Water cooled engine weights?

[petevb]

I recently heard that a dressed 997 RSR motor weighs in at almost 300 lbs even. I know it's a full-on lighweight race motor, and that fluids will add to that, but wow- can that possibly be correct?

I was wondering if anyone has the weights for any recent water cooled motors- GT3, Cup, etc? They would make very interesting comparisons to the air cooled motors we know and love.

Thanks to Bill Verburg for compiling the following list of air cooled engine weights, stolen from a previous post:

* kg lbs-- models-- Source
* 182 400 2.4L E, S, RS 1972-73 Tech. Spec. book
* 183 403 2.4L T 1972-73 Tech. Spec. book
* 200 440 2.7L 1975-1977 Aichle - 911 Engines
* 190 419 78-83 930/09,19,10 78-81 78-81 & 82-83 Tech Spec. book
* 200 441 78-83 930/03-08,13-17 78-81 & 82-83 Tech Spec. book
* 190 462 3.0L 1980-82 Aichle - 911 Engines
* 219 483 84-87 930/20,26 84-87 Tech Spec. book
* 220 485 84-87 930/21,25 84-87 Tech Spec. book
* 219 482 3.2L 1987 - 1988 Aichle - 911 Engines
* 238 524 964 89-94 M64/01,02 ROW &US 964 Tech Spec. book
* 226 497 M64/03 RS 964 Tech Spec. book
* 275 605 M30/69 3.3L 964 Tech Spec. book
* 276 608 M64/50 3.6L 964 Tech Spec. book
* 232 510 M64/05-08 993 Tech Spec. book
* 221 487 M64/20 993RS v-ram w/o ZMS 993 Tech Spec. book
* 230 507 M64/20 993RS v-ram w/ ZMS 993 Tech Spec. book

[RWebb]

Good question - I know the Boxster has a LOT fewer components than the air cooled motors (and uses a light wt. belt instead of a timing chain - which Porsche wanted to do in the 1960s but gave up on).

Let me see if I can find anything. Meanwhile here are some tidbits to feast on, with the place of harvest listed...


3.2L engine has 73bhp specific output compared to only 68 bhp/L for the 3L engine, part of this is the 0.5 higher compression ratio, but the rest is due to the larger ports & freer flowing exhaust system. Frere, p. 83.

1986 – chrome plated valve stems introduced for greater longevity – Frere, p. 84
1987 – Club Sport uses lighter, hollow intake valves – raises the rev limit to 6,700 (from 6,400) but this was already beyond the power peak so no increase in hp – Frere, p. 84

Use of CAE meant the 3.6L M64/01 engine crankshaft was 2.2 kg lighter than its predecessor, despite longer throws – Frere, p. 86

M64/05/06 engine had reinforced crankshaft, increasing its wt. from 14.4 kg to 15.4 kg – Frere, p. 93
torsional vibration damper deleted, saving 732g – Frere, p. 96
piston wt. = 602g (55g savings) – Frere, p. 96
intake valve rocker arms are 15 g lighter than on M64/01 – Frere, p. 96
exhaust valve rocker arms are 21 g lighter than on M64/01 – Frere, p. 96
total engine wt. is 232 kg (6 kg less than M64/01) – Frere, p. 97

[petevb]

Here are some tidbits I've collected, though the source is not totally consistent. Notice the small disagreement between the 964 weights quoted above vs here. Still it's interesting to consider:





The Hartley V8 is a pure race motor in there just for fun. The RSR motors do ~540 hp without restrictpr plates, so if they would be doing ~1.8 if the ~300 lbs quoted weight is correct.

[petevb]

I take it that the lack of recent reference material makes this a tricky question? I've searched high and low for weights on GT3 street or cup motors- no luck at all. Even compression seems impossible to come by on the cup motors? Any specs would be appreciated...

-Pete

[RWebb]

We might want to avoid comparing race motors with street motors.

I'd compare race motors now with those 30 years ago, or same for street but you're getting into an apples and oranges type thing...

[petevb]

Originally Posted by RWebb

We might want to avoid comparing race motors with street motors.

I'd compare race motors now with those 30 years ago, or same for street but you're getting into an apples and oranges type thing...

Good point- it's hard to find the data to make apples to apples comparisons, though.

I'm largely interested from a "what will fit, what does it weigh" point of view for a race or street/ track car.
The 993 motors with ITBs, light flywheels, light exhausts, single pulley, light internals are much lighter than I've listed above. That would be a more worthwhile comparison to a cup motor; I only have rough estimates for those weights, though. So you're point is well taken- I'd be very interested in those weights for air cooled "race" motors too, if anyone has them...

-Pete

[petevb]

I'm still looking for more info on this, but someone did come up with the following data point that I thought I'd share:

A newer cup motor "weighs 435 lbs with oil and headers, but no flywheel, exhaust or water".

Since the weight likely includes the oil tank (attached to the motor, maybe ~5 lbs?) and oil (~15 lbs) but leaves leaves out the light flywheel and exhaust (~35 lbs?) I'm guessing the dry motor weight would be ~450 lbs.

"Dressed motor weight" should include all fluids, ready to run, with headers but no exhaust- probably about 460 lbs? Pull the AC off a 993 motor and fit a light flywheel and it would be slightly more than this, I'd think...

You need to account for all the fluids and radiators to this to get your total package weight: 9 quarts of oil (~15 lbs), 30 quarts of water (60 lbs), radiators and lines (20 lbs?). So the total for everything is probably more like 545 lbs (rough).

A powerful air cooled motor would also need a big oil cooler, lines, lots of oil, etc, but this would still likely weigh slightly less than the water cooled stuff, so I suspect that the air cooled 993 still has an advantage in "total package weight".

Please speak up if this sounds wrong to anyone- I'll keep looking.

-Pete

[Grantsfo]

I did consider weight as a element when I went with the stroked 2.4 S motor in my car.

[petevb]

Originally Posted by Grantsfo

I did consider weight as a element when I went with the stroked 2.4 S motor in my car.

Yes, that would be nice and light.

I'm just talking here, grant... ;-)

FYI, per PMNA, a cup motors weigh 425-450 lbs, depending on the year.
World Challenge motors weigh a little less- no dual plenum intake, and some lighter internal parts.
RSR and especially Daytona Prototype motors are extremely light- carbon intakes instead of aluminum, exotic materials everywhere.

Porsche, however, seems not to like to talk about the weight specs. The PMNA guys try not to be specific- they're giving ranges, not hard numbers.

FYI...