All wheel drive build - blog introduction

[drunkmunky]

Hey all

My name is Billy and I'm from Ontario, Canada.

I've been prepping my 1995 Nissan Altima for a full all wheel drive conversion utilizing Nissan Attessa and Nissan related components.

My blog is a enthusiasts journey and perspective on building the car and exploring the options available in the market.

Please let me know what you think.
All comments are greatly appreciated, including suggestions on how you think I can make my blog bigger and better.

awdu13 build | All Wheel Drive Turbo Nissan Altima (http://www.awdu13.wordpress.com)

Cheers guys/gals.
- Billy

[TheWolf]

Your article on coatings is fraught with mistakes.

[stinky_180]

all i see are videos of other peoples cars...

[drunkmunky]

http://awdu13.files.wordpress.com/2011/02/picture170.jpg

Brian Crower Fully Counterweighted Crankshaft for the KA24DE

More @ http://awdu13.wordpresshttp://awdu13.wordpress.com (http://awdu13.wordpress.com/)

[drunkmunky]

Your article on coatings is fraught with mistakes.


Please do comment on the mistakes. Your response is very much appreciated.

[TheWolf]

Ok for one. If the BC crank requires bearing modifications to work. It is cut from the manufacturer incorrectly. There are only a few radius's that crankshafts use. By putting full counterweights on them doesn't change this. Someone may try and bamboozle you with talk of torsional harmonics, thrust etc. It's BS. They used the wrong wheel when grinding or they don't have the correct edge cut into the wheel. Grinding cranks is not rocket science. The radius's are there to prevent the crankshaft from breaking. Not for rigidity. There's no Radius that can't be ground due to the counterweights. You're not developing a mission to mars, you're building a KA24. I can take that crank to my local grinder and give him $50 and he can put the radius the correct size and where it needs to be. Again. Not a "feature". More of a "mistake".

But lets say. You got a crank with too big of a radius.(this happens in domestic engines usually when you regrind them to a smaller size or some cranks will run oversized thrust mains, etc) When you goto torque the rod cap down, the radius of the crankshaft will contact the rod bearing and the engine will lock up. To "fix" this you basically take a burr and relief the edge of the rod bearing. Bearings are soft. It won't take long to do. You're clearancing the bearing on the edge. A jig would make a really nice clearance but would be really really overkill. Holding a dremil with a sanding wheel at a 45 angle and knocking the square edge off the bearing would be just as functional but not as nice.

As to the purpose of skirt coatings.
"These anti-friction coatings help reduce the amount of heat generated by your pistons as it navigates up and down your cylinders. The coating itself can be scuffed or scratched off, but the purpose of the coating is to attract your lubricants (engine oil) to sit on the piston skirts for a longer period of time. The reduction of heat also reduces the amount your pistons expand and contract. This will effect the longevity of your piston rings and help maintain the compression values, essentially extending the life of your engine."

Reduction of heat due to skirts. Nope. Scuffed off. Yes. Purpose to attract oil. Nope. (purpose is to fill in about .001" of the piston to wall clearance so on cold starts, you don't have scuffing from rocking until the piston and bores warm up). This coating does nothing for heat transfer out of the piston preventing or aiding expansion of the piston. A skirt coating does nothing for the rings other than preventing the skirt from impacting the cylinder walls while cold. The skirt will then score the cylinder wall causing bad ring seal.

there are basically two custom piston alloys. 4032 and 2618. 4032 is a higher silicon alloy. It's more brittle. Doesn't tolerate nitrous as well as 2618. But. Expands less. You can run this with a tighter tolerance so when cold you don't have the knocking piston sound until they warm up. now when pistons are slaping around in there they are ruining the finish of the bore. Skirt coatings and low expansion alloys allow people to run forged pistons on the street.

2618 pistons expand more. A 2618 piston on a small ka bore could probably run a tight .003-.004" clearance and be fine on a 400hp motor. On domestic engines 600+HP with 4 and 5" bores, it's not uncommon to have a BBC running .006-.007" clearance piston wise on a race motor on a piston that is under 1.5" long. When assembling you can visibly rock them back and fourth. On small bore ka24 motors not as much. Race motors will utilize block heaters and oil heaters to "preheat" the motor so it is inspec before it's started. You'll see all sorts of pre-heaters and pre-oilers for race motors. That is to maintain that peak HP for as long as possible and prevent the scuffing of the pistons into the wall.

As to the WPC coatings. Sounds alot like glass beading but with a finer material. Can't say I'm sold on it. REM Isotropic finishing for gears is a time tested new coating. DLC coating for wrist pins and lifters is also a time tested new coating. I wouldn't rust out just quite yet for the WPC.

[drunkmunky]

Thanks a lot for that input. I will place your reference in the postings.

I went ahead and got the crankshaft knife edged. It took out two birds with one stone. I would have needed to modify the crankshaft girdle to allow the counterweights to fit, and also, i would have lost my oil squirters. The Knife edging resolved these issues, although however some modification to the oil squirters still need to be made.

http://awdu13.files.wordpress.com/2011/02/knife_edge_04.jpg

More @ AWD. U13. Nissan Altima. Turbo. Time Attack. Project Car. | A car enthusiasts blog about his all wheel drive nissan altima project (http://awdu13.wordpress.com)

Cheers
- Billy