Viscosity increase for Torque Increase

[Gene K]

Originally Posted By: TiredTrucker
As a example, modern HD diesels laying down 2000 lb of torque are coming factory filled with 10w30.


However bearings are much larger.

 

[Gene K]

Might have to rethink this after monitoring pressures and temperatures.

At 195F oil Temp Im seeing 100 psi @ 4000 rpm with Pennzoil Platinum 10W30.
A quick check of a stock engine showed 80-90 psi on Motorcraft 5W20.

Main bearing clearances per Ford are supposed to be 0.025-0.050 mm (0.001-0.002") and rod bearings 0.027-0.069 mm.

Shift point is 7200 rpm with 7400 rpm limiter.

 

[TiredTrucker]

Originally Posted By: Jetronic
yes, but not ILSAC 10w30. 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


True, I haven't seen ILSAC rating on them, but have seen API SN along with a laundry list of OEM specs that reads like a who's who in engine building..

 

[Gokhan]

Per the fundamental curve of lubrication -- Stribeck curve -- if you want to keep things the same, you want to keep the lubrication parameter nV/P the same, n being the HTHSV, V being the RPM and P being the torque. So, does the torque increase happen at the same RPM, lower RPM, or higher RPM? If it happens at the same RPM, for 40% torque increase, you need 40% HTHSV increase. If it happens at lower RPM, you need even more HTHSV increase. If it happens at higher RPM, you need less HTHSV increase. That way nV/P still stays the same. You will need to know the torque vs. RPM curves for the stock and modified configurations to calculate the needed HTHSV increase accurately.

 

[Shannow]

Originally Posted By: TiredTrucker
Originally Posted By: Jetronic
yes, but not ILSAC 10w30. 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


True, I haven't seen ILSAC rating on them, but have seen API SN along with a laundry list of OEM specs that reads like a who's who in engine building..


An ILSAC 30 has an HTHS of 2.9 to 3.0, the HDMO 30s are 3.5+, just like the old SAE30s.

They are different animals in their entirety.

It's a little bit funny that the industry ran on SAE30, then when they went multigrade went to 15W40 (3.7HTHS min), but now that they are going back to 30s, robust 30s with the same HTHS from whence they came, it's seemingly miraculous.

It's that latter 5W30s, the A3/B4 kind that I'm suggesting for the OP's use.

 

[Excel]

adding more power should not change the requirements of the engines oil to a point...RPM and Heat does imo

Ask the company that makes the power adder what they think,for instance I added a Whipple to my S550 GT and the mfg says stay with 5/20 synth

 

[mjoekingz28]

If eye wear ewe Eyed putt Too galluns of STP oil treatment into her.






Should be thick enuf, whatya say?

 

[Shannow]

Originally Posted By: Excel
adding more power should not change the requirements of the engines oil to a point...RPM and Heat does imo


Making 40% more power at the same RPM means more torque...as per OP's question.

More torque means more force transmitted through the oil film from the con rod to the big end...AT LEAST 40% more.

This squeezes the oil film more, and reduces the minimum oil film thickness commensurately...only way to recover is to increase viscosity.

If the power adder keeps max MEP (Mean effective pressure) the same, but moves it up the rev range, then revs and frictional heat come into play, but is countered somewhat by RPM bolstering film thickness.

Big engines that produce lots more than stock peak torque off idle need more than 2.6 HTHS.

 

[dustyroads]

Originally Posted By: mjoekingz28
If eye wear ewe Eyed putt Too galluns of STP oil treatment into her.


LOL! love the hillbilly talk/ spelling.

On a serious note, in the past I have confessed to using Lucas years ago and when I made a serious increase in power I also increased the Lucas. My N14 Cummins went from 1850 lb-ft to an estimated 2400 lb-ft so I thought I better add more honey.

Back then additive dilution never crossed my mind but the engine was still going strong at around 925K miles when I traded the truck in. I used 1 to 2 gallons Lucas before adding power/torque and jumped to 2.5+ gallons after bumping up power.

I always wondered about this subject of increasing vis with torque but didn't have Shannow to consult with at that time. Thanks for this thread Gene.

 

[Number_35]

Awww, I'm so disappointed ... I misinterpreted the subject line to mean that increasing the viscosity of the oil would lead to an increase in engine torque. Rats!

 

[ryanm8]

I understand the premise, but something doesn't add up here. Take a look at the Hellcat and Corvette Z06 engines. They are essentially the stock engines with a supercharger thrown on and make around 40% more power. Yet, the recommended viscosity doesn't change at all. The Z06 is making 650 ft. lbs. and only requires a 5w30.

Additionally, what if you modify an engine to make say 300% more power? A proper oil wouldn't even exist for that application.

 

[Jetronic]

with 300% more power at the same rpm, the lifespan is better measured in minutes than hours or miles. Unless you change all of the internals.

 

[ryanm8]

Originally Posted By: Jetronic
with 300% more power at the same rpm, the lifespan is better measured in minutes than hours or miles. Unless you change all of the internals.


Not necessarily. The Toyota 2JZ, Nissan RB26DETT, and BMW N54 can get that kind of power increase (or near it) and handle it reliably.

 

[zeng]

Available (additional,say 40%) increased torque from an engine may NOT be equivalent to actual increased torque (of 40%) at the four tires in everyday applications though.

One must have increased load to capitalise on increased torque available from a prime mover.

 

[Jetronic]

Originally Posted By: ryanm8
Originally Posted By: Jetronic
with 300% more power at the same rpm, the lifespan is better measured in minutes than hours or miles. Unless you change all of the internals.


Not necessarily. The Toyota 2JZ, Nissan RB26DETT, and BMW N54 can get that kind of power increase (or near it) and handle it reliably.


A BMW N54 with 1400 bhp and over 1300 lb.ft? All at the same rpm? Somehow I doubt that is reliable...

 

[ryanm8]

Originally Posted By: Jetronic
Originally Posted By: ryanm8
Originally Posted By: Jetronic
with 300% more power at the same rpm, the lifespan is better measured in minutes than hours or miles. Unless you change all of the internals.


Not necessarily. The Toyota 2JZ, Nissan RB26DETT, and BMW N54 can get that kind of power increase (or near it) and handle it reliably.


A BMW N54 with 1400 bhp and over 1300 lb.ft? All at the same rpm? Somehow I doubt that is reliable...


The N54 pushes around 290 lb. ft. stock to the wheels. 3 times that would be 870, not 1300.

Currently they seem perfectly reliable at around 650 ft. lb, and people have ran them at around 800 for a year+ before any issues appear. Usually it is the pistons that will go, not bearings. Of course you will have less reliability with more power, but they don't fail in minutes.

One thing I forgot to mention though that is all the examples I gave will reach that big power with a big single turbo, which will push the torque curve higher in the RPM range.

The N54 does have hybrid twin turbos that can make around 700 ft. lbs though. Those will have an almost identical torque curve to the stock turbos. The N54 calls for a minimum 3.5 cP HTHS. At just 200% more power than that, you would need a 7 cP HTHS which not even a 10w60 provides. And the cars are reliable at that power level with the same torque curve, using a 0w40 or 5w40 oil.

 

[Jetronic]

300% more means 4 times... 100% more means 2 times... and the N54 in the Z4 produces 330 Lbft.

If the torque comes in later, you don't need as big a viscosity increase, and maybe the stock engines have a fair bit of viscosity in excess.

 

[ryanm8]

Originally Posted By: Jetronic
300% more means 4 times... 100% more means 2 times... and the N54 in the Z4 produces 330 Lbft.

If the torque comes in later, you don't need as big a viscosity increase, and maybe the stock engines have a fair bit of viscosity in excess.


OK, I was interpreting your numbers as "percent of."

Regardless of how you word it, my point is that there is more to it than plugging numbers into an equation when an engine can produce 2x the torque (with same curve) on the same oil with no extra bearing wear to show for it.

If you want to look at stock cars, look at the Hellcat and Z06. These days where automakers are trying to squeeze every last MPG out from cars, I don't think they are specifying a lot of excess viscosity in their oil recommendations.

 

[Gene K]

Owners Manual - 5W20 SN GF5
Roush Supercharger - 5W20 SN GF5
Brenspeed - 5W20 SN GF5 Synthetic
VMP Tuning - 5W20 SN GF5 Synthetic

Joe Gibbs Racing - FR20 (Shear Stable, 2.9+ HTHS)

FRPP - 10W30, 5W40, 5W50 (3.5-4.0 HTHS)

Amsoil - 10W30 RD30 (3.6 HTHS) 5,000 mi OCI Limit

Redline - 0W40 (4.0 HTHS)

Seems we have two schools... Clearance and Torque. Apparently compromise is not possible as 3.0-3.4 HTHS is no mans land.

 

[Shannow]

Originally Posted By: ryanm8
I understand the premise, but something doesn't add up here. Take a look at the Hellcat and Corvette Z06 engines. They are essentially the stock engines with a supercharger thrown on and make around 40% more power. Yet, the recommended viscosity doesn't change at all. The Z06 is making 650 ft. lbs. and only requires a 5w30.

Additionally, what if you modify an engine to make say 300% more power? A proper oil wouldn't even exist for that application.


That was a calc on maintaining the same MOFT...simply that.

As the the hellfire, stock on the SRTs is 0W40 (3.8 hths) is it not ?

When the basic engine runs 5W20 ?

You CAN go thinner, the engineers that built the original platforms know what they are doing, and where they are, which I(we) don't know how much margin there is in the first instance.

Next is how often you use ALL of that BMEP...a few squirts down the road, or a few quarters, or a few track days.

The modded Toyotas and BMWs are producing stock power output 90% of their lives on the road...that being said, so is the OP.