http://www.ipdusa.com/products/11736/12 ... cc-kit-b20

It looks like they have brought back the big bore kit for the 74-75 B20, with 24mm wristpins. No doubt that most people here have their own impressions, sources and suppliers but this might be another option.

Correct me if I'm wrong, but I think that kit is just a set of B21F pistons (B21/B23 have 24mm pins) and a special head gasket. The head gasket has become rare but yes, I think there are options there too.

Interesting that they should bring it back out, though. Good to see they haven't completely forgotten about the older cars.

I'm not sure what you mean that you doubt we'd have our own impressions about this - that's like tossing the gauntlet. I won't take offence - but I did have one and drove one briefly. Dale's got a gasket and seriously others here have done even crazier things on this forum.

Let's review - you have to overbore the block by around 1/8" to fit those pistons (which are heavy and definitely NOT a performance piston). So you have to make sure that there wasn't any core shift when the block was made and you can't do that by looking at it. You have a shop that sonic checks blocks?

The bore then no longer fits the head, so there is work to be done there. Maybe an opportunity to do some fun things...but who really does the math there? Oh, a few of us have done a few things.

Anyway, these things were done based on the adage that there is no substitute for cubic inches. That and B20 oversize pistons were in short supply - how many cubic inches in 0.1L. I'd much rather have a B20 with a light rotating assembly with high compression and a great cam that I'm not worried about punching things through the side of a now weak block. Wait - I've got one of those as well.

Work out a nice turbo and up the air density a little - I think that's proven to be fun.

There isn't any magic in doing this conversion - but what would I know?

No offense was meant, please believe me. My sincere apologies if it was seen that way. I just thought that most people are unaware of the more specialty places like KGT and the like. I could very well be wrong. iPD is definitely easier to find on the web in my travels, but there are more and varied suppliers out there that may better fit a desired application that someone may look for. They are not the only choice for novices like myself, that's all, and the variation for experimentation is quite wide in my opinion.

People's experiences and impressions may also influence their choice to purchase from a certain manufacturer or supplier. I have had good service from iPD in the past, I thought this was an interesting part to note from them.

Haha, I don't even know where I'd start looking if I were looking for parts for these things. It wouldn't be IPD though. I think they're the first place people go to when they first get a Volvo, as I think it's about the best known spot in North America for these things. Maybe I take a dim view of the average Volvo owner, but I know how long it takes to get over the feeling that IPD is the English-speaking window to all that cutting edge Swedish performance, and that shopping overseas is not worth the hassle. Nowadays finding the most exotic Motherland parts for these engines is about as difficult as opening up Google, but many of the greybeards still won't do it. Only once you dig (a lot) into what else is out there do you see how outdated some of IPDs stuff is.

I also think that lots of people follow the "no substitute for cubic inches" routine. It is only 142cc more, but that's 7.2% more volume after all and if you're rebuilding your engine and "for a few dollars more", I'm sure many people say "why not?". Especially if they have a '74-'75 B20 and can't find "regular" oversize pistons for it.

As Craig pointed out, there are lots of things wrong with this kit, but not many of them are more "wrong" than just rebuilding a B20 to stock specification. Aside from extra money in machining and risking cylinders that are too thin, the (correctly built) classic IPD performance engine is pretty much better in every way than stock, but nowhere near as good as you can build one of these things and if you're spending the money on a full rebuild, you should spend the money to do it right. Long rods, short pistons, tight squish, big valves, modern cam, and lots of attention to detail on machining and assembly - none of that costs a lot more than the IPD kit, but will yield far better results. However, if you're unsure of what combinations to try and what to watch out for, and if you haven't spent the best part of 3 decades learning how to think along these lines, staying close to stock is not a terrible or scary idea and that's what IPD gives you: known combinations.

IMO you shouldn't feel badly for pointing out that it's back up for sale, David. A couple years ago I would have been pretty excited about it and it WASN'T too many years ago that I thought the hot ticket was a '75 B20 for this very reason. Frankly, if I wasn't in daily conversation with Craig and spent the last 20 years working on Volvos and talking to other Volvo guys, I would probably still be thinking along those lines. Some days it's hard to see how much I've learned since then.

To what Matt said - I started the cam thread and pointed out that most of the traditional MFG's of pushrod stuff have gotten out of it. I suppose I should start a "Master List" of vintage suppliers. I'm not saying my knowledge is complete for what's out there...but I can find rebuild parts for M41's . I rarely buy anything from IPD anymore and shop almost exclusively in Europe. It's a long list.

Sonic checks are wise. The tool is $127 shipped on Ebay, so hardly difficult to find. All machines shops should have by now.
Not particularly necessary in my opinion- I have a b18 block that was out .207 and then supercharged, as my daily and only insured car at the time.
The 544 stroker engine is out .14X- more than the B21 pistons @ .122. Neither block has seen a sonic tester.
The b23 block got a sleeve in the front cylinder- it was built when Richard Prince was running "unguided" pistons in a race car and convinced the TB forum the blocks were fragile. By coincidence (?), the drilling tapping for the water pump just about went through the front cylinder wall- Volvo was having an off day that day. So we sleeved it, even though that was on the side of the bore.


You know yourself the b20 cylinder head is always wider than the factory bore, so this is just plain incorrect.


Correct. There isn't. If you want to turn a car into a toy or a science experiment you can play around if you want to..
Adding displacement has no down side, and should be the starting point of any build.

Good point about the head - those that have done this with B18's do end up with some weirdness. I was recently reminded of the differences between the B18 and B20 heads. I don't see many B18's as everyone swapped engines a long time ago that had B18's when B20's were plentiful. So port sizing, valve area, sweep volume and SCR all have to he thought about. Having a HG that doesn't match the head is an issue - but on balance, not a very big one. Stand up a B21 or B23 if you want a bigger engine - they're cheaper to build (but by no means cheap) and have a better head (even the "bad" ones) than the B20. Then again - no one wants to hear that you're going to have to modify stuff to get this done and all for what...a few HP.

I'd rather not pay a ton for pistons and boring that isn't really going to yield much...hey if it's all you can get that's fine, but unless people are going to do their homework and work out compression ratios and sort out all the details, like the sonic check, then you could be in over your head pretty quickly.

That's my main point with much of this...some of us are fine playing with "science project" engines trying different things and experimenting. Others are better off evaluating a stock style rebuild with more SCR, tight squish and a big cam. Depends on what you want to do.

The days of big bores in engines passed a long time ago - there isn't much you can do with a bathtub head. I've not written my "cookbook" B20 thread and maybe I should get around to doing that but I'm a bit busy and writing all this down with pics and stuff takes more time than my life will allow right now.

Extremely unusual for there to be a problem. Early b18 to 20 was a alleged by some to be a concern (I didn't sonic check mine and drove it for a summer with a supercharger), even b21 to b23 slightly concerning when boosted, but this conversion, nah...



OE chamber width is actually wider that factory bore. So not "per se" a concern, though there is opportunity to improve the pretty bad factory chamber.

Still leaves the factory old tech rings, and the weight of the pistons and the late b20 rods(Length is ideal, longer rods with stock stroke are a bad move)