Hello Hive Mind,

So I bought my first Volvo, an '84 245 (LOVE it btw), and the previous owner installed a stock turbo and downpipe into the car. It seems like they knew what they were doing to some extent, but that there were a number of things that indicated maybe not so much. I'm pretty concerned with 10.3:1 compression ratio, and after doing a good bit of work to revitalize the engine (classic stage 0 stuff including the flame trap). Updated a couple other things and got it on the road, just to have the head gasket blow after about 15-20 minutes of driving.

My brother and I are pretty sure we're looking at stock internals, so we're of the opinion it's still at the 10.3:1 cr. I've tried to look up things here and elsewhere, and I'm feeling lost. I saw something about possibly being able to swap the head to decrease the far too high for normal boosted air scenarios, but I'm wondering if there is an easy(-ish) way forward where I can trust my gaskets just a little more.

Help me Obi-wan Kenobi's, y'all are my only hope!!

 

I'm not sure about the early 240 turbos but the 740 turbos with the B230 engine had dished pistons to lower the compression ratio. You might want to check out turbobricks.com as they do a lot of customization there.

 

I'm curious what fuel injection system is on the engine. The 240 turbos back then used the CIS injections system. Those heads had the injectors in the head. The 740-940 used electronic injection, with the injectors in the intake manifold. The 240 turbos had a fuel cut off switch to prevent overboost - don't remember what the 740-940s had to prevent that.

As far as I know the combustion chamber size (in the head) is the same for turbo and non turbo heads-

If you want to reduce boost - adjust the waste gate to open earlier -