Looking for Idea/advice on build

Because this was supposed to be an indestructible bottom end.....

There are three piston choices for you aside from a stock replacement. Two forged ones, and one Hyper-ucraptic....You can find this out all over the place,.but ..I'm here...what the hell.

2618 alloy Pistons are what I have, they grow in the bore with heat, so the cylinders have to have more clearance to allow for it. They make " that noise" while moving...kind of a rock-rock-rock.... They are heavy, and super strong, but the alloy is more tolerant of heat , and because of that they melt before they break when failure is eminent. But to get to that point it requires a very stupid tuner, and a very stupid driver to really hurt them. Very forgiving should something go wrong...usually the most expensive.
4036 alloy pistons...are everywhere else. JE, Probe,TFS, etc use this alloy because it is more inexpensive to produce. They add more silicone to the alloy, so it won't grow as much, and as a result the piston can be ran tighter in the bore. The benefit to that is it doesn't make " that noise", and the cylinder seals better because the piston isn't rocking all over the place too. It is less tolerant of heat, and will not be as forgiving if your tune is wrong. usually is a much lighter piston than its true forged buddy above.

Keith Black makes a performance Hypereutectic as an alternative. The immediate benefit is cost. They're cheap. They run super tight in the bore, so add even better cylinder seal, and reduced cylinder/piston wear.

But....the ring set grows at a considerably different rate than the piston when exposed to heat. Power makes heat. They give you a ring gap chart that is for the lack of a better description,.....Off the chart. If you are using a power adder, the recommended ring end gap is so freakin huge, I don't see how there is any benefit to it. I used these Junkers in one of my nitrous engines back in the day when I was poor,...and I believe the recommended ring end gap for a 200 hp hit was close to .040". your brain tells you that that can't be right, and you tighten the ring end gap to what makes sense in your head,..you are rewarded with a piston that has no more top ring land, because the ring cut it off the top of the piston. Even when you do everything right, these Pistons break into engine killing chunks when they fail..
The ONLY place I'd put these Pistons in would be a N/A stocker,...otherwise they'd go into the trash.

The Monster will get a 4036 piston next time around....(Well, That is depenant on where the total boost number ends this year)

a91what said:

yeah... I am using a 4032 DSS piston in the 306 but in the previous build that saw 10psi and made 400ftlbs at 2500 rpm i was running hyper pistons.

trust me im not saying that hypers are the right ones to use I am simply looking for alternatives to the stupid expensive options i have narrowed down to now...
corky bell- who literally wrote the book on turbo engines prefers to use hyper pistons

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In the long run,..it's not the piston itself I think...it's what happens when something goes wrong and the piston can't take up the slack..
Let your water meth fail,..have an injector go faulty, crank trigger come loose and move, fuel pump not deliver the right pressure, or a multitude of other small what the hells,...and the soldier that you put into battle is gonna get killed.

The problem with that is....A forged piston fails,..and the failure remains in the one hole. A hyper piston fails and it takes the rest of the engine out with it, because a chunk of piston isn't moving in the same up and down directions any more.

I have been shaking my head for the last year with some of these parts decisions. This stuff gets expensive, I get that and that is why I am not currently building a new motor. I want to wait until I can do it right.

-do not skimp on parts to save a few hundred bucks
-don't skimp on needed machine work
-don't skimp on the necessary measuring and assembly tools

Yes, you could probably get away without it, but as Mike said, you have no insurance plan if something goes bad. Ford used forged slugs in the blown mod motors for OEM reliability, which is the type of reliability I think we all want.

Joe

a91what said:

The content today was mainly to get an opinion, I am currently saving my pennies to buy all things needed for a correct build. I cannot seem to decide if i want to build a budget 357 using a stock crank- football rods- and a forged slug or do a 393 with a 3.85 crank- football rod- forged slug.....

how much power can a stock 351 crank and football rod hold?? should i just wait and buy a full rotating assembly?

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It's the same thing with me. I have stock, forged rods and a cast crank in the Monster. But,....bangers have 7 main saddles to control 6 rods going up and down in the same direction..windsors have 5 mains, holding a crank with 8 throws, traveling at opposing angles...much less disharmony at 6000 rpm.

It's why BMW uses an i6 to this day.

Secondly, a stock rod, properly prepped with aftermarket bolts will withstand a fair amount of compressive load...it just don't like to spin too fast..its the 7500 rpm thing that causes a stock rod to fail..( you ever try holding onto some one pound weight and then spin at 6000 RPM?.. your arm would pull right the puck out of your body)

It's zero balanced,..you're gonna need a balancer and a flywheel to match.

Well there you go then.
But seriously, you gotta pick a path and start walking down it.
If you're gonna put the blower on it again, it will be the equalizer if you choose to keep it at 357 inches.
If you're gonna stroke it, there will be a break point where the extra torque related wheel spin equalizes what you coulda had in a smaller engine,...at a higher boost level.

It'll all come down to what 11 psi does to the tires with a 351 ( smoke), or a 393 ( bonfire).

Scat makes a quality entry level product, in my opinion. I run their 331 9000 kit and have been for about 8 years.

Joe

Turbo or supercharged engines create a piston and ring clearance problem. The headroom from incipient detonation allows a downgrade to higher silica content pistons. Dimensional stability has to be traded off against ring clearance. The rule from the early days of competition endurance Z28 302's (forged piston with nasty piston slap but huge compression deck register)1968-1969 Camaro, 1973 Chev Firenza verses the high silica non forged Mahle 308 GM L34 Holden and F5000 enginess, it was all about going just 4 thou over on ring clearances. For good results, give it detonation head room, and avoid forged pistons. Forged pistons run cooler and reduce detonation. If a soft rev limit is used, you can avoid the grief of having to engineer around the forged piston issues. I really like neutral balance cranks, but don't buy into the forged for everything rules. The 351 W has a main bearing size which is bigger than ideal when you've got a great crank. Id stay with very disciplined bore texture, and and follow a soft 5000 mile run in with tight ring clearances.

a91what said:

So run a hyper or 4032 alloy forged slug, and cast crank.

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I think that's what he meant ... That forged piston slap thing he's talking about ? It's me...

Dude, it's like I've said before...even if you go with the cheaper I beam/cast steel rotating assy...it's gonna be better than the stock stuff, and the stock stuff, ( the right stock stuff, properly prepped) will tolerate power up to block integrity as long as you don't try to be Frankie F1 with the engine.

The Australians studied the Cologne RS2600, and its Mahle hi silica pistons, and Whamo, 7500 rpm XU1 ĢTR 202 Torana 1972, and the axle breaking L34 oil surging but 7000 rpm and 430 hp capable SLR 5000 Torana. GM Holden decided not to upgrade to the Jahns Chevy 194 L6 or 327 Chevy TRW piston, which could have bolted right in. The point is Repco decided doing proper research on proper clearances with unforgiving hard as teak slugs. Its when you fugg up with forged pistons that you think about proper 1000 kilometer race wining engine combinations.

I guess you could always weigh the rods and pistons and remove material on your own. I'd be hella nervous to do that myself. That would mean you'd need one of those pocket scales....you'll look like a drug dealer buying one. Lol

The difference in weight can't be that much. Probably would only take minor adjustments. The crank is supposed to be balanced to whatever counter weight it's supposed to have.

Then again....I know nothing of this stuff. I didn't put my engine together... and never balanced the hundreds I've put together myself. My machine shop did all that.

Just sitting in my car on my lunch break....and wanted to say somethin'

a91what said:

Ok so unless i put my own kit together all the pre-balanced kits come with 2618 forged slugs....

Do i want 2618 pistons in my streetcar?? i dont want cold start noise or excessive wear over the life of the engine.... please advise.

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