My Volvo Pocket Book says the following about the history of the B6304 engines here in the US.

to 1994, .. HP 204/6,000 rpm, TQ 197/4,300 rpm, C.R. 10.7:1
1995 only, HP 181/5,200 rpm, TQ 199/4,100 rpm. C.R. 10.7:1
1996 up, .. HP 181/5,200 rpm, TQ 202/4,350 rpm. C.R. 10.7:1

O.K. We know that Volvo changed the camshaft specs for the 1995 model year to produce the changes we see above. (The HP and TQ curves are quite different which produce a very different feel than one would expect by just looking at the numbers above.)

1) Did they change anything else for the 1995 model year in the engine besides the cam grind?

2) What did they change in model year 1996 to obtain the change in torque. They went from OBDI to OBDII in 1996, could that be responsible for the change in TQ numbers? (for example : more efficient control of the engine, as in... a second o2 sensor... thus better ECM control, that sort of thing?

DEWFPO

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1998 S90 066,800 and 1995 964 150,200

Just wanted to chime in here with my personal findings about the engine differences.
I drive a 97 964, and my mother has a 93 965. I have driven both around town and on long (8+ hr) trips and I would have to say I prefer my 97.

When you really put your foot down on the 93 it 'feels' faster, but I think thats because it's power curve is sharper than the 97. The 97 has more power lower down so it has a better starting point, which helps make up for its lack of top end HP.

I actually took the time to graph the hp/torque curves for each year. From what I remember, at a given engine speed, the 97 has about 15-20 hp/ft*lbs more than the 93, up until 4100. At that point the 93 keeps building until 6000, whereas the 97 drops off.

Consider that when you are cruising at 70 on the highway, your RPMs are right around 2500 or so, favoring the 97. I believe even downshifting to third will still briefly favor the 97s power band, unless you rev past 4100 until redline (but how fast are you going then, approaching 100?). I do a lot of highway driving and frequently drive 80-90. The 97 never feels wanting for power at those speeds, and feels better than the 93. I never got it this fast, but I imagine you have to be going 110+ to start favoring the 93 in top gear.

So ask yourself how often you find yourself going past 4100 RPM. I think that's the real question.

If this was a sports car I would prefer having power on the high end. But given the car, transmission, and the kind of driving I find myself doing, I think the 97 has the better engine.

Just some food for thought.

BTW, what does the Volvo Pocket Book base its data on? I'd like to know where the 202@4,350 torque figure comes from, I'm pretty sure my owners manual says 199@4100. Same with the 204@6000 hp, shouldn't that be 201?

Very nice analysis!

Here is my view. At steady speeds, the later engine theoretically has more torque in reserve. So if you achieve 99% of WOT and the transmission doesn't downshift, the newer cars will acc. faster than the older cars. But, if you mash the throttle and cause a downshift, the revs will typically go above 4000 and then my car now actually looses acceleration until the next upshift at 6200 RPM which which brings it back down in RPM. On a WOT acceleration run a large % of the time is spent above 4000 RPM where the breathing seems "asthmatic".

Im guessing that after, or when, I change my cams I will be pushing the accelerator further down to get the same intermediate level of acceleration around town and on the highway, but who cares if, when I'm trying for "all-out" by causing a downshift the result is a net increase in acceleration. (I often go down the entrance ramp at full throttle in order to be able to merge with the 80 MPH RT95 traffic in my neighborhood.)

What do you think?
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'96 965 with 16' wheels at 112K. Had '85 745 Turbo Diesel for 200K.

I think we both have put far too much thought into this! :)

I do agree with your viewpoint, I only wish it was possible to combine the low end power of the post 95's with the high end of the pre 95's. Or is it...?
There is a company called upsolute that may be able to make a chip for the 960. I was in contact with one of their distributors 2-3 months ago, he said they should be able to make a chip, but to be sure he would have to see my ECU, I never followed up. He claimed a 10% hp and torque increase, which for the early models, might give it enough low end to compete with the later ones, and then it would have even more at the top end. Also someone posted here a week or two ago about an intake mod for his 960 that seemed to improve his power.

Look, this has transformed into a performance thread!

Have a good one.

jbowers,if i do make any adjustment it will be to place the 94 cams where the 92's are(i will do nothing to the 92).the 92 will serve as reference only.i intend to do measurements between each engine.one i plan on doing is simply put a staight edge across the bolts of of the cam pulleys as it will sit on 1 bolt on the exhaust side and 2 bolts on the intake side and see if there's a difference in clearance.if it appears both are already set alike then i'll put the covers back on try to forget the wifes car is quicker.the last thing i want to do is trash my engine,but on the flip side there may be something very apparent.i wont know anything until the comparison.if anything i'll feel much better after i know.i am aware this is a very delicate procedure and if there is a noticable difference i will still do it in small steps and not all at once.
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83 242 DL -127k, 92-965-189k, 94-965-200k, 83-242 GLT-Gone, but not forgotten,83-245GLT-1'st one (the 1'st 3 currently on the road)

after reading the owners manual the 92 does have a 3:91 to 1 and the 94 is 3:31 to 1.i dont drive the 92 often so i'll check the cruising rpm's again to see where they're at on each one.after all aren't we all looking for those few elusive horse power!
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83 242 DL -127k, 92-965-189k, 94-965-200k, 83-242 GLT-Gone, but not forgotten,83-245GLT-1'st one (the 1'st 3 currently on the road)

our 92 has better accelleration at the touch of the gas and continues all the way thru.the way i plan on examining ANY difference is to leave the 92 alone and only compare the exact cam positions of both engines.since each cam can be adjusted i will mark the 94 before i adjust.i have replaced belts on both engines and they were replaced exactly the way they came off,but that doesn't mean any previously replaced belts were done with the precise care i do.it may be as simple as moving the cam 1 or 2mm, or it may even be a tooth off.i would definatly use the camm set-up tool if i had one.i'm not going to do anything until it warms up a bit.this engine could be 1 tooth off and not cause any damage,right?it runs fine but there's just that difference in performance between the 2.
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83 242 DL -127k, 92-965-189k, 94-965-200k, 83-242 GLT-Gone, but not forgotten,83-245GLT-1'st one (the 1'st 3 currently on the road)

If I were you, I would start by having the cams set with the tools and just make some small changes from there by loosening the bolts that hold the pulleys to the cams. (Being sure to mark things carefully before making any changes so you can return to the design location at any time.) I have no idea how close things might get if you move by a tooth.

Anyway, which cam will you move and in what direction? In a single cam engine, retarding the cam, as I remember my Triumph TR4 competition prep book, enhances higher RPM performance. I think the concept is that with the ram effects taking place at higher RPMs having the valves operate latter allows for more scavenging and "packing"????????

My $0.02!
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'96 965 with 16' wheels at 112K. Had '85 745 Turbo Diesel for 200K.

i have the 92 & 94 with the same H.P and torque,it is quite evident the 92 has more pick-up and is smoother than the 94.i noticed while reading the chart in the faq under lock-up rearends it states the 92 ratio is 3:91 to 1 while the 94 is 3:31 to 1.this would explain the increased pick-up but not the smoothness.if it ever warms up here i'm going line both cars side by side, pop the timing belt covers,bring both engines to t.d.c.(as if replacing timing belt)and closly compare the cam gear positions (the 94 to the 92).i have a gut feeling the 94 may be off a bit when compared to the 92.how-ever though the 94 starts quicker,but i'll sacrifice the couple of seconds of extra cranking for increased power.what do ya'll think?one other thing,at cruising speed(70 mph)the tach reads the same on both so i wonder if the ratio's really are different?i'll look in the owners manuals to see if they're listed.
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83 242 DL -127k, 92-965-189k, 94-965-200k, 83-242 GLT-Gone, but not forgotten,83-245GLT-1'st one (the 1'st 3 currently on the road)

That's what so interesting about our 95 feeling 'peppier' than our 98, yet they both have the 3.73 RAR and the 181 HP engines.

DEWFPO
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1998 S90 066,800 and 1995 964 150,200

dm960,

Funny you should mention this. We have a 95 960 w/151,800 miles and a 98 S90 w/67,400 miles. Mechanically almost identical machines but the 95 feels spunkier. Seems to rev. a little more freely and just in general is a little more fun to drive. I can't explain it.

I changed the timing belt on the 98 last week and plan to change the T-belt on the 95 this week. I'm curious to see where the timing marks are on the 95. It was changed once before we bought it.

DEWFPO
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1998 S90 066,800 and 1995 964 150,200

You can't tell anything by the timing marks. The cam pullies have a lot of adjustment on the ends of the cams. (Notice the slotted places where the cam bolts are installed.) The cams are set using fixtures that lock the crank at TDC and the cam at their design timing. The pullies, belt etc. are then installed and the marks added at the end as references for belt changes.

There have been cases of guys here on the board with marks that were no longer valid because a tech was sloppy while changeing cam seals or ??? and put the pullies back without regard for the existing marks.

I've got a set of cams from an early, pre '95, sitting in my workshop waitig for the weekend when I have my other projects under control and the "honey do" list taken care of. I've made careful acceleration runs and mileage checks to compare before and after. I've also measured the lift profile on the early cams to compare with my '96 cams after I do the exchange.

If anyone makes this switch before me I'll sure be interested in the results. BTW, I've also purchased a set of Volvo cam timing tools. The same tools are used for the 850s, '70s and the '40s with the 5 and 4 cylinder versions of our engines.
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'96 965 with 16' wheels at 112K. Had '85 745 Turbo Diesel for 200K.

I've got a '92 965 and a friend has a '96 964 and I've driven both back to back. My '92 feels much more sluggish around town b/c it's sweet spot is well above 3K rpm, which is rarely achieved in city driving. By contrast the 96 pulls much stronger at lower rpms and feels less "heavy" around town. There's no comparison on the highway, though. The '92 will kick the '96's arse. It'll pin you into your seat in an 80-100mph acceleration...whereas it's evident the 96 is out of it's power band. So, it's a tradeoff... I do a ton of long highway trips, so I prefer the powerband of the '92 for it's instantaneous high-speed acceleration. The later models are better suited to "everyday" driving.
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Lance '92 965 w/ 180K miles

Those are the characteristics I'm hoping for with the cam change. The car has more than adequate torque for around town. I never participate in stop-light grand-prixs but I do love high RPM/speed performance.

From a standing start my car will spin the wheels when I dump the throttle unless I'm going straight ahead on dry clean pavement anyway.
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'96 965 with 16' wheels at 112K. Had '85 745 Turbo Diesel for 200K.

I can say with my 1996 that the lower end torque is fabulous. It really pulls off the line well and is steady. I like the IRS but we are limited in shock selection, to Volvo. I'm going to check out using 740 shocks on the rear.
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Warren Bain - '99 V70GLT G-Valve > 80K mi, '96 965 >120Kmi, near Manassas Va.. Check the 700/900 FAQ via the 'features' pull down menu.

From 94 to 95 they went from Mortonic 1.8 to 4. something. Also 2 oxygen sensors instead of one.
Justin
94 965