Just placed an order on the CP pistons 86.5mm 8.5/1 found them new for $460, got that out of the way. Now need to find a good deal on apexi head gasket

 

ahh.. its always a he said she said thing... this is nothing compared to what I sometimes hear I've supposedly done... I get that a lot these days... Most recently I was working on someone's car that they were going to sell... The customer told me that the whole car / motor / tuning was done by martin... in case I knew anyone interested. (he had no idea who I was.. I had never seen that car before).. I loled at that one pretty good. hit me up on pm if you need some motor assembly help !

martin

 

yeah you were

Crankshaft Balance Factors

Crankshaft Balancing Machines,CWT Industries - Why Balance Engines?
**Scroll to the middle**

Balancing the Rotating Assembly

Crankshaft Balancing Machines,CWT Industries - Why Balance Engines?


Dude i could post facts all day

I guess all these machine shops don't know what there doing.
and spending thousands of dollars on worthless piece of equipment.

Maybe you should tell them

 

Doh, reality ftmfw.

You should have been here for high compression low boost vs. low compression high boost

 

1/8 mile times and self qoutes in sig = cruise control for cool...

you and okinawa guy should hook up, you could take turns putting each others rod and pistons into each others cylinders.

 

while crank balancing can be beneficial for certain applications, it is not necessary for others. period. we all know the benefits of doing it, but it's not needed everytime. not doing it won't self destruct your engine.

i think i'll take the advice of the engineer and the tried and true engine builder. and by that, i mean epstein and martin, whom have been building and tuning engines for a good decade now. it's one thing to have knowledge, but to come to a new forum and claim you are the end all be all of nissan know how is just laughable.

if you look at world famous engine builders, you'll probably notice that some of them differ greatly in even the most "fundamental" techniques (such as crank balancing). both martin and chris are known nationwide for some of their feats in engine output, parts engineering, and successes among nissan (and other) engines. they have both been very active and renowned among the national forum, freshalloy.com. and yes, freshalloy > zilvia.

we respect that you have knowledge, and first hand experience (not matter where you've done these things), but please understand that the tampa area has some very highly regarded tuners and engine builders, especially within the nissan world. calling them kids, and rejecting their advices as stupid will get you no where and will certainly not earn you any respect.


OP - good luck with your SR build. you seem to be on the right track. in the end, it is YOUR ride and YOUR choice on what parts to ultimately pick. my advice has always been to do it right, or do it twice; and to reach a certain point, plan/build for beyond that. always set the ceiling higher than where you want to jump, so you don't accidentally hit it.

 

So you are saying after spending the money on aftermarket Pistons rods and bearings that are different weight from stock (knowing that the crank is balanced for the Stock rods and pistons) you would not balance the crankshaft for the new set up??

I mentioned nothing of myself being A Super Nissan Genius.

I know how ppl get when new ppl come to a forum giving technical advice and seeing little green sq, alot of ppl want proof of accomplishments and knowledge There for I provided a little bit of it, I was mearily showing you all im not some 16 year old kid who just bought an SR already installed into a Chassis and claiming i know everything.

I have countless manhours, days, weeks...ect of building/workin on engines

But I apologize for being disrespectful to those of you that that deserve respect.

Like you said each builder has different techniques and I was taught my way. So my bad for being an asshole.

 

I can appreciate your angle, too. You do things your way, they work, what's to argue?

Here's my side. I just finished brushing up on my engine physics relating to 4cyl inline arrangements (I actually learned some stuff, 3cyl wee!). This configuration is inherently balanced in the 1-3-4-2 order simply due to the fact that 2 pistons are going up while 2 pistons are going down. That is, the same mass of pistons/rods are going in opposite directions at any given time. The counterweight mass of the crank also cancels out as it's symetrical. This assumes that the crank is balanced with itself and each reciprocating mass is equivalent (rods and pistons basically the same weight between assemblies). This is primary balance. There are secondary balance issue to tackle, but without balance shafts (see QR25) there's not a lot you're going to do about it. Counterweight mass does not affect this.

Let me be clear that what I think you're implying is that by balancing the crank to the rods/pistons you mean that we're dramatically changing the inertia of the counterweights to match the lightened components. Stop me if I'm wrong. This is a lot more critical for V motors as you have 2 planes to worry about with the same number of counterweights. Even so, the mass of the counterweights is still a rough formula with the highly scientific "50%" showing up a lot in practice.

I can tell you that in practice, the counterweight mass of a crankshaft does not matter as much in an inline 4cyl given the following, relevant example. The SR20 crank that is used in all Silvia turbo 8.5cr motors is the 12200-60J10 part. This is also the same part used in the 10.0cr non-turbo flat top Silvia motors. And it's used in the FWD 9.5cr motors with lighter rods, and the GTiR motor with heavier rods, and some VE motors with drastically different pistons, and they even kept it the same when switching from the 79E to 54C pistons in Silvias. Nissan is manufacturing these cranks and then balancing them alone. The counterweight mass is not being set by process (QA, finishing), it's set by design. Then take that data and combine it with the fact that Nissan later started placing 4-counter cranks in SR20's and SR16's, thereby halving the countering inertia with largely the same reciprotating mass.

Given all of this theoritical and practical info, I can tell you this about balance in a lightweight, performance build: Ensure that your piston/rod/wristpin/clip/bolt assemblies are significantly similar in mass. We're talking less than 1% here. Then you can do one of two things. Assume that your crank is still balanced as is from the factory (why wouldn't it be?), or send it out to be balanced and verified. Neither of which depends on your reciprocating mass. As you turn more RPMs, any potential imbalance becomes more of an issue. Consider this when dealing with the difference between a P11 6800rpm rebuild and a drag 9500rpm engine.

I hope I'm being factual and practical enough to make my arguement clear. V6 and V8 people, you're on your own. Don't even get me started about the flywheel/pressure plate assembly and the different crank (pulley) dampers.

 

i never get the point of wanting a budget 500 hp car.
why not have a reliable 350ish hp car, that will still be way fast, and not be broken all the time due to cut corners, and cheap parts?

 

Chris said everything I tried to say, and then had a busted internet connection.


I would b emuch more concerned with a reliable cylinder head with proper valvetrain than i would a balanced crankshaft on an SR. The oem 8 counterweighted crank is the best one money can buy.