Viscosity increase for Torque Increase

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That requires engine component redesign for same relative service life. What does the blower MFG recommend? They have test mules that lived more than a couple WOT passes ... I assume
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My built engines from the 70's and 80s lived, but the 3rd member, axles, bearings, motor mounts, wheel lugs, trans mounts, spicer joints, even the bottom of the oil pan ... didn't

Not having done a blower, and with no other input, I would jump to a 30 grade ACEA with improved HTHS. Maybe similar to a merc engine with blower.
 
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Were the factory bearing clearances altered? If not, there may be little difference before vs. after. For example the 707 HP supercharged Dodge Hellcat uses 0w-40. That's not a whole lot different than the 5w-30 recommended for my 327 hp 1999 Camaro SS. The oil used is probably less a factor than the needed mechanical upgrades to keep other engine and drive train parts from breaking.
 
Originally Posted By: A_Harman
There's no simple answer to that question.


I agree...go thicker, and the oil heats a little more...in design, there's an iterative loop that you have to use until you converge on an answer.

Bearing characteristic number is

(r/c)^2*KV*N/P
r= radius of shaft
c= clearance
N = Revs per second
P = bearing load.

So basically for a non modified bottom end, the first part remains constant, and you are left with
KV*N/P

So for an unmodified bottom end, and assuming the torque peak hasn't moved, the 40% more torque is essentially 40% more MEP.

So the KV100 should move up 40%...now HTHS ISN'T KV at 150, you need to work out the density at 150 and divide HTHS by density to get KV.

BUT...using HTHS as a proxy, and that the bottom end does well on 20s (2.6HTHS min), I'm reckoning that 3.6HTHS is a reasonable target, so A3/B4 xW30, or one of the 0W40s, 5W40s that take your fancy.
 
Originally Posted By: Shannow
Originally Posted By: A_Harman
There's no simple answer to that question.


I agree...go thicker, and the oil heats a little more...in design, there's an iterative loop that you have to use until you converge on an answer.

Bearing characteristic number is

(r/c)^2*KV*N/P
r= radius of shaft
c= clearance
N = Revs per second
P = bearing load.

So basically for a non modified bottom end, the first part remains constant, and you are left with
KV*N/P

So for an unmodified bottom end, and assuming the torque peak hasn't moved, the 40% more torque is essentially 40% more MEP.

So the KV100 should move up 40%...now HTHS ISN'T KV at 150, you need to work out the density at 150 and divide HTHS by density to get KV.

BUT...using HTHS as a proxy, and that the bottom end does well on 20s (2.6HTHS min), I'm reckoning that 3.6HTHS is a reasonable target, so A3/B4 xW30, or one of the 0W40s, 5W40s that take your fancy.


Thanks Shannow. Interesting that its a 1:1 relationship as I really didnt expect that.

Peak torque is up 43% at approximately the same rpm (maybe 100 rpm less) and peak horsepower is up by 60% at 700 rpm higher. Guess I better reconsider my 20% increase in viscosity.
 
Originally Posted By: Gene K
Thanks Shannow. Interesting that its a 1:1 relationship as I really didnt expect that.

Peak torque is up 43% at approximately the same rpm (maybe 100 rpm less) and peak horsepower is up by 60% at 700 rpm higher. Guess I better reconsider my 20% increase in viscosity.


It's not linear, just the first approximation gets you that result. Design is an iterative process, as the thicker oil will generate some amount of additional heat and become slightly thinner as a result.

Here's a bearing design curve...you can see the bearing characterist number that I used on the bottom axis, and the vertical axis is MOFT/clearance.
minf is minimum friction, Max W is the maximum power consumption. L/D is the ratio of bearing length to diameter.
Sommerfeld%20MOFT.jpg


You don'tknow where your engine designer put it ON a curve, so making everything else equal gets you nearly there...good enough to first do no harm.

If you just increased the load (torque), and changed nothing else, you could drop the MOFT by 25%...maybe not an issue, and certainly maybe an issue...thickening up makes sense.
 
Originally Posted By: Shannow
Originally Posted By: A_Harman
There's no simple answer to that question.


I agree...go thicker, and the oil heats a little more...in design, there's an iterative loop that you have to use until you converge on an answer.

Bearing characteristic number is

(r/c)^2*KV*N/P
r= radius of shaft
c= clearance
N = Revs per second
P = bearing load.

So basically for a non modified bottom end, the first part remains constant, and you are left with
KV*N/P

So for an unmodified bottom end, and assuming the torque peak hasn't moved, the 40% more torque is essentially 40% more MEP.

So the KV100 should move up 40%...now HTHS ISN'T KV at 150, you need to work out the density at 150 and divide HTHS by density to get KV.

BUT...using HTHS as a proxy, and that the bottom end does well on 20s (2.6HTHS min), I'm reckoning that 3.6HTHS is a reasonable target, so A3/B4 xW30, or one of the 0W40s, 5W40s that take your fancy.


Shannow how does an A3 oil with HTHS 3.6 but in a 5w-30 grade fit in here.
 
Originally Posted By: FordCapriDriver
Hi err Dr. Haas here i suggest you run Wd40 in your engine as you know thinner is better , can't talk now gotta go pur some of that new 0w16 in my Ferrari see ya


Didn't you heard of the minus10w0? Great [censored] oil.
 
Originally Posted By: virginoil
Shannow how does an A3 oil with HTHS 3.6 but in a 5w-30 grade fit in here.


Choosing between a 3.8 5W40 and a 3.6 5W30, I'd take the 5w30 personally...little bit heavier basestock, and Kinematic closer to high shear viscosity.
 
5W20 or 5W50 (Track Pack)

Allegedly the Track Pack is identical other than the addition of an oil cooler and ECM programming (Higher Oil Temp for Power Derate and possibly different VCT perimeters).

The car in question is a 5W20 car and evidence seems to suggest they do well on it during street and strip use if normally aspirated.
 
yes, but not ILSAC 10w-30. and that's a huge difference. physically much larger engines aswell, with heavier bocks to keep flexing under control, and bigger bearings compared to a PC engine
 
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