I am looking into a mild built motor due to the OC problem with the current motor. I was just wondering what are the chances that built motors can also have catastrophic oil consumption problems? Is the OC chance moderately reduced since the forged internals are stronger? As far as i know the design flaw in these motors is with the piston rings which causes the major OC, so replacing the stock internals with forged internals should prevent this problem from reoccurring correct? Thanks in advance.

 

Oil consumption is primarily caused by ring design and the roundness perfection and crosshatching of cylinder bores. Piston rocking in bores is more of a problem with V6 than V8 or V12/I6.

You can select different ring materials [and pistons materials] and design and lose 3% in peak HP but never use any oil between 90 day changes. Same with Viton valve stem seals where you might only lose 1/2%.

Nascar engines burn 7-8 quarts in 500 miles.

http://courses.washington.edu/engr10...on%20Rings.htm
http://www.riken.co.jp/e/piston/b/b_6.html

This paper will explain rings in detail:
http://www.federal-mogul.com/NR/rdon...S200976080.pdf

 

The materials that Nissan uses for their pistons and rings wears down quick. So replacing those pistons and rings with a material thats stronger should eliminate the problem, correct?

 

No, it is primarily ring force angle changes between accelerating and decelerating, thus the piston ring grooves are involved.
Nissan has very low ring tension against the cylinder wall to reduce friction [increase power] they just went too far in try to squeeze every HP out.

Cutting back on power with more tension [friction] is the easy fix.

 

Would that be solved by replacing the piston rings?

 

Building a short block lets the machinist control all the factors that cause the oil consumption problems in the OEM engine build.

I'm not sure why pistons rocking in the bores would be a quantity-of-cylinders issue. I would think piston rocking would be more of a stroke versus rod length versus wrist pin location versus skirt length issue...

But, Q45tech is a smart guy... I would never bet against him...


-jb

 

The Q45 [90-93] burned almost zero oil between 90 day changes even to 300,000+ miles. It had 561.75 cc per cylinder the 3.5 is only ~~4% larger.

The Q engine were precision built and hand fitted and assembled to a level of accuracy not usually obtainable by any shop in US short of NASCAR or a very few professional shops in US.

Things were balanced statically to < 1/2 gram.

A 60 degree V6 has serious imbalances/wear points that cannot be fixed. Why BMW avoids this configuration.

Study second order vibrations:
http://www.epi-eng.com/piston_engine...on_engines.htm
http://www.epi-eng.com/piston_engine...e_bearings.htm
http://www.nissan-global.com/EN/DOCU...Engine_Eng.pdf

 

I know I'm late but I'd like to ask, if you replaced the pistons and rings with lets say... JE Forged pistons, which come with the stronger rings, wouldn't the higher compression pistons offset the power loss of higher tension rings?
and what are the cons of high compression pistons?

 

Assuming you can custom blend your gasoline you can run any CR you wish.

Modern gasoline is so inferior compared to even 2000 gasoline, the btu per gallon has declined [10>20%] to save costs and oil per gallon it is almost worthless to try to use common station gasoline if power output is the goal.

Manufacturers use custom blends [unavailable to public] to specify power output to standardize dyno test............but the real reason is to increase published power output.

Then people buy E10 and wonder where the power went.

 

how are they allowed to use "custom blend gas" to show power when there is no way we can use it?

its like dyno'ing on race gas or jet fuel and saying "the power is there"