View Full Version : B18 with B20 Fuel Injected Head??

02-22-2015, 12:26 PM
Does anyone know if is possible/of value to put a fuel injected B20 head on a standard B18 to improve performance?
I'm assuming the SU's would have to be rejetted but can't think of much else that would change. Perhaps the cam?
I have a dual hole exhaust manifold on the engine and C cam.

Any insights appreciated.

Phil Singher
02-22-2015, 04:12 PM
Possible, yes. It would bolt right on without problems. I would use a B20 carb head gasket, not a B20 injection head gasket. You would have to use an injection manifold gasket.

Of value? Anecdotally, yes (I have not doe it myself), but it would have to be a '70-'71 B20E head to maintain a reasonable compression ratio, not the later F head.

02-22-2015, 08:04 PM
Thanks Phil.

02-25-2015, 04:41 AM
I was running the F head on my B18, after having it machined to the same spec height as the E head. With thin head gasket, you get a 10.5:1 compression ratio. Ported, polished, large cam & exhaust, bored .060 over, push rod & steel gear kits, etc. worked well, but worth money?? Currently moving some of the bits onto a B20 block after many enjoyable years with the B18.

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04-02-2015, 04:48 PM
B20E or F head whith its 92 mm wide combustion chamber wont work optimal on a b18 engine . It will work but it hurts flow/combustion=less power,, when chamber is wider then bore. The b20E/f head works real well when bore is 92mm.. Best choice of head for B18 is a ported original head. Modify whith coned/shorted guides & unshrouding valves, porting etc.. The later B20 head whith is wider chamber is best for 92mm bore.A bored out B18 to B20 works well whith B20 head up to -72. The chamber should never be wider then its bore. Volvo planned the b20 to be 2,1 liter thats why the chamber was wider (from -73 and up).. B21 OHC got it instead... Greetings from Sweden

Phil Singher
04-02-2015, 06:20 PM
Yes, I agree completely. In fact, I almost always bore a B18 to 87mm so it matches the chamber diameter, I use 90mm pistons with B20B heads, and very often 92mm with injection heads, all of which improves volumetric efficiency (VE). I have heard from several others, though, who say they had decent results with B20 heads on B18s, even with the mismatch. I wouldn't do it myself.