164 supercharging: Strength of B30 crank?

[Pigeon]

Wonder if anyone here can provide some information. I've tried the search function but it doesn't show anything up...

I'm interested in supercharging my Volvo 164 and in looking for information I find just enough to worry me concerning the crankshaft of the B30 engine and not enough to resolve the doubt

Everything seems to be very vague and I've not been able to find any definite answers. Seems that not many people are interested in tuning 164s and those who are tend to get responses along the lines of "get rid of the B30 and put a four-pot in and tune that"... er, no thanks, I want a straight six which is why I got a 164 in the first place!

Some people seem to say that the crank's lack of torsional rigidity limits power increases to 200bhp or so unless you fit a steel crank.

Some people seem to say that actually the B30 has a steel crank already...

Some people seem to say that the marine B30 has a steel crank but the car version has a cast iron one.

Would be useful if anyone on here can provide a definite answer

Thanks...

[rbodor3]

there's only 1 definite way to know - do it.

But seeing as you have a bit more mind than that, you can pull the crank and inspect it yourself.

I have no experience with the 164, but judging by it's age and likely that it's a cast iron block I would imagine the crank will hold up to supercharging, depending on what size.

Why have you passed up turbocharging? Yes you'll have to consider the exhaust manifold and oil feeding issue, but honestly it's not really much more work than a supercharger kit and you won't have that hideous whine!

[Pigeon]

The B30 is indeed a cast iron block and in normal use it pretty well shares the usual Volvo redblock robustness, but it has less margin to handle uprating than the fours. It didn't have much development - Volvo basically multiplied the B20 four by 1.5 without doing much else to it and effectively used up some of the margin in so doing. This shows in odd things like the oil pump having less excess capacity so the engine is more at risk of low oil pressure due to wear as it ages, and poor coolant circulation around the rear cylinders - not significant in stock form but a concern when uprating, albeit easily sorted.

Straight sixes in general are more prone to torsional rigidity problems with the crank due to its length, and it's not clear whether Volvo did take this particular bull by the horns or simply relied on being able to take advantage of the general robustness of the four from which it was derived.

The car is my daily driver and as such I don't really want to be taking it apart just to see what it's made of however for the same reason I would be after getting a spare engine to work on and then simply swapping it for the existing one once the mods are complete. So I could certainly find out by inspecting the crank of the spare engine - thing is that especially since if I do end up needing an uprated crank it'll be an expensive component, I'd rather know more definitely before I make a start.

Turbocharging I'm not so keen on for various reasons. One is simply space - I'm in the UK, so it's RHD, and the steering column and box get in the way on the manifold side (similar considerations with the 240 being why Volvo never made an RHD 240 turbo) - I think it would still be possible to find space, but it would be very cramped and awkward. But by the same token there is plenty of space on the other side of the engine to install a supercharger.

Underbonnet temperatures are another consideration - it gets pretty hot in the engine bay as it is and the extra heat from a turbo, especially in the cramped installation that would be necessary, could be a problem.

The main reason though is that it's much harder to engineer a turbo installation for good driveability without the resources of the manufacturer. Minimising lag and obtaining boost from as low in the rev range as possible while not overboosting at the top end, and also keeping a reasonable fuel consumption, takes a fair bit of experimentation and expense to get right. A positive displacement supercharger inherently provides linear boost throughout the rev range and zero lag - good driveability is more or less assured simply by doing the calculations properly, and any necessary adjustment is a simple matter of changing drive pulley sizes. Good responsiveness is particularly important on the congested, twisty UK roads with few overtaking opportunities, and a supercharger makes it much simpler to get what I want.

I'll always remember reading a road test in the 80s of three V6 Ford Sierras - one standard, one with a Turbo Technics turbo conversion, and one with a Lysholm-screw supercharger conversion. The maximum power and torque figures for the two forced induction setups were the same. The testers reported the turbo version as being awkward to drive and getting 2mpg worse than standard, while the supercharged one was lovely to drive and actually got 2mpg better than standard.