piston options???

[mikey]

I am planning my engine rebuild soon. I am boring my stock 94mm 2 liter cylinders out to 96mm and am wondering about my piston options. I have heard that keith black pistons are great. Do they come in the right size for 96mm jugs??? And what do they cost? Are there any other options that maybe don't cost as much money?

Thanks,
Mike

[Alfred1]

Raby has said that the KBs are great for daily drivers and are better for street use than forged pistons because they rattle less and burn less oil. Piston to skirt clearance should be .002" measured at .500" above the skirt. Also, match the weights of the pistons to within at least 1/2 grams.

Pelican supposedly can get the KBs (I eventually need a set myself) but they're not listed in the online catalog. AC.net has the KB piston and rings listed for $275.

[mikey]

Hmmmm........Would it be cheaper to just to keep the jugs at 94mm, keep the stock pistons, and stroke the crack to 74mm or 78mm??? Or will I need new con rods then??

Mike

[mikey]

oops....I mean crank!!! Heheheheh

[Alfred1]

AC.net lists a good 78mm crank for $480 so that alone is more than the KB pistons and machining of your old cylinders. I don't know but 94 bore x 78 stroke may make a decent combination if you're going to use carbs or aftermarket F/I.

[Jake Raby]

KBs are great.. BUT check each skirt clearance closely, they can vary by a thou and seize..

Out of 200 engines with them I have seized 7 on the dyno.

[mikey]

What other pistons would you recommend Jake? I am kinda doing a "budget" rebuild. Also......what cam and lifters do you recommend after all the failure issues you have seen and been talking about lately?

Thanks,
Mike

[Jake Raby]

always a Web Cam.... But there are no proven lifters out there right now. My lifter fixture should be done over the weekend and the tests begin.

As for pistons, the KBs are the only thing out there that are worth a damn, unless you step up to a JE

[mikey]

Jake......if I were to just re-ring my stock 94mm pistons and hone my jugs, and stroke the crank to 74mm would that be a good combo??
Can you stroke the stock 2 liter crank to 74mm and use stock con rods???

Thanks,
Mike

[Jake Raby]

Yes you can- BUT remember that the stock rod is too short for even a stock stroke when one follows the rule of Ricardo on rod ratio..

The biggest key to unlocking power in the bottom end of the engine is getting rid of that short, heavy rod.

[Alfred1]

Everytime I thought about rebuilding my 2.0 with the 96mm KB pistons I would feel incredibly guilty so I've changed my mind (again) and decided that I'm going to buy the OEM Euro P/Cs and go more for originality than performance. I guess that I'm really a concours weenie at heart.

[mikey]

What rods do you recommend then????

[lmcchesney]

Mikey, get some information regarding KB pistons at this site:
http://kb-silvolite.com/index2.php
Review information regarding dynamic compression ratio vs static. Squishy technology. Their information suggest you can increase your CR while avoiding detonation with street octane. Also, interesting concept of oil injector directed at the undersurface of the piston to lower piston temperatures.
L. McC

[Dave at Pelican Parts]

"Piston squirter". Done in many cars, including the 911 over about 2.2 liters I think. Notching the rods on our engines provides something like a "poor man's piston squirter", in that it splashes a little bit of oil onto the backside of the piston.

--DD

[lmcchesney]

What are the thoughts on the dynamic CR information provided by KB? Does anyone increase their CR based on this?
Dave, could you go into a little more regarding, "notching the rods"? The concept is attractive in that lowering of piston temp would allow for increased CR without detonation.
L. McC

[Dave at Pelican Parts]

http://www.dolphinsci.com/techbull.html

[lmcchesney]

Got it Dave. Kinda like collecting water in your hands to clean the shower door.
L. MCc

[Zeke]

I ran .003 on KB's. Noisy as hell at start up. If you get the KB's, send them over to RIMCO and tell them what clearance you want. Mine came back perfect for what I had asked for. It WAS a track motor. They do need to be balanced. Mine varied 2 grams from lightest to heaviest.

[Jake Raby]

I run .0018 on KBS according to RPM range and application.