BC

We are all watching the sleeved V-8 Carl. All of us. The 944 guys have been having problems with the dry sleeves and some have moved to wqet sleeves. The webbing in the middle area is a question on the 928 that I couldn't answer without actually spending the 3k, and I didn't wish to do that.

Please keep us all informed and go big on the boost.

slate blue

Hi Carl are scales accurate in measuring the outright weight? Mine must be way off if mine (the rods) weigh 850 grams each! Are the early rods lighter than my 944 rods? Does anybody know out there? They certainly look the same, materials can make a difference though.

Carl Fausett

Greg - sorry, my weights are only relative to each other, I have no idea what the real weight was - was not measuring for that. In the picture with the scale, you'll see a big ol' nut hanging by safety wire off the end of the beams - that just brought my scale into range.

I did not bother to weigh my rods to find out what they weighed. As these were the rods that came out of that engine, and they were the rods I had made up my mind I was going to use, I didn't care. I DID care what the weight of the rods were relative to each other.

BrendanC - dry sleeving.... again I did not have this motor dry sleeved - it was like that when I bought it. I do not know who sleeved it. It was unsuccessfuly rebuilt by a friend of mine with a knife edge crank and Pauter rods and a bunch of goodies, and the engine did not last a week fo reasons I beleiv related to the crank and the rods in use. So I bought the block because he was spooked by it and wanted rid of it.

I beleive the block is fine, and had it over-bored .01 for my new psitons. We will know in a month if I was right or not. Who knows?

As to steel sleeving an aluminum block - not much rocket-science there... this is mature technology that is in common use all over the world in all sorts of engines. I do not understand the puzzlement. They have been doing it for years, why do you wonder about whether it will work on the Porsche or not?

BC

The puzzlement is me specifically showing 4 seperate machine shops the 928 blocks and them saying no way. The issues that the 944 guys have had with the dry sleeves leave some questions unanswered.

I've always held your position that its no rocket science. Its not anything special - just an aluminum block.

FBIII

How can you accurately balance the crank if you don't know the actual weights being added to each crank throw ?

MarkRobinson

Balance that clutch too. When I rebuilt my 32v engine, my "new" clutch was off by about 70 pounds counting the intertia generated by the off-balance of the pressure plate. Made a HUGE difference once fixed (as you can imagine)

Carl Fausett

Mark Robinson is right - once the engine is internally balanced, you take your clutch and flywheel and your harmonic dampner in and have them balanced as separate and independant units also.

FBIII - the answer you seek is further up this thread.

Herr-Kuhn

So, now you can turn the screws to that thing....18 lbs, 20 lbs?

slate blue

Thanks for clearing up the weight issue, I used some good scales today. I got exactly what I had been getting on what I thought were the dodgy scales, it was 850 grams, are these rods going to be too heavy for 7250 rpm. It would be occasional use, but I don't know about the strength of the bolts either.

Cheers Greg

UKKid35

Didn't the SE/CS engines have tighter balancing tollerances?

Carl Fausett

Greg Gray - rod selection has so many variables it is over my head. Yes, lighter rods revhigher, faster, but often sacrifice reliability or componant life to do so.

Example: Two racers both want max HP from their motors (they all do). One is a Rolex 24 Hr series racer, one is a quarter-miler. They will not end up using the same rods.

Not quite sure WHY you want 7200 RPM from your 928 engine... unless you have the gearing to work with that, you will likely be beyond your power band at that RPM and should have shifted at 6400 RPM instead and gotten into the next gear.

Building a CAR (think CAR, not MOTOR) that perfroms well at 6500 RPM and down will save you a lot of money and add reliability too boot. IMHO

Rob Roy

Stupid question time - sleeving accomplishes what?

I would think possible allow a larger bore, with a greater choice of pistons (both size and forge vs. cast)?
Does it increase structural rigidity/strength allowing for greater c/r?

Anything else?

Thanks

mark kibort

if you balance your rotating assembly, why whould you need to balance clutch flywheel? if you change the flyweel to be 10lbs ligher, the intertia is 10lbs less on the flywheel, but that wont change the balance or your ability to achieve high rpms safely.
what do you mean your clutch was off 70lbs? I if out of balance, i certainly wouldnt want to match your rotating assembly to a poorly balanced clutch, as when you change it, your engine internals would be off. (or when the clutch is depressed the engine would see different intertias. going a step further, if you "balance" the clutch with the rotating engine internals, why then not the torque tube and the entire rear end!!!

balance the engine and make sure the clutch and flywheel are balanced alone, and you probably are in good shape.

I think im right here, but im not an engine building expert, they may be able to chime in and confirm.

Mk

mark kibort

I think thats a good point. each piston rod and all the nuts, etc, are weighed and then those weights are replaced with slugs attached to the crank and then the crank i spun and balanced . (right?) so, you do need to know the weight of the rods,pistons, wrist pins, clips, etc as they are added to the crank in balancing.

MK

Carl Fausett

Let me say it again a different way than I did above...

I GAVE my engine balancer guy a: He weighed them and determined the flyweight from that.