Scat's drop in 383 - Simple Build -Simple Budget

[rsicard]

Dusty: Thanks for the answers. Ring width or thickness is one factor but I had not thought about using a scotchpad on the piston rings to remove any irregularities. As you said this should be done to both the bores and the rings. Mahle supplies rings with their pistons, but I am unsure what the face materials are used on the top, middle and Oil Rings. Please expand on the supplier of the titanium nitride coated rings. Thanks again.

[rsicard]

Dusty: In detail, what is the preferred technique to obtain friction numbers of the short block? Please advise. Thanks.

[Dusty]

I just use a torque wrench no technique really just try to get a full revolution without having the wrench click. You'll notice the numbers drop the more you spin it over as the rings break in a bit. If the engine sits a while torque will go up until everything gets oil over it again. Having the real seal in can effect numbers quite a bit so I don't check it with the seal. I don't know if theres a universal standard on how to do this cause I can fudge numbers if I want by breaking the static friction.

[Cammer]

Great to see you use engineering terms in your posts. Petroff would be proud of you!

Perhaps you could elaborate on some of these terms and formulas for GFN members.

Do you remember Sommerfeld numbers? Beauchamp Tower’s experiment? Osborne Reynolds?

[Dusty]

I"M ON SUMMER VACATION DARN IT!!!!....
I might have some numbers already available for that stuff let me dig through the foot high pile from last semester

[Dusty]

I found it I'll get to it in a little while

[Dusty]

Petroffs
F=ηA v/Δy
Where F is the viscous drag, eta is the dynamic viscosity, A is the bearing area, v is the linear velocity, y is the film thickness

viscous hp loss= (F*v)/550 (in English opps excuse me American units)

most likely you will need to convert kinematic viscosity to get your dynamic viscosity. Try to find the centistoke rating of your oil as this is the kinematic viscosity then multiply it by .00001076 then multiply it by the density of the oil in question to get eta

So to reduce hp loss you can run less viscous oil, decrease journal size which decreases the apparent velocity of the two surfaces with respect to each other and decreases bearing area, reduce engine rpm, or increase clearance. Its really easy to test petroffs theory. Get a piece of paper or something like it we used an overhead transparentcy. Pour some oil on a flat surface ie table. Place the paper on top of the oil and spread it out pull the paper out parallel to the table surface. Take note of the force required to do this. Now do it again but squeeze more oil out to reduce the film thickness now you should notice an increase in the force required to pull the paper. Do this once more but pull it as fast as you can now the force should really increase.

[rsicard]

Dusty: DV did an article in Popular Hotrodding magazine of a T&L SBC 383 stroker which yielded 500HP and 500 Ft/Lbs of torque. If I build a 383 with a one-piece rear seal, hydraulic roller camshaft of the same specs, Scat crank, 6" Q-Lite Scat H beam rods and Mahle pistons, what are my chances of replicating the results that David Vizard was able to obtain? Please advise. Thanks.

[Dusty]

pretty good if you get similair rockers, heads, intake and carb

[rsicard]

Dustly:

With the light weight Mahle pistons and Scat Rods, why was the heavy metal added to the Scat crankshaft? Please advise. Thanks.

Originally Posted by Dusty

Ring width is a factor. I saw some neat little 0.5 millimeter rings coated with titanium nitride not to long ago. They had a daytona 500 on them and were going back in a engine looked brand new!! In this engine we spent some time preping the bores with a scotch brite pad and polishing the the faces of the rings. I think that by doing this you present mating surfaces much more realistic to what will be had after break in. In essence its a pre break in process that knocks off surface irregularities. It cuts down the severity of the break in and junk in the oil pan. I've since broken that engine down to cut the pistons reassembled it with a different lube and with the cam installed it cranks over at 19 ft-lbs. There is nothing fancy about the bearings just plain old clevites. I don't think in the end any of this will contribute much to the turning torque when the motor is broken in. What I can say from working with the petroff (did I spell that right?) equations for an idealized bearing there are gains to be had using 283 mains and IRL journal like the cup teams do. It creates less area for viscous drag and cuts temperatures. Probably the most practical thing to do is use a 350 main with a honda journal. A plus is the honda or IRL journal will get you some extra clearance in a stroker motor