volvo 740 Engine swap / tune for power

[Joost]

Dear everybody,

Not sure this is the right place, but I'll give a short introduction. I'm a Dutch Volvo enthusiast. My parents used to drive 240s, my first car was a 460 I still own. I've owned (and still own 1) Volvo 850 T5s, my family still drive 850s, V50s, V70s...

As a mechanic, I have been intrigued by converting a Volvo 740 into a powerhouse 350-400 HP. I've searched online and found plenty people who have, but I've never read it form a budget frame of mind. Being a mechanic in daily life, my main concern is budget. The car cannot become a bottomless pit, I need to know approximately how much a conversion/tune will be. I cannot do machinework myself, but overhauling/repairing etc. is not a problem at all being a mechanic.

As I said, I've read several things about it. There seems to be a tendency of using a T5 engine (B5234T I assume) and turning it into RWD using several 960 parts including a M90 gearbox.

Then there are people who stick to a Redblock usually GLTs 2.3 Turbo. I understand that the stock gearbox might not withstand 350-400 HP and improvements to do so are costly.

I have access to 2 B5234T engines, but the state and mileage is unknown. I also have access to an M90 (H2 I think). Being stock engines, I am not sure how worn out they will be. Being whiteblocks, they will be need to be resleeved when worn out. I think this is a costly business, while Redblocks can be overbored without a problem being cast-iron.

I understand the early T5 engines like the B5234T should be good to 350-400 HP, but for safety reasons, it might be best to swap rods with forged ones. I understand that the Motronic 4.3 is relatively easy to tune. There are sometimes discussions of using the 2.3 Turbo B5234T, B5234T3, B5234T4 or even the 2.4 or 2.5 Turbos. As I understand it, the internals of the 2.3 turbos are all the same and that engine management and turbos are the differences, as they were offered 225, 240 and 250 HP stock. I have read that cilinder walls in especially 2.5 engines might cause problems when reaching 400 HP

When looking at newer whiteblocks, most notably the B5254T4, it was stock 300 HP. I have read that the stock internals can easily take 400 HP. However, immobilzers and tuning might be more of a problem in use of a 740. Also, these engines are harder to find and more expensive to start with.

All in all, I would really appreciate it if you could point me in the right direction and explain exeriences in this application. I don't have anything yet, but I would like to be able to understand how much money will go into the project taking one route or the other. Again, my goal is to reliably reach 350-400 BHP on a budget which be street legal.

Hope to hear from you!

Joost