gearbox

[TimS]

I believe the final drive ratio is higher on the 140?

I used to have a 170 P2 manual. Below about 4k, the performance is virtually identical. After that, the 170 steps up slightly (you can just feel it), whereas the 140 tails off. So unless you rev it, you won't get any benefit from the 170.

[tony209]

Originally Posted by TimS

I believe the final drive ratio is higher on the 140?

I used to have a 170 P2 manual. Below about 4k, the performance is virtually identical. After that, the 170 steps up slightly (you can just feel it), whereas the 140 tails off. So unless you rev it, you won't get any benefit from the 170.

Thanks for that, you have just confirmed what I was thinking, I did suspect that the gearboxes/ratios may be diferent. The gear ratios are a bit strange on the 140, 3rd is like a 3.5 and 4th a 4.5. might as well stick with the 140 - the engine swap will be less hassle!

[greasyfingers]

If it's an automatic, even the drive ratios are the same.

From what I understand, if you drop a 170bhp lump into a 140bhp car, you will end up back with a 140bhp car again. This is because they are identical - it is the software that makes the difference, and the software is chassis specific - a 140 car will always be a 140 car unless you change all the major electronic modules as well, because they will all carry the original chassis identity, and may not talk to parts they don't recognise. I hate the mentality that came up with that.

Conversely, presumably, if you drop a 140 lump into a 170 car, the engine will become upgraded.

[tony209]

Originally Posted by greasyfingers

If it's an automatic, even the drive ratios are the same.

From what I understand, if you drop a 170bhp lump into a 140bhp car, you will end up back with a 140bhp car again. This is because they are identical - it is the software that makes the difference, and the software is chassis specific - a 140 car will always be a 140 car unless you change all the major electronic modules as well, because they will all carry the original chassis identity, and may not talk to parts they don't recognise. I hate the mentality that came up with that.

Conversely, presumably, if you drop a 140 lump into a 170 car, the engine will become upgraded.

I find this very puzzling but interesting all the same. What makes me think that there is something different between the two engines are the different engine codes and that maximum power outputs are at different revs. I would have thought that the ECU would control throttle response and maximum output, maximum power at a give specific revs would be down to gear ratios - or is this 'old school' thinking!

[TimS]

I've read that you can get aftermarket maps for the 140 to take it to about 180, but not from Volvo.

I've got the engine graphs here (drop me a PM if you want a PDF). The final drive is 4.00 for the 140, & 4.25 for the 170 manuals. For the Geartronics, it's 2.44 for both. In the manual box, 1st, 2nd & reverse are slightly different, & 3,4,5 are identical. The auto boxes are an identical number, but the ratios are not given (AW55-50 box for both).

The 140 engine looks from the graph to be fractionally more torquey (surprisingly) around 3k, so maybe that's why the final drives are different. Perhaps that's for emissions or something? However the 170 falls off slower above 4k, hence the greater power.

It's torque that determines power (power is basically torque times engine speed), & gears are just torque multipliers, to change the available torque: you have a low gear to multiply the torque from the engine at low engine speeds (when you set off), but at cruise, you don't need to multiply the torque so much, because the engine is producing more of it at those RPMs. It'a a bit of an oversimplification, but that's how I picture it.