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Discussion Starter · #1 ·
Well I'm getting a few more miles on the SI6 3.2 and now I would like to see that graph if anyone has it. I do recall in the past seeing the graphs for the 2.5 Turbo and Volvo really did a marvelous job using variable valve timing to put virtually ALL of the torque way down low where it could be used immediately on day-to-day driving. The 2.5 is a great motor by the way, as recently posted we just traded a 2.5 2004 AWD XC90 with 135,000 miles and it never had the first motor problem ever, nor did we ever have a transmission problem.

Now after driving the torquey 2.5 I am experiencing the 3.2 normally aspirated motor which i understand has the same 236 footpounds as the 2.5 but much higher up on the rpm band. As a result, the SI6 motor (short inline six) is coupled with a six speed transmission to make up for it, and it does, but there is quite a lot of transmission action going on. On a slow take off to 40 miles per hour for instance, the 3.2 six-speed will shift 3 times just to get to 40 miles per hour.

I like the 3.2, it is a rpm motor very happy to rev, internally balanced due to having six cylinders, chain driven cams, variable cam on one bank of valves. Interestingly enough, I am also a 427 Ford solid lifter fan, owning four of those motors now, (the one that won LeMans 1, 2, 3, finishing 32 miles ahead of the next manufacturer) and that motor has a bore of 4.23 x 3.784 stroke. Interesting that the Volvo SI6 motor has the identical crankshaft stroke of 3.78" (but with the smaller bore of 3.31") At that rate the cubic inch displacement for the 3.2 should it be transformed into a V8 with the same piston size would equate to around 254 cubic inches, or the same size as the original little 260 V8 Ford installed in their 1963 Fairlane. The 3.2 SI6 produces a lot more power than that old 260 Fairlane.

best,

P
 

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Discussion Starter · #2 ·
looking further into the SI6 engine family that obviously came from the 5 cylinder development Volvo did with Porsche, I see some additional features that may have come from Porsche, such as the variable valve timing and the interesting lack of main bearing caps in the traditional sense that we see here in US built V8 motors for instance.

Porsche has long used a complete single piece bottom end girdle to secure their crankshafts, rather than individual main bearing caps, and I was rather suprised to see this same concept being used in the 2.5 and SI6, which is an expensive solution but a good one.

I know I have seen the power graphs for the 2.5 before, and I may well have posted some of these in the past. Can't seem to find them now. It would be fun to compare the 2.5 turbo with the 3.2, come on guys I know someone has this info !

regards,

P
 
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